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?"

Ugly hack

[Richard_J_N]

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.

All Your Rechargeables

[Anonymous Coward]

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

My partial solar solution in my grid tied house

[netsavior]

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.

hot water solar

[andrew_d_allen]

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.

Separate 12vdc

[sillivalley]

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:Renewable fuel

[tha_mink]

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

[SQLGuru]

Actually, isn't power tools a good case for NOT cutting the cord? Why charge up a device that you use "periodically" when you could just have one that is "always ready" and never "runs out of juice"? I have a corded drill that is more powerful than most cordless drills and doesn't have a constant draw while the battery is being charged. Sure you have to deal with load spikes, but you reduce the non-spiking load to zero.

Maybe someone (other than me) will run the numbers on charging a 12v cordless drill vs using a simple corded drill. Include initial full charge and assume a 30 minute session with the drill (which isn't 30 minutes of continuously running the drill).

Layne

Re:Renewable fuel

[Anonymous Coward]

Your solutions are basic and cool, and it's great that they are working for you.

BUT..

The cost of your proposition is astronomical!

Laptop, all new power tools, solar panels, inverters and deep cycle batteries, these things are not cheap!

Also, they can damage some electronics unless you have true sine wave inverters, which add to the cost considerably.

I think the question was aimed at a single collection, storage, inverting solution for the purpose of saving money.

Re:details?

[netsavior]

I replied this to a ranked 0 post so it is buried... for simplicity sake, here is the text (this is the highest ranked request for more info)

unfortunatly I am a software developer, so I tend to resist all forms of documentation. Here is my rundown (the setup of my house means I didn't even run any wires through the house so this was so freaking simple:

Wall unit AC (was what we used before the conversion) is on the back wall of the house) 115v 10,000 BTU unit I think they retail for ~$400-$500 (but we already had it)

My solar panels were second hand, so they were cheap, they were operating at ~81% their original capacity, so the company sold them to me for less than 1$/watt I have about 1300 watts, and the AC when it is on (it switches off and on throughout the day) it uses up to 875 watts. I got very lucky on the price for the panels, and the additional wiring and stuff, so maybe my $1000 number was not very "honest" maybe double or triple that if you are buying with urgency instead of waiting for a killer deal like I did. The capacitors I use are a cluster of those 2000 Farad Car stereo ones (I know I know it is not the right thing to do but it is the cheap thing to do, and they are firewalled). They are before the inverter, to feed it continuous power. And seriously that is about it, I mean wiring solar panels is about like wiring batteries (parallel banks of your desired series of voltage), then do the same with the capacitors, then the inverter, which can be bought for cheap from a Truck Supply store (some bigrigs use them, to run things like 1000 watt Routers, jackhammers, etc) From there, my inverter is mounted on my back porch (near the A/C unit) and the A/C is plugged directly into that (it has A/C outlets in it).

The roof vents are just seperate left over panels, with DC fans that run directly wired to the panels.
So basically I bought cheap ass panels, some consumer electronics, and put it all on my roof/porch. Doesn't sound as glorious when I put it that way, but in all I have almost made my money back in energy savings as compared to the bills from last year... and that is significant for me since I really only did it for fun. I think I will be in the black in August of this year, and the gear is still going strong, so hopefully it will be an actual cost savings.

Re:Renewable fuel

[pclminion]

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

No, you need one if you want your entire house rigged for solar power. Being able to sell excess power back to the power company is just a side-effect. I started with a battery/inverter based system, and I hated it, so I went whole-house. You simply need a grid-tie inverter for that, if you aren't making enough power on your own to run your entire house.

I've never even come close to having an excess of power to sell back to the power company. That wasn't the goal of the project.

Re:Use a 'fan center' to isolate when grid power d

[Spillman]

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!

You're doing it wrong

[mcmonkey]

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?

Re:Renewable fuel

[johnlcallaway]

If I wanted to buy a home that Joe Hobby had transformed using spare parts, I'd probably tell him to yank it all out. It if breaks, there is no one to fix it except Joe because he is the only one that understands it, short of paying an electrician to sort it all out. Who knows if it is even up to code?? And who knows how long the parts he has used is going to last.

Now, if his neighbor has gone out and purchase the latest GE Solar System, I might consider it.

Re:Not cheap

[dpilot]

Cheap is relative.

Fossil fuels are becoming more rare, and their price is going up.
Technology is making advances for other energy sources, so their prices are going down.

Besides, as someone else mentions, there are already tremendous hidden subsidies in place for current sources. The same issue comes up with rail transport, because rail subsidies are explicit while air and road subsidies are hidden.

Re:Renewable fuel

[rs79]

Bloody Americans :-)

You need to keep going. You guys can get (if you're a farmer or remote business) Federal grants and Federal financing for a 15 Kw wind turbine.

Here in Canada we can get sales tax refunded. Woopee.

Re:Renewable fuel

[dpilot]

But if we want to pick nits, Li ion cells also self-discharge, given time. So imagine your drill is sitting in the basement for a month or two between uses, plugged in. The battery charges, and the charger shuts off. The battery self-discharges, the charger comes on and tops it off, then shuts off. Repeat previous step until you use the tool next time. Plus Li ion also wear out with heat and cycling, so leaving it plugged in is slowly wearing it out. I've heard that you get the best lifetime out of Li ion by leaving it at 1/3 charge when not in use, then fully charge it for use. (or was that 2/3 charge?)

Re:Use a 'fan center' to isolate when grid power d

[ahfoo]

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 [globalspec.com]

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 [wikipedia.org]
http://en.wikipedia.org/wiki/Mppt [wikipedia.org]

Re:You're doing it wrong

[rs79]

" I should have probably elaborated a bit more. My point was, which I was admittedly unclear about, that since this is a hobbyist discussion, it would be a good idea to start small. Clock radios, electric toothbrush, etc... Once you've got that under control, use what you've learned from the experience to move on to the next level."

That's what I did. Butg once I got the laptop and the satellite working off solar the rest became suddenly far less important. Har.

Imagine if everybody in America ran just once device off solar power this year. And one the next year. The reduced power consumption and boost to the solar industry could only yield good things.

If you want to run just your laptiop say, you need about 20-40 Ahrs of battery which is under $200 new and about 60W of panels which is under $400, a $50 invertrer and a $29 charge controller. Now your laptop works forever, period. The batteries should last a very long time as they're not even breathing hard.

There are $99 6V deep cycle Exide industrial batteries at crappy tire. They're a good deal. The next step up really is the 800 Ahr 1500LB one that's 24V but that's overkill for most laptops.

The $99 15W panels at crappy tire are an extremely attractive price per watt. Forget tghe bigger sizes, get lots of these. Plus the bigger ones come with a terminal block and no wires. The terminal block is now outdated in soilar panels. The 15W ones come with 5 cabales, murettes, screwes... all this crap makes a difference when you're hooking up a number of them. Plus the 5 cables let you play all sorts of games.

Hot tip: use mirrors to concentrate light - even on cloudy days. I've observed up to a 3X iuncreas in power by adding mirrors.

Yes, you can overclock solar cells. No go get one and start playing dammit.

Re:Use a 'fan center' to isolate when grid power d

[smellsofbikes]

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.

Re:go 12 volt

[rs79]

" 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 "

And if yoiu do 4 you can run then off a car battery. Pretty much forever.

Plus, don't give up on dead car batteries. I have a 10 year old Optima (gel cel spiral wound deep cycle) that I killed this February starting my diesel. Although it was $180 new, 10 years is unprecedented for a battery, especially in a diesel,. But ow it's dead. It puts out a steady 9V nop matter how much you charge it. So it's useless for cars or anything 12V.

But it'll run 1000 hi pwer LED's for about a week, and I can charge it from the sun in under half a day. And it would have got thrown out.

Ask around golf coursds around this time of year. TGypically they may renew their golf cart bartteries and if you ask they may give you the old ones as they just dump them - thwy pay to recycle them actually.

There's a fella near here that got 6 free, a small generator and hge lives off grid for $50/mo in electricy fro a generator he runs once a week.

You think Tesla waited for a fucking tax rebate?

Get to work...

Here's how:

[RecycledElectrons]

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!

Re:Renewable fuel

[Anonymous Coward]

Just remember, crops grow on your own property for your own consumption are subject to Federal farming, drug, labor, and income tax regulations, among others because the Supreme Court opinions below have established that any productive enterprise in the U.S. that could conceivably affect interstate commerce, no matter how indirect or trivial, is subject to Federal jurisdiction.

http://en.wikipedia.org/wiki/Wickard_v._Filburn [wikipedia.org]
http://en.wikipedia.org/wiki/Gonzales_v._Raich [wikipedia.org]

Re:Use a 'fan center' to isolate when grid power d

[Anonymous Coward]

The issue of sync-ing to the grid does seem to be a little tough especially with the regulatory concerns. I would suggest you consider keeping your alternative energy system off the grid entirely. You can try to find some parts of the house that you want to supplement with your renewable energy and install a manual transfer switch to switch that section to your own "mini-grid". If the wind dies down, you can switch back to the utility if desired. There's a bit of inconvenience here, but I bet you can find a solution where you don't have to switch often at all.

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!

Re:Don't do it

[sjames]

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.