1. The problem statement, all variables and given/known data The task is to compare the power outputs of solar cells, and solar panels. For solar cells, a circuit is devised to work out the power, solar panels a beaker of water is heated. 2. Relevant equations Power=voltagextime Q=mc(delta)T Power=Energy/time 3. The attempt at a solution Here is a scan of my two circuits at the moment (The link is in my signature, it won't let me post it here ;) 0 For the solar cell, i will use the voltmeter and ammeter to work out the power. However, not sure if a resistor is nnecessary, will it affect the measured output power? Also, how would I make the experement more accurate? I've already got mirrors to reflect as much light as possible, but would making thew beaker black absorb more light? Aditionally, am I right in thinking that 100g of water = 100ml? Finally, would I have to multiply the powewr output for the cells by the lenght of time the solar panel is heating? Thanks very much!