Is Solar Worth It in Singapore? The Honest 25-Year Calculation
Yes, solar is worth it for most Singapore landed homeowners in 2026. A 10kWp system delivers a net present value of S$40,600 in the base case and S$32,400 even in the pessimistic scenario with 1% degradation and no tariff growth.
Key Takeaways
- 1
At a 4% discount rate, a 10kWp Singapore system generates a net present value of approximately S$40,600 — positive in every realistic scenario
- 2
Even in a pessimistic scenario with 1% annual panel degradation and zero tariff growth, the 25-year NPV remains strongly positive at S$32,400
- 3
The question is not whether solar pays off in Singapore — it is how far the economics stretch when conditions are unfavourable
Short answer: yes, for most Singapore landed homeowners, solar is worth it in 2026. The fuller answer involves two scenarios, a base case and a pessimistic case, run over 25 years with a proper discount rate. Even the pessimistic scenario returns a strongly positive net present value. The question is not whether solar pays off. It is how much it pays off and under what assumptions the economics start to weaken.
The Setup: What This Calculation Uses
A 10kWp terrace house system at a total cost of S$13,000. Annual generation of 11,060 kWh based on Singapore's 4.33 peak sun hours and 70% system yield. Year-one saving of S$3,103, calculated at the Q3 2026 tariff of S$0.3478/kWh for 25% self-consumed electricity and the Solar Crediting Tariff of S$0.2581/kWh for 75% exported.
For the discount rate, we use 4%, reflecting a conservative low-risk benchmark return you could earn on a fixed deposit or Singapore Savings Bond. If your alternative is doing nothing with the S$13,000, the comparison changes. This analysis assumes the capital has an opportunity cost of 4% per year.
Base Case vs Pessimistic: The Full 25-Year Numbers
The base case uses 0.5% annual panel degradation and 0.5% annual tariff escalation. These two effects broadly cancel, leaving the annual saving relatively flat in nominal terms at approximately S$3,103 per year throughout the period.
The present value of S$3,103 per year over 25 years, discounted at 4%, equals approximately S$53,600. Subtract the S$13,000 upfront cost, and the net present value is approximately S$40,600.
The pessimistic case assumes 1% annual degradation (twice the industry standard) and zero tariff escalation, a scenario where energy prices stay flat for 25 years and your panels degrade twice as fast as the spec sheet projects. Year-one saving is still S$3,103. By year 25, degradation reduces that to approximately S$2,497. The present value of this declining stream, discounted at 4%, is approximately S$45,400. Subtract S$13,000, and the net present value is approximately S$32,400.
Where the Calculation Falls Apart
Solar stops making financial sense when at least two of the following are true simultaneously: the system is significantly oversized for the roof and household (more than 15kWp for a household using under 400kWh per month), the installation cost is significantly above market (above S$1,600 per kWp), and the household has very low daytime occupancy with no prospect of change.
One factor that genuinely does affect the economics: roof condition. Clay tile roofs older than 20 years sometimes require additional structural reinforcement before a racking system can be installed, which adds S$1,500 to S$3,000 to the cost. For a terrace with a compromised roof, the upfront cost rises and the NPV contracts accordingly. Get a structural assessment before committing if your roof is over 15 years old.
The pessimistic scenario, where panels degrade twice as fast as the spec sheet says and electricity prices never rise, still returns S$32,400 above the cost of the system over 25 years. That is not a marginal call. That is a comfortable margin of safety.
The honest caveats: this analysis assumes the inverter runs for 25 years with no replacement. In practice, most string inverters are replaced once in a 25-year system life, typically around year 10 to 12, at a cost of S$1,500 to S$3,000. Factoring in one inverter replacement in year 11, discounted at 4%, reduces the base-case NPV from S$40,600 to approximately S$38,000. Still significantly positive.
For your own roof and household, the Sunnify estimate tool uses the current tariff and your inputs to show the specific payback and NPV for your situation. Run your numbers here before you request installer quotes. The cost guide includes worked examples across different system sizes.
Further reading: SP Group solar energy information · IRENA residential solar cost trends.
At what electricity tariff does solar stop making sense in Singapore?
Running the base-case 10kWp model backwards: at a tariff of S$0.18/kWh (roughly 48% below the Q3 2026 level), the payback period stretches to approximately 9 years and the 25-year NPV at 4% discount rate approaches zero. Singapore tariffs have not been at S$0.18/kWh since before 2016, and the structural trajectory points upward rather than down. There is no realistic tariff scenario in which solar becomes financially irrational for a well-specified Singapore terrace or bungalow system at current installation prices.
Should I wait for solar panels to get cheaper before installing?
Panel costs have fallen roughly 90% over the past 15 years but have plateaued in recent years as manufacturing capacity caught up with demand. A further 10% fall in panel prices would reduce system cost by approximately S$800 on a 10kWp terrace system, moving payback from 4.2 years to 4.0 years. Meanwhile, every year you wait is a year without S$3,100 in electricity savings. The opportunity cost of waiting one year to save S$800 is approximately S$2,300 in foregone savings. Waiting makes sense only if you have a known upcoming event (roof replacement, major renovation) that would require decommissioning the system anyway.
See your numbers
What does this mean for your home?
Tariffs and technology change the math. The calculator uses current SP figures to show your actual payback and savings.
