Solar and Photovoltaic cells

[Troytempest]

how would you design an experiment to find out the difference in energy output, of photovoltaic cells, and a solar panel, using a 150W light bulb?
any help would be much appreciated.

[beso]

The energy output of a photovoltaic cell is highly dependent on the load. In sunlight at 25 degrees Celcius the maximum output occurs at about half a volt per cell.

You will need a variable load so you can find the maximum point under the operating conditons with the lamp.

The voltage falls with temperature rise so you need to monitor cell temperature. You also need to monitor the voltage to the lamp as the flux is quite sensitive to the supply voltage.

[beso]

Normally during manufacture solar cells are flash tested with a special lamp that matches the spectrum of sunlight. Solar cells use the short end of the light spectrum. Use a halogen lamp.

Power specifications are normally presented as a set of curves on a Voltage vs Current chart. Each curve represents a different temperature.

Manufacturers publish these charts and you can probably download one from a panel manufacturers website to get an idea of what they look like.

[Troytempest]

thanks beso. do you know how one should, compensate for / take into account, the internal resistance of the circuit?

[beso]

Measure the voltage at the terminals of the cell. The voltage here times the current gives the power produced by the cell. Any circuit resistance becomes part of the load.