PV Gap

Everett Said:

How many volts of electricity does solar panels generate?

We Answered:

The link below shows a fairly typical 12V panel with 36 cells of the silicon polycrystalline type.

- You will see the O/C voltage is 21.6V. This is the maximum voltage with no load connected, @ 25C. There is no current.
- The voltage with maximum power is 17.3V. This corresponds to the voltage with the optimum load current to get the most power from the cell. It applies at the standard illumination of 1000W/m^2.
- The voltage drops further as the load is increased. If the load attempts to draw more current than the limited current provided by a given illumination, the voltage drops. With a short circuit there is no voltage, but a current representing the illumination.

You will also see the maximum system voltage is 600V, which is the insulation rating of an individual panel. It shows that a number of panels can be connected in series up to 600V for use with larger systems. That would be something like 26 panels. The voltage and current from such a panel string even with moderate sunlight can be considered as dangerous. More than 2 of these panels connected in series can be considered hazardous.

The voltage is relatively independent of the illumination at around 600mV per cell at 25C. It reduces with increasing temperature, and increases at lower temperatures. The cell voltage may also depend on the cell type, and there are panels with different numbers of cells to the 36 cell x 12V panel described.

Agnes Said:

How much power can 10 square feet of solar panels generate?

We Answered:

depends on the solar panel. for most commercial panels, ten square feet can get you 50 to 100 watts.

Tim Said:

How much power could a car covered in solar panels generate?

We Answered:

It depends on how big the car is, but in general the answer ends up being "not much". There's about one kilowatt, a bit more than a horsepower, per square meter of sunlight in good sunny conditions with the sun close to directly overhead. Current common solar cells have a conversion rate of about 15%, as you said. So, if a car is two meters wide, and three meters long, this will get you 600 watts, about 8/10ths of a horsepower, under ideal conditions. These conditions are that the sky is clear and the sun is close to directly overhead, and so on.

As far as how advanced solar cells will change this, the best available now are around 35% efficient. These are intended for space use where every little bit of weight savings counts, and are much, much more expensive than conventional solar cells. Use of these would get you over 1.5 horsepower under ideal conditions. The maximum, assuming hypothetical 100% efficient solar cells, something we have no idea how to make currently, and which will probably never be possible, would, like I said, be about 1kW per square meter of car space, again assuming ideal conditions.

It is possible to make a solar powered car that is fully driveable and can cover a good distance, but it's going to have to be very lightweight, very aerodynamic, and have an extremely low rolling resistance if it's to have anything resembling reasonable acceleration and top speed.

Jenny Said:

How many watts do solar panels generate?

We Answered:

depends on the size they generate about 10 to 200 watts

Philip Said:

Solar panels that generate the most electricity?

We Answered:

The most efficient ones that you can buy on the open market are probably the Sanyo HIT. Sunpower makes more efficient modules, but they are only sold to installers. You can probably buy one if you poke around.

When people say price is no object, usually, they realize that price is an object when the see the cost of more exotic technologies. It would theoretically be possible to hire an engineering firm to design a durable, custom panel for you, built out of Spectolab triple-junction cells. I'd put the task at $50,000, plus $50,000 for the cells, for a 200-watt panel. I'm not aware of anyone doing this, as one can get the same power panel for less than $1000, only it would be perhaps 25% larger in area.