Most people glance at the total amount due on their KPLC bill and move on. But that bill actually has everything needed to get a realistic starting estimate of what solar system size would suit your home — if you know what to look for. Here’s how to read it properly.
The number that actually matters: units consumed (kWh)
Somewhere on your bill, usually near the top of the billing details, you’ll find your consumption measured in kWh (kilowatt-hours) for that billing period — this is the actual amount of electricity you used, separate from the shillings amount, which is affected by tariff rates and other charges that don’t reflect your real usage.
This kWh figure is the single most useful number for sizing a solar system, because it tells us your real monthly consumption, not an estimate based on guessing your appliances.
Not sure where to find this figure on your specific bill, or want help reading it? Send us a photo of your bill on WhatsApp — +254 741 163020 — and we’ll walk you through it.
Turning monthly units into a rough system size
Once you know your monthly kWh, divide by roughly 30 to get a rough daily average. For example, 450 kWh a month works out to about 15 kWh a day.
Given Kenya’s typical 5–6 peak sun hours, a very rough rule of thumb is: daily kWh usage ÷ peak sun hours ≈ the system size in kW you’d need to cover most of your daytime load. Using the example above: 15 kWh ÷ 5.5 hours ≈ roughly a 2.7kW array just to cover daytime usage — before accounting for battery storage to cover evening and night usage, which is a separate calculation.
This is a starting estimate, not a final number — your actual usage pattern throughout the day (not just the monthly total) affects how much battery capacity you’d need on top of the panel array, which is why a proper energy audit looks at more than just this one figure.
What else to check on your bill
Look at a few months, not just one. A single month can be unusually high or low — a month with visitors staying, unusually hot or cold weather affecting appliance use, or simply an off month. Three to six months of bills gives a much more reliable average than any single one.
Check for seasonal patterns. If your bill is noticeably higher in certain months (more AC use in hot months, more lighting in shorter-daylight months), that’s worth factoring into sizing — you want a system that comfortably handles your higher months, not just your average.
Note the tariff band you’re in. KPLC’s domestic tariffs are structured in bands, where usage above certain thresholds is charged at a higher rate per unit. If you’re consistently in a higher band, solar’s savings impact is proportionally larger, because you’re displacing your most expensive units of grid electricity first.
Want a proper reading of your last few months of bills, with a realistic system size and savings estimate based on your actual pattern? Email the bills to info@happysolar.co.ke or WhatsApp +254 741 163020 — we’ll do the maths properly.
Why a DIY estimate still isn’t the final word
The calculation above gets you in the right ballpark, which is genuinely useful before you even pick up the phone — but it doesn’t account for things like your roof’s actual orientation and any shading, which hours of the day your usage is concentrated in (daytime-heavy usage needs less battery than evening-heavy usage for the same total kWh), or appliances you might be planning to add later (an electric cooker, AC, a new fridge) that your historical bill doesn’t yet reflect.
This is exactly what a free site assessment fills in — turning your rough estimate into an actual, confident recommendation.
What to do with this information
Pull your last 3–6 months of KPLC bills, find the kWh figure on each, and you’ll have a genuinely useful starting point for any conversation with a solar installer — including us. You’ll also be in a much stronger position to spot whether a quote you receive is realistically sized for your actual usage, or built around a generic assumption.
Get in touch or call +254 741 163020, and bring your last few bills — we’ll turn them into a proper, confident system recommendation rather than a rough estimate.
