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DIY Solar Resources?

kdawson posted more than 6 years ago | from the bright-idea dept.

Earth 311

TihSon writes "I'm building a large shed out back and I want to power the lighting using a surplus solar panel. In searching for information on how to go about this, I have found a lot of rough DIY guides for various projects that are close to my goal. But none seem to explain the reasoning and theory behind using solar panels, so hacking their project to suit my own needs could be pretty much hit-and-miss. I don't want to do a hacked-up job, and future solar projects are not out of the question, so something a bit more in-depth is required. Do you have suggestions for books or Web sites you have used to learn the ins and outs of using solar panels? Something that starts with basic theory and ends with the ability to wire a house would be perfect."

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311 comments

Well? (5, Funny)

Anonymous Coward | more than 6 years ago | (#23889545)

I someone please shed some light on this issue.

Re:Well? (1, Informative)

donguru (595418) | more than 6 years ago | (#23890245)

See http://www.tinaja.com/glib/morenrgf.pdf [tinaja.com] for a tutorial the underlying math. And why today's pv panels are TOTALLY POINTLESS in that they clearly remain net energy sinks. At present, the cost of the synchronous inverter alone will often consume more than 100 percent of the value of the electricity fed through it. Assuming a panel cost of ZERO.

Mod parent up! (1, Informative)

mrbluze (1034940) | more than 6 years ago | (#23890359)

Mod parent up - this comment needs discussion because it's very interesting indeed!

Free energy (0)

Anonymous Coward | more than 6 years ago | (#23889551)

Just hook it up to your neighbor's power cable.

Re:Free energy (0, Offtopic)

rs79 (71822) | more than 6 years ago | (#23889563)

Hook up solar cell to charge controller (so you don't overcharge the battery, they hate that).

Hook up the battery to an inverter (to make 115V AC)

Plug light into inverter.

If the battery or solar cell aren't big enough, you'll know real quick.

Wind and river turbines are a pig to hook up. Solar cels are stupid easy. Just hook up the wires.

Re:Free energy (4, Interesting)

xaxa (988988) | more than 6 years ago | (#23889627)

Hook up the battery to an inverter (to make 115V AC)

Plug light into inverter.

Why not skip this bit, and use a lower-voltage bulb? An LED array might be best, for the very low power needed.

Re:Free energy (1)

rs79 (71822) | more than 6 years ago | (#23889903)

I guess you could do that. But I'm buessing he(she?) already has lights. Chasing
down low voltage lights aint no fun either. Hard to get and not as many options...

I used led's in my solar setup. Now I use a lot of candles instead. LED lighting is damn damn ugly.

I use fluorescents if I need a lot of light.

The odd thing too is, once you stop using electric lights you tend ot go to sleep at night and wake up with the sun and I'm saying this as somebody whose been a night owl, a serious one, for decades. No longer.

While you're at it - light tubes! (4, Interesting)

BLKMGK (34057) | more than 6 years ago | (#23890141)

I have three light tubes aka light pipes in my home. They consist of an acrylic dome on the roof, a mirrored rigid pipe, and a diffuser at the end facing the inside. I often do not need to turn on lights with these suckers - very nice! Some tips - do NOT put them anywhere near a ceiling fan unless you want a disco and do NOT put them in your bedroom lest a full moon have you howling all night - yes moonlight is strong enough to light the room!

Other than that yeah go compact fluorescent or MAYBE LED. I have both and find that the LED is pretty directional and very stark white with a tinge of blue. The CF stuff lasts a good while but be careful not to get the crappy ones that take forever to light up :-( I have one of these and it pisses me off but it fits the fixture, the LED lights I bought wouldn't fit in the "can" fixture.

BTW notice that many holiday lights and tube lights are LED. These actually work pretty good for lighting some areas!

Re:While you're at it - light tubes! (1)

kklein (900361) | more than 6 years ago | (#23890393)

I can't find any CF bulb that doesn't take a long time to light up. I've tried every brand I've seen (major brands--Toshiba, Panasonic--I live in Japan), and the best ones are slow, and the worst are already in the trash (before I knew how toxic they are!). I have decided that, like PC fan noise, my standards are just way higher than other people's (that's not bragging--I'm open to the idea that I may just be a whiny bastard).

And don't even get me started on the color.

Oh, and I have observed exactly NO change in my monthly electricity usage. I think I have to admit that the biggest draw in my house is this Mac Pro with its kilowatt PSU, plus all the vampire appliances I have.

But lightpipes... Now that's sexy. I love natural light. Too bad I live in an apartment.

Re:While you're at it - light tubes! (1)

BLKMGK (34057) | more than 6 years ago | (#23890475)

Well this won't help since you are in Japan but the best ones I've gotten have been from Costco. (lol) The worst from Walmart and they are pushing these HARD. Some hope I've seen on the horizon is a new bulb that has an incandescent bulb in the middle for fast light off and then it goes out as the CF warms up. What you'll do when that inner incandescent fails I dunno'

Light pipes are cool in that unlike skylights you can have the roof some distance away from the diffuser. My roof is a good 8 feet away from my ceilings but the light quality is excellent. You can also route them around a little bit but performance will go down. Some of them use flexible pipes too with aluminized foil but these do NOT transmit nearly the same amount of lumens - but perhaps good for tight spaces. I worried about heat loss through it in Winter but so far it seems fine, both ends are pretty well sealed and I have spray foam insulation sealing it to my ceiling so no drafts that way either. Certainly something worth considering if you ever have a chance to use them!

Re:Free energy (2, Informative)

Bill, Shooter of Bul (629286) | more than 6 years ago | (#23890025)

Even better, just run as much stuff on dc as possible. There are dc Florescent, and led lights you can buy. Its sort of ridiculous creating dc power with the panels, converting it to ac, only to have your light bulb switch it back to dc. Some inverters also have a dc out for this purpose. They also have dc refrigerators and other small appliances as well. I'd give the questioner more advice, but I did my conversion project in a third world country where the electrical code was non existent. So we just did the best we could, following the relevant us codes we knew about.

Re:Free energy (1)

Codifex Maximus (639) | more than 6 years ago | (#23890413)

Bill said:
"Even better, just run as much stuff on dc as possible."

Edison would be proud of you!

Re:Free energy (1)

Bill, Shooter of Bul (629286) | more than 6 years ago | (#23890439)

Yeah Edison would be, but my elephant is even more grateful [wikipedia.org] .

Re:Free energy (3, Informative)

Ken_g6 (775014) | more than 6 years ago | (#23889645)

Since you're doing the lighting from scratch, and you want it exclusively powered by solar, I'd suggest looking at low-voltage DC lighting. DC bypasses the inverter, so it's more efficient for the same type of lighting. It's also probably less likely to kill you/burn down your shed if you make a mistake.

Disclaimer: IANAE - I am not an electrician

Re:Free energy (1)

barakn (641218) | more than 6 years ago | (#23889773)

Heck, you can even get a 12/24 volt DC air conditioner http://www.dcbreeze.com/ [dcbreeze.com] There's plenty of low voltage DC appliances.

Re:Free energy (1)

Yvan256 (722131) | more than 6 years ago | (#23889845)

Given that most of the things we have today are DC, wouldn't it make sense to develop a new electricity plug/standard? Or do we just go with the damn huge "cigarette lighter" connector?

Re:Free energy (1)

peragrin (659227) | more than 6 years ago | (#23889899)

Yes and no. it wouldn't hurt for a standard 12volt DC connector to help keep things going, the problem is in most DC system one of the leads is bonded to the car/boat/plane/train/etc to bring back the current.

Re:Free energy (1)

Ken_g6 (775014) | more than 6 years ago | (#23889969)

Given that most of the things we have today are DC, wouldn't it make sense to develop a new electricity plug/standard?

Or do we just go with the damn huge "cigarette lighter" connector?

No need for a new standard. There appear to be several existing choices [wikipedia.org] .

Re:Free energy (2, Informative)

Anonymous Coward | more than 6 years ago | (#23890011)

And then you need the damn huge cables to go with it. DC current has huge line losses unless you're willing to buy expensive, fine-stranded cable at #4AWG or bigger. That 1500W monster power supply you have sitting in your living room suddenly requires 125 amps of 12V power at full load. That'll melt the insulation right off a standard 14-2 solid copper AC line.

Re:Free energy (4, Informative)

orangesquid (79734) | more than 6 years ago | (#23890301)

DC power transmission over short distances is feasible. Over long distances, it isn't. Look up the Current Wars and AC power distribution. For DC, P=I^2*R=V^2/R. For AC, Prms=Irms^2*Z=Vrms^2/Z. Ignoring phase shift and comparing RMS AC quantities with DC quantities, the equations look the same. The longer the lines, the larger R, so the larger your power lost to heat. DC-DC power conversion is a modern solid-state technology (using charge pumps?) and still tends to be expensive, intolerant of transients (without proper filtering), and limited to small voltages and/or currents. AC-AC power conversion is simple, cheap, and can handle huge currents and voltages. Also, it's much harder to go from DC to AC than the other way around. Until modern solid state, in fact, there was no reliable, efficient way to convert DC to AC in any significant quantity.

If you had a shed and a house on two sides of a large property, and you wanted to put solar panels on one and bring some power to the other (perhaps it is in the shade), inverter + step-up transformer + step-down transformer + AC-to-DC is going to have a noticeable improvement in efficiency over trying to carry DC long distances. If you're generating any serious amount of power, you're also going to need some thick, thick cables to carry lo-volt hi-amp DC around in order to safely dissipate the heat, especially for wires running indoors. Even if you don't care about losses, converting to/from AC is much cheaper than replacing everything in a burned-down house.

Re:Free energy (1)

Codifex Maximus (639) | more than 6 years ago | (#23890469)

Well,

Power = Volts X Amps. AC Power is measured in Root Mean Square approx = 0.707 of total AC amplitude.

So, let's see. Using DC with a 2000W device would be:
A = P/V = 2000 / 12 = 166+ Amps. Doh! As the AC said, Amps tend to melt wires.

BTW, IWAEFAW (I was an electrician for a while.)

Re:Free energy (1)

Yvan256 (722131) | more than 6 years ago | (#23890041)

Replying to myself.... it seems that the USB connector itself is becoming a low-power 5V connector (I remember reading something about this a few weeks ago, about asian cellphones or something).

Re:Free energy (2, Interesting)

BLKMGK (34057) | more than 6 years ago | (#23890169)

Actually this is a pretty big problem! One of the things I have consistently read in magazines like Home Power is that 12volt devices can be a problem with regard to sockets and plugs. Lighter sockets do not carry current very well and are flimsy for one thing. Using standard 120 sockets is simply asking for it because as soon as you turn your back a guest or baby sitter is going to make a mistake. Lots of things have been tried but so far I've seen nothing really good.

I DID just read the other day about some new power standard being adopted by some companies to help get rid of wall warts. You'd have some sort of power strip that could power multiple devices using a standard power and it would completely shut the device down when not being used. I didn't pay much attention to that but perhaps that is a ray of hope? Whatever plugs they use might be useful for this. Best part of it is that hopefully all of those devices will use the SAME power instead of one being 9volts, another 13, yet another 12, and so on. It's crazy to have to have an entire BOX of chargers and wall warts (seriously)...

Re:Free energy (1)

barakn (641218) | more than 6 years ago | (#23889967)

Hang on. I just checked out the price, $2500. This looks like an emerging , unsaturated market.

No, no, no (2, Insightful)

gnuman99 (746007) | more than 6 years ago | (#23889579)

DIY project for wiring your house? Yeah, if you wish to invalidate your insurance and burn down your house. You need to properly wire the stuff. And if you can't figure it out, you can't do it with instructions properly either.

Want to use solar that maximizes your bang for the dollar? Want a DYI project? Invest in some thermal solar cells, you can even make them yourself. Then you can heat your hot water or even heat your house if you have wanter radiant heating (geothermal heatpump augmented with solar cells - saves oodles of cash). And thermal solar panels are 95%+ efficient, not the 20% or something like that for electrical systems.

Re:No, no, no (5, Funny)

ScrewMaster (602015) | more than 6 years ago | (#23889595)

Want a DYI project?

I presume you meant a "Do Yourself In" project, which is what usually happens when people who don't know what they're doing attempt to rewire their homes.

Re:No, no, no (4, Funny)

wellingj (1030460) | more than 6 years ago | (#23890351)

All Americans suck because they attempt to rewire their homes.

Re:No, no, no (2, Insightful)

Anonymous Coward | more than 6 years ago | (#23889661)

Wiring is not hard. Talk of burning your house down is pure hyperbole.

Re:No, no, no (3, Informative)

Anonymous Coward | more than 6 years ago | (#23889819)

There are lots of little things with wiring that can have serious consequences. Where to put the ground? Please not too near a metal anything especially pipe. Why? It'll accelerate corrosion. Possibly greatly. You can screw up your neighborhood's cable this way too.

There are fire risks for improperly installed wiring as well. Or just improper choice of materials. In a house there are other concerns such as fumes given off if cabling ends up in a fire irreguardless of what precipitated it. Builing codes exist for a reason. The 1 in 10 occurances are obvious enough and easily avoided, it's the non-intuitive 1 in 10,000 occurences that take a little foresight. With 100s of thousands at stake for millions of home owners, and the virtual impossibility of knowing all the minutia of one's own particular circumstance, best to go with building code safe as opposed to back of cocktail napkin sorry.

That said: A solar shed is probably pretty straight forward. You know the voltage you want, get battery configuration that will give the amount of stored current you want, and set it up for the voltage you desire, and just run the shed off a properly installed and secured stack of batteries with the solar charging them. They probably have a weekend workshop at a Home Depot or Lowes that would get one at least half way there.

As another person above states that's not the biggest bang for the buck, but it's certainly doable as a little project.

Re:No, no, no (4, Informative)

Fjandr (66656) | more than 6 years ago | (#23890091)

There are lots of little things with wiring that can have serious consequences.

No, there really aren't. There are a few little things and a few big things, and very few of them are arcane. Electrical systems in a typical residence are neither rocket science nor magic. A relatively good primer for residential electrical systems for a typical homeowner would be B&D Complete Guide to Home Wiring [amazon.com] .

Where to put the ground? Please not too near a metal anything especially pipe. Why? It'll accelerate corrosion. Possibly greatly. You can screw up your neighborhood's cable this way too.

Please, please tell me you're not an electrician, nor are studying to become one. Either you WAY oversimplified to the point of making your statement meaningless or you know nothing about the ways galvanic reactions are mitigated in residential wiring. Any text on residential wiring will mention the problems and the very simple ways to avoid them ever becoming an issue.

You're right though, there are fire risks if you don't take any care with your wiring practices. Good wiring practices are amazingly simple to learn. That said, most homeowners I'm aware of who undertake electrical work for themselves do not ever bother to do so.

virtual impossibility of knowing all the minutia of one's own particular circumstance

This statement is a crock. Residential wiring is pretty straightforward for anyone willing to crack any number of simplified wiring books. Solar systems are relatively straightforward as well. I'm honestly not sure why the submitter believes that any number of other project descriptions could not be adapted to a solar shed, unless they plan on tying it into something else at a later date.

However, and it's a big one, solar intertie systems can be enormously complicated. If the submitter is planning on later tying the solar system in a shed to one in a house, said person is going about things bass-ackwards. An intertie needs to be planned from the ground up, or the likelihood of large (and costly) problems shoots through the roof.

Many things need to be answered right from the start. Am I installing a system tied to the power grid? A backup system not tied to the grid? Are there going to be batteries involved? Do I plan to convert to AC, and if so do I need clean sine-wave power? Can my charge controller handle the potential expansion of solar panels? Can additional inverters and/or charge controllers be added to the system without a great deal of hassle should the initially chosen models not handle panel additions? Am I just planning to run dedicated DC lighting circuits? These answers should take into account future plans to expand the system, as picking one particular route and then later making substantial changes to the upgrade path can dramatically increase equipment expenses.

Depending on the complexity of the situation and whether the DIYer actually intends to acquire the knowledge necessary to execute high-quality, functionally correct work, professional help may or may not be necessary.

Re:No, no, no (3, Interesting)

mrbluze (1034940) | more than 6 years ago | (#23889689)

DIY project for wiring your house? Yeah, if you wish to invalidate your insurance and burn down your house.

Nobody is saying you have to do it at AC 110V (or 240V / 220V). AFAIK running 12V or 24V cabling through your house does not require an electrician, and to achieve low resistance you can use T-bars or other large metal structures (or just some automotive copper) for return currents to avoid voltage drops, or alternatively transport the energy via AC/240V (might need professional work for that).

Just have smaller, cheaper inverters at specific locations for the high voltage/AC appliances such as fridges, computers etc.

Re:No, no, no (3, Interesting)

ScrewMaster (602015) | more than 6 years ago | (#23890005)

Low voltage power wiring can be more dangerous than regular 115/220 VAC. If a circuit is shorted the I2R losses will much greater. For example, I have a Hawker 6FV11 12V 105 AH battery that runs my sump pumps. It's capable of dumping tens of thousands of amperes across a dead short: if that ever happened the results would be Biblical. I took a number of precautions when building that system, one of which was to have 200 amp fuses mounted directly to the battery terminals and covered in heat-shrink tubing. Big battery arrays are dangerous, make no mistake. A neophyte is better off getting a book on home wiring and learning how to handle conduit and junction boxes rather than fooling around with a battery bank that's more dangerous than a tank full of gasoline.

Re:No, no, no (1)

mrbluze (1034940) | more than 6 years ago | (#23890151)

Low voltage power wiring can be more dangerous than regular 115/220 VAC.
The return current (black) is usually a single large wire running down the axis of the circuit and is far from the active wires which by and large are thinner. So short circuits are unlikely except at the wall socket. Battery arrays, as is written pretty much everywhere, should be stored away from the building in a separate ventilated and locked enclosure.

Re:No, no, no (1)

ScrewMaster (602015) | more than 6 years ago | (#23890395)

Sure ... but this discussion is about people who install this stuff and don't know what they're doing. My point is that working with a low-voltage system doesn't necessarily make you safer.

Re:No, no, no (1)

mrbluze (1034940) | more than 6 years ago | (#23890411)

My point is that working with a low-voltage system doesn't necessarily make you safer.
Yeah, considering people don't even switch the light off before climbing a metal ladder and replacing the bulb, using the socket to help them balance.

Re:No, no, no (1)

BLKMGK (34057) | more than 6 years ago | (#23890195)

With enough amperage even 12volt wiring can start a fire. Don't think so? Go short the terminals on your car battery sometime...

Re:No, no, no (2, Informative)

Fjandr (66656) | more than 6 years ago | (#23890197)

DC cabling is not going to be adequate to carry residential loads. While you could hack together a cheap system, you'll get the quality that you pay for.

While I honestly couldn't care less if homeowners do so without permits, most jurisdictions do require electrical permits and inspections for installing DC systems. The "burn down your house" is hyperbole, but if you have homeowner's insurance you'll likely need to comply with permitting requirements. In the event of a fire or other damage as a result of wiring, your insurance may not pay even if the work you did played no role in the damage to the structure.

Using small, cheap inverters at point-of-use is going to introduce problems. For one thing, the power produced by cheap inverters is by no means high quality. Most cheap inverters produce modified sine-wave power, which can be problematic for certain appliances (computers, battery chargers, A/V electronics, some electrical appliance motors). You're unlikely to be able to find out whether a particular appliance is affected until after you plug it in. Another problem is that transporting DC at lower voltages means you need conductors larger than a typical AC run would require for the same distance. I'm not sure if you've checked copper prices recently, but it adds up pretty quickly.

For an AC-DC system, the best-practice route would be to install one or more inverters at the location of the mains entrance to the house. This allows for typical residential AC wiring practices to be used, which vastly simplify the situation. It'll save time, money, and headaches in the long run, though the system will initially be a fair bit more expensive. Even an on-the-cheap installation is really anything but cheap.

Re:No, no, no (1)

mrbluze (1034940) | more than 6 years ago | (#23890327)

This allows for typical residential AC wiring practices to be used, which vastly simplify the situation. It'll save time, money, and headaches in the long run, though the system will initially be a fair bit more expensive. Even an on-the-cheap installation is really anything but cheap.
You're right. But we were talking about lighting (not microwave ovens, washing machines and other high-load devices). I don't know what the best solution for things like dish-washers and washing machines is, but smallish solar panel arrays tend to be a bit inadequate for it (and deep cycle batteries don't like being drawn).

Re:No, no, no (1)

Fjandr (66656) | more than 6 years ago | (#23890407)

Well, he talked about starting with lighting. The end point was left pretty open, and he mentions wanting to get resources that culminate with whole-house wiring. Expansion past lighting is what requires planning, and it seems that he is at least interested in the possibility of expansion. That's the only reason I've brought up points of consideration that have very little bearing on wiring for DC-only lighting.

Were DC-only lighting his only goal, his mention of being unable to adapt other published projects to his goal and asking how to do it on Slashdot would put him firmly in my "You don't belong anywhere near an attempt to wire anything, ever" group. I hope that is not the case. :)

Re:No, no, no (1)

mrbluze (1034940) | more than 6 years ago | (#23890433)

I hope that is not the case. :)
No amount of advice and no amount of insulation can stop a determined idiot from short circuiting something. But yeah, we're assuming this guy is not a few short of a dozen.

Re:No, no, no (4, Insightful)

evilviper (135110) | more than 6 years ago | (#23890213)

Nobody is saying you have to do it at AC 110V (or 240V / 220V). AFAIK running 12V or 24V cabling through your house does not require an electrician

The fact that you think low current 120/240v is dangerous, but very high current 12/24V is safe, throughly proves the point that you do NOT understand electricity, and should certainly NOT be giving advice to others.

and to achieve low resistance you can use T-bars or other large metal structures (or just some automotive copper)

With amateur-installed T-Bars, I would fully expect the frame of your house to start slowly roasting itself in short order, if you're lucky, and not using quite enough current, it might not catch fire until the next heavy rain.

Automotive cables are designed to carry the current of ONE small car battery over just a meter or perhaps two. Drawing power from multiple batteries, or over much longer distances, and those cables will be getting very hot. It won't take long for the insulation to melt off, and start cooking adjacent objects.

Re:No, no, no (1)

mrbluze (1034940) | more than 6 years ago | (#23890341)

The fact that you think low current 120/240v is dangerous, but very high current 12/24V is safe

I didn't say either was safe. I just said it does not require an electrician by law (AFAIK - but of course it's as far as I know).

With amateur-installed T-Bars, I would fully expect the frame of your house to start slowly roasting itself in short order, if you're lucky, and not using quite enough current, it might not catch fire until the next heavy rain.

These are for lighting systems not ovens or dish-washers or other things.

Why are you assuming that the designer was so stupid as to design a system that could not cope with the designated load? What are fuses for?

Re:No, no, no (1)

evilviper (135110) | more than 6 years ago | (#23890481)

I didn't say either was safe.

Sure you did... Suggesting you can't burn your house down with 12/24V (as opposed to 120/240V).

I just said it does not require an electrician by law (AFAIK - but of course it's as far as I know).

And for the record, you ARE wrong, BTW.

These are for lighting systems not ovens or dish-washers or other things.

A full-scale home lighting system is going to use vast amounts of electricity. In excess of a single oven, refrigerator, or the like.

Besides, you've already LISTED the large appliances you want to be power from this: "such as fridges, computers etc."

Why are you assuming that the designer was so stupid as to design a system that could not cope with the designated load?

Because it's a DIY project, requested by someone without basic electrical knowledge. And your tips are providing clearly bad advice.

What are fuses for?

Fuses are to prevent an appliance that has malfunctioned from destroying the whole works. They help avoid a fire ONLY in a few specific circumstances, like a sudden short. They will not protect you from a fundamentally under-designed wiring system... They will also not do anything when the person installing them doesn't know how they should be sized.

Re:No, no, no (3, Informative)

Vectronic (1221470) | more than 6 years ago | (#23889713)

But he doesn't seem to want to wire his house... "I'm building a large shed out back and I want to power the lighting..." or even bother with other electrical devices, nevermind water.

I'd have to agree, and other people have mentioned this already, use LED type lighting, this negates stuff like inversion to get 115/220 volts, etc. and requires far less power in the first places, which means less solar panels, less batteries, probably less wiring, and LEDs last longer than incandescent, and provide better lighting than neon.

Re:No, no, no (1)

Fjandr (66656) | more than 6 years ago | (#23890217)

Something that starts with basic theory and ends with the ability to wire a house would be perfect.

RTFS? :)

Re:No, no, no (1)

robertjw (728654) | more than 6 years ago | (#23889813)

Wiring is not rocket science. There is no reason a person cannot get instructions, educate himself and do it properly. No one should just 'figure it out'. Electricians are trained an licensed to do their job - they aren't born with the skill.

In my community, it's perfectly legal for a homeowner to complete work to their house as long as they pull a permit and have the work inspected. If this is an option (check your local laws) it's a good way to make sure you don't burn anything down. The inspector will make sure your work is up to code and won't burn your house down.

Re:No, no, no (1)

I'm just joshin (633449) | more than 6 years ago | (#23889951)

Oh yay, heat from solar. Just what I want here in sunny Arizona on the first day of summer. It is 114F/45C outside today. The water coming into the house is too hot to give the kids a bath. Greater efficiency is nice but when the problem is a lack of light, efficient creation of heat is less than helpful. :)

Yes, Yes, Yes (0)

Anonymous Coward | more than 6 years ago | (#23890117)

The first thing is to keep the solar powered lighting system separate from the regular electricity. Given that it's a shed and TihSon is thinking of going solar, I assume there is no mains power. Solar is a good idea if bringing mains power to the shed is expensive.

The second thing is to use very efficient lighting. The LEDs they use in flashlights are pretty good. This accomplishes a couple of things. I don't have my code book at hand but iirc you want to do class 3 wiring. ie. less than 32 volts and inherently current limited (I forget the current but you should be able to keep it to the tens of ma. anyway.). With class 3, you can pretty much get away with anything because there's no way it can start a fire and therefore there is no insurance problem. The other thing efficiency does is reduce the overall system cost.

So, you need efficient lights, a switch, a solar panel, battery and some kind of regulator to keep the battery from overcharging. Our local car parts supplier has everything because RVs use such systems. I assume yours does too. Make sure your battery is small. A car battery can supply way too much current to be safe if you're not confident of your wiring abilities (current not voltage starts fires).

This isn't rocket science and you shouldn't be afraid of it. Unless you want to spend a lot of time in the shed, the solar panel you want is quite small. You can probably get away with the cheapest thing they have at the aforementioned car parts supplier. My WAG is that, even if you buy everything new, you should be able to do this for less than fifty bucks. (I just googled, they have a 1.8 watt panel for thirty dollars.)

Re:No, no, no (0)

Anonymous Coward | more than 6 years ago | (#23890175)

After you have installed the wiring, you have it inspected.

Re:No, no, no (1)

BLKMGK (34057) | more than 6 years ago | (#23890353)

Good luck finding inspectors that know anything about DC wiring. And yeah, apparently DC wiring has it's own set of tricks that need to be followed that are separate from AC wiring - circuit breakers for instance act differently on DC than AC. Heck in my area two inspectors couldn't even agree on the right way to do something when asked by my contractor! We waited till post inspection to do the work as a result these two inspectors literally had an argument on the best way to solve the problem right in front of my contractor - it was pathetic.

2 words Home Power (5, Informative)

SubComdTaco (1199449) | more than 6 years ago | (#23889597)

Home Power is what you want to look at. http://www.homepower.com/home/ [homepower.com]

Re:2 words Home Power (1)

BLKMGK (34057) | more than 6 years ago | (#23890205)

Amen! This magazine can be found at many good bookstores and subscriptions aren't too bad either. This is an invaluable source of information on ways to save money and power IMO. I do wish they would bring back their guerrilla power features though :-)

Car and Caravan components (1)

MichaelSmith (789609) | more than 6 years ago | (#23889603)

  1. Dashboard solar panel intended to boost a car battery $50 AUD
  2. Car Battery
  3. 12V Light fittings intended for a caravan or similar

Re:Car and Caravan components (1)

jeiler (1106393) | more than 6 years ago | (#23889721)

You forgot "4. Profit!!!"

Seriously, there is one other thing to remember--a skylight. What good is it to run even "green" electricity in the daytime if you have sunlight available for the job?

Re:Car and Caravan components (1)

robertjw (728654) | more than 6 years ago | (#23889837)

  1. Dashboard solar panel intended to boost a car battery $50 AUD
  2. Car Battery
  3. 12V Light fittings intended for a caravan or similar
Interesting. Purchasing a car battery is expensive (both up front and every 3-5 years when you have to replace it), plus environmentally bad. The battery will likely offset any gains to be had from the solar installation itself.

Re:Car and Caravan components (1)

MichaelSmith (789609) | more than 6 years ago | (#23889895)

Interesting. Purchasing a car battery is expensive (both up front and every 3-5 years when you have to replace it), plus environmentally bad. The battery will likely offset any gains to be had from the solar installation itself.
He could use a battery from a car with a dead cell. Lights will still work at 10V. A new battery should last more than five years. A cheap battery where I live is about the same price as the solar cell, and the application is not particularly demanding.

You could always use a gell cell in place of the lead acid battery.

Re:Car and Caravan components (1)

peragrin (659227) | more than 6 years ago | (#23889947)

but it is a requirement in any pure solar system. what happens when you want to turn the lights on at night? a Pure Solar system fails. You need a storage system for it. On the plus side with a steady charge, a small motorcycle battery will last 6-7 years powering a shed's lights.

Batteries are going to be standard in all solar systems, until Ultra Capacitors become a reality. Who ever figures out how to mass build ultra capacitors will be billionaires. Once Ultra Capacitors begin to work. you can use solar and small vertical wind turbines to recharge them and run the bulk of your house off of them.

Re:Car and Caravan components (1)

karnal (22275) | more than 6 years ago | (#23889987)

Is there any other technology battery-wise for a project like this that is feasable?

I have done some basic looking at solar, and everyone seems to use lead acid banks. Similar to what's in UPSs. I can vouch that these batteries usually don't last more than 5 years in my own UPS equipment, and anything after the 5 year mark if they do last, the minute you need them they'll proabably fail.

Re:Car and Caravan components (1)

zach_d (782013) | more than 6 years ago | (#23890039)

If you use good deep-cycle batteries, and maintain them, lead acid batteries will last decades. I've worked on boats with 20 year old batteries that work perfectly well, and have no need to be replaced.

Re:Car and Caravan components (1)

Fjandr (66656) | more than 6 years ago | (#23890255)

Second this. Another option is to look around for telcos who are cycling out their backup deep cycles. Usually done every 5 years, these batteries are typically cheap, durable, and have many years of life left in them.

Mini Hydro (1)

mrbluze (1034940) | more than 6 years ago | (#23890219)

Is there any other technology battery-wise for a project like this that is feasable?

I discussed this exact type of project (in a farm setting) with a civil engineer who did the same thing. He found that using excess energy (also from wind power) by pumping water up an incline was more efficient than batteries. He used two dams at different parts of a hill which worked well. Also shared the power storage with a neighbour since the dams were large enough and this reduced the infrastructure cost.

Re:Car and Caravan components (0)

Anonymous Coward | more than 6 years ago | (#23890057)

A proper deep cycle battery will last longer - and they can be recycled

Re:Car and Caravan components (1)

maxume (22995) | more than 6 years ago | (#23890155)

What environmental cost are you worried about?

These parts, it is illegal to dispose of batteries as waste, they are supposed to be recycled (this doesn't mean that everybody recycles them, but it does mean that it is straightforward to do it).

Re:Car and Caravan components (1)

BLKMGK (34057) | more than 6 years ago | (#23890235)

Properly disposed of and recycled I'd argue that lead cells aren't nearly so bad. Throwing them in the trash on the other hand would NOT be a good idea....

Re:Car and Caravan components (4, Informative)

xaxa (988988) | more than 6 years ago | (#23889949)

  1. Dashboard solar panel intended to boost a car battery $50 AUD
  2. Car Battery
  3. 12V Light fittings intended for a caravan or similar
No, not a car battery. Get a caravan battery (or one with a similar intended use). Car batteries are designed for high current draws for a short period of time, and draining them reduces their lifetime significantly. Caravan batteries are designed to be drained, and to have a low current draw.

Re:Car and Caravan components (1)

BLKMGK (34057) | more than 6 years ago | (#23890223)

Not nearly enough amperage to power anything with these - I know because I have a couple. You might get AN LED or two going but not nearly enough to be happy. You could use these to recharge a couple of 12 volt batteries that would provide you with more amps for more LEDs but I do not think those panels have much in the way of protection from overcharging nor would there be protection from drawing the batteries down too far which will damage them. The panels are really just designed to help keep a charge while the car is being transported or parked for long periods of time - things like the ECU and clock draw some power and these offset that. You can find them from VWs on eBay pretty easily and they aren't expensive - but not ideal either...

DIY? Why? (0)

jamrock (863246) | more than 6 years ago | (#23889631)

Are you absolutely positive that you want to do it yourself? Personally, I'd strongly suggest that you get someone who knows what they're doing.

How did the person that knows learn? (0)

Anonymous Coward | more than 6 years ago | (#23889955)

It's great to say hire someone, but he was asking how to do it. The person that knows how to do it learned somewhere.

Re:DIY? Why? (4, Informative)

FarmerGeoff (237413) | more than 6 years ago | (#23889993)

Why not? I am off-grid with two sets of solar panels (house and well). Did the whole thing mysef with a little help from my friends at Home Power. Not a problem unless you're totally clueless, which, being a Slashdot reader, you're obviously not. Got to homepower.com, buy the CDs.

Re:DIY? Why? (1)

jamrock (863246) | more than 6 years ago | (#23890149)

I was just wondering if the submitter had any DIY experience whatsoever. Slashdot reader or not, intelligence has nothing to do with whether someone is adept at the practical stuff. My brother is one of the most remarkable intellects I have ever encountered, and he's absolutely baffled by a screwdriver. Thanks much for the Home Power info, by the way.

The Otherpower forum (5, Informative)

knarf (34928) | more than 6 years ago | (#23889637)

Try the Otherpower forum. Not just solar but other independent power generation forms as well:

Re:The Otherpower forum (1)

BLKMGK (34057) | more than 6 years ago | (#23890249)

Oh yeah! Great source for strong magnets too! Those guys do some really cool stuff but sadly I'm not located where I can do any of it myself. Their waterwheels in particular interest me since that's pretty steady power. Look into the Indian and other knockoff slow speed diesels for some really cool reading. They can be run on bio too but sadly it looks like importing them is no longer so easy due to recent emission constraints :-( One of those in the garage would ROCK for power outages!

Re:The Otherpower forum (1)

noidentity (188756) | more than 6 years ago | (#23890425)

Try the Otherpower forum. Not just solar but other independent power generation forms as well:

What about perpetual motion? That's the most promising!

Step one..... (0)

Anonymous Coward | more than 6 years ago | (#23889651)

expose panel to sunlight.

Step two press tonuge against panel's contacts.

Step three do not repeat step two.

Simple, in theory (1)

SEWilco (27983) | more than 6 years ago | (#23889659)

Do-it-yourself solar is pretty simple, in theory. In practice, it's not easy to gather enough hydrogen in an empty area of space. Darned stuff keeps spreading out whenever you turn your back to get another batch.

Doing it the wrong way (1)

MichaelSmith (789609) | more than 6 years ago | (#23889925)

It was easy enough in Utah.

Re:Simple, in theory (1)

spazdor (902907) | more than 6 years ago | (#23890291)

Cool it down. The gas coalesces better when there's no Brownian motion to fling it everywhere.

Solar is hit and miss ... (2, Insightful)

jxliv7 (512531) | more than 6 years ago | (#23889665)

... you've got clouds and rain and much less than 12 hours of sunshine available on any given day year round.
 
Check out the wind instead. Generators can produce power in very low winds if you've got the right windmill (the ones that look like upright cylinders seem best, not the big blades).
 
Don't limit yourself to 110v, think about 12v and 24v DC lighting systems and battery storage and you'll be amazed at the inexpensive, 24/7, energy producing capabilities of the wind.
 
I'd toss a few links out except that you'll have more fun exploring on your own - you'll find exactly what you need the more you look around.

Re:Solar is hit and miss ... (2, Informative)

MichaelSmith (789609) | more than 6 years ago | (#23889941)

... you've got clouds and rain and much less than 12 hours of sunshine available on any given day year round.

It depends on where you are.

At the Equator: solar

At the Poles: wind

In between: combination of the two

Re:Solar is hit and miss ... (2, Informative)

BLKMGK (34057) | more than 6 years ago | (#23890293)

Sorry but axial generators are NOT an ideal solution at all - very inefficient. You will also find that your neighbors may not like you putting up a tower that sits so high above the surrounding trees - as it must in order to get clean air and be free of debris. On top of that the cost of the crane required to loft many of these is expensive. Add to that the fact that not *many* areas get enough wind to be useful and you'll find that wind isn't too great - especially for just a shed!

This isn't the best chart but perhaps this will help http://www.awea.org/faq/usresource.html [awea.org]

P.S. Wind isn't 24X7 in many places either. I have a wind gauge on my roof on top of a pole and can go for hours with ZERO wind, I go DAYS without useful winds for power generation too.

DIY hack = take apart consumer stuff. (4, Interesting)

Original Replica (908688) | more than 6 years ago | (#23889673)

I know a bit about solar from the perspective of a cruising sailboat, in that scenario you would take a 12V solar panel, some deep cycle 12v batteries (car battery would work) and a charge controller, connect solar panel thru the charge controller to the batteries and you are done. Everything on a boat is 12VDC lights, radio, etc so running straight from battery power is easy. You could get a inverter for regular 120VAC, but it consumes your battery charge fairly quickly. For learning the parts and functions on the cheap (solar stuff can be expensive) I would suggest taking apart a solar sidewalk light [aquasuperstore.com] and extending the wires to put the light inside your shed, and the little solar panel on the roof. To make good use of a larger solar panel you will need a larger battery bank, and probably a better charge controller. What is the output of the solar panel you want to use?

Re:DIY hack = take apart consumer stuff. (0)

Anonymous Coward | more than 6 years ago | (#23889939)

Stick to 12v. Several reasons, first - you only want lights and 12 is enough.
Second, 12v electrics are legal to work on and safe.
Finally - efficiency.

As a few others have said, LED's will be the way to go and you won't need a large battery.

Rather than lighting the whole area well, accept "O.K. illumination" generally, and make up some good movable spotlights.

Finally - use a transparent panel in the roof !.

Re:DIY hack = take apart consumer stuff. (2, Interesting)

cptdondo (59460) | more than 6 years ago | (#23890309)

Look at RV sources as well; same stuff as marine, but 1/10 the price.

One major caveat: a car battery will *not* work for this. A car battery is designed to provide very high current for a limited length of time, the exact opposite of a solar system need. A car battery will fail quickly in this application.

You want deep cycle batteries; google for trojan batteries.

homepower.com (-1, Redundant)

Ritz_Just_Ritz (883997) | more than 6 years ago | (#23889679)

This is a great site (you can also subscribe to their paper magazine) for the DIY types that want to use alternative methods to power their homes.

http://www.homepower.com/ [homepower.com]

Cheers,

What scale? (1)

rthille (8526) | more than 6 years ago | (#23889703)


Do you need 120VAC, or can you go with low-voltage? Going with low-voltage, driving LED lights directly from the battery will probably help with efficiency over incandescent driven by an inverter, but I'm not sure about direct-drive of LEDs vs inverter-driven CFLs. For 120VAC, you may have to hire an electrician to comply with local laws. Either way, you'll need a charge controller to properly manage the current flowing from the panel(s) into the battery and to the lights.

The Solar Living Institute (a couple of hours north of me here, 3 north of SF) have lots of resources: http://www.solarliving.org/ [solarliving.org]

non-grid-tied?; requirements? (1)

bcrowell (177657) | more than 6 years ago | (#23889761)

For your shed, presumably the reason you're thinking of solar is because you don't have AC wiring going out to it, which means you're talking about a non-grid-tied system. This raises some issues. (1) Running wiring from your house out to the shed is probably much cheaper and easier than doing solar and getting 110 V AC just in the shed. (2) A non-grid-tied system is actually a more complex, expensive, and and difficult project than a grid-tied system. You'd need a battery and a charging system. The battery is big, needs maintenance, doesn't have a long design lifetime, and can be dangerous as hell if you screw up.

You also don't state your requirements. How much power do you need? Do you need AC, or can you get by with DC? DC is safer, and also doesn't require an inverter. Getting rid of the inverter means your efficiency is higher, and it also cuts the cost of the system. A classic application for DC solar is a pool pump. Pool pumps use DC motors, so it's wasteful to use an inverter to convert to AC, and then rectify it back to DC for the pump again. I would imagine that if all you want is lighting, you can probably do 12 V DC without an inverter.

Save yourself the trouble (1)

iminplaya (723125) | more than 6 years ago | (#23889781)

Cut a big hole in the roof and put in a sky light.

Re:Save yourself the trouble (1)

themushroom (197365) | more than 6 years ago | (#23889867)

...which works wonders after 6pm. Try again.

Re:Save yourself the trouble (1)

maxume (22995) | more than 6 years ago | (#23890191)

Obviously you just add a hole in the floor to let the light in from China.

Step #1: $pend money.... (5, Insightful)

Slugster (635830) | more than 6 years ago | (#23889853)

Generally speaking, if you already have on-site utility power, that's going to be cheaper over the long run than solar cells.

But say you just want to do it 'cause it's nifty? One web forum is
http://www.solarpowerforum.net/forumVB/ [solarpowerforum.net]

You can set up a solar panel to charge a car battery, and run small things off that. Basically it goes like this: solar panel->battery regulator->battery->invertor-> small-wattage wall current appliance. Alternately, you can use 12-volt RV lights that can be run straight off the battery; there's LED lights now that don't draw squat for power. The battery regulator is a necessary device that prevents the batteries from overcharging.

...About that "wiring a house" business... There's not a lot of people out there who have solar+battery storage systems to run all the junk in their houses, 24 hours a day. Most of the residential systems (in the US) use solar panels with no storage batteries, the solar panels instead feed back into the electrical grid, which gets you credit off your electricity usage but usually not your total electricity bill (you still have to pay the line maintenance charge and the natural gas charge, if it exists).

The only states where these are common is southern California and Arizona, with Nevada and New Mexico being two more possible candidates. It takes a lot of sun before solar panels are even financially worth considering. Also,,, Cali and Arizona have the biggest gov't rebate programs--and if it weren't for that, NOBODY there would have a solar setup. For what they cost, it simply wouldn't make sense.

Because solar systems are so expensive, most people who want a whole-house system start by building a house that is as energy-efficient as practically possible.... So you see, there's no way to do this cheaply. Either you spend a lot of money to build a new house, or you spend a lot of money on the greater amount of solar panels to run a "typical" house off of.

...And even having done that, solar cells are generally not considered "cheaper" than utility power, even over the long-term. It will cost very close to what 30 years of utility bills would have totaled. What you get with a whole-house setup is--you're basically paying your 30 years of utility bills "up front", and you aren't dependent upon the utility company's reliability.

In certain circumstances, a solar+battery setup can be cheaper than utility power. If you buy very remote property that is literally miles from the nearest power line, the fee that the power company may charge to extend the line to your property can run into the tens of thousands of dollars.
In this rare instance, it can be cheaper to go solar.

------

When I eventually move to the desert, I'd like to play with using some solar panels to run an air-cooling setup. Using solar power to run air conditioning in the desert just makes sense, and I don't know what else I'd run every day. Will probably try Peltiers first; I know their poor efficiency but the mechanical and electrical simplicity makes them attractive for a stand-alone setup, and easy to try on a small scale. In particular--they can be run basically straight off a battery, and need no invertor. The 3-phase invertor and the amount of solar panels you'd need to run a good-sized room air conditioner would cost six or seven thousand dollars, at least.
~

Re:Step #1: $pend money.... (1)

asackett (161377) | more than 6 years ago | (#23890445)

"Using solar power to run air conditioning in the desert just makes sense..." is at least somewhat debatable. Be that as it may, you might want to at least think about ditching the air conditioner for a swamp cooler.

garden lights (1)

El Puerco Loco (31491) | more than 6 years ago | (#23889981)

just steal a bunch of those ugly little garden lights. i'm sure that with those, a roll of duct tape and some speaker wire, you could figure a way to rig something up.

Why *IS* this so hard? (2, Funny)

f2x (1168695) | more than 6 years ago | (#23890087)

Seeing this question and various responses makes me sad. I've seen this song and dance repeated time after time. Don't forget to queue the people who keep trying to cram a kitchen sink into everything. ("Why not use wind?", "Better leave this to the professionals!", "It's as easy as 1, 2, ...1536. Profit!")

Photovoltaic technology has been around for decades, and yet manufacturing a simple solar cell to trickle out a couple of watts is regarded as black magic, wrapped in ignorance, surrounded by controversy. It always begins with the assumption that you just "happen" to get hands on photovoltaic panels.

"Surplus solar panel"? Obviously these mystical artifacts either grow on trees or have to be pumped out of shale, because no one seems to know how to make them from scratch. In any event, think of it like an array of conventional self-charging batteries that only works in daylight.

Next, you'll want to take what energy you can get out of it and store it into something that has a more reliable on-demand containment... Let's call it a battery! It must be new technology because Chevron owns the patent on all of them and thus prevents us from freely whizzing around in electric cars. Oh, and disposing of them when they expire requires an act of congress to transport them to a cave inside of Yucca mountain.

The charge controller can almost be ignored. They just pop out of the ground when you need one. This gets placed between the solar panel and the battery. Pick up the wireless version if possible to keep things simple.

Finally, you'll want to go out and buy a bunch of proprietary light fixtures that are manufactured by an obscure gnome in the land of "Walmartia". In the event that one of the fixtures ever goes bad, you must then go to "Lowesia" to find a whole new set of proprietary fixtures since the "Walmartian" gnomes only live for about a year.

Good luck with your project, and be sure to purchase futures in petroleum based technologies. That bubble won't burst without your support!

There is a very good Yahoo Group (1)

Aging_Newbie (16932) | more than 6 years ago | (#23890103)

12VDC_Power [yahoo.com] is a very good Yahoo group that covers solar power and off-grid living based on 12 volt electrical systems, which are among the best alternatives for solar using current technologies.

Here's a solution for $69.99 (1)

rharkins (307487) | more than 6 years ago | (#23890113)

This is a solar security light with motion sensor. The solar panel is attached to the light/battery/motion sensor by 4 meters of wire. Put the panel on the roof of the shed. Put the security light inside. Whenever it senses motion, it will turn the light on for a few minutes. When you leave, it turns off. No switch, no wiring, no problems.

http://solarilluminations.com/acatalog/Security_Lighting.html [solarilluminations.com]

This one uses a 10W halogen bulb, so it isn't very efficient. I'm sure there are others that use LEDs, or perhaps you could convert this yourself.

Hold on... (1)

epp_b (944299) | more than 6 years ago | (#23890131)

So, your goal is to get light from solar energy...

May I suggest a window? ;)

Re:Hold on... (1)

Teriblows (1138203) | more than 6 years ago | (#23890247)

lol yea that or a light tube/skylight. most other solar is just hobbiest stuff. impractical/costly

DIY Solar Resources? (1)

Codifex Maximus (639) | more than 6 years ago | (#23890369)

Try using a skylight. i.e. a hole or plexi-glass covered hole in the ceiling. Then, cover the rest of the shed's roof with solar panels to generate DC for charging 12V deep cycle lead acid batteries. Then use 12V droplight at night.

12 volt, but.... (1)

CBob (722532) | more than 6 years ago | (#23890447)

12 volt DC is the easiest for lighting w/o a doubt. The hard part is finding "affordable" panels of decent quality. There used to be a large number of surplus panels, but those days are long gone. Cheating & going for the obvious http://www.google.com/search?hl=en&q=DIY+Solar&btnG=Google+Search [google.com] The 12 volt airco price is scary, an inverter setup for 115 would be cheaper. As long as you're not connecting to mains, it's a simple TabA-SlotB type of setup. If you're even thinking of going to connecting it up to commercial power, get a certified electrician who knows PV systems. Your local utility will usually REQUIRE you do that if you're going to touch their system & run PV.
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