# Science project Help

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I am doing a science project on solar panels and their effectiveness. Can anyone tell me if all solar panels generate the same amount of electricity based on their size (i.e. 2 sq. ft, 4 sq. ft etc) and where I might be able to find out how much electricity each can generate?

Amy

• Solar Expert Posts: 10,300 ✭✭✭✭
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Re: Science project Help

i'll get you started here and tell you that not all solar panels will produce the same for a given area. firstly let's correct the terminology here as these aren't solar panels as solar panels are usually in reference to panels that collect the sun's heat. these panels that produce electricity are called photovoltaic panels or as we refer to them, pvs. the reason for producing differently is due to different efficiencies and these are referenced to the standard of 1000 watts per square meter which is also known as 1 full sun. when you receive that amount of solar energy for 1 hour we call that 1 hour of sun. if you have clouds around that give you 333w/square meter per hour, your 3 hour total is 1000w or 1 full hour of sun. this is also the standard test conditions or stc. realistically you won't get this amount on a steady basis. others that are beter indicators are ptc and cec. you could either wait until somebody explains those to you or you can look them up.
getting back to it here, if you have a pv module that is 15% efficient(is good btw) and if that module also happens to be a square meter, then during an hour that has the intensity of 1000w/m^2 you will get 150w. that is .15x1000=150. you can look at some of the pvs in the northern arizona wind & sun store and see the power they are rated at with a notation of the current and voltage and how large the pvs are.
from there you go on to your controller which is a voltage regulator. there are basic 3 types and they are linear, pulse width modulation(pwm), and maximum power point tracking(mppt). the mppt does more than deal with voltage though as it boosts the current too.
i went more in depth with your question area than the other parts of the general parts of a system and they do vary as for instance some do not using batteries and are strictly tied to the grid. some have batteries and are tied to the grid too and makes it a kind of backups system, but on a larger scale. some don't connect to the grid at all, but there are batteries to accomodate times of no sun, wind, or hydro when using wind or water generators in conjunction with pvs. there is much more to all of this than i am saying to you and it's up to you to dig further, like there are rules to follow from the NEC or local municipalities also incorporate other rules they deem to be necessary with inspection for not just electrical, but structural as well and you have to have wires, fuses/breakers, connections, grounds, etc. this forum covers much of these areas and you have your work cut out for you. good luck.
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Re: Science project Help

Hi, Amy.

I'm not sure what grade level your science project is for, but if all you need is an appoximation, the answer is yes, the power out of a panel is proportional to area for each type of panel, the two main types being crystalline and amorphous. If your project needs to consider fine differences between panels from different manufacturers, or the advancement of efficiency over time, then that's beyond what I'll say here.

In practical terms, the solar panels today are all silicon, and are either monocrystalline, polycrystalline, or amorphous.  Mono- and polycrystalline panels are in the same ballpark (say, within 20% of each other) at power output per unit area, and amorphous is lower.  The panels made by Sunpower are more efficient - you can take a look at their website.

Take a look here

http://store.solar-electric.com/hiposopa.html

and click down on several of the panels to see complete specifications.  This will tell you the dimensions of the panels, and their power output.

The single-family installations I've seen seem to take the majority of space on one roof surface to provide for the electric needs of the house.  But if the house is in a hot place that needs air conditioners in the summer, or a cold place that needs electric heaters in the winter, even that whole roof surface is generally not enough.  You can take a look at your own electric bills to see how much energy your family uses in a year.  Again, as a crude approximation, if you're in an area similar to mine (Northern California), you can take the watt-hours of a panel, and multiply by 1.6 to get kilowatt-hours you would expect to get in a year.  So if you had a 100-watt panel, you could get 160 kilowatt-hours out of it over the course of a year.  If you live in Phoenix, you would get more, if you live in Portland, you would get less.

I hope the others here aren't cringing at the inexact nature of this answer, but I hope this is enough to get you started.  Try searching the internet for "photovoltaic efficiency" or "solar cost effectiveness" for more info.