Why Does Battery Size Matter for Singapore Solar Homes?
A home battery stores surplus solar energy generated during the day so you can use it at night instead of buying electricity from the grid. In Singapore, solar panels generate power between roughly 7 am and 6 pm, but most households consume 50–60% of their electricity in the evening and overnight — for air conditioning, cooking, and entertainment.
Without a battery, surplus daytime solar is exported to the grid under the Net Energy Rebate (NER) at the wholesale rate (15–20 ¢/kWh). With a correctly sized battery, you store that energy and use it yourself at the full retail rate (31–33 ¢/kWh), effectively doubling the value of each stored kilowatt-hour.
But choosing too large a battery wastes capital on unused capacity, while too small a battery leaves savings on the table. This guide walks you through how to size a home battery for Singapore conditions, with real numbers, tables, and product comparisons.
How Much Electricity Does a Singapore Home Use at Night?
The critical metric for battery sizing is your evening and overnight consumption — the electricity you use from roughly 6 pm to 7 am the next day when solar panels are not generating. In Singapore's tropical climate, air conditioning dominates night-time load.
| Property Type | Total Daily Usage (kWh) | Evening/Night Usage (kWh) | Recommended Battery Size |
|---|---|---|---|
| Terrace house | 25–40 | 12–22 | 10–13.5 kWh |
| Semi-detached | 35–60 | 18–33 | 13.5–20 kWh |
| Detached / Bungalow | 50–100 | 27–55 | 20–40 kWh |
| GCB / Large estate | 80–150+ | 45–85+ | 40–60+ kWh |
These recommendations assume you want to cover 50–70% of evening consumption from battery, which is the economically optimal zone for most households. Covering 100% of overnight load requires a significantly larger (and more expensive) battery that may not deliver proportional financial returns.
To determine your specific evening usage, review your SP bill or smart meter data. Sunollo's site assessment includes a detailed consumption analysis that identifies the optimal battery size for your household pattern. You can also check your historical bills against the benchmarks in our complete home battery storage guide.
How Do You Calculate the Right Battery Size in kWh?
Battery sizing follows a straightforward formula, but several Singapore-specific factors affect the result:
Step 1 — Estimate daily solar surplus. A typical 10 kWp system in Singapore generates around 35–38 kWh/day. If daytime household consumption is 15 kWh, the surplus available for storage is approximately 20–23 kWh.
Step 2 — Estimate evening consumption. For a semi-detached home running 2–3 air conditioning units at night plus standard appliances, expect 20–30 kWh between 6 pm and 7 am.
Step 3 — Match battery to the smaller of the two figures. There is no point installing a 30 kWh battery if you only have 20 kWh of solar surplus — the extra capacity sits empty. Equally, a 10 kWh battery with 20 kWh of surplus leaves half the storable energy unbanked.
Step 4 — Apply depth of discharge (DoD). Modern LFP (Lithium Iron Phosphate) batteries like those used in Sunollo's Abundance Pro system offer 90–100% usable DoD. A 13.5 kWh battery at 95% DoD provides 12.8 kWh of usable capacity.
Step 5 — Factor in degradation. LFP batteries retain 80%+ capacity after 6,000 cycles (approximately 15–16 years of daily cycling). Size slightly above your minimum requirement to maintain adequate capacity over the battery's lifetime.
What Are the Best Home Batteries Available in Singapore?
Singapore's residential battery market is dominated by a few proven systems. All models below use LFP chemistry, which is preferred for its thermal stability (critical in Singapore's climate), long cycle life, and absence of cobalt.
| Battery System | Usable Capacity | Power Output | Warranty | Chemistry | Key Feature |
|---|---|---|---|---|---|
| SolarEdge Energy Bank | 10 kWh (stackable to 30 kWh) | 5 kW per unit | 10 years / 70% retention | LFP | Seamless integration with SolarEdge EnergyHub inverter; DC-coupled for higher efficiency |
| Tesla Powerwall 3 | 13.5 kWh | 11.5 kW continuous | 10 years / 70% retention | LFP | Integrated inverter; high continuous power output; whole-home backup capable |
| BYD HVS / HVM | 5.1–22.1 kWh (modular) | 5–10 kW (inverter-dependent) | 10 years / 80% retention | LFP | Highly modular — add capacity in 2.56 kWh increments; wide inverter compatibility |
| GoodWe Lynx Home U | 9.6–19.2 kWh (modular) | 4.6 kW per unit | 10 years / 70% retention | LFP | Compact wall-mounted design; integrates natively with GoodWe hybrid inverters |
Sunollo's Abundance Pro package pairs rooftop solar panels with the SolarEdge EnergyHub inverter, which provides integrated battery management, per-panel optimisation, and seamless DC-coupled battery integration. This DC-coupled architecture delivers 3–5% higher round-trip efficiency compared to AC-coupled alternatives — a meaningful difference over 15+ years of daily cycling.
How Much Does a Home Battery Cost in Singapore — and What Is the Payback?
Battery costs have declined significantly but remain a meaningful investment. The table below shows realistic installed costs and payback periods for Singapore landed homes as of 2026.
| Battery Capacity | Estimated Installed Cost (SGD) | Annual Savings from Stored Energy | Simple Payback Period | Best For |
|---|---|---|---|---|
| 10 kWh | $12,000–$16,000 | $1,100–$1,500/year | 9–12 years | Terrace homes; moderate consumption |
| 13.5 kWh | $15,000–$20,000 | $1,400–$1,900/year | 8–11 years | Semi-detached homes; high evening A/C use |
| 20 kWh | $20,000–$27,000 | $1,800–$2,600/year | 8–12 years | Detached homes; blackout backup priority |
| 30+ kWh | $28,000–$40,000+ | $2,400–$3,500+/year | 9–13 years | Large homes; GCBs; maximum self-sufficiency |
Annual savings are calculated based on the value of stored solar energy consumed at the retail tariff (~31.78 ¢/kWh) minus the wholesale export rate (~17.6 ¢/kWh) that would have been earned through NER — a net benefit of approximately 14 ¢/kWh per stored kWh. For more detailed cost analysis, see our home battery storage cost breakdown.
Important: These payback figures are for standalone battery economics. When paired with solar as part of a complete system (like Sunollo's Abundance Pro), the combined payback is faster because the solar panels are already generating free electricity — the battery simply shifts when you use it.
What Is Self-Consumption and Why Does Battery Size Affect It?
Self-consumption is the percentage of your solar generation that you use directly in your home, rather than exporting to the grid. It is the single most important metric for maximising the financial return on your solar investment.
- Solar only (no battery): Typical self-consumption is 60–70% for Singapore landed homes. The remaining 30–40% is exported at the lower wholesale NER rate.
- Solar + 10 kWh battery: Self-consumption rises to 80–88%, depending on consumption pattern.
- Solar + 13.5–20 kWh battery: Self-consumption reaches 85–95%, capturing nearly all surplus solar generation.
Diminishing returns set in beyond a certain battery size. Going from 13.5 kWh to 20 kWh might only improve self-consumption by 3–5 percentage points, while the cost increases by $5,000–$7,000. The optimal point depends on your specific consumption pattern — which is why Sunollo's site assessment models your actual load profile before recommending a battery size.
For a deeper dive into self-consumption economics, see our self-consumption vs grid export guide.
Should You Size Your Battery for Backup Power?
Singapore enjoys one of the most reliable electricity grids in the world, with average outage times under 1 minute per customer per year. However, some homeowners prioritise battery backup for peace of mind or to protect sensitive equipment.
If backup is a priority, battery sizing changes significantly:
- Essential circuits only (lights, fridge, router, phone charging): 5–10 kWh provides 8–16 hours of backup.
- Essential + 1 air conditioning unit: A 13.5 kWh battery sustains about 6–8 hours.
- Whole-home backup including multiple A/C units: Requires 20+ kWh and a high-power inverter (≥10 kW continuous output) to handle surge loads from compressor startups.
Not all battery systems support backup equally. The SolarEdge EnergyHub with Energy Bank supports automatic backup switchover with configurable backup reserve, meaning you can designate a percentage of battery capacity exclusively for outage protection while the remainder cycles for daily self-consumption.
How Does Singapore's Climate Affect Battery Performance?
Singapore's year-round temperatures of 25–35°C are within the optimal operating range for LFP batteries (15–35°C), making LFP chemistry particularly well-suited for local conditions. Key climate considerations:
- No cold-weather degradation: Unlike cold climates, Singapore batteries never face reduced capacity from low temperatures.
- Thermal management: Quality battery systems include active cooling to prevent overheating during heavy charge/discharge cycles. Indoor installation (common in Singapore landed homes) typically keeps batteries within optimal temperature ranges.
- Consistent solar generation: Singapore receives 1,580–1,620 peak sun hours per year with relatively low seasonal variation. This means your battery charges fully almost every day — maximising utilisation and financial return.
- Humidity protection: Batteries installed in Singapore must have IP65 or higher ingress protection ratings if installed in semi-outdoor locations like carports.
LFP chemistry also offers inherent safety advantages — it is thermally stable up to 270°C and does not experience thermal runaway under normal failure conditions. This is why Sunollo exclusively uses LFP-based battery solutions. For a broader overview of battery technology in the Singapore context, read our solar battery storage guide.
What Is the Difference Between DC-Coupled and AC-Coupled Batteries?
This distinction affects efficiency, cost, and system design:
- DC-coupled batteries connect directly to the solar inverter on the DC side. Solar energy flows to the battery without an additional DC-to-AC conversion step, achieving round-trip efficiency of 90–95%. The SolarEdge EnergyHub + Energy Bank is a DC-coupled system.
- AC-coupled batteries have their own built-in inverter and connect on the AC side of the electrical panel. Solar energy is converted DC→AC→DC→AC, which introduces 5–10% additional conversion losses. The Tesla Powerwall 3 is an AC-coupled system.
For new solar + battery installations, DC-coupled systems are generally preferred because they are more efficient and require fewer components. AC-coupled batteries are better suited for retrofitting onto existing solar systems where the original inverter cannot be replaced.
Can You Add More Battery Capacity Later?
Yes — but the ease of expansion depends on the system architecture:
- SolarEdge Energy Bank: Stackable up to 3 units (30 kWh total) on a single EnergyHub inverter. Adding a second unit later is straightforward.
- BYD HVS/HVM: Modular design allows adding battery modules in 2.56 kWh increments up to the system maximum.
- Tesla Powerwall 3: Multiple units can be installed in parallel (up to 4 units / 54 kWh), but each unit is self-contained.
- GoodWe Lynx Home U: Expandable within the same stack up to the inverter's maximum battery capacity.
Sunollo recommends planning for your likely future needs rather than the absolute minimum today. The incremental cost of installing slightly more capacity upfront is lower than retrofitting additional units later, which may require additional wiring and commissioning.
Frequently Asked Questions
How many kWh battery do I need for a terrace house in Singapore?
A typical Singapore terrace house uses 25–40 kWh per day, with 12–22 kWh consumed in the evening and overnight. A 10–13.5 kWh battery covers the majority of this evening load and is the most cost-effective size. If you run multiple air conditioning units overnight, consider 13.5 kWh as the starting point.
Is a 5 kWh battery enough for a Singapore home?
A 5 kWh battery is generally too small for meaningful self-consumption gains in a Singapore landed home. It would cover only 3–5 hours of base load without air conditioning. For most households, the minimum recommended size is 10 kWh. A 5 kWh battery might suit a very small apartment or a system designed purely for essential-circuit backup.
What is the lifespan of a home battery in Singapore?
Modern LFP (Lithium Iron Phosphate) batteries are rated for 6,000–10,000 cycles at 90–100% depth of discharge. With daily cycling, this translates to 15–25+ years of operational life. Most manufacturers warrant 10 years or a specified number of cycles, with guaranteed minimum capacity retention of 70–80%. Singapore's warm climate is actually favourable for LFP chemistry, which performs well between 15–35°C.
Can I use a battery without solar panels?
Technically yes — a battery can charge from the grid during off-peak periods and discharge during peak hours. However, Singapore does not have time-of-use (TOU) electricity pricing for residential consumers, so there is no financial arbitrage opportunity. Without solar panels, a standalone battery offers backup power only and has no meaningful payback. Batteries are most cost-effective when paired with solar.
How does battery size affect the payback period?
Larger batteries have longer payback periods due to diminishing returns on self-consumption. A 10 kWh battery paired with a well-sized solar system typically pays back in 9–12 years. A 20 kWh battery on the same system might take 10–13 years because the additional 10 kWh captures less marginal value. The optimal economic size is usually the point where the battery captures 85–90% of available solar surplus.
What happens to my battery during a grid outage?
If your battery system supports backup mode (such as the SolarEdge EnergyHub), it automatically disconnects from the grid and powers designated circuits from stored energy. The switchover takes milliseconds. During daylight hours, your solar panels can continue charging the battery even while the grid is down, potentially extending backup duration indefinitely for modest loads. Not all systems support this — confirm backup capability before purchase.
Should I choose one large battery or two smaller ones?
Multiple smaller units can offer redundancy (if one fails, the other continues operating) and more flexible installation in space-constrained Singapore homes. However, a single larger unit is typically cheaper per kWh and simpler to install. For most Singapore landed homes, a single 10–13.5 kWh unit is the practical choice. Homes needing 20+ kWh may benefit from a stacked or modular approach like the SolarEdge Energy Bank or BYD HVS.
Does Sunollo install batteries for homes that already have solar panels?
Yes. Sunollo can retrofit battery storage onto existing solar installations. The approach depends on your current inverter: if you have a SolarEdge inverter, the Energy Bank integrates seamlessly via DC coupling. For systems with other inverters, an AC-coupled battery like the Tesla Powerwall or BYD with a compatible hybrid inverter can be added. Contact Sunollo through the battery enquiry page for a retrofit assessment.
