Battery Price Break-Even (Sezibwa)

[!info] Conservative,Conservative bank-facingbasis. basisTariff: UEDCL Code 10.2 Q3 2026 (revised666.5 after/ independent562.1 review)/ 429.7, configurable). Turnkey installed capex andcapex, real day-to-day weather. Independent of the other docs because it rests on a battery-price assumption rather than a fixed quote.assumption.

The question

The optimal-allocation case found that atAt today's battery price, adding battery capacity lowers the return: the money is better spent on solar. But Aaron's point stands: the long-term microgrid model wants more storage, so the real question is a price one. How cheap does battery have to get before expanding it pays? That turns the result into a procurement target.

ItBase takes Aaron's framing as the base case: net meteringcase is notno theeconomically playusable export for Sezibwa (bestERA's Net Metering Regulations 2024 exist, but eligibility, interconnection and credit value isare sellingunresolved onsite,and nottypically feedingpay abelow grid that already has a generation surplus)retail). So this uses no feed-in and asks only what storage is worth for shifting onsite solar into the evening.

Method

The same 20-year model (real load, real weather, battery aging to 50 percent by year 20, turnkey solar, Q3 2026 tariff, 15 percent discount) but with the battery price swept as a variable. At each price the model re-finds the best allocation and compares its NPV against the best allocation that adds no battery. Today's price: SR-SE10B is 5,568,000 UGX for 8.9 kWh usable, about 626,000 UGX per kWh.

Result

The break-even is anchor-dependent (it depends how much solar you already have, because a bigger array spills more surplus that a battery could soak up):. On the current tariff:

Solar anchor	Break-even battery price	vs today's 626k/kWh
4 kWp	about 264,236,000 UGX/kWh	about 42~38 percent (needs ~5862 percent cheaper)
5 kWp (the optimum)	about 410,367,000 UGX/kWh	about 66~59 percent (needs ~3441 percent cheaper)
6 kWp	about 512,459,000 UGX/kWh	about 82~73 percent (needs ~1827 percent cheaper)

At the 5 kWp optimum, battery must fall to about 410,367,000 UGX/kWh (aboutroughly a40 thirdpercent cheaper than today)cheaper) before the first extra unit pays. Below that,(On the gaincompressed grows.Q3 tariff this threshold is lower than an earlier draft's estimate, because storage now shifts cheaper energy.)

Investment metrics (15at percentcheaper cost of capital)battery)

Allocation	Upfront	Payback	ROI (20-yr cumulative)Capex	IRR	Simple / disc. payback	NPV at 15%@15%
6 kWp + 1 unit at 200,000 per kWh	9.3M	37%	2.57 / 3.7 yr	636 percent	40 percent	13.2M11.7M
6 kWp + 3 units at recycled / near-free	7.6M	1.850%	2.0 / 2.5 yr	938 percent	54 percent	17.6M15.9M

Findings

1. Break-even at the 5 kWp optimum is about 410,367,000 UGX/kWh, roughly a third below today.kWh Higheron the current tariff — higher if you have already scaled solar to 6 kWp, lower at 4 kWp.
2. For material value you want battery well below break-even, toward ~200,000 UGX/kWh or less (6 kWp + 1 unit gives about 13.2M NPV at that price).kWh.
3. AtWhat this validates is "cheap storage," not "second-life batteries." Very low-cost storage would make a cheap or free source the storage-heavy configuration attractive. But this model winsdoes outrightnot: recycledyet validate recycled/EV cells giveas 6the kWproute plus three units, about 17.6M NPV andthere: a 54second-life percent IRR, better than solar-only.
4. This validates the recycled-battery strategy. Second-life cells (discarded by cars while still holding 60 to 80 percent) are the path into the price range where expansion pays. Aim for roughly 200,000 UGX/kWh or below.

Caveats

Second-life cells arestarts already partlypartially aged, so the fade-to-50-percent-over-20-years assumption is optimistic for them;it. Whether recycled cells actually deliver low installed cost needs its own model (acquisition, testing and grading, BMS integration, pack assembly, safety, warranty risk, heterogeneous cell health, and a shorter effectiveremaining life). Promising avenue, but the finance should not run ahead of that evidence.

Toward a break-even surface

A single break-even price is an oversimplification. The right output is a surface over four axes: battery price x remaining life raisesx solar capacity x reliability/outage value. Remaining life matters as much as price: for example, 250,000 UGX/kWh for a cell expected to last 5 years can be worse than 400,000 UGX/kWh for one expected to last 12 years. And once the battery's backup value in outages is monetised, the threshold price targetrises. (makesThis itsurface, stricter).computed per site, is what NFE's site optimizer should eventually output.

Caveats

This prices energy value only; battery also buys backup, which has its own value not counted here. Second-life economics need the separate model above before recycled storage is treated as validated.

Related

Builds on Optimal Solar and Battery Allocation. Companion cases: Battery Arbitrage (alone) and, Solar Plus Battery.