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?"

Renewable energy comer in many forms

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

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 http://science.slashdot.org/article.pl?sid=08/03/13/1710223&from=rss [slashdot.org] that can live on land and still provide us with delicious whale meat and oil.

Use a 'fan center' to isolate when grid power down

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.

One teeny problem...

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.

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

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

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.

Don't do it

> 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.

go 12 volt

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

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;
http://www.outbackpower.com/ [outbackpower.com]

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.
http://www.partsonsale.com/outbackgridtie.html [partsonsale.com]

Re:go 12 volt

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.

The purpose of the grid tie isn't to provide security or to support a critical load. The purpose of a grid tie is to prevent the home power system from powering the grid when the grid goes down - if you pump power into the grid when it's down, you risk the health and life of workers trying to restore the grid.
 
For example - A line went down that supplies my road. Before workers started repairing the line, they isolated it at the substation, rendering it safe. Without a grid tie the line remains powered from the home systems - which can kill.
 
If you have a critical load, put it on a UPS. Don't skip the grid tie unless your home system is entirely isolated from the grid.
 
Seriously, there's times to home brew and jury rig and save a few bucks, this isn't one of them. Do it right and don't put lives and property at risk.

Go 12 volt...and burn your house down!

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

Yes. [mini-box.com]

Re:go 12 volt

" 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...

Keep your cheapo gear off my power grid

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

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.

Not cheap

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

My partial solar solution in my grid tied house

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

A company called Solatube makes pre-made solar powered attic fans [solatube.com]

Re:My partial solar solution in my grid tied house

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.

hot water solar

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.

Burning a house down is the least of his concerns

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:Renewable fuel

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)

Re:Renewable fuel

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

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:Renewable fuel

Certainly the 30K investment would NOT translate to $30K in the value of your home. Your home's value would probably go up the $30K regardless of the power thing.

It would also take a very special kind of buyer to pay any significantly higher price because of it. You'd be severely limiting your potential buyer base.

But, if the price of the home was basically on par with others in the area, you'd probably have an advantage.

It's like swimming pools. They don't necessarily add any value to the home, and they attract only people that WANT a pool. A lot of people don't want a pool, as I suspect a lot of people wouldn't want all that extra complexity that a supplemental power generation system could introduce.

Only spend the money if you KNOW you will stay there long enough for this to pay for itself for YOU.