This is one of those questions where the honest answer is “it depends,” and we know that’s not satisfying when you’re trying to budget. So instead of leaving it there, let’s actually walk through how the number gets calculated, so you can get a realistic estimate yourself before you even call anyone.
The calculation, in plain terms
It comes down to three things: how much electricity you use in a day (measured in kWh), how many peak sun hours your location gets, and how big each panel is. Nairobi and most of Kenya get roughly 5 to 6 peak sun hours a day — meaning a panel produces close to its rated output for about that many hours, even though daylight lasts longer. Divide your daily usage by your peak sun hours, then divide that by your panel’s wattage, and you’ve got a rough panel count.
It sounds more complicated written out than it is in practice. Here’s what that looks like for real households.
Want us to just run these numbers for your actual home instead of estimating? Call or WhatsApp +254 741 163020 and we’ll do it properly, free of charge.
By household size — real examples
A small home (1–2 bedrooms), light usage Lights, fridge, TV, router, phone charging, occasional kettle use. Typically around 5–8 kWh/day. On a 585W panel, that works to roughly 4 panels, which lines up with our Family package (5kWh system, four 585W panels).
A medium home (3–4 bedrooms), everyday usage Add a washing machine, more lighting circuits, an extra fridge or deep freezer, more devices charging throughout the day. Usage tends to sit around 10–15 kWh/day, which puts you closer to 8 panels — our Standard package territory.
A larger home, higher consumption Electric cooker, AC in one or two rooms, a pool pump, a home office running throughout the day. This can push usage to 20–30 kWh/day or more, landing around 16 panels, matching our Premium and Ultimate packages.
These are starting points, not a substitute for an actual audit — two “medium” homes can have genuinely different real usage depending on habits, not just headcount.
This is the part people most often get wrong doing it themselves — not the maths, but guessing their actual daily usage. If you want it measured instead of guessed, email info@happysolar.co.ke or call +254 741 163020 to book a free energy audit.
Why guessing costs you either way
Undersize the system, and you’ll find yourself rationing power during cloudy stretches, running the generator more than you expected to, or simply not getting the blackout protection you thought you’d paid for. Oversize it, and you’ve spent money on panels and battery capacity you’ll genuinely never use — which, at the prices involved, isn’t a small mistake to make.
The appliances that catch people out most aren’t the big obvious ones. It’s the stuff that runs quietly in the background all day — the fridge compressor cycling on and off, the router, security system, water pump if you have a borehole. None of these look significant individually, but added up over 24 hours they’re often a bigger chunk of your daily usage than people expect.
Rather talk it through than do the maths yourself? We’re on WhatsApp at +254 741 163020 most of the day — send us your current KPLC bill and we’ll give you a rough panel count within minutes.
What actually happens during a proper energy audit
When we visit a site, we’re not just counting bedrooms. We look at your actual appliances, how many hours a day each genuinely runs, your roof orientation and any shading from trees or neighbouring buildings, and — if you have one — your last few months of KPLC bills, which tell us more about your real usage pattern than any estimate could. That’s how we land on a panel count and battery size that actually matches your life, rather than a generic package that’s close enough.
If you’d rather skip the estimating altogether and get an exact number for your home, book a free site assessment or reach us directly on +254 741 163020 (call, text, or WhatsApp) — info@happysolar.co.ke if you’d prefer email. It costs nothing, and it’s the difference between a system that fits your home and one that’s just a reasonable guess.
