Sizing is the most important part of any solar project. Panels catch the energy, inverters convert it and batteries store it — but if any part is sized by guesswork, the system will either fail when you need it or cost far more than it should. Here is how we think about it.
1. Start with your load, not your budget
Write down everything you want the solar system to carry: lights, fans, TV, fridge, freezer, pumping machine, AC units, security system, WiFi router. For each item note the wattage and how many hours per day it runs. Multiply watts × hours for each item and add them up — that is your daily energy need in watt-hours (Wh).
Our solar load calculator does this maths for you in a minute.
2. Inverter size: think about the peak, not the average
The inverter must handle the moment when many things are on at once — especially motor loads like fridges, freezers, ACs and pumps, which draw a surge when starting. As a rule of thumb, the inverter should be at least 25% larger than your expected peak load. This is why we always check which appliances you actually own before quoting.
3. Battery capacity: how long must the lights stay on?
Battery size comes from two numbers: how much energy you use per day, and how many hours of backup you want. For lithium (LiFePO4) batteries you can safely use about 80–85% of the rated capacity, so a 5 kWh lithium battery gives roughly 4–4.5 kWh of usable energy. If you use 2 kWh per day and want one full day of backup, you need about 2.5 kWh of rated battery capacity — plus a margin for cloudy days.
4. Solar array: it must recharge what you use
The panels must replace the energy you draw from the batteries every day. In southern Nigeria we plan with about 4–5 peak sun hours per day on average, then apply a margin for heat, dust, wiring losses and rainy-season weather. If your daily use is 3 kWh, you will generally want a panel array comfortably above 1.5 kW — your installer should show you the calculation.
5. Roof, shade and future growth
Panel placement matters as much as panel count. Shade from trees, neighbouring buildings or a water tank can slash output. Also think ahead: if you may add AC units, a shop extension or an electric vehicle later, tell your installer now — it is far cheaper to design for growth than to redo the system.
6. Get it checked by a professional
Online calculators are a great start, but a site visit turns estimates into a design: roof measurements, shade survey, existing wiring checks and a conversation about how you actually use power. That is exactly what our energy audit covers — and it is the reason our customers' backup lasts as promised.
Ready to size your system properly? Chat with us on WhatsApp or request a quote.