Example a 14" stand fan 75W to run 3 hours at night and a 15W light to run 4 hours at night. Solar panel needed is 90W.

1. There is no formula needed but to get a charge controller more than the maximum power of the solar panel produced.

2. The maximum charge controller in the market is 60A. If you are running high power system on 12Vdc, the high current will be also too high to handle. It is adviced to convert to 24V or 48V dc system.

3. The output power of the charge controller is also a point that most of the people neglected. From the example the 90W solar panel selected will need a charge controller of more than 5.15A (maximum currrent that a 90W panel produced) input. The Phocos charge controller selected wil be the 12V 8A. The output power from the charge controller will be limited (12Vx8A) 96W. The charge controller will alarm cut off the output if the currrent drawn is more than 8A. If your equipment has a high startup current or power, you will need to select a higher range charge controller to suit your equipment.

See the next page on how to select the inverter.