Solar Calculator: What Size System Do I Need?

The biggest mistake people make when going solar is buying the wrong size system — either too small (constant power cuts) or too large (wasted money). Here's how to get it right.

Step 1: List Your Appliances

Start by writing down every appliance you want to run on solar. For each one, note how many you have and how many hours per day you typically use it. Don't worry about the technical numbers yet — we'll handle that.

Common appliances and their approximate wattage:

Step 2: Calculate Your Total Load

Add up the wattage of all appliances you want to run simultaneously. This is your peak load. For example: 1 × AC (1,200W) + 1 × fridge (200W) + 2 × fans (130W) + 6 × LED bulbs (60W) + 1 × TV (60W) = 1,650W total.

For safety, add 20–25% headroom. So 1,650W × 1.25 = 2,062W, which rounds up to a 3kVA inverter.

Step 3: Choose Your Battery Capacity

Batteries determine how long your system runs without sun or grid. The formula is: (daily energy use in Wh) ÷ (battery voltage × usable depth × efficiency). In practice, for a typical 3kVA residential system in Nigeria running 8–10 hours daily, you'd need 4 × 200Ah batteries.

More batteries = more backup hours, but also more cost and weight. Your installer will help you find the right balance based on your actual usage pattern.

Step 4: Size Your Solar Panels

Nigeria gets excellent sun — typically 5–6 peak sun hours per day. To calculate panels needed: daily energy use in Wh ÷ (peak sun hours × panel efficiency). For a 3kVA system using 6kWh/day, you'd need approximately 4–6 × 400W panels.

The Easier Way: Use Our Calculator

All of this math is built into our free solar calculator. You just select your appliances, set quantities, and we calculate your recommended system size, battery count, panel count, and estimated cost — in under 60 seconds.

After calculating, you can immediately browse verified installers in your city who can handle your exact system size.