PV Gap

Lauren Said:

Need help with a chem question?

We Answered:

power reqd = 385/30 kW per month = 385/(30*8) kW/day = 1.60417 kw per day

efficieny = 15%

.15 kW requires 1 m^2
1.60417 kW requires (1/.15)*1.60417 m^2 = 10.69447 m^2

Frank Said:

Would Reflecting Mirrors Make Solar Energy?

We Answered:

This question is worth a look because while it's true that solar cell panels have a relatively low photovoltaic efficiency, why not keep bouncing the same beam of light on it, sort kind of like redepositing the same bad check at the bank until it goes through? Assuming that unabsorbed light reflects from the solar panels (it's a different problem if the reflection is diffuse), we can create a well between a solar panel and a mirror set at an angle to it, so that light infall reflects repeatedly inside it. It's an interesting problem, because I can see that there's a lot of design tradeoffs involved here, and it would depend on how light is scattered from the solar panels. Enough usable light has to be scattered from the solar panels to make it worthwhile, it's no good if the scattered light is at a different wavelength that's not absorbed by the panels.

I'm SURE solar panel engineers have already thought of this angle, pun fully intended.

Addendum: For those that think that efficiency of solar cells is "very high", check out the link to a chart showing that most solar cell technologies are from 12% to 24% efficient in converting sunlight.

Jay Said:

energy use and environment (frustrating problem, been working on for over an hr) HELPPPP?

We Answered:

If the sun shines for 8 hours a day and assuming there are 30 days in each month, then in a month the sun shines for 8x30 = 240 hours

If a typical family home uses 380kW-h per month, then the power they actually use per month = 380kW-h /240hr = 1.5833 kW

Sunlight has power density of 1 kW/m^2 & photovoltaic cells can convert this to electricity with 16% efficiency. This means that one actually gets 0.16 x 1 kW/m^2 = 0.16 kW/m^2 from the cells

so the square meters of cells needed to meet energy requirement of home = (1.5833 kW / 0.16 kW/m^2) = 9.896 m^2

Cindy Said:

Solar Powered TV Question?

We Answered:

Actual watts per square meter equals maximum watts per square meter times efficiency of photovoltaic cells.

Assuming your hint is correct:

Actual watts per square meter = (200w / square meter) x .13 = 26

Number of square meters required equals the number of watts required divided by the actual watts per square meter.

Number of square meters required = (400 watts) / [(26 watts) / (1 square meter)] = 15.385 sq. meters