Case study · Industrial
Sized for the season, not the spreadsheet
An annual average would have built the wrong system. The season is the only number that matters here.
- Client
- Coffee washing station, Mbale
- Location
- Eastern Region
- Year
- 2023
- Diesel displaced
- ~60%Diesel displaced
- Sized to the season
- 45 kWpSized to the season
- order dispatch
- Meritorder dispatch
- Generator retained
- StandbyGenerator retained
Figures are representative of work delivered and are rounded. Full documentation available on request.
01 — The challenge
What they asked for
A washing station with a violently seasonal load had been quoted systems sized on annual-average consumption — an approach that would have produced an array far too small for the months that actually matter. We sized to the processing season and displaced roughly 60% of diesel generation.
Coffee processing does not care about annual averages. For a few intense months the washing station runs a near-continuous load; for the rest of the year demand is negligible. Every proposal the client had received sized the array against annual consumption divided by 365 — arithmetic that is perfectly correct and completely useless here, because it produces a system too small to matter during the only period when generation has value. Meanwhile diesel filled the gap, hauled in over poor roads at a cost that climbed with every delivery.
02 — The solution
What the data told us
We sized against the processing season and accepted the consequence: for much of the year the array is larger than the site needs, and that is the correct trade because the season is where the money is. 45 kWp of ground-mounted modules — ground-mounted because the processing shed roof already carried equipment loads we were not willing to add to — feed a hybrid inverter running grid, solar and generator in parallel with merit-order dispatch: solar first, grid second, diesel last and only when genuinely required. The generator stays, deliberately. Removing it would have been a good headline and a bad engineering decision on a site with intermittent grid and a season that cannot pause.
Everyone else asked what we used in a year. They asked what we used in September. That turned out to be the whole question.
03 — The outcome
What changed
Roughly 60% of diesel generation was displaced across the first full processing season, and with it went the fuel haulage that had been the operation’s most persistent logistical burden — a benefit the client rates above the fuel saving itself. Cost per kilogram processed fell in a way that survives an audit against production records, which is the number their buyers care about. Outside the season the array quietly serves the base load. The transferable point is that a load profile, not a total, should size a system — and any proposal that does not ask for your seasonal shape is not engineering, it is arithmetic.
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