Quick answer: solar storage specification for Nigeria
A usable solar storage specification fixes eighteen things before anyone quotes: the load basis, chemistry, nominal and usable kWh, C-rate, cycle life, efficiency, inverter rating and surge, protection, enclosure, warranty scope, spares and compliance. Fix them and two bids become comparable; leave them open and the cheapest number usually belongs to the smallest battery.
On this page
- Why two identical quotes differ by 40%
- The 18-line schedule
- The six lines suppliers omit
- How to score the responses
- What it does to the price
- Five specification errors
Why Two “Identical” Quotes Differ by 40%
Ask five suppliers for “500kWh of storage” and you will get five prices spanning a wide range. They are not quoting the same thing, because a solar storage specification that only states kWh is no specification at all. Nominal capacity quoted at 0.25C is a different product from the same capacity at 0.5C; eighty percent depth of discharge and ninety percent turn the same nominal kWh into two different usable batteries; a ten-year parts-only warranty and a ten-year warranty covering labour and travel are not the same promise.
None of that is dishonest — it is simply unspecified. A solar storage specification exists to remove the degrees of freedom, and it is the cheapest document in the whole project: an afternoon of writing against weeks of re-quoting and, worse, a change order raised after the container has already landed.
Start from the load, not the equipment. The sizing method in factory solar sizing by load profile gives you the two numbers everything else hangs off — array kW and battery kWh. Put both of them in line 1 of your own solar storage specification rather than leaving the bidder to assume them.
What to Attach to the Request for Quotation
The schedule only works if every bidder is working from the same inputs. Attach four things to the solar storage specification before you send it: the load table from your own logging period, a single-line diagram of the existing distribution board, a dimensioned layout of the roof or yard with obstructions marked, and the nameplate data of the generator you already own. Without these, the schedule is still open to interpretation, because each bidder fills the gaps in whichever direction suits them.
State the response format as well. Ask for one completed schedule, one bill of materials naming makes and models, and one price. If a supplier answers with a brochure, send it back — that is the fastest way to find out whether they can actually build what you described, and it costs you an email rather than a container.
Set a validity period and a currency. Prices quoted in naira against a dollar-denominated bill of materials move with the exchange rate between quotation and order, and ninety days is the normal validity window for imported equipment. Ask for the price in both currencies and state which one the contract will settle in.
Finally, say how questions will be handled: one round of written clarification, answers circulated to all bidders, and a fixed submission deadline. That single rule removes the informal advantage a supplier gains by being the one who called you.
The 18-Line Solar Storage Specification
Use this as the schedule attached to every request for quotation. A written solar storage specification is the whole difference between tendering and shopping. Copy it, fill in your own numbers in lines 1 to 3, and require a written “complies / does not comply” against each of the remaining fifteen.
| # | Line | What to state | Why it moves the price |
|---|---|---|---|
| 1 | Site and load basis | Attach 7-14 days of logged demand, peak kW, shift pattern and generator runtime. | Without it every bidder assumes a different load, so no two numbers are comparable. |
| 2 | Operating profile | State hours per day, days per week, and whether the grid, a genset or both are present. | Decides whether the system is sized for cycling or for standby. |
| 3 | Grid and genset interface | Nominal voltage, phases, frequency, and whether the genset can run in parallel. | Wrong interface assumptions are the most common cause of commissioning failure. |
| 4 | Battery chemistry | Require LFP (LiFePO4). State the cell maker or an approved-equivalent clause. | LFP is the only chemistry that pairs 6,000+ cycles with no thermal runaway risk in Nigerian heat. |
| 5 | Nominal capacity | State kWh nominal at 25 deg C and at the agreed C-rate. | Capacity quoted at a different C-rate is a different battery. |
| 6 | Usable capacity | State usable kWh at the agreed depth of discharge, typically 80 percent. | Usable kWh, not nominal kWh, is what your night load actually draws. |
| 7 | C-rate and power limit | Continuous and peak charge/discharge rate, e.g. 0.5C continuous. | A 0.25C battery and a 0.5C battery of the same kWh serve different peaks. |
| 8 | Cycle life and warranty | Cycles to 80 percent retained capacity, years, and whichever comes first. | 6,000 cycles at 80 percent DoD is the current LFP benchmark to require. |
| 9 | Round-trip efficiency | DC round-trip efficiency at 25 deg C and at 40 deg C. | Efficiency losses size the array you have to buy. |
| 10 | Inverter rating and surge | kVA continuous, kW, and surge rating with duration in seconds. | Motor starts trip undersized inverters, however large the battery is. |
| 11 | AC/DC ratio | State array kWp against inverter kW as a fixed design ratio. | Above roughly 1.4 you clip generation you have already paid for. |
| 12 | MPPT window and strings | MPPT voltage range, number of MPPTs, max DC voltage and string length. | Fixes the string layout the roof has to accommodate. |
| 13 | Transfer time | Max break in supply when the grid fails, in milliseconds. | Above about 20ms sensitive process equipment drops out. |
| 14 | Protection and earthing | AC and DC protection, surge arrestors, earthing scheme, RCD class. | Most site faults trace back to protection that was never specified. |
| 15 | Enclosure and cooling | IP rating, operating temperature range, and whether cooling is active. | A battery room without ventilation loses usable capacity and cycle life. |
| 16 | Warranty scope | Parts, labour, travel, and whether capacity degradation is covered. | A ten-year parts-only warranty still leaves you paying for the technician's flight. |
| 17 | Spares and response | Critical spares held locally, response time, remote monitoring access. | Downtime cost usually dwarfs the price of the spare. |
| 18 | Documentation and compliance | Test reports, cell traceability, UN38.3, IEC 62619, SONCAP dossier. | Missing conformity paperwork stops clearance at Lagos or Onne entirely. |
Eighteen lines looks like a lot until you compare it with the alternative. Every line in a solar storage specification here corresponds to a question a supplier will otherwise answer for you, in whichever direction makes their number look best.
One practical note: send the same solar storage specification to the suppliers you already deal with, not only to new ones. An incumbent who has been quoting you on a single kWh number for years will often sharpen their terms once the schedule removes the ambiguity they were relying on, and you learn whether the relationship was ever giving you a comparable price in the first place.
The Six Lines Suppliers Quietly Leave Out
In practice six lines account for most of the gap between a headline price and a real one. They are the ones buyers forget to ask for and suppliers are happiest not to volunteer, and every one of them belongs in your solar storage specification.
- Usable kWh at a stated DoD. The single biggest lever. Insist on it in writing next to nominal capacity.
- C-rate. Capacity is only meaningful at a discharge rate; make it explicit.
- Degradation curve. How much capacity remains at year five and year ten, not just the cycle count.
- Warranty scope. Labour, travel and diagnostics, or parts only.
- Commissioning and training. Who signs off, and who is taught to run it.
- Documentation for customs. SONCAP dossier, test reports and cell traceability, without which nothing clears at Lagos or Onne.
Ask for all six in the solar storage specification and the spread between bids usually narrows sharply, because the cheap bid is forced to disclose what it was leaving out.
How to Score the Responses
Score each line of the solar storage specification as met, partial or unmet, then price the unmet lines as additions rather than negotiating them away. The table below is the whole method.
| Verdict | Meaning | What to do |
|---|---|---|
| Met | Stated value matches or exceeds the requirement | Accept |
| Partial | Stated but below requirement, or conditional | Price the gap, then decide |
| Unmet | Not stated, or answered with marketing copy | Add the cost, or drop the bid |
Two bids that both pass are then compared on delivered cost per usable kWh over the warranted life, not on the headline figure. A complete solar storage specification makes that comparison possible. At $140–185/kWh CIF Lagos for installed LFP, a 215kWh block runs $30,100–39,775 inside a 100kW + 215kWh system we ship at CIF $88,000–115,000 — roughly a third of the total.
What a Complete Specification Does to the Price
Fixing the solar storage specification usually raises the headline number slightly and lowers the real one. You stop paying for capacity you cannot use, you stop discovering after delivery that cooling or protection was an extra, and you stop re-buying the same system twice.
It also changes what you can negotiate. With eighteen fixed lines, a supplier competing on price has to compete on the equipment itself — module class, cell maker, inverter brand — which is exactly the comparison you want. That is the same logic as the 7-point factory audit, applied before the order instead of after it.
For reference, the two configurations most Nigerian factories land on are 100kW + 215kWh at CIF $88,000–115,000 and 500kW + 1MWh at CIF $390,000–480,000, with modules at $0.28–0.48/W. Duty of 5–7 percent, VAT at 7.5 percent, clearing at ₦500,000–₦1,500,000 per container and ₦1.5M–4M for the last mile all sit on top; the full walk-through is in the BESS cost and import guide.
Five Specification Errors Buyers Make
None of these five is a technical mistake. Each one is an omission in the solar storage specification — a line that was left blank and therefore filled in by somebody whose interest is not identical to yours. Read them as a checklist against your own draft before it goes out.
- Quoting kWh and stopping there. Capacity without C-rate and DoD is not a specification.
- Leaving chemistry open. “Lithium” covers very different cycle lives and thermal behaviour.
- Ignoring surge. Motor starting current, not nameplate, sets the inverter.
- Accepting a parts-only warranty. Labour and travel are where the real cost hides.
- Forgetting the paperwork. No SONCAP dossier means no clearance, however good the equipment is.
Each one is a single line in the schedule. Together they are the difference between a solar storage specification that protects you, a solar storage specification that only looks complete, and a price list that does neither.