What size solar inverter do I need in Kenya?

Most oversized systems in Kenya were sized by adding up every appliance in the house. Most undersized ones were sized by guessing. The correct method takes ten minutes with a pen.

Step one: add up what runs at the same time

Load	Running watts	Surge watts
LED lighting, whole house	100–250 W	—
Television	60–150 W	—
Fridge / freezer	150–250 W	600–1,200 W
Router and phone charging	30–60 W	—
Laptop	60–90 W	—
Water pump (0.5 hp)	370 W	1,100–1,800 W
Kettle	1,500–2,200 W	—
Iron	1,000–2,000 W	—

Lights, television, fridge, router and a laptop together come to roughly 600W. That is a 1kVA load, not a 5kVA one. The kettle and the iron are what push people into buying a much larger inverter — and the usual advice is simply to leave them off the backup circuit and boil water when the grid is up.

Step two: check the surge rating

A fridge or a pump draws three to five times its running current for about a second when the motor starts. An inverter without surge headroom shuts down on that spike even though the running load is well inside its rating. Look for a surge figure of at least twice the continuous rating.

Step three: size the battery to hours, not to the inverter

The inverter sets how much you can run. The battery sets how long. A 600W load for five hours is 3kWh — which after inverter losses means about 3.3kWh of usable storage, or roughly 130Ah at 24V in lithium.

This is where lead-acid and lithium diverge sharply. A lead-acid bank should not be discharged below 50% without shortening its life dramatically, so you need twice the nominal capacity. Lithium can be taken to 80–100% depth of discharge for thousands of cycles.

Step four: match the panels to the controller

Panels in series add voltage; in parallel they add current. The string's open-circuit voltage must stay under the charge controller's maximum input — including the rise on a cold morning, which is when Voc is highest. Three 550W panels in series reach about 150V, which is above the limit of many smaller MPPT controllers.

Getting this wrong destroys controllers, and it is the single most common installation error in the Kenyan market.

A worked example

A three-bedroom house in Nairobi wanting lights, television, fridge, router and phones through a four-hour evening outage:

• Inverter: 3kVA hybrid, pure sine wave, 60A MPPT built in
• Battery: 24V 100Ah LiFePO4 (2.56 kWh) — comfortably covers the evening
• Panels: 4 × 550W = 2.2 kW, enough to recharge in a normal Nairobi day

Have the installation done by an EPRA-licensed technician. DC protection and earthing are where amateur installations go wrong, and they are not visible faults until something happens.