Solar Panels?

wizendwizard

I am thinking of installing solar panels to my personal home.

I recently saw on TOH in green building they were actually producing enough energy from solar panels to run an entire 2800 sq ft home. It was said to back feed the meter and make it run backwards.

I have 1500 sq ft. How many panels would i need to install to make this happen?

Not asking for a quote, just seeking info to educate myself before dealing with a contractor on this.

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DAVIS081404

You will need to review your usage history to find that answer. Generally this takes your last 12 months utility bills to find an average KWH ussage. For new homes we recomend 2 watts/ft.

Magnettica

You'll also want to consider installing a battery to store the energy when you're not selling it back to the utility.

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mdshunk

I'm no mind-reader, but I think that I can easily say that when you find the total price of all the equipment you'll need, you won't do anything. You'll have at least 25K involved.

sniperelectech

I agree to that if you buy the battery back up system with it. Do the math and crunch the numbers of how many years it would take to finally break even on your solar power system. The average homeowner lives in there house 7 years before moving. My guess is you will have wasted your money unless your trying to safe the earth and that is priceless to you.

wizendwizard

This is a restored family home we've been in this house going on 35 years and I intend to die living here. Not to mention that it would be a fantastic selling point if I were to ever put this home on the market.

MD, I did the numbers and it seems the system would pay for itself in 7 years. That would be in accordance with the $25,000. If i do this it will be a hard hit at first but the fact that it pays for itself and makes the system self reliant is quite impressive.

The overall savings on a monthly scale after paying for itself saves me or my family $100,000 over the next 30 years which is the life of the panels themselves.

All in all..a wise investment i think.

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mdshunk

Keep researching. You'll be on battery on cloudy days and at night, and those expensive forklift batteries don't last that long. Not nearly. You'll have thousands of dollars every few years in batteries.

Do what you want to do, but as an "investment", solar makes no sense whatsoever at this point in history. Just keep researching.

Magnettica

I saw Tom Silva installing roof-mounted, solar-powered attic exhaust fan once.

That was pretty cool.

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neolitic

Pretty sure most of the newer generation
solar systems have left the "off the grid"
mentality behind.
They are meant to integrate with the POCO,
and make provisions for sell backs.
More POCO back up than battery on the
ones that are starting to be commercially
viable.
I'll try and come back with some sourcing when
I have some idea where I might have been
reading on this lately.

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woodchuck2

I agree, i have looked into this already several years ago to get off the grid. There only 4 states in the union that offer grants or tax write offs for solar energy, Cal. and Arizona are two of them, i cant remember what the other two are but i do know they are on the western sea board. Like said this system will cost $25k at minimum and the batteries need replacing every 4-5 years. You should also buy a battery tester too which will be a couple hundred bucks too. This system is also computerized too so it senses line voltage and will supply power when there is no sun and the batteries are low, the system needs to know when the grid is down so there is no back feed or you will have someones life in your hands and of course so the Grid company can reimburse you for the power you supplied. The life expectancy is around 25 yrs so will it really pay for itself after 5 sets of batteries and the headaches?

bauler

My question has always been, do the panels really last 20-30 years. I doubt it. Especially out here in the desert southwest. I bet the fine print in the warranty excludes practically everything. I wouldn't want to bet my contractors license on it. Solar is great for some applications, just not quite ready for a whole house.

newenergy

If you have net metering you generally won't want batteries. You get power from the grid when you aren't producing enough and you sell it back when you are producing more than you need. You are using the grid as your battery.

If you do have batteries though, decent ones will generally last about 10 years if you don't abuse them.

A typical panel warranty is for at least 80% production in 20-25 years. Photovoltaic panels are very reliable. The first silicon cell made in the 50's in Bell Labs is still working.

CNC

A SOLAR GUY! just what this thread needed, so technology is improving? Or a solar panel system, with no batteries is worth it? Give us some insight? it got quite.

newenergy

It depends on a lot of things. My last proposal had a payback period of less than 7 years. California has good rebates, very expensive power for someone who uses a lot and is in a public utility, and a lot of sun so it's good here.

There are several other states where conditions are favorable as well.

Technology has been improving, though PV (photovoltaic) panels have always been reliable. They are a LOT tougher though. People who aren't too heavy and walk carefully will even walk on them during installation. I understand they used to be very fragile and would often break in shipping.

Demand has been huge, so prices haven't come down for a few years. Production is increasing though so prices should come down in the next few years. The main raw material is like the second most common element on earth and is in sand, so it's just a matter of manufacturing enough. By far the biggest demand the last few years has been in Germany where incentives are much higher.

Battery backup is expensive, but in some cases people want it anyway because they have life support or something like that that needs backup. It's also a practical alternative if you live in the middle of nowhere and all your choices are expensive anyway.

One other thing about improving technology - the inverters have definitely improved a lot and costs for them have come down quite a bit.

Ed the Roofer

NewEnergy,

Are you familiar with the solar roof panels integrated with the roof membrane, such as the one from IB Roof Systems?

Also, what about solar roof shingles or tiles?

Where is an accurate source to do research for myself?

How do I calculate the energy savings comparisons if I wanted to point out ROI to a purchaser? Are there online calculators?

Also, whay about nanotechnology, where I read it can be integrated with paint and pick up energy somehow?

Thanks,

Ed

newenergy

I've never installed any of those things, but I have read a lot and talked to some salespeople. I did a proposal of a solar shingle, but that product lost its UL listing I think because of the wiring required in the attic space. Solar tiles, as opposed to shingles keep the wiring out of the attic (at least the product I know) and are still ok.

I know a company in LA that builds custom amorphous solar panels to integrate into roof systems. They do a lot of work on gas stations.

The most comprehensive financial tool for solar that I know about is by Andy Black at ongrid dot net . It's kind of expensive though. I just do it myself. I gotta get going, but I can go through an example later if you'd like.

The nanotechnology stuff is for the future. I don't know how far, but it's not commercially available yet - at least not outside very special cases. Who knows though, it could be never or just a few years away.

I don't think it will ever be worth it or necessary to paint walls with some solar paint, but I wouldn't be surprised if in a while there were very cheap solar tiles and maybe those would have some nano-technology or something that they use in the factory. You still have to have wiring for all this stuff and assemble it safely as you are dealing with a lot of power when you put it all together.

mickeyco

.......

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newenergy

(ug. I didn't notice this was an old thread and I'm repeating myself. I guess I'm getting old. I added some more stuff, so I'll reply anyway. An update for Ed the Roofer though. I recently saw some solar tile product from Open Energy which looks very good. Roofers do the installation with an electrician doing some checking and doing the work after the wires leave the roof. They also have a product for flat commercial roofs. There are a few more products if you're interested)

South Carolina gets about 5 to 5.1 solar hours per day. What that means is that you get the equivalent of an average of 5 hours of 1000 watts/square meter of sun every day. This is averaged over the whole year.

This is important because the output of solar panels is rated in how much power they produce when there is 1000 watts/square meter of sunlight. That is the STC rating which is usually what you see when you buy a panel. It is also rated at 25 degrees C and a couple other conditions.

In the real world there are derating factors. High temperatures, dust, losses in the inverter, losses in the wires, and probably a couple other things will make it so you get less power than the panel rating. The orientation and tilt of your system will also affect how much power you are getting. You might start by derating the system to about .8 or .75 and then again multiplying by about .9 or so if you have to face east or west or have a flat roof (and aren't tilting the panels). The perfect orientation and angle is true south (magnetic is off) and tilted at the angle of your latitude.

So, multiply the total watts of the panels (just add them up) by about .8 to get the real watts, then multiply by 5 to give you how many watt-hours a day you'll be making on average.

If you are net-metered/grid tied, you will always have power and will always be able to sell back to the utility when you are using less than you generate (not counting when power is out for the utilities). Battery back-up adds a lot of expense and maintenance.

SC seems to have a 25% tax credit. This is very solid. This, along with the federal tax credit will most likely make it possible for you to have very good economic return on the investment. The cost of your electricity is a big factor in determining that.

If you don't mind using factory seconds you can get good prices. I've heard good things about http://www.sunelec.com/ . They say some of the seconds they have are only cosmetically damaged and qualify for all state rebate programs. You should verify that for your state/utility.

You may move soon, but there is a study by Wells Fargo and/or The Appraisal Institute showing home improvement related to energy efficiency are good economically. I know that's vague, but I don't want to misquote the numbers.

There are lots of states that have lots of grants/tax credits/rebates. http://www.dsireusa.org

Again, batteries add a ton to the cost and are clearly not cost efficient unless you are off-grid, which in many cases means that utility power is not an option. If you just want back-up power for when the utility is down a generator is much more efficient. Battery back-up not only means expensive batteries that have to be replaced often, but it means sizing the system larger so that you can charge the batteries and run your house during good weather, so that you can still run your house during bad weather.

Life-expectancy is longer than 25 years for the panels. They are typically warrantied to be producing at least 80% of their rated power in 25 years. They will keep producing for much longer. The first silicon solar cell ever made by Bell Labs in like 1954 is still producing power.

Oh wait, I already said this. It's an old thread. Oh well.

Ed the Roofer

It wasn't that old of a thread and your information sounds very informative and useful.

I will definitely be checking the links and manufacturers you supplied and if you run across any more, I will check into those as well.

Thank you.

Ed

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mickeyco

When we can get $25.00 solar panels, I'll think about getting some (I did have one on a trailer), until then, to me it's not worth it. Of course that might be because of where I'm located, but I don't see the value for anything other than mobile and rural applications where you're off the grid.


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