Power cuts shouldn’t stop your home or business. A well-sized solar backup keeps lights, fridges, TVs, routers and computers running — but “well-sized” is the key phrase. Undersize and it trips at the worst moment; oversize and you’ve paid for capacity you never use. Here’s the honest way to size a system.
Step 1: Audit Your Loads
List only what must run during an outage. Check the label on each appliance for its wattage:
| Appliance | Typical Watts | Hours/Day | Wh/Day |
|---|---|---|---|
| LED lights ×8 | 80 | 5 | 400 |
| Fridge (medium) | 150 | 8 (compressor) | 1,200 |
| TV + decoder | 120 | 4 | 480 |
| Wi-Fi router | 15 | 12 | 180 |
| Laptops ×2 | 120 | 4 | 480 |
| Total | 485W | ~2,740Wh |
Step 2: Size The Inverter
Your inverter must handle the running load plus start-up surges (a fridge compressor can briefly draw 3× its rated power). Take your total running watts, add the largest surge, then add 25% headroom. For the example above, a 3kVA pure sine wave inverter is comfortable — and pure sine wave matters: modified sine units damage fridge compressors and electronics over time.
Step 3: Size The Battery Bank
Divide your daily backup energy by the battery voltage to get amp-hours, then allow for depth of discharge. A 12.8V 200Ah LiFePO4 lithium battery stores about 2,560Wh and can safely use 80–90% of it — almost exactly one evening of the load above. Lead-acid needs double the rated capacity for the same usable energy, which is why lithium wins on lifetime cost despite the higher sticker price: 6,000+ cycles versus 500–1,000.
Step 4: Size The Panels
To recharge 2,700Wh in a day of Kenyan sun (roughly 5 peak hours), you need about 700W of panels after system losses — in practice, two 400W monocrystalline panels. Add a third if you also run daytime loads directly from solar.
The Complete Example System
- 1 × 3kVA hybrid pure sine wave inverter (built-in MPPT)
- 1 × 200Ah LiFePO4 lithium battery
- 2–3 × 400W monocrystalline panels
- Mounting rails, 6mm² solar cable, breakers and surge protection
Every home is different — a borehole pump or freezer changes the numbers significantly. Browse our solar, battery and inverter ranges, then send us your appliance list on WhatsApp — we’ll size and quote a complete system for free, with installation support available.