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What size solar power system do you need

Switching to solar power can require a substantial outlay of money. At a minimum, you need to determine the following in order to get a good idea what size solar power system do you need.

How to calculate the size of solar system for your home
1.Look at your energy bill
Your most recent energy bills are the best way to calculate. Like other energy companies, we can set out your average daily energy consumption if you provide us your energy bills. 
Depending on where you are in Africa and how much daylight you receive on average per day, a 1kW solar power system will usually produce around 4kWh to 5kWh of energy per day. 
Here is a great tool for you to estimate how much solar energy you can expect to produce if you go solar—— PVWatts. You can adjust you system size and location variables anytime.
2. Estimate how much electricity you use during daylight hours
Your solar panels will only meet your electricity requirement during the daytime hours unless you have the battery storage. The electricity from your solar panels will flow first into any appliances in use within your home at the time, saving you money by reducing the amount of electricity. Any surplus solar will go into the grid, to net you only 6-10c/kWh. This means that you want a solar system that generates enough electricity to meet your daytime electricity usage.

This can most easily be done by estimating what percentage of your total electricity consumption happens when the sun is shining. For example, if you use 20kWh of electricity per day on average, but only about 1/3 of that during the day, then you’ll want a solar PV system that generates about 7kWh per day. These are rough estimates, we will give you more precise estimate based on your circumstances
3.Choose a solar system size that will generate enough electricity to meet daytime demand
So with an average daily household electricity demand of 20kWh with about 33% of that occurring during daylight hours, a 2kW solar system would probably be the best solar system size – it would generate just enough solar energy to offset a chunk of your daytime energy usage without ‘wasting’ too much solar by exporting it into the grid (a ‘self-consumption’ rate of about 60%).
 What size solar power system do you need 
The ‘double hump’ electricity usage pattern, common in homes with school-age children. The times of highest electricity consumption happen outside of peak solar production times – the trough in the middle of the graph. Red bars represent ‘wasted’ solar going into the grid.
A 3kW solar energy installation, on the other hand, would probably be slightly too large for your home if it’s not occupied during the day, exporting nearly 50% of the energy produced on average. However, if you are home during the day (retired or have a home office, for example), it would make a good fit, with only 30% of the solar energy going back to the grid on average.
How to calculate the size of solar system for your home
The ‘day focus’ electricity usage pattern, common in homes occupied by retirees or those who work from home. With the appropriately-sized solar system, such homes can easily use a significant portion of the solar energy produced, sending only a small amount into the grid.