We can assist with solar system sizing but in order to assist we provide some basics:

1. System sizing

Start with a list of equipment, the watt rating of each item, the number of hours in use per 24 hour period. Example:

Item Watt rating No of hours per day Watt X Hours Divide by 12
54cm Color TV 75 4 300 25
Light 11 6 66 5.5
Total 30.5

30.5a = daily requirement plus 30% for battery/inverter loss and recovery from unfavourable weather = 39.65 say 40a

2. Solar Panel Sizing

Winter optimum sun hours should be used and differ from 5.5 to 7 hours in Southern Africa. Divide 40a by say 7 =
5.71a per hour. A mono crystalline solar panel of 100w or 2 of 50w in parallel connection will suffice provided it generate 17v in closed circuit ie 100 divided by 17 = 5.88a per hour.

3. Battery Sizing

40a per day plus allowance for 3 to 5 days for unfavourable weather say 120a. The lifespan of a battery is affected by the rate and depth of energy withdrawn on a regular basis. 2 x 100a/h batteries in parallel should be adequate as the daily withdrawel is 40a ie 20% per battery.

4. Regulator sizing

A 12v regulator with 6a rating as a minimum should be used.

5. Inverter sizing

An inverter with ability to handle at least 75w plus 11w = 86w simultaneously will be required.


For large systems it is advisable to consider 24, 48v or even larger voltage as the elecrtrical resistance is substantially reduced.

Consideration of components should take into account the possible future expansion of the system to avoid having to replace the inverter, regulator and also availability of component in future.

Tasol Solar with its wealth of experience can assist in the planning and sourcing of components for your system,
please contact us.