Solar Energy Solutions

Solar PV is misunderstood as a panel-and-inverter purchase. It is in fact a complete electrical system: array, DC isolation, MPPT optimisation, inverter, AC isolation, metering, storage, and distribution. The panel rating in watts is barely a quarter of what determines whether the plant pays back inside 5 years or 15.

Site irradiance is the first input. Nairobi sees ≈ 5.5 kWh/m²/day average GHI; Northern Kenya pushes 6.5; Mombasa coastal humidity drops effective generation. NASA POWER and Solargis databases give locational means but only on-site pyranometer data — even one month — captures soil, shade and microclimate.

Tilt and orientation: in Kenya (latitude 1° S to 4° N) the equator-facing tilt of 10–15° is mathematically optimal but visually almost flat; many architects insist on 15–25° for self-cleaning. The trade-off is annual yield vs water-shedding — a 5-degree mismatch costs ~1% annual generation, soil loss to dust costs 3–5%.

Module choice today is between mono-PERC, TOPCon, and HJT cells. Bifacial modules add 5–15% rear-side gain when mounted over high-albedo surfaces. Polycrystalline still appears in cheap imports but is now obsolete — efficiency 15% vs 21–24% for current mono-PERC, with worse temperature coefficient.

String voltage matters more than panel count. Voc(stc) × N × 1.25 must remain below the inverter's max DC voltage at the coldest expected morning temperature (Kenya highlands can hit 5 °C at dawn → Voc 13% above STC). Designs that ignore the 1.25 factor strand panels offline whenever a cool morning combines with high irradiance.

Inverter topology: string inverters (Sungrow, Huawei, SolarEdge, Fronius, GoodWe) for residential and small-commercial; central inverters (SMA, Sungrow, Power Electronics) for utility scale; microinverters (Enphase) for residential with shading. Hybrid inverters (Victron, Deye, Sungrow Hybrid, GoodWe ET) integrate batteries on the same DC bus.

Battery technology in 2026 is dominated by LiFePO₄ (LFP) cells. Lead-acid is gone from new commercial installs — its 50% depth-of-discharge ceiling and 1,500-cycle life can't compete with LFP's 80–90% DoD and 6,000 cycles. Pylontech, BYD, BSLBATT, Dyness and Huawei LUNA are the workhorses; Tesla Powerwall remains premium residential.

DC isolation is non-negotiable. IEC 60364-7-712 and the AS/NZS 5033 derivative require lockable DC isolators within 3 m of the array (rooftop) and at the inverter end. We see imported Chinese kits omit the rooftop isolator — that single missing component blocks any compliance certificate and voids fire insurance.

Earthing and lightning: PV arrays are large equipotential mats that attract direct strikes. Class I SPDs at array entry and class II at inverter AC output are mandatory. Equipment earth bonding must achieve < 0.1 Ω across the array structure. Inadequate bonding is the leading cause of inverter electronics frying after thunderstorms in the highlands.

Long-term performance is dominated by soiling and degradation. Modules degrade 0.4–0.7%/yr (LID + LeTID); soiling can cost 5–10%/yr if uncleaned. A robust O&M contract includes monthly cleaning, quarterly thermography (cell hot-spots indicate cracks), and annual IV-curve tracing. Sites without it lose 15–20% generation by year 5 vs spec.