Can I Run Aircon (AC) with a Solar Panel in Singapore?

In Singapore’s warm and humid climate, air conditioning is a necessity in most homes and workplaces. At the same time, rising electricity costs and greater environmental awareness have prompted many to explore renewable energy solutions like solar power. A common question that arises is: Can you run your aircon using solar panels? The answer is yes—but the feasibility depends on several key factors including system size, energy consumption patterns, and whether your solar setup includes batteries or is connected to the grid.

Understanding Aircon Energy Usage

To evaluate whether solar panels can run your aircon, it’s important to understand how much electricity your AC system consumes.

• A typical single-split inverter aircon unit uses about 0.8 to 1.2 kilowatts (kW) per hour.

• A multi-split system for a three-bedroom HDB flat or a terrace home might use 2.5 to 3.5 kW per hour.

• Larger centralised or commercial units, such as those used in offices, warehouses, or shopping malls, can consume between 5 and 15 kW per hour depending on the cooling load.

If you run a 1 kW unit for 6 hours per night, that equals about 6 kilowatt-hours (kWh) per day. Multiply that by 30 days, and you get around 180 kWh per month for just one unit. For households running several aircon units daily, the total can easily exceed 500 to 700 kWh monthly.

Solar Panel Output in Singapore

Singapore’s tropical location makes it ideal for solar power generation. A 1 kWp (kilowatt-peak) solar system in Singapore typically produces between 1,300 and 1,500 kWh per year. That translates to about 3.5 to 4.1 kWh per day, depending on roof orientation, system quality, and weather conditions.

So, to generate 6 kWh of electricity daily (enough to power one small aircon unit), you would need around a 2 kWp solar system. If you run multiple aircon units, a larger system—ranging from 5 to 10 kWp—may be necessary just to cover air conditioning use.

Daytime vs Night-Time Usage

One key challenge when using solar energy for air conditioning is the timing of energy use. Solar panels only generate power during the day, typically from 8am to 6pm, with peak output between 11am and 3pm. However, most people in Singapore use aircon at night, especially between 9pm and 7am.

This creates a mismatch between energy generation and consumption. To bridge this gap, there are two main options:

1. Export excess solar power to the grid during the day, and draw electricity from the grid at night.

2. Store solar energy in batteries for use during the night.

Let’s explore both in detail.

Option 1: Grid-Tied Solar System with Net Metering

The most common and cost-effective setup for residential properties in Singapore is a grid-tied solar system. In this setup, your home stays connected to the national electricity grid while also generating electricity through solar panels.

Here’s how it works:

• During the day, your solar panels generate electricity.

• This electricity is used to power your household appliances and any surplus is exported to the grid.

• At night, when your panels stop generating power, your home draws electricity from the grid.

• Through a scheme called net metering, the exported electricity during the day is credited against your night-time usage.

In this arrangement, even though you are not directly using solar power to run your aircon at night, you are still offsetting your total electricity costs by selling surplus energy to the grid. Effectively, your daytime solar generation helps to subsidise your night-time aircon use.

This method is ideal for most homeowners in Singapore, particularly those who don’t want to invest in expensive battery systems.

Option 2: Solar Panels with Battery Storage

If you want to run your aircon entirely off solar energy—including at night—you’ll need to install a battery storage system along with your solar panels. Batteries store the excess energy produced during the day and discharge it when needed after sunset.

To run a 1 kW aircon unit for 6 hours, you’d need a battery with at least 6 kWh usable capacity. To account for system inefficiencies and depth-of-discharge limits, the practical requirement may be closer to 7 to 8 kWh per night per unit. For a home with three rooms running AC, you might need 15 to 20 kWh of storage to stay off-grid for the night.

Battery options in Singapore typically include lithium-ion solutions ranging from 5 to 13 kWh. Some well-known options offer integrated inverters and smart energy management, but they come at a premium. Battery systems alone can cost between S$10,000 and S$20,000 depending on capacity and brand.

Case Study: Landed Home Solar Setup

Consider a 3-storey landed property in Bukit Timah with four inverter split aircon units running from 8pm to 7am daily. The total monthly aircon consumption is around 450 kWh. The homeowner installs a 10 kWp solar system, which generates about 1,200 to 1,300 kWh per month.

The home remains grid-tied and exports about 500 kWh of unused daytime energy monthly. This offsets most of the aircon energy drawn from the grid at night. Without a battery, the system still manages to reduce the monthly electricity bill by over 60%. Payback for the system is projected at around 6 to 7 years.

Commercial Aircon Systems and Solar

Commercial buildings, warehouses, and factories often have large aircon systems running during the day—the same time solar panels generate electricity. This makes solar particularly attractive for commercial use.

For example, a factory with a 180 kWp rooftop solar system can generate around 700 to 750 kWh per day. This can cover a significant portion of its daytime aircon, lighting, and machine loads. In these setups, solar power directly reduces the electricity bill during peak operational hours without the need for batteries.

Commercial buildings also benefit from larger roof space and economies of scale. Installation costs can fall to S$940 per kWp, compared to S$1,500 to S$2,000 per kWp for smaller residential systems.

Cost Breakdown for Running AC on Solar

Here’s a simplified overview of the costs involved in running aircon with solar:

Most residential users choose the grid-tied option due to the high upfront cost of batteries. However, prices for storage are gradually decreasing, making full off-grid solutions more realistic in the future.

Environmental and Financial Benefits

Using solar panels to offset or directly power aircon usage has both environmental and economic benefits. Every kWh of solar energy used reduces reliance on fossil fuels, lowering carbon emissions. A 10 kWp system can offset around 6,000 kilograms of CO₂ emissions per year.

Financially, homeowners can save between S$1,500 and S$3,000 annually depending on system size and household energy habits. With proper maintenance, most systems last over 25 years, offering a strong return on investment.

Conclusion: Is It Worth Running AC with Solar?

Yes, it is definitely possible to run your aircon using solar panels in Singapore, but the practicality depends on your specific setup.

• If your aircon runs mostly during the day, solar panels can directly power it.

• For night-time aircon use, a grid-tied system allows you to offset usage through net metering.

• If full independence is your goal, battery storage will be required, but at a higher cost.

For most homes, a well-sized grid-tied solar system provides an effective way to reduce the overall cost of running aircon while also lowering carbon emissions. The combination of energy savings, government incentives, and long-term performance makes solar an increasingly attractive option for both residential and commercial users in Singapore.

FAQ: Solar Panels and Air Conditioning in Singapore

How many AC units can a 5kW solar system run?

A 5kW solar system in Singapore generates approximately 20 kWh per day. If each inverter-type aircon unit consumes around 1.2 kWh per hour and runs for 6 hours daily, that equates to 7.2 kWh per day per unit.
A 5kW solar system can support around 2 small to mid-sized AC units, assuming daytime usage and favourable weather conditions.

How many AC units can run on a 10kW solar system?

A 10kW solar system typically produces about 40 kWh per day.
This output is sufficient to run 4 to 5 inverter-type aircon units for 6 hours each day, depending on usage patterns and other electrical loads in the home.

What size room will a 5kW aircon cool?

A 5kW air conditioning unit provides approximately 17,000 BTU/hour of cooling capacity.
This is suitable for cooling a room between 40 to 50 square metres, such as a large living room, open-plan space, or a small shopfront.

How many kW do I need for an aircon?

Aircon capacity should be matched to room size:

• Bedrooms up to 15 m²: 1.0 to 1.2 kW

• Medium rooms (15–25 m²): 2.0 to 2.5 kW

• Larger living spaces (25–40 m²): 3.5 to 5.0 kW

Proper sizing ensures both efficiency and comfort.

How many fans can run on a 5kW solar system?

Ceiling fans typically use 50 to 75 watts per hour. A 5kW solar system producing 20,000 watt-hours (20 kWh) per day can support 20 to 30 fans for 8 to 10 hours, depending on sun conditions and simultaneous power usage.

How many batteries are required for a 5kW solar system?

To store the full daily energy generated by a 5kW solar system (about 20 kWh), you would need 2 to 3 lithium-ion batteries, each rated between 7 to 10 kWh.
This setup provides overnight usage and backup capabilities for running appliances including air conditioners and refrigerators.

How much does it cost to install a 5kW solar system in Singapore?

A 5kW solar panel system in Singapore typically costs between S$10,000 and S$13,000, including installation.
The system usually requires around 25 to 30 square metres of roof space. Final pricing depends on panel type, inverter brand, and installation complexity.

Sources

1. Energy Market Authority (EMA), Singapore: Solar Photovoltaic Systems – Cost and Performance Benchmarks

2. National Climate Change Secretariat (NCCS): Solar Energy Technology Primer

3. Residential AC Usage Estimates from Singapore Electricity Retailers

4. Cooling capacity conversion: 1 kW ≈ 3,412 BTU/hour

5. Typical ceiling fan consumption data from appliance energy usage references