How Solar Power Systems Cut Utility Bills in SG

The Actual PRM Math: Solar Byte vs SP Tariff

The core cut comes from grid offtake avoidance. SP Group’s tariff in late 2025 is around 30.55 cents per kWh without GST, while the average landed home on the SP Services “Monthly” plan draws 800-1,200 kWh. A 5 kWp rooftop array in Singapore receives about 1,580 kWh of irradiation per year per kWp, so it yields around 7,900 kWh annually—over 60% of that landed home’s yearly use.

The bill doesn’t just drop linearly. Because SP’s tariff includes grid costs, market energy cost, and carbon tax, every avoided kWh is priced at the full blended rate. A 5 kWp system producing 650 kWh monthly replaces roughly $199 worth of grid electricity at current rates. Over a 500-month degradation curve (26 years), that’s a lifetime displacement of about 14,000 kWh per year for larger systems.

Night Draw and the Zero-Cost Swap

Solar output peaks from 11 AM to 4 PM, when household load in an HDB flat is minimal—aircon runs at night, no one is home during work hours. The critical cut relies on SP’s net-metering regime (BESS pilot aside) where the grid functions as a free battery. The meter runs backward for every kWh exported, erasing consumption fully before SP charges for the residual net usage.

But here’s the granular reality: residential installers like SolarCI or Emerald Sun configure the inverter for no grid-export from storage, and most landed homes don’t get feed-in revenue. The system simply zeros out the daytime draw. The full saving shows up as a single line on the SP bill: “Net Adjustment” bottoming out in dry months.

NEM / SEM Connection: The Export Cap Changes Everything

For landed properties, SP’s pilot for residential solar export had a capped eligibility—meter export was limited to 50% of installation capacity per month under older rules. The moment a system exceeds that cap, the surplus becomes a straight giveaway to the grid. So cutting utility bills is measured by system sizing: oversize a 10 kWp array for a family using 1,000 kWh monthly, and you lose 400 kWh of export value every month.

The real sweet spot is under-sizing to match daytime self-consumption plus a modest export buffer. Professional estimators in SG push a 7.5 kWp system for an 800 kWh monthly family—enough to eliminate nearly the entire bill in cloudy northwest monsoon months while avoiding export forfeiture.

HDB vs Landed: Different Payback Curves

HDB residents rarely own their rooftops; the SolarNova programme uses third-party operators like Sembcorp and Cleantech who lease the space, selling white and green energy credits back to owners, not retail homeowners. The utility-bill cut for an HDB unit comes only through SP’s “Green Electricity” tariff—if the household subscribes to solar-wind blended REMA, there’s no component-level reduction in the bottom line, just a green-label price stabilisation.

Landed homeowners see the real benefit. A 10 kWp install in Singapore costs about S$12,000–S$15,000. With monthly savings of S$280–S$350 on the SP bill, the cash payback lands between 3.8 and 4.6 years. However, note the replacement cost of inverters at year 10 (S$1,200) and panel cleaning debts.

The BESS Add-On: Pushing Off the Peak

The overlooked cut comes from energy storage. Households with a 10 kWh LFP battery (e.g., Fortress Power or Pylontech) can shift midday solar to the 6 PM–10 PM peak window when SP’s tariff is still blended but aircon load spikes. The battery doesn’t export to the grid—it directly offsets consumption that would otherwise be charged at the same 30.55¢/kWh. On a 1 kWh/h hourly load differential, a 10 kWh battery compresses the evening draw to zero for four hours.

That makes the payback tighter: battery costs around S$8,000, and the monthly saving climbs to S$420–S$480. Break-even is 5.4–6.2 years, but with S$0.03/kWh battery cycle costs, the lifetime cut beats pure PV by 30% in 2025 pricing.