Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Hobbyist Renewable Energy?

ScuttleMonkey posted more than 6 years ago | from the green-to-go-green dept.

Power 607

vossman77 writes "I was looking into renewable energy from a hobbyist perspective, maybe generating a few watts of solar or wind power, just to reduce my electric bill. But upon further review, I found out that I need a special grid-tied AC inverter that shuts off when the grid turns off (for worker safety reasons) and makes the current in-phase with the grid. These two additional features, over the cheap inverters sold at department store, make the cost upwards of $2000, but support more watts than I need. While this is fine for large-scale projects, it is out of range for a small scale hobbyist. A Google search came with some home-brew hacks at best. So, are there any Slashdotters out there doing small-scale renewable energy projects with grid-tied systems? What are other options for the hobbyist to play around with renewable energy, other than charging a cell phone?"

Sorry! There are no comments related to the filter you selected.

Renewable energy comer in many forms (5, Funny)

Anonymous Coward | more than 6 years ago | (#23276818)

What are other options for the hobbyist to play around with renewable energy, other than charging a cell phone?

Breed Whales, burn the oil.

Re:Renewable energy comer in many forms (2, Funny)

bigdadro (452037) | more than 6 years ago | (#23276854)

Curse you anonymous coward! You made me snarf diet pepsi all over my keyboard!

Use a 'fan center' to isolate when grid power down (4, Informative)

mollog (841386) | more than 6 years ago | (#23277404)

Off the top of my head, a $100 fan center could shut the power connection when the feed from the power company goes down. Attach a 24V AC transformer to the power company line and wire it to the fan center's controller. Power goes down, circuit opens.

I can probably fabricate a circuit with an oscillator that syncs up to the 60Hz of power. After that, it's a matter of how to convert from DC to AC. It doesn't seem hard to me.

Re:Renewable energy comer in many forms (3, Funny)

MozeeToby (1163751) | more than 6 years ago | (#23277116)

Oh sure, that works for you people on the coast but what about the rest of us? That's why we should be focussing on cow-whale hybrids [] that can live on land and still provide us with delicious whale meat and oil.

Re:Renewable energy comer in many forms (-1, Troll)

kilgor (461669) | more than 6 years ago | (#23277170)

Power some grow-bulbs and become a marijuana producer until you have enough cash to buy a decent grid tie AC inverter.

Alternatively you could kidnap some dirty hobos, buy some alligator clips and a torture manual, and begin another more useful hobby.

Re:Renewable energy comer in many forms (1)

SlashSnot (647926) | more than 6 years ago | (#23277350)

I like breaded whales. Fried in oil.

Renewable fuel (2, Insightful)

somersault (912633) | more than 6 years ago | (#23276832)

What are other options for the hobbyist to play around with renewable energy, other than charging a cell phone?
Well, you could grow your own crops for eating, or for bio-fuel? ;) Or have a separate circuit for your renewable power source so that it isn't connected to the mains..

Re:Renewable fuel (1)

magarity (164372) | more than 6 years ago | (#23276866)

Yes indeed; further, it seems the trick is to first identify what is to be powered by this project since some whole-system project is off the table. If not a cell phone, then what? Without answering that first this seems like a search for a solution in search of a problem.

Re:Renewable fuel (2, Interesting)

tha_mink (518151) | more than 6 years ago | (#23277208)

Yes indeed; further, it seems the trick is to first identify what is to be powered by this project since some whole-system project is off the table. If not a cell phone, then what? Without answering that first this seems like a search for a solution in search of a problem.
I think, by reading the original post, that the poster would like to leverage renewable energy to power his home. Or at least supplement the power provided to him by his local power company. I'm very interested in doing the same but in my investigation, it's going to cost upwards of $30,000 to do any serious power generation. In the summertime, I get ~$450 power bills which I'd love to offset using solar power since I've got tons of exposure at my house. The problem is, the costs before installation are prohibitive. Let's assume I can completely power my home with solar energy at a cost of $30,000, it'd take like 6-10 years for me to make back the costs of rolling it out unless I move, at which point I think I'd get the $30,000 back in the sale price of my home. ( Somehow home prices in my neighborhood seem to be insulated from the housing dip )

Anyways, I have nothing to offer the poster but I'm sure interested to see if anyone else does.

Re:Renewable fuel (5, Informative)

rs79 (71822) | more than 6 years ago | (#23277330)

Your problem is you use too much power. I had the same problem and just unplugged or rplaced everything that was overconsumptive. 700W desktop tower goes away in favouir of 45W laptop. Cordless drill that takes hours to recharge is replaced by a fast charginbh lithium ionh one. etc.

I cut my power to 1/4 doing this. THEN went solar. Your 30K cost is now 7K.

The OP doesbn't need a grid tie invertor. That's for selling excess power back to the power company.

I run a sat receiver by having it plugged into a ups with a ubiquitous 7Ah SLA battery, fully charged, with two 30W solar panels hooked up directly to the battery. It just sits there and works.

I have lots of solar panels, i just hook them up in lotrs of little autonomous systems than do one thing. Free, and forver (or until some part beaks or the sun stop shining).

I've got a bunch of these setups for various things with various batteries and inverters.

I can't for the life of my see how "small scale" and "grid tie" relate at all.

If you had an 18Kw hydro plant I could see it but...

Re:Renewable fuel (1, Insightful)

Anonymous Coward | more than 6 years ago | (#23277342)

How about a solar hot water heater they are cheap and the payback is fast.

Re:Renewable fuel (4, Insightful)

element-o.p. (939033) | more than 6 years ago | (#23277368)

That's kind of what the "hobbyist" label implies :)

For a lot of hobbyists, the plan goes something like this:
  1. 1) I'd like to learn something new, like how to generate electricity from renewable sources.
  2. 2) Where can I apply this technology in a useful, but small-scale, experimental, non-critical way?
  3. 3) Search for a problem that can be solved by this solution.
  4. 4) ?
  5. 5) profit!!! (sorry, couldn't resist)

use an induction motor (1, Informative)

Anonymous Coward | more than 6 years ago | (#23276842)

use an induction motor as used in commercial windmills

Induction motors can be used as generators
and they automatically shut down when grid is down.

go 12 volt (5, Insightful)

Jailbrekr (73837) | more than 6 years ago | (#23276852)

You can try converting parts of your house to 12 or 24 volt, which would negate the need for expensive inverters and whatnot. All you'd need is a simple charging circuit for a battery (could be as simple as a diode) and then feed the 12/24 volt lights straight off it.

Re:go 12 volt (0)

Anonymous Coward | more than 6 years ago | (#23276992)

I really like this idea -- wiring the house, or at least certain positions in it, with low-voltage DC. This could be in addition to existing AC wiring, and you could incrementally switch over. Is there such a thing as an ATX power supply that takes 12V DC as an input?

Re:go 12 volt (3, Informative)

MoOsEb0y (2177) | more than 6 years ago | (#23277100)

Yes. []

Re:go 12 volt (1)

mweather (1089505) | more than 6 years ago | (#23277010)

I have a feeling the electrician and new appliances will cost over $2000. Good advice for those doing larger conversions, though. If not from a cost perspective, from a power loss perspective.

Re:go 12 volt (2, Insightful)

Jailbrekr (73837) | more than 6 years ago | (#23277074)

Low voltage requires no permits or city inspections when the work is done, hence why you can string networking cable in your home without requiring a city permit or inspector.

Re:go 12 volt (1)

denis-The-menace (471988) | more than 6 years ago | (#23277014)

With LED lighting becoming all the rage, when are going to get a DC wiring standard for lighting in regular homes?

All LEDs need DC, AFAIK.

Re:go 12 volt (2, Informative)

TypoNAM (695420) | more than 6 years ago | (#23277190)

LEDs will work perfectly fine with AC, but they'll blink/flicker at the 60Hz or so of the alternating frequency (because LEDs are diodes, as in they only allow current to flow in one direction). Now if you hook up LEDs in a series make sure that the cathods ends connect to the non-cathods ends which I hope nobody is actually doing a series of LEDs instead of parallel because if you have say three LEDs and they consume 3 volts each, you'll need 9 volts to power them to get full light output.

Re:go 12 volt (1)

element-o.p. (939033) | more than 6 years ago | (#23277416)

...and because if one LED or the wire between two LEDs becomes damaged, the entire string of lights will go out.

Re:go 12 volt (1)

Gat0r30y (957941) | more than 6 years ago | (#23277384)

Well, you could put AC over a light emitting diode, but it would flash at 60 Hz - which is a little nauseating to look at.

Re:go 12 volt Naw -48 vDC (0)

Anonymous Coward | more than 6 years ago | (#23277068)

Nope. Go to -48VDC - just like the phone company.

(Still looking for copies of the old bellcore engineering documents on the 48VDC systems.)

Re:go 12 volt (1)

EXMSFT (935404) | more than 6 years ago | (#23277122)

I've thought about that... how come more people aren't thinking about it?

Re:go 12 volt (5, Informative)

Technician (215283) | more than 6 years ago | (#23277250)

You can try converting parts of your house to 12 or 24 volt, which would negate the need for expensive inverters and whatnot. All you'd need is a simple charging circuit for a battery (could be as simple as a diode) and then feed the 12/24 volt lights straight off it.

This is a common mistake and is only good for very low power stuff. In picking a wire size people often think going from 120 volts to 12 volts only involves the math of supplying a wire 10X larger to handle the current without overheating. In a 120 volt application, you are permitted a 5% voltage drop. This isn't much as 5% of 120 volts is only about 6 volts. No big deal when running a 1200 watt portable hair dryer. If you simply size the wire to now do the same thing on 12 volts, you no longer have a 5% voltage drop. At the same current you still have a 6 volt drop with the 10X larger wire but you now lost 50% of your power in the wire. Take a hint from the pro.. Use an inverter. The 10% the inverter lost is made up by the 45% not lost in the wire. Do the math. Engineer the project.

Either your high draw items (Microwave, toaster, blender, etc) are either within 20 inches of the battery, or you will want an inverter. With an inverter you can use standard appliances. Look for energy effecient ones.

Another item is to ditch the grid tie for small systems. It goes down with the grid providing no security. Put the critical load on an Outback inverter. It was made just for this application. Small solar, battery maitenance, load transfer to and from solar and battery, etc. You don't have a surplus to sell to the utility, so don't connect that way. Use it to supplimant your load and reduce your total load. As a bonus, you don't have to enter a grid tie agreement with the utility where they buy your power whosale and sell it back to you retail.

Find Outback stuff here; []

Disclaimer, I just use it. I am not otherwise involved with this company. The company has grid-tie stuff if you decide you really want it. I don't recommend it except for larger installations. This company has done a great job meeting the market. Their grid tie units are the first that I know of that operate instead of shutting down in the event of a blackout. They solved the number 1 problem with grid tie stuff.. blackouts. []

Go 12 volt...and burn your house down! (4, Informative)

Roger W Moore (538166) | more than 6 years ago | (#23277254)

Err...not necessarily a good idea. If you lower the voltage your current requirements increase for the same power load. This increases the heating in the cables and thus increases the chance of an electrical fire.

I'm sure that you can do it safely but you will need far thicker cables than a 240V system and be careful that you have good connections. Plus you will loose 10-20 times more in power transmission than before.

Re:Go 12 volt...and burn your house down! (2, Informative)

Roger W Moore (538166) | more than 6 years ago | (#23277260)

Sorry that should be 100-400 times more power lost in transmission - it goes as current squared.

Re:go 12 volt (1)

Hatta (162192) | more than 6 years ago | (#23277314)

If you're like me, you have a half a dozen game consoles in your basement with AC adapters constantly draining energy. Why not hack your old Sega Genesis to run on renewable AC power?

Re:go 12 volt (0)

Anonymous Coward | more than 6 years ago | (#23277354)

You mean a separate system with air-gap between the regular voltage and the LV. Power generation would be more efficient for the LV system, wouldn't it?

Really, $2000? (3, Insightful)

jmauro (32523) | more than 6 years ago | (#23276856)

If your house isn't worth $2000 then go a head jury rig something (that would probably cause your house to burn down and void your insurance to boot). Else stop screwing around, pay the $2000 and get the parts you need to do this sort of work.

Electricity is a dangerous thing, jury rigging solutions is not an option when your safety is at risk. The device is $2000 because it must pass safety, UL, and a whole host of standards so it doesn't you know kill you or blow up the local transformer when somthing goes wrong.

Re:Really, $2000? (0)

Anonymous Coward | more than 6 years ago | (#23276976)

I hope he has FIRE insurance that not only covers him but his neighbours :)

Only stupid idiots think skimping up front is a good economy.

Re:Really, $2000? (1)

drinkypoo (153816) | more than 6 years ago | (#23277042)

It's nonsense anyway, you can get it for around $1500. Dig around a little more...

Burning a house down is the least of his concerns (4, Insightful)

Ellis D. Tripp (755736) | more than 6 years ago | (#23277162)

I would also think long and hard about criminal liability for the death or injury to utility workers who get killed because his system was backfeeding the power grid.

Those transformers on the poles work just as well when operated backwards, stepping the 120V output from your inverter up to the 7-13 kV distribution level. Unless your inverter has enough "smarts" to isolate itself from the grid in the absence of utility power, your system will attempt to power up your part of the utility network, resulting in a severely overloaded inverter (with resultant blown fuses/smoke/fire) at the best, or a serious hazard to lineworkers at the worst.

People HAVE been sued when lineworkers are killed/injured by improperly installed generators or PV systems that resulted in backfeed. Prosecution for criminally negligent homicide is also a possibility, especially if the prosecution can prove that you KNEW of the need for automatic isolation, but failed to provide it in order to save a buck.

In short, use properly designed equipment, installed according to manufacturer's instructions (and get the proper permits/inspections as required), or stick with a completely isolated low voltage DC system.

Re:Burning a house down is the least of his concer (0)

Anonymous Coward | more than 6 years ago | (#23277320)

I would also think long and hard about criminal liability for the death or injury to utility workers who get killed because his system was backfeeding the power grid.

In an era where the power grid is considered a terrorist target and government is in an overreacting mood I suspect there may be serious criminal liability even if no one is hurt.

Hardware switch (1)

wiredog (43288) | more than 6 years ago | (#23276858)

Whenever you're going on solar, you throw a switch that cuts off mains and cuts in the solar (or whatever).

Re:Hardware switch (0)

Anonymous Coward | more than 6 years ago | (#23277106)

This has ALWAYS bugged me as many customers say this too.

How the hell do you "cut on" something? Seriously.

I can understand cutting off the power, but how the hell do you "cut on" the power? The act of cutting cannot add anything.

I suppose you could "cut in" something, but it doesn't sound as right.

Re:Hardware switch (1)

DaveV1.0 (203135) | more than 6 years ago | (#23277396)

Please see "Knife Switch"

Ugly hack (2, Interesting)

Richard_J_N (631241) | more than 6 years ago | (#23276862)

The easy way is just to find some subset of your electrical appliances, and arrange them with a switch, to be supplied by either your own electricity, or the grid. This is trivial to do manually, and can be automated with a relay. The downsides are:
    - at the moment of switchover, your appliance gets cut off.
    - you are always wasting some or all of your power - assuming that both supply and demand vary, and the switching is granular.
To some extent, you can improve on this by using a UPS downstream of your switch.

This isn't exactly an "efficient" solution, but it will work, and it's simple and cheap.

Keep your cheapo gear off my power grid (3, Insightful)

Falstius (963333) | more than 6 years ago | (#23276870)

I imagine anything you want to hook up to the grid will need to be regulated, approved and expensive. So, the alternative is a power source large enough for a single task, like running your computer, and a hefty UPS to carry you through shady spots. Plus an automatic switch over to grid power for when your batteries run down.

The joys of regulation and insurance (4, Informative)

stox (131684) | more than 6 years ago | (#23276890)

Sorry, a home brew solution won't cut it. The power company won't allow a non-certified piece of equipment to be hooked up, nor will your homeowners insurance. The liabilities are simply not worth the savings.

Re:The joys of regulation and insurance (1)

mweather (1089505) | more than 6 years ago | (#23277038)

It's one thing to not electrocute the utility workers, it's quite another to ask the power company's approval. You can do one without doing the other.

Seperate Circuit (0)

Anonymous Coward | more than 6 years ago | (#23276894)

If you don't want to tie-into the grid, the easiest option would be to have a circuit that is powered by your renewable source. Put things on that circuit to use about the same energy that your source would produce over a day, and make sure you have enough storage (lead acid batteries) to store 2 days worth of energy at regular load.

Re:Seperate Circuit (1)

Ironsides (739422) | more than 6 years ago | (#23277022)

This is what I was thinking of suggesting as well. One thing to remember is that some states will require a licensed electricion to do certain work on household wiring, particularly work involving the main breaker box. Given most people I've run into, it's a good idea to have an electrician do the work anyway, as they know the building code for the state and are less likely to hurt themselves.

Re:Seperate Circuit (0)

Anonymous Coward | more than 6 years ago | (#23277296)

I imagine a centralized system is probably more efficient than a lot of separate converters for AC to DC... for cell phones, computers, video screens, electronics of all sorts.

Does anyone know how much more efficient it would be? Would we need big thick wires for DC outlets throughout a house?

All Your Rechargeables (1, Interesting)

Anonymous Coward | more than 6 years ago | (#23276898)

At the hobby level, set up a recharging station with a small solar panel, controller and a small 12 volt gel battery for all of your battery driven devices. Cell phones, laptops, quick recharge AA and C batteries. Save a few bucks and be prepared in the event of emergencies or grid brownouts that the Utilities seem to suggest may be coming in the near future unless rates are hiked.

Good Luck

Why connect it to your house? (1)

sensibile (1271954) | more than 6 years ago | (#23276900)

Why not just run a separate line using roaming wire to wherever you'd want the juice? I see no reason to tie it back into your regular electricity. That way you can use the cheap inverter plus whatever storage you want and power up select electronic devices. I have a friend who does just that with a home made solar panel on his garage roof. He uses it to power his laptop & lights in his man-cave during the summer. Just be sure to be safe and not overload the wires.

Not cheap (4, Insightful)

Lord_Frederick (642312) | more than 6 years ago | (#23276904)

If going green was cheap, fossil fuels would die out on their own without incentives and subsidies.

Re:Not cheap (0)

Anonymous Coward | more than 6 years ago | (#23277166)

fossil fuels are already dead (hence the name fossil) so they can't die out, but must live forever.

conventional sources subsidised for generations (3, Informative)

zogger (617870) | more than 6 years ago | (#23277236)

Conventional sources have had decades of government subsidies. For example AFAIK, there isn't a single commercial nuke plant out there (US) that has all private insurance, the government insures them for big failure, plus the government picked up the billions of dollars (in 1950s and 60s money) tab to even develop the things in the first place. Centralized magecorpos grid electricity relies on land seizures with no compensation to the owners for powerlines. buncha stuff. Back in ye olden days (1920s) they *forced* people to give up their early model windchargers (there was a really robust market then too) if they wanted to add into the grid. Basically killed that market off on purpose to prop up the fatcats who wanted to send you a bill every month forever. Anyway, here's an overview site: []

So, as a corollary, if conventional sources were really cheap, they wouldn't have needed subsidies, and decentralized "green" power would have done much better (rent, or build equity and own, two choices there)

Do you HAVE to grid-tie? (1, Informative)

Anonymous Coward | more than 6 years ago | (#23276906)

You don't have to grid-tie to have solar power.
You could run the energy to a bank of batteries.

Does this mean your whole house is powered? No, but you could run quite a few things off of that bank of batteries, like a PC:,1685.html

Re:Do you HAVE to grid-tie? (1)

raddan (519638) | more than 6 years ago | (#23277218)

Cool article. Thanks.

Keep it simple (1)

flyingfsck (986395) | more than 6 years ago | (#23276916)

Keep it simple and separated. Also, DC power at 12V is much simpler and cheaper to generate and good enough for RV style lighting fixtures.

To generate 12V DC to charge a car battery, get a 24V or 36V cooling fan for a stationary motor (for something like a large industrial compressor) and mount it on a post. Add a big diode and hook it to the battery. Simple as that.

Re:Keep it simple (1)

denis-The-menace (471988) | more than 6 years ago | (#23277034)

Don't forger the fuses in case the DC wires get crossed!

either/or (1)

zogger (617870) | more than 6 years ago | (#23276918)

You really don't need the grid tie if you just want to (completely) isolate one circuit in your house, and run that solar and batteries and do-dads, etc. Other options, how about those electric lawn mowers? You could keep one of those charged up. You can keep some deepcycle batteries charged for use when the power goes out (I do this myself), run your laptop with a car adapter and the radio and some 12 VDC lights, whatever. You can get some *really spiffy* efficient food freezers now that are designed to run from one good panel. [] -that is a "cool" idea methinks. Practical.

In Soviet Russia... (0)

Anonymous Coward | more than 6 years ago | (#23276924)

You don't tie into their grid, THEY tie YOU into THE GRID.

why not use a transfer switch? (1)

sricetx (806767) | more than 6 years ago | (#23276932)

The fact that the grid inverter shuts off when the grid shuts off makes this a poor backup power solution. You should use a transfer switch to isolate the backup power source from the grid to use it if the grid is down.

Re:why not use a transfer switch? (1)

mweather (1089505) | more than 6 years ago | (#23277080)

Any grid-intertie system with no battery backup won't be powering your appliances if the grid goes out, whether it shuts down or not. You'd have your very own brownout. Grid-intertie isn't about backup power.

You can't tie into the net with non-approved gear. (2, Informative)

TigerNut (718742) | more than 6 years ago | (#23276934)

Tying into the grid (i.e. anything where you need to dig into the hardwired electrical system of your house) legally requires a development permit and inspection. In my location (Calgary) the homeowner can pull a permit and do the work themselves, provided it gets inspected after the fact. However, I'm pretty sure that installation of non-certified (UL or the Canadian equivalent) is strictly forbidden.

The consequence of doing things like that without permits and/or inspection is that on the off chance that there was ever a problem, you'd be financially liable for any consequences.

There are opportunities to do strictly off-grid stuff, or at least you could keep to the low-voltage side of things. If you have a UPS for your computer or phone/router infrastructure, you could put up a solar panel to keep the standby battery charged. To the extent that the system runs off of DC power, you could supplant the power drawn from the grid with a panel, and reduce your electrical footprint that way.

Not necessarily true.... (1)

postbigbang (761081) | more than 6 years ago | (#23277308)

Without a doubt, you should use safe practices, but a homeowner/lessee have a lot of latitude. While UL equipment is the norm, there are many safe home-brew systems that can save money depending vastly on what you do with them.

The conventional wisdom of pubs like HomePowerNews and The Mother Earth News seem to advocate understanding battery technology and inverters, and also where you're consuming juice where those consuming devices can be better used (unplugged when not in use) or replaced with more cost-effective devices.

Low-voltage devices might be able to be used but may be actually more expensive to both buy and power over the long term with a shorter usage life.

Driving the power company's meter backwards may or may not even be legal in some states/areas, so you need to consider running dual systems (not as tough as it sounds) to get genuine savings over the investment life of what you do.

Solar may not work in some regions or areas; windmills may be restricted, and other generating schemes may have additional implications. Every site is different and needs to be treated that way. That said, the more we can save initially (and rationally) the better. Generating your own juice needs some thought because there's a varying amount of wisdom about what works in different applications. But by all means, DO IT. Permits aren't often required, but it's municipally defined, or thru state laws, or by the National Electrical Code and whatever your insurance company agrees with.

My partial solar solution in my grid tied house (5, Interesting)

netsavior (627338) | more than 6 years ago | (#23276966)

My main cost for electricity is the Air conditioning system. Conveniently enough, I am in California, so I only need A/C when the sun is out, this makes it a perfect project for a closed solar system.

My house is grid tied, but my wall unit Air conditioner (and roof vents, and 2 of the outlets on my porch) are 100% real time solar (with no batteries capacitors), in their own closed circuit, which is not at all grid tied. So, basically I cool my house for free, and it cost less than $1000 for everything (panels, raw materials to do the wiring myself).

My next step is to get an outlet in the kitchen to run my next worse appliance that only needs to run part time: The washing machine, then The Dishwasher.

Like the OP mentioned, this is a hobby thing just as much as a "green" or "money saving" thing, so I found the approach of taking the low hanging fruit (electricity I NEED to use only during the sunny time) was a favorable approach over using batteries, and expensive grid-tied adaptors/regulators/converters.

Re:My partial solar solution in my grid tied house (0)

Anonymous Coward | more than 6 years ago | (#23277078)

this sounds very interesting. I just moved to florida from oregon and am highly reluctant to use the grid-powered A/C, which will become quite daunting when summer arrives.

I was thinking about doing something with a brine cooler where I could make big ice blocks to keep around (with a fan) to cool the space I'm in.

Do you have any resources and information about your A/C project? I'm really curious to know more about your setup.

Re:My partial solar solution in my grid tied house (1)

Thelasko (1196535) | more than 6 years ago | (#23277120)

Good comment:
I would add that with heating and cooling you could always get two units. If your renewable power can't take up all of the load the grid powered one can help out. i.e. set your grid powered air conditioner thermostat a few degrees higher than your renewable one.

Re:My partial solar solution in my grid tied house (0)

Anonymous Coward | more than 6 years ago | (#23277214)

Would you mind sharing the equipment you used for this? I'd be interested in seeing the details.


Re:My partial solar solution in my grid tied house (1)

i.r.id10t (595143) | more than 6 years ago | (#23277358)

I'd like to do similar with my pool pump and a second set up to just power the ceiling fans I have 24/7... since when you aren't around to feel 'em, they are wasting NRG. Also need to look into a small panel for powering the pump on my outside fish pond...

Re:My partial solar solution in my grid tied house (1)

TheSimkin (639033) | more than 6 years ago | (#23277382)

Can you post a how to on how you did this? this sounds like a great project!

details? (2)

phorm (591458) | more than 6 years ago | (#23277408)

An AC has already asked, but I'll chime in too.

Details! I'd love to hear more about how you did this, and I'm sure that many others on here would equally appreciate any hints/information/etc you can offer.

Off the top of my head... (1)

mweather (1089505) | more than 6 years ago | (#23276972)

Any inverter you get should be in phase with the grid, since that's the type of power expected by your appliances. If you mean pure sine wave 60hz, that's not needed. The grid power isn't that clean. It's nice to have for battery systems, though. It'll keep your appliances quieter. That's probably your best bet is going with an off-grid RV/cabin inverter with a basic battery system. That's sill going to cost quite a bit, though. Generally speaking, a grid-intertie inverter is cheaper than batteries, but That's for larger systems, I'm not sure how the prices scales on the low end.

Re:Off the top of my head... (1)

TigerNut (718742) | more than 6 years ago | (#23277096)

The grid power isn't totally "clean" at 60 Hz, because it typically contains harmonics at multiples of the 60 Hz fundamental, but it is kept at very close to 60 Hz at a long term average. When you're tied into the grid, your generator or inverter is kept at 60 Hz because it costs a decent amount of power to stray away from the reference, but as soon as the grid reference disappears, your local power source will drift away from the reference phase. When the power comes back on, your local system has to resume its connection to the grid only when the phase difference is near zero, or very bad things will happen to the circuit breakers and/or your local generating equipment.

The local electrical engineering school has a Power Lab experiment where you synchronize your 3-phase experimental generator to the University's grid. The year after I went through, one lab group misunderstood the procedure and tried to close the breakers when their generator was 180 degrees out of phase. They killed power to the building wing for most of the afternoon, and the basement smelled like burning insulation for about a week.

Re:Off the top of my head... (1)

Simon80 (874052) | more than 6 years ago | (#23277248)

I'm no expert on this stuff, but it seems that you don't what what it means to be out of phase. If your system is producing an AC voltage at the same frequency and amplitude as the grid, but 180 degrees out of phase, it will cancel out the grid signal, which can only cause Terrible Things to happen. Keeping the signals in phase is definitely a must if you are going to tie the inverter and the grid together. The fact that the inverter produces the same frequency and amplitude, since this is what appliances expect, does not automatically cause the two signals to be in phase.

Re:Off the top of my head... (1)

KUHurdler (584689) | more than 6 years ago | (#23277284)

60Hz is easy. Unless you're 180 degrees out of phase with the grid...
so you better be N'sync.

or in their own words...

You might've been hurt babe, that ain't no lieeeee...

Re:Off the top of my head... (1, Informative)

Anonymous Coward | more than 6 years ago | (#23277312)

Any inverter you get should be in phase with the grid, since that's the type of power expected by your appliances

I think you're confusing frequency and phase. Frequency is how often a signal repeats. Phase is what part of that repeat cycle you are on. Think of it like ocean waves; if you specify frequency as a function of distance, you could say something like "One wave exists per five feet of ocean surface", or in more familiar terms maybe "the waves arrive on the shoreline one per second"... in this example, phase would be like putting a floating ball on the surface of the water and asking "ok, what's the height of that ball above or below sea level right now?"

To continue the analogy, mains and inverter power might both have waves five-feet apart... but that doesn't mean those waves would line up exactly if you superimposed them...

I assure you, if I take my 12V car inventer, plug it into my car's socket, and compare it to my wall current... it will be out of phase. I'd even be willing to bet if I plug that same inverter up to a 12V bench supply in my house, running off of mains... the inverted signal would still be out of phase with mains.

What happens when you put two signals on top of each other? Interference. Constructive interference (increasing the signal strength) happens wherever the two signals are in phase. Destructive interference (decreasing the signal strength - in this case the two electric fields meet and cancel within the wire, creating thermodynamic noise out of the electrical energy) happens whenever the two signals are out of phase.

Basically, then...

If the inverter is phase-locked with mains (like a grid tie-in inverter will be), you will add your generated power to the mains line (and your meter will credit you for the watt-hours)

If the inverter is 180-degrees out of phase with mains, you will subtract your generated power from the mains line (and your meter will charge you for it!)

The real situation of course will be in between the two - some part of the phase loop, you'll be adding, some part, you'll be subtracting. The average case will be, therefore, no overall change (assuming the inverter's phase wanders somewhat randomly - it's most likely not going to be the exact same measure of 60Hz that the electricity company is giving you... thermal effects alone will likely drift it enough on top of that to make it change over time)

So, just hooking up any old inverter... is useless at best, and a huge fire hazard at worst. And as others have pointed out, non-UL listed equipment will invalidate your insurance, put your building out of code, and make your children grow horns, so DIY seems a bad way to go. A quick search on hobbyist solar and wind power sites reveals that those who publish pricing information on grid tie in inverters generally do charge $2000 and up for mid-to-large systems... and like the OP, I couldn't find published prices for smaller equipment...

hot water solar (5, Interesting)

andrew_d_allen (971588) | more than 6 years ago | (#23276980)

It's not electrical, but solar hot water heating (with a storage tank that feeds into your main water heater) is certainly something that you can use your "hobbyist" skills to save money, that you can put together with a couple hundred dollars and some plumbing skills and basic wiring (pump & temperature switch). It can save you a bunch of money, whether or not you use electric or gas to heat your water currently.

Re:hot water solar (1)

nogginthenog (582552) | more than 6 years ago | (#23277376)

This is very, very common in Greece and Turkey and I suspect other Mediterranean countries.

How about (0)

Anonymous Coward | more than 6 years ago | (#23276982)

Just reducing how much electricity you use. That's free and easy.

Or - buy and energy efficient appliance. That will probably save you more electricity than any rinky dink solar system you set up.

Keep it simple... (0)

Anonymous Coward | more than 6 years ago | (#23276986)

Just don't hook to the grid. Keep a stack of DC devices like say.. a PC, lighting, refrigerator, LCD, etc that are powered off of battery when the sun don't shine/wind doesn't blow, and you'll be good to go.

120v automatic transfer switch (1)

James McP (3700) | more than 6 years ago | (#23276990)

Get an automatic transfer switch at the appliance level. Let's say you've got a window air conditioner unit. Get an $85 120v/30A transfer switch ( hooked up to your solar-charged UPS and regular house voltage.

When the UPS dies, the ATS will switch to regular house power.

Use a transfer switch (1)

popocatapetl (223570) | more than 6 years ago | (#23276998)

In order to protect workers, you really do need to use high grade gear if you connect your generator to the grid (I don't know whether $2K is a reasonable price). But, if you want to just power some circuits in the house, get a transfer switch and connect the circuits to it. You will then be able to switch the circuits from being powered by the grid to being powered by what you generate.

Separate 12vdc (2, Interesting)

sillivalley (411349) | more than 6 years ago | (#23277008)

A lot of ham radio operators set up separate 12vdc systems for powering radios and other emergency equipment. 12v deep cycle batteries plus ways of charging them -- solar panels and a solar charge controller, ac chargers, and a handful of diodes and maybe some relays so the ac operated charger only runs when needed (and there's no solar power available). Such systems are fairly simple and robust.

Re:Separate 12vdc (0)

Anonymous Coward | more than 6 years ago | (#23277184)

Industrial Ni-Cad batteries (which are very different from the rechargeables you buy in the store) are great for this. While they cost three times more than deep-cycle lead acid, they last ten times longer and can totally discharge without damage.

Add a 12vdc refrigerator or freezer, such as a sundanzer or the type sold for RVs. Automobile adapter for your laptop and cell phone. You could build a parallel 12vdc system a little at a time, and achieve partial energy independence.

Buffer the power through batteries (0)

Anonymous Coward | more than 6 years ago | (#23277026)

Use your homebrew power generating equipment to charge a bank of marine (deep-cycle) batteries. Then run the output from these through an inverter (large one) to power your AC equipment (optionally use the DC directly when possible. You then also use the grid to charge the batteries.The grid cuts off and there is no backfeeding to the grid.

There is a fair amount of info on this type of thing, as many people in remote locations live like this, with no grid power at all. They just run a generator every so often to charge their batteries.

This type of thing can be DYI'ed on the cheap fairly easily.

Note that you will be loosing some energy (mainly as heat) when running exclusively off the grid power. Converting the power from AC to DC and back isn't free. But if you have enough current coming in from your alternative source it may be worth it.

Also look in to peak and offpeak pricing from your power company. Some offer this even to residences. This would allow you to run the charger only during offpeak hours and pay a lower rate per kilowatt hour.

Would this pass your local electrical codes? Who knows...

On a budget? Just do one room! (1)

odin84gk (1162545) | more than 6 years ago | (#23277032)

Instead of doing your whole house, maybe you should do something a bit different: limit it to one or two circuits and put those on the homebrew solution (Easiest and best solution: Your lighting for multiple rooms). You can use a single relay (double pole) to control the source. When you have enough solar/wind power to power these units, the relay switches the load to your system. When you run low on juice, it switches to the main system. This also protects people on the mains because you cannot put power on the grid. (You probably won't generate enough power to do that anyways, especially on a budget).

Segregate your home wiring (1)

davidwr (791652) | more than 6 years ago | (#23277064)

Converting part of the house to DC has already been mentioned.

Another option is to split your house wiring. Put some circuits on your home generator and some on the grid.

Of course, with solar or wind you run into the problem if downtime.

If you put a switch between the two that makes sure the two never feed the same circuit within a few seconds of each other, and you only plug in devices that can tolerate several seconds of down-time, then you should be in decent shape. If the elements on the circuit are purely resistive then a fraction of a second of downtime is all you need.

One other legal option (0)

Anonymous Coward | more than 6 years ago | (#23277086)

There is one other option that would meet all insurance regulations. Buy a large UPS device, some of these can be charged by either 120v mains or low voltage (solar). Then pick the few small appliances or maybe 1 large appliance that you want to run off mostly renewable energy. No exactly a "grid tie in" but it would give you the benifit of using solar to charge the battery when available, and charge off 120v mains when it's not - and as long as the device is approved - you'd be fine. UPS boxes are smart enough not to send power back to the lines.

separate circuits in the house (1)

BigGar' (411008) | more than 6 years ago | (#23277090)

You could move a circuit or two off of the grid breaker box to their own solar/wind powered circuit(s).
Simply install a small second breaker / fuse box and move a couple of wires. Might want to have an electrician do the work or inspect it to make sure you've covered everything. Do you want to have battery backup for night time /no wind use? That does change the options available for the inverter selection /components as they have to manage multiple inputs, charging, etc.
Once your hobby has progressed to the point of wanting more of the house on the other solar wind then you can think about the grid inter-tie inverter.

The higher end inverters also tend have a cleaner A/C output, that is its closer to a sine wave than the lower end ones, at least that used to be the case. It isn't much of a deal for most things but some electronics are picky about the shape of the input wave.

Just some things to think about.

Low voltage DC lighting is a good answer (1)

Whuffo (1043790) | more than 6 years ago | (#23277124)

You can find 12 volt versions of "normal" incandescent bulbs at camper / trailer supply houses as well as 12 volt florescent fixtures. There's also a very wide range of automotive lamps and fixtures that run on 12 volts.

Run these on their own completely separate circuit; you can use regular 12 volt batteries as your energy storage and charge the batteries with solar cells or a automotive alternator driven by some kind of alternate energy (steam? water wheel? windmill?) or any combination thereof. If you have multiple generators be sure to electronically isolate their outputs; big diodes are the usual solution.

If no alternate energy is available and you need lights then a common battery charger will take care of your needs. If your house was wired to "standard" then your overhead lighting is probably already on a separate circuit of its own; this makes it even easier.

There you go; by using commonly available items and starting small you can start generating your own power on a budget. A few hundred watts of lights goes a long way...

Run LEDs - they're more efficient (1)

cheros (223479) | more than 6 years ago | (#23277352)

We're currently examining replacing a lot of lights on a boat with LEDs, because they make the battery last a lot longer before we need to kick in the generator (it's also safer because the mooring lights don't burn out). Maybe we'll add solar panels, but that's phase II.

Your average lightbulb converts (AFAIK) about 65% of the energy into heat - which we don't need as the boat already in a hot climate :-).

Calculate load/power (1)

ZonkerWilliam (953437) | more than 6 years ago | (#23277126)

I would suggest breaking down what you want to divert to solar and what you don't, in other words do you just want to power the fridge or air conditioner on solar, then rewiring for it. I've only setup a solar generator to supply power to a UPS, in case of blackouts, I can recharge most items.

You in5ensitive clod! (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#23277152)

troubled OS. Now Is mir3d in an walk up to a play

non-grid-tied DC motors, pool pump (2, Informative)

bcrowell (177657) | more than 6 years ago | (#23277230)

If you have a pool, there are systems you can buy that run your pool pump off of photovoltaics. Pool pumps are infamous energy hogs, and you can run a pump off of DC, which cuts out the inverter. Getting rid of the inverter improves efficiency and cuts the cost of the project. This is not a grid-tied system.

Experience with solar heating (1)

OriginalArlen (726444) | more than 6 years ago | (#23277238)

I live in the west of England, so our climate is generally cool with a lot of cloudy days. We got solar water-heating panels put in the roof a couple of years back; it cost approx £6000, we get free hot water ~ nine months of the year (they absorb IR, so they work when it's cloudy... a vital feature for us!) They should pay for themselves in another 7 years.

The problem with enthusiast wind generation is that power scales exponentially with the size of the turbine blades. Hence the attractiveness of offshore windfarms, as honking great beast turbines don't spoil people's view.

Line feed (1)

MrJSuppish (1235718) | more than 6 years ago | (#23277262)

When I was going through CERT training, I was amazed at some of the precautions that folks from DTE (Detroit's electrical company) and the fire departments have to take. I was also amazed at the number of people - pole workers and firemen - who have died on the job because people run generators and don't have backfeed handling. Forget your house being worth 2000 bucks; think about the people on the line. Also, just to put it in a capitalist perspective, when the lineworks got to a downed neighborhood, they would first try to listen for the buzz of a generator. If they heard one and they couldn't get the owner to shut it off, they would try and surge the line locally into the house and blow the generator/fuses. Apparently, it often worked and they've never been successfully sued.

Storage (1)

exploder (196936) | more than 6 years ago | (#23277264)

Sounds like you need to be looking at storage options, not grid-tie.

How I homebuilt electricity producing Wind turbine (1)

dharm0us (1224656) | more than 6 years ago | (#23277276)

I am not sure if it will be useful, but here is an article on something similar : []

Conservation is best (0)

Anonymous Coward | more than 6 years ago | (#23277306)

Energy conservation is the most cost effective/easiest way to reduce net power consumption. Electric Generation facilities tend to become cheaper per watt as the generation system gets larger.

Hobbits Renewable Energy? (1)

kopo (890010) | more than 6 years ago | (#23277348)

Did anyone else initially misread the headline?

Try hot water first (0)

Anonymous Coward | more than 6 years ago | (#23277362)

The whole electricity thing is overrated. Making solar hot water is much less dangerous and cheaper (and you get to use a blow torch). Look at the roofs in your neighborhood, there are sure to be some unused/abandoned hot water panels that you can pick up cheap or for free.

Don't worry about the grid (1)

solweil (1168955) | more than 6 years ago | (#23277372)

Only use electricity for what makes sense. For heating water, think about concentrated solar or methane. This focus on the grid overemphasizes unreasonable centralization of alternative energy that can be made on the homestead and power the needs of a family.

Outdoor lighting (1)

tekten (755932) | more than 6 years ago | (#23277400)

I bought a 60 watt kit from, which I have charging a deep cycle battery that powers my 12-volt outdoor landscaping lights at night. The lights are much brighter than the typical solar lights, but still completely solar powered. I also have a 3kw grid-tie system, but no battery storage on it.

Don't help this loon. (1)

Awptimus Prime (695459) | more than 6 years ago | (#23277418)

You can't attach a 'home-brew hack' for putting electricity back into to the power grid. It must be taken into consideration that your house would have to survive an inspection and nobody at the power company is willing to risk death because you were too cheap to provide a tested or approved solution.

Also, if you are going to waste bandwidth on the Internet, why not give some damn details about your plan? Make it interesting at least. Right now, your ramblings seem to indicate you want free help for a possibly commercial idea you want to keep secret.

Load More Comments
Slashdot Login

Need an Account?

Forgot your password?