Field notes

A battery sold as 400 MWh will not deliver 400 MWh to the meter. Two factors cut it before fade begins: the usable state-of-charge window is typically 85% of nameplate, and part of the energy is lost on the way out.

400 MWh × 0.85 window × √0.88 one-way efficiency ≈ 319 MWh at the grid

Against a 300 MWh contract, that is a 6% margin. LFP cells lose about 2–3% a year, so the margin is gone in about two years. Ask for usable energy at the point of connection in the guarantee, not nameplate at the cell.

Debt is sized on P90, the energy figure the plant should beat nine years in ten. P90 is not a fixed share of P50: it depends on the total uncertainty, and independent uncertainties combine by root-sum-square.

√(4² + 5² + 3² + 3² + 1²) = √60 ≈ 7.75%
P90 = P50 × (1 − 1.282 × 0.0775) ≈ 0.90 × P50

A report showing P90 only 2–3% below P50 has usually dropped a term, most often year-to-year weather. Put it back, and the debt the project can carry falls.

A 315 kW motor at 400 V draws about 550 A at full load. Started direct on line, it pulls about 6.5 times that for a few seconds: roughly 2.5 MVA.

On a 100 MVA grid: 2.5 ÷ 100 ≈ 2.5% voltage dip
On inverters alone, about 10.7 MVA of fault capacity: 2.5 ÷ 10.7 ≈ 23% dip
With a variable-speed drive: about 0.4 MVA ÷ 9 ≈ 5% dip

A 23% dip trips drives across the plant. On a hybrid that must run with the grid down, every large motor needs a drive or soft starter, or the generators must carry the start.

Captive solar on your own site, net metering (for systems up to 1 MW), private wire from a neighbouring plant, or bilateral supply as Kenya's open-access rules come into force. Each has different licensing exposure, balance-sheet treatment and a different Scope 2 number for IFRS S2 reporting.

The gap between what the rules allow and what actually gets signed, financed and connected is where most projects stall. We start every C&I review by confirming the route is real for your site.