The number that matters: cost per USABLE kWh over life
Comparing battery prices by their kWh rating is misleading, because you cannot use all of a battery and different chemistries last very different numbers of cycles. The honest metric is cost per usable kWh delivered over the battery life — the purchase price divided by (usable capacity x cycles). On that basis, the expensive battery is often the cheap one.
Depth of discharge: how much you can actually use
- Lead-acid (flooded, AGM, gel) hates deep cycling. Draw it below ~50% routinely and its life collapses. So a "200 Ah" lead-acid battery really gives you ~100 Ah per cycle.
- LiFePO4 (lithium iron phosphate) comfortably uses 80-90% of its capacity every cycle, for thousands of cycles. A "200 Ah" LiFePO4 gives you ~170-180 Ah, and keeps doing so for years.
Cycle life: where lithium pulls away
| Chemistry | Usable DoD | Cycle life | Best for |
|---|---|---|---|
| Flooded lead-acid | ~50% | 500-800 | Lowest upfront, occasional backup |
| Sealed AGM / gel | ~50% | 600-1,200 | Maintenance-free standby (UPS) |
| LiFePO4 (LFP) | 80-90% | 3,000-6,000 | Daily solar cycling, best lifetime cost |
| NMC lithium | 80-90% | 2,000-4,000 | Compact, weight-sensitive sites |
For a system that charges and discharges every single day (solar self-consumption), those cycle numbers translate directly into years of service — and lithium wins decisively.
Heat: the Kenyan factor
Battery life is temperature-sensitive. For lead-acid especially, life roughly halves for every 8-10 degC above 20-25 degC. In a hot, unventilated container or comms room, a lead-acid bank can fail in a fraction of its rated life. LiFePO4 tolerates heat better but still prefers cool and dry. We always specify the battery location and ventilation as part of the design, not an afterthought.
So which should you choose?
- Daily solar cycling: LiFePO4 almost always — lowest lifetime cost, deep usable capacity, long life.
- Occasional UPS standby (rarely discharged): sealed AGM lead-acid can still be cost-effective, since cycle life matters less when you rarely cycle.
- Weight or space constrained: lithium (LFP or NMC) for its energy density.
- Tightest upfront budget, infrequent use: flooded lead-acid, accepting shorter life.
The bottom line
Do not buy batteries on sticker price. Work out the usable kWh and the cycles you will get, factor in your site temperature, and compare cost per usable kWh over the life. For daily-cycling solar in Kenya, that maths usually points to lithium.
Tell us your daily energy and how often the battery will cycle and we will recommend the right chemistry and size with a lifetime-cost comparison. Call +254 768 860 665 or +254 782 914 717.