Photovoltaic Systems

[tayj_2000]

I am wondering what size solar panel I'd need to run a 400 watt light bulb. In addition, how should the rest of the system be set up, i.e. should I use batteries or an inverter or what?

[deleted-71712]

Hi tayj_2000,

Welcome to the forum!

This isn't something that I've done before, but I'm going to try to provide some general resources, and there might be someone around who has specific experience in this area.

This article [ http://science.howstuffworks.com/solar-cell6.htm ] has a discussion of setting up solar power for a home including some of the components you mention. While a residential system is a somewhat larger scale than you're looking at, 400 W is still a lot. If your goal is to gain experience with a fairly large solar-cell system, then that makes sense. However, if it's a smaller part of something else and you want to minimize the hassle, you might want to consider whether 400 W is really necessary. Most incandescent bulbs around the house are between 25 and 100 W. You could also look at CFLs, which can use around 1/6 of the power to produce the same amount of light:
http://www.popularmechanics.com/home_jo ... 15199.html
http://en.wikipedia.org/wiki/Compact_fl ... cent_lamps

Back to solar panels: The HSW article linked above estimates the cost to be $9 per peak watt -- "peak" is key, because the performance of a solar cell depends on the amount of sunlight available, which varies with time of day and weather. If you wanted to charge a large battery, you might be able to use panels with output much lower than your bulb's rate of energy consumption -- but you'd have to charge the system for a long time in between uses. So whether that makes sense depends on how you want to use the system. This website [ http://www.solarpanelstore.com/solar-po ... anels.html ] has info about many different models of solar panels. The largest single panels go up to around 200 W. For example, one has 165 W peak output, weighs 37.5 lb, is about 62" by 32", and costs $770. If you look in the small solar panels section, you can find a 10 W panel that's 20" by 14" and costs $118. (These don't exactly match the $9/W figure. There are plenty of other retailers, too -- just examples here.)

Another thing to note is that if you're planning to combine multiple components (solar panel(s), battery, inverter, etc), you'll have to make sure that voltage and current outputs are compatible so that you don't accidentally fry one or more pieces of equipment. Power is the product of voltage and current (P = IV), so you could get the same power output from different voltage and current combinations. Most devices have ratings and specifications, and you can always contact the manufacturer or do more research about electronics.

Hope that helps -- let us know your currents thoughts about the project, and maybe we can help more!

Amanda

[deleted-2574]

Hi tayj_2000,

There's a good discussion of solar panels at http://www.answers.com/topic/solar-panels-1

This page includes a discussion of solar cell efficiency and angles of mounting of the solar panels.

Following a link from this page one gets:

http://www.answers.com/topic/solar-cell?cat=technology
which includes background on "How is a solar cell made?" and other solar cell background.