Solar Water Heater vs Solar Power

Almost every house in Malaysia has a solar water heater installed on its roof. It is perhaps one of the first few things Malaysians will include when planning out their house renovation budget. But how much does a solar water heater actually help you save? And more importantly, which is a better investment when compared — solar water heater or solar power? Let’s explore below.


For comparison, we shall be using a solar water heater that is listed to be worth RM5290. Now, to determine how much cost of electricity this solar water heater can save you, we will need to compare it with how much you will actually need to pay, if you were to use an instant water heater during showers. The assumptions made are:

  1. A typical instant water heater is rated at 3.6 kW. However, not everyone will be showering at 100% heating at all times. Most will set a temperature of between 50% to 100%, depending on personal preference and the weather. As such, we shall take an average of 75%, or 2.7 kW rating.
  2. The solar water heater is suitable for 6 people.
  3. Assuming that each person takes a shower 2 times a day.
  4. Assuming that each shower is between 5-10 minutes, or an average of 7.5 minutes.
  5. Electricity tariff is assumed to be at RM0.497 (see below for explanation).

Electricity for instant water heater
= 2.7 kW x 6 people x 2 times x (7.5/60) hours x RM0.497 x 365 days
= RM734.69 a year


Payback duration for solar water heater
= RM5290 / RM734.69
= 7.2 years


For solar power, we shall use a 12.0 kWp system; which will typically cost about RM4500 per kWp, or RM54000 in total. This system is suitable for a monthly TNB bill of about RM800-RM850 a month, which should be the average electricity bill of a typical 6-person household living in an intermediate terrace house. The assumptions are:

  1. RM800 TNB bill translates to 1608.23kW of electricity. Here’s a breakdown:
    • Tier 1 (21.8sen first 200kW): RM43.60
    • Tier 2 (33.4sen next 100kW): RM33.40
    • Tier 3 (51.6sen next 300kW): RM154.80
    • Tier 4 (54.6sen next 300kW): RM163.80
    • Tier 5 (57.1sen next 708.23kW): RM404.40
    • TOTAL: RM800 for 1608.23kW electricity
    • Or average RM800 / 1608.23kW
    = RM0.497 per kW (tariff used for instant water heater calculation)
  2. Total sun peak hours a day in Malaysia
    = 3.8 hours
  3. Total electricity generated by solar
    = 12.0 kWp x 3.8 hours x 30 days
    = 1368 kW a month
  4. Under the Net Energy Metering (NEM) scheme, the savings for 1368 kW electricity generated by the solar:
    • Tier 5 (57.1 sen 708.23kW): RM404.40
    • Tier 4 (54.6 sen 300kW): RM163.80
    • Tier 3 (51.6 sen 300kW): RM154.80
    • Tier 2 (33.4 sen 59.77kW): RM19.96
    • TOTAL SAVINGS: RM742.96 a month or RM8915.52 a year


Payback duration for solar power system
= RM54000 / RM8915.52
= 6.1 years


With this, it is evident to see that a solar power system with returns of 6.1 years is a better investment compared to a solar water heater system with returns of 7.2 years. Other advantages of a solar power system include:

  1. Solar power systems have 25 years of performance warranty, compared to 10 years for solar water heaters.
  2. Government double tax incentives for businesses that could reduce cost of solar power systems by up to 48%. In other words, this could reduce a typical solar power system payback period of 6 years, down to about 3.1 years.
  3. The bigger the solar power system, the lower the cost per kWp; essentially shortening payback duration to below 6.1 years.

Granted that the total cost of a solar water heater system is much lower compared to a solar power system. But the question remains: Why do people hesitate when it comes to installing a solar power system, while most don’t think twice when installing a solar water heater?

For more information, simply get in touch with our SEDA certified Solar PV Engineers here. We will be glad to answer any questions you might have regarding this article, or to even provide you with a free power survey of your property.