Sizing guide
Solar inverter and battery sizing guide for Nigeria
The inverter is sized on your peak load. The battery is sized on how long you want to run without sun or grid. Getting these two right is most of a good solar design.
Matching inverter rating to your load
| Inverter | What it comfortably runs | Typical daily use |
|---|---|---|
| 1.5 kVA | Lights, fans, TV, phone charging | 3 – 5 kWh |
| 3 kVA | Above plus a fridge and a small pump | 6 – 10 kWh |
| 5 kVA | Family home with one or two AC units used sparingly | 12 – 18 kWh |
| 10 kVA | Large home, several AC units, borehole | 25 – 40 kWh |
| 20 kVA+ | Shops, clinics, offices, small production | 60 kWh and up |
Sizing the battery bank
Work out the average power your protected loads draw during the hours you need backup, multiply by those hours, then divide by the usable depth of discharge. Lithium gives you about 80% usable; tubular lead-acid is closer to 50% if you want a reasonable cycle life.
Worked example
700W average overnight draw × 10 hours = 7 kWh needed. At 80% usable depth that is 8.75 kWh of lithium, so a 10 kWh bank. The same job on tubular at 50% usable would need 14 kWh of nameplate capacity.
Lithium vs tubular lead-acid
| Lithium (LiFePO4) | Tubular lead-acid | |
|---|---|---|
| Usable depth | ~80% | ~50% |
| Cycle life | Longer — check the warranted cycle count on the datasheet | Shorter — typically replaced several times over a lithium bank's life |
| Upfront cost | Higher | Lower |
| Cost per usable kWh over system life | Usually lower once replacements are counted | Usually higher once replacements are counted |
| Maintenance | None | Ventilation, topping up, terminal care |
Depth-of-discharge figures are the PureWatts design standards used across the tools. Cycle life varies widely by manufacturer and operating temperature — compare warranted cycle counts on the specific datasheets you are quoted, not category averages.
Size your inverter and battery
Your prepaid meter token shows units purchased in kWh. Monthly figure ÷ 30 gives your daily average.
How long the battery should carry your load with no sun and no grid.
4.6 kW
Solar array
6.3 kWh
Battery storage
3.8 kW
Hybrid inverter
Indicative installed cost
₦2.7m – ₦3.7m
Hardware ₦2.7m + installation ₦485,280. Generates about 14.9 kWh on an average day.
These are planning estimates. System sizes use measured Nigerian irradiance and PureWatts engineering standards; costs use the supply-and-install rates installers configure in the platform. Engineered numbers, equipment selection and a bankable financial model come from the full analysis.
These are planning estimates. System sizes use measured Nigerian irradiance and PureWatts engineering standards; costs use the supply-and-install rates installers configure in the platform. Engineered numbers, equipment selection and a bankable financial model come from the full analysis.