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Solar PV FAQs

1. How much would it cost to install a solar PV system on my rooftop?
  The estimated cost ranges between $750-$1,000 per kWp (kilowatt peak) installed. The cost depends on a wide variety of factors, such as building height, type of roof, etc.
2. How long is the payback period of a solar PV system?
  The payback period is typically between 3 to 4 years.
3. What are the authorities’ submissions required for the installation of a solar PV system? 
  Submissions to SCDF (for fire safety) and SP (for grid connection and export of electricity) will be required. In certain circumstances, submissions to BCA and URA may also be required.
4. Can my roof withstand the additional weight from the solar panels?
  Yes, the roof is capable of withstanding additional loading from solar panels.
For metal roofs, the additional loading is approximately 0.15kN/m2 and for RC roofs, the additional loading is approximately 0.6kN/m2.
5. How should solar panels be placed/secured on the rooftop?
  The solar panels should be placed at a location free from shading between 10am to 4pm and placed at an incline of 3 to 10 degrees to allow rainwater to flow down freely.
  For metal roof, clamps are used to secure the solar panel mounting structures to the ribs of the metal roofing sheet. For RC roof, concrete ballasts are used as weight to hold down the solar panel mounting structures.
6. How much electricity can my solar panel generate each year?
  Based on the average annual solar irradiation of 1580 kWh/m2/year and performance ratio of between 0.77 to 0.80, the amount of solar energy ranges between 1215 to 1265 kWh for each kWp installed each year.
7. Where does the electricity generated from my solar panels go to?
  The solar energy will be first be consumed by the building’s electrical loads. If there are any excess solar energy, it will be exported to the grid.
8. Will I be paid for electricity sold to SP?
  Yes. SP will replace your existing meter with a bi-directional meter to track the amount of solar energy exported to the grid.
9. Can the electricity generated from the solar panels be stored for later use?
  The solar energy cannot be stored for later use, unless an Energy Storage System (ESS) is installed to store excess solar energy for later use.
10. How does shading affect the performance of the solar panels?
  The output current from the solar panels will be substantially reduced, resulting in reduced power output and energy generation.
10. How does shading affect the performance of the solar panels?
  The output current from the solar panels will be substantially reduced, resulting in reduced power output and energy generation.
11. How often do solar panels need maintenance and cleaning?
  The recommended frequency is once per year.
12. Which component of the solar PV system is most prone to damage?
  The most critical component of the solar PV system is the inverter.
  The inverter is responsible for converting DC (Direct Current) generated from the solar modules into AC (Alternating Current) which is used to power the building’s electrical loads.
13. In the event of an emergency (such as fire), are there any safety devices to shut off the solar PV system?
  Yes. Each inverter is equipped with an AC isolator to disconnect the power supply feeding into the grid. However, solar panels will continue to generate power even when the AC isolator is disconnected. An additional device, the RSD (Rapid Shutdown Device), acts as a switch to reduce the output voltage to safe levels.
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