PV Gap

Ivan Said:

Love you forever if u can help me......energy?

We Answered:

1. 10 mA at 200 W/cm² means 30 mA at 600 W/cm², since we're told that the current is proportional to the intensity.
E = IR = (0.03 A)(4 ?) = 0.12 V.

2. P = E²/R = (0.46 V)²/(400 ?) = 5.3×10^-4 W = 0.53 mW.

Marion Said:

Electricity Output Help?

We Answered:

i. 1.2 kW --- 11 sq ft
x kW --- 1200 sq ft (for one solar panel)

x = (1200 * 1.2) / 11 = 130.909090... = 130.91kW

ii. 130.91 * 5 = 654.55 kWh

iii. Considering that 1 mile = 5280 ft
100 miles = 528000 ft
Square footage: 528000 * 528000 = 278784000000 sq ft
1.2 kW --- 11 sq ft
x kW --- 278784000000 sq ft

x = (278784000000 * 1.2) / 11 = 30412800000 kW

Power consumption: 30412800000 kW * 1/3 h = 10137600000 kWh

Connie Said:

Those who speak English, can you help?

We Answered:

The first application of Photovoltaic electricity were for space craft. These were crazy expensive but were the only practical way to power satellites.
The sentence refers to the first applications on the ground. For remote telecommunications or weather observation sites running miles of wire to power commercially would cost a lot. Manning a site to take care of generators could be done, but anelectricityy source that did not require fuel would pay for the upfront cost.

Cynthia Said:

What colleges offer courses related to solar technologies?

We Answered:

Any college which races solar cars every year like University of MD, Virginia Tech, MIT and others.

Henry Said:

the best material for PHOTOVOLTAIC CELLS?

We Answered:

Depends what you mean by best.

The cheapest ones are made from silicon.
The most efficient ones are made from multiple materials (called multi-junction cells). I'm not sure exactly which materials the highest efficiency cells are made of though.

And if by best you mean most promising (which would be a pretty weird 'best' I guess), then those would be thin-film solar cells (an example would be cells made of a material called CIGS, or copper indium gallium selenide). Thin-film cells may eventually have the best efficiency/price ratio.

As for the conductivities; semiconductors can be doped to changed their conductivity (one of the major reasons for using semiconductors), so there isn't a single conductivity value for any of the semiconductors (unless you use the 'intrinsic' value, which isn't representative of the materials in solar cells).