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Hobbyist Renewable Energy?
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?"
What are other options for the hobbyist to play around with renewable energy, other than charging a cell phone?
Breed Whales, burn the oil.
which is totally what she said
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.
Feed the need: Digitaladdiction.net
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.
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.
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.
http://www.otherpower.com/
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.
"To those who are overly cautious, everything is impossible. "
If going green was cheap, fossil fuels would die out on their own without incentives and subsidies.
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.
Less is more.
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.
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.
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.
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.
Remember "News for Nerds, Stuff that Matters"? Help make it a reality again! http://soylentnews.org
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.
Find free books.
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: http://www.taxpayer.net/energy/oil-gas.htm
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)
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.
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.
Best regards.
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.
Having a renewable energy system backfeed the grid under normal circumstances is perfectly fine (and lots of fun to see your electric meter spin backwards). It took a lot of effort by system manufacturers and RE hobbyists to get utilities to reluctantly accept so-called "net metering", and allow small producers to sell power back to the utility. But there are very specific requirtements for doing so, including automatic isolation of inverters and a visible, accessible disconnect switch on your house so that you can be physically disconnected is required.
Remember "News for Nerds, Stuff that Matters"? Help make it a reality again! http://soylentnews.org
I'm curious about this, because I've paper-designed some similar things -- trying to use car alternators as generators by driving the field coil with AC from the grid, so the output is automatically synchronized with the grid. The problem is that since you're feeding power back into the grid, how do you detect that the grid's down? coz it won't be if you're feeding power back into it. Likewise, you seem to be doing the same sort of thing: how is your fan controller going to know whether the electricity it sees is from the local coal plant or from your little cogeneration setup? If your setup works, I'd love to know how and why, because I'd love to build something like this. I just can't figure out how to get it to work without resorting to ugly, dangerous things.
Nostalgia's not what it used to be.
Check in old issues of Home Power Magazine. There were articles where people were setting up grid tie solar setups on a small scale safely without some of the expensive utility work. The articles were titled Gorilla Solar.
I am unsure how an alternator would sync phase, but I don't know that much about car altenators. But if I wanted to hook an inverter to the mains I would use a simple system: for my inverter pulse the DC through some power transistors using a capacitor afterwards to smooth things out. As far as syncing: the oscillator controlling my inverter would be ran off a phase-locked loop. (http://en.wikipedia.org/wiki/Phase_locked_loop) Continuously syncing phase with whats on the mains. For islanding mode operation (shutting power off to the line when the line goes down. I have though about this for a long while. (I like thinking)If the line goes down its either because of a short or an open. A downed line or one shut off for maintenance Your inverter has to respond within 60ish ms to be legal to use as grid-tie IIRC. If there is a short your out flowing current is going to shoot way up and max out your inverter. If its an open the current will drop way down, not always to zero. So if you monitor the outgoing current and if there is a big change from the average current have it shut off outgoing power to the grid. This would take some trial-and error and research, however. FYI, I am not an EE, but I am a CET!
sig?
How many city electric workers are going to agree to touch your electricity when they see some homebrew box rigged up to your breaker? I'm guessing that whatever you attach to your city's power grid has to be approved and licensed, and has to meet local electric code requirements. That probably kills most homebrew solutions.
why not just have separate circuits to power small items like alarm clocks, charging electric toothbrushes, etc....
Are there really people investing in new sources of energy so they can power a toothbrush? Remember the mantra is reduce, reuse, recycle...
Ditch the electric toothbrush and can opener, the constantly charging rechargable tools you use infrequently, the wall warts that are always buzzing, and maybe it won't take as many solar panels you keep your household running.
But for a small scale system, the ability to tie in to the grid is essentially useless.
I don't think the primary goal is to sell your excess production back to the grid. I think the goal is to not have to put a new seperate set of cicuits. What are you going to do on a cloudy day when the solar panels aren't putting out as much juice, or on a windy day when the windmill kicks in to overdrive? Run around switching plugs from one outlet to the other?
I got the impression that the author was looking more for alternative ways to use the power than "homebrew grid tie-in". For example, I used to run the vent fan on my greenhouse based on solar power. When the sun went down or when it was cloudy (i.e., when you didn't want the fan running), it'd stop. I'd imagine something like that would be nice for an attic fan setup, too.
Think of things in your house that you really don't need to run on grid power -- nonessential items. Perhaps, since this is just for a hobby, you could create a single dedicated socket that you don't use all the time that provides your renewable power to household devices. Your power could be fed into a battery, which would then be fed into a cheap store inverter. You'd want it to be on a switch so that your inverter doesn't run nonstop and drain your batteries, of course. You would, of course, have to have a battery back for such a solution.
"99 dead duelists of Dios on the wall. 99 dead duelists of Dios! Take one's ring, pass it around..."
Okay, I've been interested in this for a long time and I read a good thread on the topic that I will put a copy of in this post.
But first I would like to make a quick point which is that this is a major political obstacle to alternative energy. It's not a technical obstacle, it's a political issue because we've "deregulated" utilities by letting them regulate themselves and this is insanity. At least it is one way to ensure that we remain bound to fossil fuel solutions.
So, on the topic of a DIY grid-tie inverter here are a few posts from a thread started by a guy looking to outsource the design.
Some dude makes the snarky remark about why don't you just pay the price and this is the response of a user named MarkM
(I've reformatted a couple of his posts into a single thread for readability.)
"Why don't you just buy one"
BECAUSE THEY ARE WAY OVER PRICED. That was yelled a the top of my lungs.
Solar panels cost about $4-5/Watt, inverters cost $1-2/watt. This is crazy. These grid tie inverters are no more complicated than a computer power supply which will cost you about $0.08/watt. The inherint nature of the grid tie inverters is to track the sinusoidal input and drive it to a higher voltage, thus selling the solar power on it. The IEEE 1547 require all kinds of hoops to jump thru and the inverter companies use this as an excuse to charge what they do. Again the hoops are simply jumped by a programed algorithum that monitors frequency and voltage levels. WOOOOO. I see this mans drive to find/build an inexpensive alternativ and do the gorella thing.
The way the grid tie inverters work per the regulatory hurdles is it syncs in on the line power voltage level and sine wave siganture. If power goes down it shuts off, no harm can come to the line man. This type of statement from you or utility companies is old school old day problems stemming from someone hooking a rotatry generator or non-monitoring piece of equipmnet to the line. And if a lineman is doing as he is suposed to he grounds live wires to ground before working on a "dead line". (that's a rule)
Utility companies have this power thing locked up and are going to be very reluctant to let small producers get in the game. Utility companies should not fear small producers they should embrace them and buy their excess power and resell it at a profit without any over head. The largest source of funds to build the power supply sytem is in the pockets of consumers: let consumers build it.
And as far as the regulatory cost as a part of the inverter cost that to is a pile. When the cost of regulation of a certain product is spread over the number of units sold it is small. Again we have a situation of free market and what the buyer will pay. In verter builders are maximizing there profits because competition is nill. I am all for free market but too I am for some of the Chinese or Indian products to slap the US, German and Australan made manufactures into a stop gouging mode.
The original thread is here.
http://cr4.globalspec.com/thread/4482
On the general topic of grid-tie inverters you may find the following Wikipedia posts of interest. You will find the following components mentioned in the documentation for many grid-tie inverters.
http://en.wikipedia.org/wiki/SEPIC_converter
http://en.wikipedia.org/wiki/Mppt
That's a good approach. So what happens if, say, the grid goes open across the street, meaning you and your neighbors are on an isolated circuit and you're now driving their house, as well as yours -- how would that look different than driving into the grid while it was still up? Likewise, transitory opens or shorts in a windstorm might be detectable but how do you react to them? How long do you go offline? When it comes back up how do you synch up without mangling any of your electronics that rely on a fairly clean sine wave? (Not as much of a problem these days, what with switching power supplies in everything.)
Obviously it can be done, but it seems Very Complicated, and may be something where you want to have a commercial concern do the engineering so that if something goes wrong, you're not the one responsible. Because, let's be clear here: we're talking about generating lethal amounts of power and driving it into wiring that goes into other people's houses and into systems that other people are maintaining.
As for alternators, basically, an alternator is a variable three-phase AC generator. A voltage regulator controls the power flowing through field winding in the alternator, based on the feedback it gets from the charging system as a whole. If you replace the voltage regulator with a simple AC input line (stepped down so as to not arc over) you can get AC out that's related to the AC in, and use that to get phase matching. It's not pretty (given that alternators want to output three-phase) but it looks possible. I don't think it's a great idea, just tempting because junk alternators are cheap.
Nostalgia's not what it used to be.
It is amusing how easy it is to spot people who have never actually thought about the matter by comments like these.
The purpose of grid-tie is to avoid having to futz around with batteries. Batteries need charge-controllers, they need to be serviced, they have a finite life-time and they're either over- or under-speced because no two weeks will ever have the precise same power.
So you used the grid as your battery. It's as simple as that. You over-produce in the afternoon (assuming solar -- maybe in the evening for wind)? Just feed it into the grid. You don't produce at all in the night? Just take it right back from the grid. Here in the pacific southwest, loads peak in the afternoon when everybody runs an AC - so the power company will be more than happy to receive your added input. And loads are lightest around 3am, so they'll be just as happy to "give you back" your electricity then. Actually they're giving you cheap power in exchange for expensive power -- but in return you don't have to think about batteries at all.
In addition, with a grid-tie you're as scalable and as granular as you want to. Got some bucks to spend on a Panel this week? Great, you're now producing 5.37% of your household's electricity over what you were doing before. Without having to run new circuits or worry what consumer in the house will run on 5.37% of your total consumption. Without the grid-tie, you either produce all the electricity your fridge needs or it'll die. Or you change plugs whenever it's cloudy.
We're all born with nothing.
If you die in debt, you're ahead.
1. Hugh Piggott has been building windmills from brake rotors (drum brakes) and plywood for decades. If you have the room, take a look at his books.
2. Savonius windmills also seem to be efficient, according to the Internet, but I have not tried it.
3. If you are lucky enough to have running water, look into micro-hydro-power and micro hydro generation. Water carries a lot more punch than air. Some people even use micro hydro on drain spouts from gutters on their roofs.
4. The real efficiency is not the percentage of the power in the air converted into electricity. The real efficiency is the cost per watt. We only care about efficiently using scarce resources. Land area to put up wind mills or solar cells is abundant. Money to finance these projects is scarce.
5. You use a lot of energy you don't see in water. Try collecting rain water off the roof and trying to use it in selected areas - flushing toilets, for example.
6. Big money people live grid-tie systems. I would rather power a bank of 12V batteries under a computer desk, and run my laptop & accessories off these batteries. If I don't generate enough 12V power, I can always plug in a battery charger.
7. Small-scale (100W) solar systems are available, from Northern Tool, Harbor Freight, Fry's etc.
8. The only economically viable "alternative" energy system I've seen is solar-thermal. 90% of power plants use heat to boil water and create steam, then they run turbines off the steam to generate electricity. You can do the same with solar heat to boil the water, but it's tricky and not safe for idiots.
9. Solar heating & solar hot water are possible. Take a look at the black tanks to pre-heat water that some build.
10. Learn to charge batteries - it's not as simple as it sounds. Learn as much about batteries as you can. I like 3 loads: emergency (red,) normal (yellow,) and dump (green.) The red socket will remain on if I have any power at all left in my 12V battery (i.e., if V > 12.0v.) The yellow socket will remain on if I have normal amounts of power, but it shuts down when I get close to being dead (i.e., V > 13.5v.) The green socket only comes on when I am dumping power (i.e., V> 15.0v.) Of course, you have to build hysteresis into this system or you get crazy on/off flickering. The dump load may be to run an air compressor or to pump water up hill, or to run a space heater / ac unit in an unused shed. If you don't have a dump load, you will overcharge your battery and ruin it. You also need to cut off all power at some voltage to avoid ruining your batteries.
11. Ways to store energy (other than batteries) include compressed air and pumping water.
Andy Out!
> Because, let's be clear here: we're talking about generating lethal
> amounts of power and driving it into wiring that goes into other
> people's houses and into systems that other people are maintaining.
This is the key part. I'm as Libertarian as they come but a power grid implies a need for some sort of standards and real enforcement of same. Forget the legal implications for a minute, do YOU want to kill your lineman? Then don't conduct unannounced experiments on the production power network. Ya got three choices here:
1. Man up and buy the commerical, TESTED AND CERTIFIED product for that key interconnection point.
2. Build a test grid, do your R&D and produce a TESTED AND CERTIFIED product of your own.
3. Restrict your alternative power experiments to those that do not require an interconnect to the grid.
Democrat delenda est
As an alternative, you can also add the ability to power the house completely from your renewable energy source. Just add another manual switch. If the power goes out, just flip a switch and you'll be back up and running!
...we're talking about generating lethal amounts of power and driving it into wiring that goes into other people's houses and into systems that other people are maintaining. You make it sound like a bad idea.All rites reversed 2010
This is exactly why you want to buy a real isolating inverter and not try to make your own.
If the failure is isolated to your circuit from the power company (like if the transformer at your pole fails), then your circuit would never detect that the grid power went down if your home power system is producing enough power to feed the grid -- since your home system is tied directly to the grid, it would also be powering your 24AC transformer so would never see the grid side go down.
So, when the lineman goes to fix your transformer, he's dealing with a live circuit from your house.
Real isolation inverters look at the waveform and frequency to determine if the grid is offline.
In addition to not wanting to kill someone, many utilities and state lawws require such a certified unit. Assurances of a homebrew designer won't satisfy that no matter how good the tech actually is.
One potentially interesting idea would be to modufy a UPS to accept additional charging current from the solar rig. The desired behaviour would be to run on battery as long as the battery charge is greater than x% capacity (charging only from solar), run from the grid if available (still charge only from solar) when below x. Charge from the grid when below y% or some similar ruleset. That way, instead of an inter-tie, you're only mucking about with DC and can't accidentally backfeed the grid.
Whatever modifications are made, use (keep) the double throw relay setup that doesn't allow the inverter to connect to the wall plug.
You realize that a grid tie inverter is the opposite of a computer power supply don't you? They don't even have to consider phase, their output doesn't HAVE a phase.
Meanwhile, the non grid-tie inverters often output stepped voltage rather than a sinewave (and so harmonics). It's cheaper by far and good enough for many applications, but not for feeding into a big iron core transformer. They don't care about phase either. They just need to be somewhere close (ish) to 60 Hz.
They may still be overpriced, but not by 25 times as you suggest.
tying into the grid is nice, if you're going to be producing enough power to light up 5 homes with an insanely large wind turbine, but this guy was talking about a hobbyist sized deal, where he's gone wrong is thinking he needs to tie in the grid at all. Batteries, cheap lead acid car batteries, they're really easy and cheap, and for a small project you might only need one $25 dollar battery and some cheap electronics that are quality but not certified for tying in the grid... then you can run a few lamps, maybe a refrigerator, maybe a tv, maybe even a computer... if you can predict the amount of energy produced all day, and the amount consumed, you can design the setup so the battery never dies, and always stays charged up...
why tie into the grid, when you're only producing enough wattage to power a single light bulb? eg: a home made windmill with a used car alternator.
why would you even consider tying into the grid instead of using a recyclable efficient lead acid battery?
as an example a nice DIY windmill might cost you $200 for a 16' pole, $30 for a used alternator, and $10-20 for wood and screws, and $40 for a new lead acid battery, plus $20-40 for wiring and electronics parts all told a DIY windmill for under $350 again it will probably only run a couple lamps, but the whole project is DIY
why tie into the grid when they sell lead acid batteries so cheap?
https://www.gnu.org/philosophy/free-sw.html