Batteries
Why is usable battery kWh less than the sticker kWh in South Africa?
Sticker kWh is installed capacity; usable kWh is what your settings and warranty DoD allow after BMS reserves. A 10 kWh pack at 80% DoD is about 8 kWh usable — heat and ageing cut that further. Demand usable kWh on every quote.
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Multiply sticker kWh by the warranty’s recommended DoD (often ~80–90% for LiFePO₄), then subtract what your SoC floors reserve for Stages. That usable figure — not the brochure — sizes runtime. The same buffer logic applies when you want daytime solar into an EV at night: the pack stores noon surplus for a later wallbox session.
Worked example
- 10 kWh sticker × 80% DoD = 8 kWh usable.
- Reserve 20% SoC for Stage → you may only plan ~6.4 kWh for daily TOU cycling.
- Hot garage derates effective capacity — keep within OEM temperature band.
Quote language to demand
“Usable kWh at warranty DoD”, round-trip efficiency, and parallel limits. Reject vague “10 kWh backup for 8 hours” without load watts — usable kWh · DoD · 10 kWh cost.
BlueNova MKII note
OEM docs for BlueNova SBB MKII BN52V-314-16k list ~16 kWh installed and ~12.9 kWh usable at 80% DoD — always prefer the live datasheet. Dated distributor price: ACDC Dynamics — the distributor BlueNova names for MKII — lists BN52V-314-16K/SBB-MK2 at R46 008 excl. VAT list, special net R32 471.26 excl. / R37 341.95 incl. VAT, out of stock at all five branches on 27 Oct 2026 (ACDC Dynamics); that is about R2 900 per usable kWh on the OEM’s 12.86 kWh usable at 80% DoD (BlueNova manual v1.2). TERVOL L16 ≠ MKII.
SA desk notes that keep quotes honest
Ask every partner for Incl. VAT line items, NRS-listed SKUs where relevant, and who owns metro paperwork after deposit. Compare at least two written scopes before you pay — read a quote · choose installer · NRS list · SSEG.
Worked homeowner checklist
- Photograph the DB, roof and meter before the survey.
- Export twelve months of kWh or summer+winter bills.
- Write Stage priorities (fridge, routers, lights) before shopping kWh.
- File CoC, warranties and SSEG refs in one folder after handover.
Related hubs: load shedding · metro tariffs · costs & savings · check a quote.
Tariff and fixed-charge reminder
Self-use savings sit on top of fixed charges that do not disappear. Model both before you celebrate a payback slide — fixed charges · monthly savings · export vs self-use · tariffs 2026.
Safety and paperwork close
- No DIY on dual-supply boards or MC4 strings.
- Keep dual-supply labels readable for inspectors.
- Register warranties before the deadline printed on the pack.
More: CoC · inspector tips · warranties · DIY risks · red flags.
Monitoring and aftercare
Watch daily kWh, backup SoC before forecast Stages, and any new earth-leakage or isolation alarms. Export CSVs monthly — monitoring numbers · Wi-Fi dongle · SoC settings.
When to call vs when to wait
Call for burning smells, repeated RCD trips, zero production in full sun with isolators on, or firmware prompts you do not understand — fault codes · MC4.
Runtime maths homeowners should demand
Essential watts × hours ÷ 1000 = kWh needed. Divide by usable fraction (DoD × (1 − reserve)). Example: 600 W essentials × 4 h Stage = 2.4 kWh needed. On a 10 kWh sticker pack at 80% DoD with 20% Stage reserve, planned cycling energy is roughly 6.4 kWh — so one Stage is easy, but two long Stages plus evening cooking is not. Put that arithmetic on the quote.
- List fridge, routers, lights, Wi-Fi, gate motor separately.
- Reject “whole house for 8 hours” claims without watt totals.
- For EV overnight from solar, size the buffer for commute kWh + losses — Stage 4 · runtime tool · cheap public DC.
Heat, parallel packs and warranty small print
Parallel packs only add usable kWh if each pack is healthy and within OEM parallel rules. Heat above the datasheet band cuts both immediate capacity and long-term retention. Register warranties with serial photos the week of install — parallel · heat · warranty claims · cycles warranty.
MKII / street price discipline again
Cite OEM usable-kWh tables and dated distributor listings: BlueNova MKII at ACDC Dynamics is R37 341.95 incl. VAT special net (out of stock, 27 Oct 2026) on 12.86 kWh usable. TERVOL L16 is not MKII. Prefer Solar MD / Pylontech / Hubble / Freedom Won / BlueNova peers with live Incl. VAT stock lists when comparing rand per usable kWh.
Quote red flags on capacity language
- “10 kWh” with no DoD or usable figure.
- Runtime claims without listing essential watts.
- Mixing sticker kWh across brands as if usable fractions match.
- Promising EV charging + whole-house Stages from a single small pack.
Ask the salesperson to rewrite the slide as usable kWh at warranty DoD, then re-run Stage and EV-buffer scenarios. Related hubs: batteries · size system · do I need a battery · 10 kWh cost · battery brands.
Field note on Solar MD / peers
When comparing local packs, use published warranty years, cycle claims, and usable kWh — not soft rankings. Cape Town manufacturing/support can matter for claim logistics; it is not a substitute for correct sizing. Leave unverified street RRPs OPEN.
Extra SA context for battery sticker kwh vs usable sa
Keep primary PDFs open while you read this page. When a WhatsApp forward disagrees with a metro tariff book, OEM manual or DriveElectric-cited rate card, the primary wins. File CoC, warranties and app screenshots after every install or public-charging expense claim. Related: FAQ · about · choose installer · NRS list · SSEG · load shedding · metro tariffs · costs & savings · get quotes · check a quote.
Worked Stage + EV buffer example
Sticker: 16 kWh. Warranty DoD 80% → 12.8 kWh usable. Reserve 25% SoC for Stage surprises → about 9.6 kWh for daily cycling. Evening essentials average 0.7 kW for 5 hours = 3.5 kWh. That leaves roughly 6 kWh theoretical for shifting solar into an EV overnight — before inverter/cable losses. A 40 kWh weekly commute (~6 kWh/day) therefore needs disciplined SoC management or a second pack, or you lean on workplace charging / public DC (including Richmond’s published cheap window when available) instead of pretending one pack does everything.
- Write the commute kWh/day on the survey sheet.
- Decide Stage reserve before EV-buffer ambitions.
- Recalculate after the first month of portal data — not brochure hope.
Links: Stage 4 battery · usable kWh · DoD · SoC settings · cheap public DC · EV from solar.
Shopping peers without soft rankings
Compare Solar MD, Pylontech, Hubble, Freedom Won, BlueNova and other locally supported packs on usable kWh, warranty registration, cycle claims, and Incl. VAT stock — among peers. Quote MKII from the dated ACDC listing, not from undated retailer pages. Ask every vendor for the same usable-kWh denominator.
Handover sheet fields that lock usable kWh
On handover day, write sticker kWh, warranty DoD, configured SoC floors, parallel count, and firmware version on one laminated card stuck inside the DB door. When a technician later changes floors, update the card. That single habit prevents “the battery shrank” arguments that are actually settings drift — guest monitoring · inverter warranty · battery warranty.
Buy usable kWh, not the sticker
Quote every installer on usable kWh at the DoD the warranty actually allows, not the nameplate. A 10 kWh sticker pack at 90% DoD is ~9 kWh of real evening energy; the same sticker at 80% DoD is 8 kWh. Stage-4 backup maths fails when the quote uses the bigger number.
Ask for the BMS usable window in writing, the cycle warranty at that DoD, and whether parallel packs lose usable capacity to bottom-balance. Reject any quote that only lists “kWh” without usable % — that is sales language, not engineering. Size nights of cover from usable kWh ÷ evening essential load, then add 15–20% for winter and inverter losses.
On handover day, discharge the pack under a known essential load and time it. Compare measured kWh to the usable figure on the quote. A gap bigger than inverter losses means the sales number was sticker kWh — raise it before final payment clears.
For parallel packs, usable kWh is the sum after balance — not nameplate × count. Commissioning that skips a measured discharge test leaves that gap invisible until Stage 4 exposes it.
Quick questions
Is 100% DoD OK?
Only if the OEM warranty explicitly allows it — many LiFePO₄ warranties are tested at ~80% DoD.
Why did my portal show less after a year?
Calendar ageing, heat and throughput. Check warranty registration and operating temperatures.
Do I size batteries on sticker or usable?
Usable — and on essential load watts × hours, not hope.