Solar Calculator FAQ: How to Size a Solar System in South Africa
Answers to common questions about sizing a solar system and using the Sun Pays solar sizing calculator. The calculator is a free guide for 48V systems. It is not a quotation, so confirm your final system with us before you buy. Call 012 734 0915 or WhatsApp 082 515 1655 (messages only).
Using the calculator
How does the solar calculator work?
You enter your electricity use in one of three ways: your monthly bill in rands, your monthly units in kWh, or a list of appliances with the hours they run (the most accurate method). You then choose a battery, a panel layout and an inverter, or click "Help me Choose". The tool shows your day and night energy use, how long the battery lasts overnight, and an estimated monthly saving.
Which method should I use?
The appliance method is the most accurate and is the one we recommend. The rand and kWh methods are quicker but give a rougher estimate.
Is the calculator accurate?
It is a guide, not a quotation. It does not replace a site assessment, and prices shown are indicative only. Send us your result and we will check the system for you.
Does the calculator cover all system types?
At this stage it is for 48V systems only. Contact us if you need something different.
Sizing basics
How do I calculate the size of a solar system?
Work out what you use during the day (served directly by the panels), what you use at night (served by the battery) and the highest load that runs at the same time (which sets the inverter size). Panels, batteries and inverter are then chosen to match those three numbers.
What size inverter do I need?
Add up everything that can run at the same time and allow extra for motor start-up surges. See our inverter size guide.
How many solar panels does a house need?
It depends on your daily energy use and the panel size. See our panel and battery guide.
Where can I get help with my result?
Send your result to us on WhatsApp (082 515 1655, messages only) or call the office on 012 734 0915. Our general solar FAQ covers more questions.
