Needing some input into what other solar powered home / hangers . How many watts ? What about efficient ? And battery's types and how many , voltage etc. I can read the ads that have glowing description want real world experience . Several hangers at airport have those 45 watt units from harbor freight to runs lights and some other devices. Need bigger unit for house to decrease utility bill especially in summer . Thanks Bill Reid

I owned a solar home for many years in Laramie, using a Tromb wall for heat supplement and a large panel for hot water supplement. Photo-voltaics for electricity were not even remotely available at any decent cost at that time, so I didn't consider those.

The Tromb wall worked pretty well, as my winter time fuel costs were quite low. I also had a pretty efficient catalytic wood stove, which I would fill up in the evening as the Tromb wall started to cool down, and again stoke in the morning before the sun started coming into the windows. So the gas furnace didn't come on much, other than in the mornings before I had stoked the wood stove; it had a timer thermostat to kick on at 5:45, I would have the stove stoked by 6:30, and the furnace would be off by 7:00 or so.

The Tromb wall, if properly utilized, is cost effective. It involves mostly a lot of solid mass (concrete) heated by the sun through large windows, and then drapes to close off the drapes to keep the heat in at night. It would remain warm to the touch well into the night. Of course, the house has to be pretty well insulated (mine had a foot of fiberglass in the attic and 6" of fiberglass in the walls) to benefit.

But the equipment for the hot water system, which involved the panels on the roof, the pumps, and an additional water heater with a heat exchanger heated only by the panels, plus all of the plumbing, was pretty pricey. I calculated about a 16 or 17 year payback, assuming no equipment breakdowns, due to only a little savings on the gas to run the regular water heater and the cost of maintaining the solar system (replacing the anti-freeze every 2 years, mostly). Then when one of the pumps failed, that payback got extended by a few years--they're expensive! So I concluded that the savings of having solar heated water just wasn't worth it, and I would not do it again.

I understand that photo-voltaic systems have been improved a lot, in the last few years. In fact, there's an outfit here in Fort Collins that advertises its "solar shingles", and I've noticed several houses on my route to the airport which have much of their roofs covered with photo-voltaic panels. But how well they work and how much they cost, I've not considered--although with the cost of electricity these days especially running the AC in the summer, that might be worth it.

Cary

We live 90 miles from the nearest transmission grid system and power both our house and hangar with solar power most of the year. Winter time here in Alaska is not conducive to solar power so we must use a generator for a couple hours each day to help charge our batteries for when the sun is not shining. Ours is a 12 volt system powered by 1000 watts of solar panels. We store the power in six L-16 deep cycle batteries (each weighs approximately 115 pounds). The batteries give us roughly 1300 amp-hours of storage. We bundle the power at the panel at 48 volts and then download to the batteries configured to 12 volts using an Outback controller. We invert most of the power to 115 volts AC but run some of the key appliances, such as the freezer, using 12 volt DC current.

While the system is adequate for most of our needs, the hangar door motor requires more than the capacity of the system so we use a 5 kw generator to raise and lower the door. Every thing else in the hangar runs on 115V inverted solar power. Occasionally I have power-tool needs that exceed the capacity of the system, and run a small 2000 watt Honda generator as necessary. We designed and installed our entire system and it has worked flawlessly for several years -- we love it. The capital cost is somewhat high, but better then the alternative of continuously running a generator -- and it is noiseless (except for the hum of the inverter).

Nizina

There are a number of variables in determining what size solar electric system is best. Some things to consider:

A rule of thumb is 1 watt of solar panel power for each AH (amp hour) of battery bank capacity. If you are using a grid intertie, where excess power is being sold back to the utility company, then the battery bank need only be sized to carry you through cloudy days and power failures . . . so the one to one ratio would not apply.

In order to determine the system size, you'll first need to do a load study, i.e. how much power do you need?

Many, including me, think that even with the price of panels now below $2 per watt, unless you are doing your own installation or there are other extenuating circumstances, solar panels still don't quite noodle out, money wise or green wise. The energy used to make solar panels was in excess of what the panel would generate in its lifetime - - don't know it that's still the case though.

For off-grid and RV systems, solar makes much more sense. We almost never camp with hook-ups, so I have a 400 watt array on my motorhome roof along with a 2000 watt inverter. We can run the microwave without starting the generator.

bumper

182 STOL driver wrote:Needing some input into what other solar powered home / hangers . How many watts ? What about efficient ? And battery's types and how many , voltage etc. I can read the ads that have glowing description want real world experience . Several hangers at airport have those 45 watt units from harbor freight to runs lights and some other devices. Need bigger unit for house to decrease utility bill especially in summer . Thanks Bill Reid

Bill,
As one of my day jobs is solar power of all types, your query is like a newbie to flying asking, " I like the flip up window on the J-3, but the air stair on the G-IV is neat too, which should I get? I won't even attempt to line you out, other then to give some good sources for further reading: Home Power Magazine (www.homepower.com) by far the best info source out there, not bs and pie in the sky like other publications, just real life info warts and all. They have searchable cd's covering years of past issues, anything you want to know is there and it will be accurate.

FWIW, anyone who has a Harbor Freight solar panel setup automatically is disqualified from offering up any info on the subject, as they clearly don't know they are doing, just saying.

bumper wrote:Many, including me, think that even with the price of panels now below $2 per watt, unless you are doing your own installation or there are other extenuating circumstances, solar panels still don't quite noodle out, money wise or green wise. The energy used to make solar panels was in excess of what the panel would generate in its lifetime - - don't know it that's still the case though.

That hasn't been true for quite some time. The energy payback is now 1-3 years depending on how sunny the install location is. The entire industry will have paid back all the energy ever used (including when the panels were harder to make) around 2020.

So why doesn't someone here just list out a nice little package to start out with. Say cover 1/2 a average home use, grid tie option, add on option to cover more later on? Size of panel, inverter,etc etc etc and just list out what I have to buy and where to get it?

Bighorn wrote:So why doesn't someone here just list out a nice little package to start out with. Say cover 1/2 a average home use, grid tie option, add on option to cover more later on? Size of panel, inverter,etc etc etc and just list out what I have to buy and where to get it?

My current project is a simple 6 KW grid tied system (no battery backup, in case of grid failure light a candle or buy a generator, batteries are a PITA, unless you're off grid, a whole different subject) for a local vet. Not counting the licensed electrician to wire my arrays (2 pole mounts of 3 KW ea.) to the panel, it came in at $20,208.00.

How much power is that? Here's how you figure it: an average of 6 hrs full output per day year round= so 36 KWH per day LESS system losses (dirt on the panels, wiring losses, inverter losses,) you knock off 20 to 30% of that, lets call it 25% (just like a 300 horse pickup doesn't get 300 horse to the pavement, you have unavoidable losses) so 27 KWH per day. Times 30 = 810 KWH per month as a conservative estimate. Get your power bill out and see where that gets you. Then figure in any and all tax dodges/credits/deductions you think you can get away with, (possibly unlike writing the monthly check out to your utility, might as well take that cash out of your wallet and set it on fire). Then ask yourself "is the price of electricity going to rise or fall in the next 30 years, (I have panels over that age, still working fine) and do I think I'll continue to use and need electricity"? And don't forget....you had to earn and pay taxes on the money you give on a monthly basis to your power provider, I keep that money in my pocket, a penny earned is a blah blah blah.

FWIW: This is coming from someone who has not paid a power bill, or a heating bill, in 35 years, and who won't until I kick the bucket. Free hot water all that time also. I could have pissed the money away it cost me to get set up (new pickups, ATV's, etc., etc.airplanes don't count of course) and just paid a bill every month like most, but I spent a chunk up front and now I'm done, for life Most will just pay the monthly bill, some misfits and malcontents like myself like taking charge of our own power production and frankly I could care less about payback.

Solar panels are about to take a quantum leap down in cost, down in weight, and down in energy needed to produce (green-ness) with thin-film pv as well as up in applications. Pretty soon they will be "printing" solar panels with a deposition process on flexible substrates rather than the current technology of growing semiconductor crystalline wafers (which competes with electronics for raw materials too).

http://www.pvthin.org/

I have a 7kw system on my house and have not had an electric bill for usage since it has been commissioned almost 4 years ago. The easiest way to size the system is first determine how many kwh's annually you will use or currently use. Go to PV watts website http://rredc.nrel.gov/solar/calculators/pvwatts/version1/ use the calculator to see what size system you would need for your location, tilt and azimuth to produce the needed kwh's annually.

For sake of ease and lower cost I would recommend sticking with grid tied and not mess with battery backup unless you don't have grid available of course.

Courierguy
I sure wish I lived closer to you, I'd come out and help on a job for nothing just to learn. The whole subject is fascinating to me and I would love to build something even small just even run some lights just to say I did it. There seems to be a mystique about the whole thing on which panel and that inverter, and this switch etc etc and then get the straight skinny from a salesman is another whole issue. For me , I would not want to hire it done,1) wouldn't learn anything and 2) miss out on the enjoyment of accomplishment.
Any place to land a 206 in your backyard ........

Thanks and keep posting especially about your solar jobs, like reading them

Bighorn- if you have the spare time and the course fee, these guys put on some good trainings:

Solar Energy International

I lived off a 60 watt solar panel, and (1) "group 27" gel battery for about 12 months. Tropics only, just needed lights to read at night. Circa 1991, Hawaii.

I've been working around solar power transmitter sites for close to 30 years, and the bottom line is that when you include the price of replacing the solar panels and batteries as they wear out, and the in ongoing maintenance, it is a lot cheaper to buy power from the power company. solar panels are typically warrantied for 90% power output after 10 years, they usually produce 50% or less at 15 years. car batteries, deep cycle marine batteries and golf cart batteries don't last more than 1-2 years of average use. sealed gel cells and absorbed glass matt batteries can last up to 20 years but they are expensive. The battery stack I have installed several of recently is 1040 amp/hours at 48 volts, it weighs over 3 tons, and costs $16.204.00 Small sites can be put up about anywhere with some panels and a small battery bank, but a major site that has critical equipment gets very expensive to design and build. we have one site with 39 tons of batteries in it, and they have a life span of 15-20 years before they become 39 tons of hazardous waste to be disposed of. In my experience if it is possible to run commercial power to a site, that is the cheapest way to run it. As for the "new thin-film" solar panels, I have been reading about them for at least 5 years, every article says they will be on the market in 6-12 months. I'm not holding my breath waiting for them. One more thing, the price of copper wire to install these things is disgusting right now.

You don't specify how you determined solar panels degrade to 50% output in 15 years, that is certainly not my experience and many others. Did you flash test under lab conditions, or test them in the field with a pyranometer while adjusting for less, or more then standard conditions? Or is this just a guess based on whole system problems (could have been the batteries or wiring losses/problems in other words).I can't let that statement stand, no more then if someone said "all small airplanes are dangerous"! I've been around them too long, living with them day to day, and don't see the degradation you mention. On the contrary, I've seen panels putting out MORE then their rated power more often then not after the time frame of 15 years, part of that is the thinner air up here as they are rated at sea level.

Comparing the price of their power to the grid misses the point, if we're talking off grid applications it's a given grid power is simply not available, period. They sure beat a generator!

I'm with you on the batteries, don't use them unless you have to. But, I recently bought a little over a ton of FIAMM AGM 580 AH batteries from a electrical contractor who sold them to me for 100 bucks. My local recycler, after seeing them, offered me 26 cents a pound for them, so $572.00. The first battery place said they were worthless, then gradually went up to 12 cents a pound. The place that offered me more did their homework and got educated on the amount of lead in them. I ended up donating half of them (for a juicy charitable donation receipt) to the local Ski Patrol for their new warming shack PV system I am putting in for them at cost, and sold the other half for $500.00 for an off grid cabin system. They came out of a natural gas pump station and were part of the backup power system I guess.

Another 3,000 lb battery (Absolyte GP's) that also came out of some industrial backup system, has been in use for 4 years now on a remote ranch. We have 240 VAC with dual inverters, and besides moving 14,000 gallons of water a day we also run a 2.5 horsepower squeeze chute and electric branding irons. The battery may be below specs but still offers great servie, I paid 500 bucks for it.

Thin film, I'm not holding my breath.

A 3,000 watt grid tie array going out of the shop, another one will be towed out on a trailer behind, so 6,ooo watts going down the road. Once on the jobsite I'll lift them both up with the crane and set them on the vert pipe installed earlier. This pre fabbing allows me to work at home, in the shop, and spend the min time elsewhere, the crane makes it easy

Measuring output on a panel is simple. wait until solar noon on a cloudless day (about 1:00 pm daylight savings time), disconnect the charge controller and put a resistor and voltmeter across the panel. Watts = voltage squared devided by resistance. (W=v2/r). use a resistor that will give about the rated voltage of the panel at full power, for a 100 watt 12 volt panel use 1.5 ohms, for a 50 watt 12 volt panel use 3 ohms. The panel either produces rated power under load or it doesn't. I realise that some places it is not possible to get commercial power at any cost, most places in the lower 48 can get power, but it may be VERY expensive. The trade off on large sites is the long term price including replacement cycles and disposing of old batteries. One state site was built as solar because it cost $25,000 less than several miles of power lines, but when the batteries need replacing they will cost at least $150,000, probabally more. It would have been cheaper to buy the power lines in the first place. GNB cells in particular no local recycler will take them more than once, because the equipment they use to cut the cells open on car batteries will not work on them, they're to big. Also buying and selling used GNB cells or similar batteries can be dangerous to your buisness, the cells are serial numbered and when they finally give out if someone dumps them in the woods the last tracable owner can get stuck for "enviormental cleanup costs" by the EPA, this has happened more than once. the state will not give away or sell any used battery because of this, when they are removed from service we recycle them to get rid of any possible liabillity later on down the road. As they used to say in the Catterpiller ads, "there are no simple answers, just intelligent choices".