How many panels?


Old 12-02-09, 12:25 PM
Thread Starter
Join Date: Nov 2009
Location: Greece
Posts: 103
How many panels?


I was thinking of installing an electricity based method for heating up my house and I thought of installing some solar panels just for covering the electricity that is consumed from the electric heaters.
Problem is that after making the calculation for the electricity needs in kw I used some of the online calculations methods in order to determine how many panels I would need but with inputting the same data in each of the calculation programs I got very different results from each.
Does anyone know a reliable calulation program or a formula that will determine the number of panels needed for producing an X amount of energy per year?
Thank you very much

Last edited by Volnix; 12-02-09 at 12:25 PM. Reason: forgot something
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Old 12-02-09, 12:58 PM
Join Date: Aug 2009
Location: USA
Posts: 4,941
I don't know of any software for making that calculation, but I do have a few questions. How do you plan to heat your home during the night? Will you use electricity off the grid to do that? If so, maybe using the evacuated tube solar panels to heat water for a hydronic system may be better. That way you can use natural gas to heat at night. It might be cheaper to run than your electric setup. Just an idea.
Old 12-03-09, 12:29 AM
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Join Date: Nov 2009
Location: Greece
Posts: 103
Thanks for your reply. What I was thinking off was installing some solar panels that will produce the electricity that will be consumed per year from the electric heaters. These will be operating from electricity from the grid.
I thought that by using the panels I would produce the energy for the heaters from the solar panels instead of choosing another option which will require a water pipe line installation.
I found some calculation programs on the internet to calculation how many kw the panels will produce but the results differ from one to another and I also found one that calculates how panels to install but the results differ also.
Old 12-03-09, 08:10 AM
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Join Date: Mar 2003
Location: CANADA
Posts: 893
Hi Volnix

I'd suggest that you check this website of the Department of Energy. It has lots of energy resources
Old 12-03-09, 08:20 AM
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I'm not sure anyone realized the poster is in Greece?

You aren't going to be able to calculate anything until you decide on the supplier of the panels. Not every PV panel produces the same output. Once you decide where you will buy, then contact the seller/manufacturer with your power needs and they will be able to assist you.

Electric heat, whether it be portable heaters, baseboard, radiant..whatever, will require very heavy loads (amps) when operating. You will probably not be able to put enough panels up to supply the load directly, so you will need a storage source, normally batteries. This will mean you need to consider storage and ventilation. You will also need the electronics required to convert from DC to AC.

This can be a DIY project, but not w/o professional engineering and design of the system.
Old 12-03-09, 09:33 AM
Thread Starter
Join Date: Nov 2009
Location: Greece
Posts: 103

I didnt think about batteries. I was thinking of just installing the panels connected to an inverter which will be connected to the supply.
This can be a DIY project up to a point, but starting to solder the cells to make the panels might make things more complicated...
I have seen a few solar panels specifications and they state the kw output but in order to calculate the average output of the installation per year there are also probably several factors in the calculation of which I have no idea of.
Old 12-04-09, 09:12 PM
Join Date: Dec 2009
Location: montana
Posts: 6
solar calcs

here's a starting point....

U.S. Solar Radiation Resource Maps

you'll end up concluding that it would be cheaper to build a super insulated passive solar home from scratch than it would to put up enough solar electric panels to run your electric heaters.

i installed at 1.3 kilowatt system 3 weeks ago, (street value $10,000 before rebates) and i just calculated today that so far, I've generated almost $3 dollars worth of electricity. (granted, its nearly the winter solstice here in montana)

there's a great magazine out there called "home power"
Old 12-28-09, 12:01 PM
Join Date: Dec 2009
Location: ma
Posts: 12
solar panel for heating

solar hot water is a better approach for heating there are baseboard/ radiators systems made for this. Solar voltaic panels probably won't provide enough power. Home power is a good resource for more info.

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