Off Grid Engineering

Solar Savings Calculator

Enter your monthly Eskom spend and see what solar could save you over 25 years — including a full LCOE and payback comparison.

Monthly Eskom spend

R 25 000per month

R 5 000R 200 000

Eskom tariff

Connection type

Application

System size

72.5 kWp

117 × 620W panels

Monthly saving

R 19 644/mo

~79% of bill

Payback

4.7 / 3.4 yrs

Sigen / Deye

LCOE — cost per kWh over 25 years

Eskom (25yr avg)

R8.04/kWh

SigEnergy Premium

R0.46/kWh

Deye Value

R0.45/kWh

Cumulative cost over 25 years

Eskom spendSigEnergy totalDeye total

Indicative investment range

Option A — SigEnergy Premium

R 1 101 574

incl VAT

10 000 cycles at 100% DoD

Built-in fire suppression on every module

IP66 outdoor rated

No midlife battery replacement

Option B — Deye Value

R 795 169

incl VAT

6 000 cycles at 90% DoD

No built-in fire suppression

IP20 indoor rated — plant room required

Battery replacement required at year 16

Important — Option B: Deye battery limitations vs Option A

Cycle life6 000 cycles at 90% DoD vs Option A at 10 000 cycles at 100% DoD. At one cycle per day, Deye batteries reach end of warranty life at approximately year 16 — battery replacement will be required before the end of the 25-year system life.

Replacement costEstimated replacement at year 16 is factored into the Option B LCOE shown above. Option A (Sigenergy) requires no battery replacement within the 25-year system life.

Annual cycle capDeye warranty is capped at 700 charge cycles per year. A double-peak TOU strategy voids the warranty. Option A (Sigenergy) has no annual cycle cap.

Fire suppressionThe Deye BOS-B Pro does not include built-in fire suppression or gas detection. Option A Sigenergy batteries include aerosol extinguishing, smoke sensor, and exhaust system as standard across all modules.

IP ratingDeye BOS-B Pro is IP20 rated — indoor rack installation only, requires a plant room. Option A Sigenergy batteries are IP66 outdoor rated.

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These are indicative estimates. A site-specific proposal includes exact system design, pricing, and Section 12C tax analysis.

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Estimates based on indicative pricing and average SA irradiance data. Actual system size, cost, and savings depend on site conditions, load profile, and on-site assessment. All costs include VAT at 15%. Eskom escalation assumed at 8.76% per year. Section 12C tax benefit not included in payback calculation.