PV Gap

Janet Said:

In photovoltaic cells, electrons flow from boron-enriched silicon to phosphorous-enriched silicon to generate?

We Answered:

boron is n type
phos is p type


current goes form n to p
electrons goes from p to n
electrons go from Phos to Boron doped

FALSE

Rebecca Said:

Those who speak English, can you help?

We Answered:

Photovoltaic cells are devices that convert light into electricity. Silicon is sliced into wafers, which are used to produce cells, which are connected into modules that produce electricity. Different companies produce these items, each adding value to their product before moving it along to the next level.

It would be similar to a steel plant supplying metal to shops that produce sheet metal, fasteners and parts of many kinds that then are purchased by an automobile manufacturer who assembles them into a car. Each company takes someone else's finished product, which becomes their own raw material, converts it to something else which is their finished product. That becomes the next company's raw material to be used in production. Each has added value along the way.

Donald Said:

does the semiconductor in a photovoltaic cell need to be silicon? Are there cheaper materials that can be used

We Answered:

well the only other element used in semi conductors to my knowledge is germanium. i have never heard of a germanium solar cell. semi conductors occupy a certain place on the periodic table of elements. it's the atomic structure that gives them this special property.

Elsie Said:

A single silicon photovoltaic cell is found to have an open-circuit voltage of 0.6 V and a short-circuit curr?

We Answered:

first you have to calculate the voltage of the cell at peak power, and this value is about (0.8-0.85) the open cct voltage, so the output voltage of one cell is:
v=0.8*0.6=0.48 v.

the current that the cell can produce at peak power is about 0.9 the short cct current, so the output current you expect to draw is:
i=0.9*15=13.5 mA.

now you know the the voltage and current you expect from your cell you can calculate the number of cell in series to produce 9v:
9/0.48=18.75=19 cells in series.
your load is 500mW, which draws 500/9=55.55mA at 9v, the number of branches required is:
55.55/13.5=4.11 to be safe, you'll need 5 branches, each of 19 cells in series.

so, you need 5 parallel branches, each contains 19 cells in series.

Edna Said:

why does the resistance of a silicon photovoltaic cell decrease as its current + voltage rises?

We Answered:

I think all solar cell compositions do this.

The solar cell does not have a preset efficiency and it becomes more efficient as solar radiation increases. A cell receiving 10,000 lumens over a certain area might be 12% efficient at conversion and the same cell will be 18% efficient with 20,000 lumens in the same area.

Since cells have an established potential (voltage) based on the distance between electron generation and electron receiving ground base the only thing that can increase in a solar cell is the volume of electrons that jump that potential difference space. The stronger the sun power is the more volume of electrons that is dislodged from the silicon surface to jump that p-n substrate.

This amounts to an increase in current without an increase in voltage. Then it is just the simple equation that shows the drop in resistance as current increases:

V = IR
R = V / I
for example, if voltage is 12V and current is 2 amp in the series cell, that is 6 ohms of resistance. Raise the current to three amps by increasing sun strength by placing cells at better sun angle or high noon solar generation and you might get 4 amps from the same solar panel:
R = V / I
3 ohms = 12V / 4 amps.

So resistance dropped by 3 ohms by increasing sun strength and therby raising efficiency of panel light conversion

Beverly Said:

Are there any semiconductors other than silicon that can be used in photovoltaic cells?

We Answered:

germanium is another possibility. but, Silicon gives more potential difference than germanium. a single silicon cell gives 0.7V drop, while that of germanium gives 0.3V drop. the electrical characteristics of silicon r better than germanium's. also, silicon is abundantly available and easily extractable.