You don't need an engineer to get within 20% of the right system size. You need last month's fuel bill, your generator's rating and a calculator. Here is the method we use for a first estimate.
Key facts
- A generator burns about 0.28 litres per kWh; litres ÷ 0.28 = daily kWh.
- Solar in most of Africa yields roughly 4–5 kWh per kWp per day; daily kWh ÷ 4.5 = array size in kWp.
- Battery: overnight hours × 60–70% of daytime average load (for cold rooms and night operations).
- Inverter: sized for peak demand plus motor surge — or a VFD on the big motors.
Step 1 — daily energy
Take a typical day's diesel litres (or generator hours × kVA × 0.8 × average load factor, usually 40–60%). Divide litres by 0.28 to get kWh. A site burning 400 litres a day uses about 1,430 kWh a day.
Step 2 — array size
Divide daily kWh by 4.5 to get kWp. That 1,430 kWh site needs about 320 kWp of solar — call it 300–350 kWp depending on shading and roof orientation. Round up if the load is growing.
Step 3 — battery and inverter
If you run cold rooms or a night shift, estimate the overnight load at 60–70% of the daytime average and multiply by 12 hours. For the example site, about 60 kW average × 0.65 × 12 ≈ 470 kWh — a 500 kWh battery. Size the inverter for the peak, and put a VFD on any motor over 5 kW so the surge doesn't dictate the inverter.
Want the real numbers? Try the calculator, then book the audit.
Talk to Frontières BayFrequently asked
Is this accurate enough to buy on?
No — it's for budgeting. A metered audit replaces the assumptions with measurements before any quote.
What if I have some grid?
Grid hours reduce the battery; tell us how many hours a day, honestly.