About Singapore Polytechnic

Singapore Polytechnic (SP) is Singapore’s first polytechnic institution of higher learning specializing in science, technology, business, and the arts. At SP, there are over 15,000 students on a 38-hectare campus supporting 11 academic schools.

Searching for Relief from Soaring Electric Costs

At SP, it is expensive to keep classrooms and laboratories comfortable enough for students to learn and for professors to teach effectively. Extensive sports facilities on campus also require climate control for both players and spectators alike.

Furthermore, the need for relief from the hot and humid Singaporean weather is present all year round. So, running electric air conditioners most of the time is a significant component of their monthly utility bill.

Although Singapore Polytechnic already receives some of its electric power from solar panels on its campus, the school still pays enormous electric bills. Finding a way to integrate more solar power into their day-to-day operations would lower their energy expenses substantially.

The Performance of Enovatek’s Solar Hybrid Air Conditioner versus a Conventional Air Conditioner

To demonstrate the energy savings Enovatek’s Solar Hybrid Air Conditioning System offers, we set up three of our systems in two classrooms at SP. Two of our units had five already existing photovoltaic (PV) panels attached to each one. The third system did not.

Here is a photo of the complete solar panel set up:

The indoor air conditioning component of our system appears inconspicuously near the ceiling:

We attached electric meters to each of the air conditioners and measured the energy consumption over  24 hours. We also maintained the temperature at a comfortable 24℃. Here is a table of results from this trial:


Air Conditioner

Average Energy Consumed in 12 Hrs. (kWh)

Average Energy Consumer per Hour (kWh)

Enovatek Solar Hybrid with panels – #1



Enovatek Solar Hybrid with panels – #2



Enovatek Solar Hybrid w/o panels – #3



Conventional Air Conditioner




Conclusions: Enovatek’s Solar Hybrid Air Conditioning System (with solar panels) used approximately half as much energy as a conventional air conditioner. Enovatek’s Solar Hybrid Air Conditioning System without panels used significantly less energy than a traditional air conditioner.

Part of the reason for this difference — apart from the solar panels — is that Enovatek’s models consume less electric power than a traditional air conditioner, making it more energy-efficient. In terms of wattage, Enovatek’s Solar Hybrid Air Conditioning System (18,000 BTU capacity) operates on 1,475 watts per hour. A standard AC unit runs on approximately 1,740 watts/hr.

Although both types of air conditioners carry 5-year warranties for their compressors, Enovatek’s product carries a 3-year warranty compared to the one-year warranty for the conventional cooling system.

Furthermore, we back our photovoltaic panels for 12 years and guarantee their energy-efficient performance for 25 years. A standard air conditioner has no such guarantees of continued operation at peak levels.

Energy and Cost Savings from Enovatek’s Solar Hybrid Air Conditioning System Compared to a Conventional Air Conditioner

The energy savings generated from using our cooling system translated into cost savings for Singapore Polytechnic. This data permits a return on investment (ROI) calculation with values given in the following table.

Note that when it is not sunny, our solar hybrid system will partially default to the power grid and pull electric current off of it to function. Its ability to do so is what makes it a “hybrid” model. The figures in the table below reflect this.

However, even on cloudy or rainy days, our solar hybrid air conditioner will work — to a smaller degree — off of reduced solar energy. Additionally, our system will depend on the power grid during some parts of these days. Our calculations account for this too.

(All values based on $0.2385/kWh in SGD.)


Air Conditioner

Daily Consumption (kWh)

Daily Cost (SGD)

Annual Consumption (kWh)

Annual Cost (SGD)

Enovatek Solar Hybrid (sunny day)





Enovatek Solar Hybrid (cloudy day)





Enovatek Solar Hybrid (rainy day)











Conclusions: Under sunny conditions, Enovatek’s system requires only a fraction of the energy and costs – approximately 80% less – to operate compared to a conventional air conditioner. On a cloudy day, Enovatek’s hybrid solar AC consumes less than half the energy and costs only half as much to run versus a standard air conditioner. When it rains, Enovatek’s solar air conditioner still operates on about half the energy and at half the cost of a conventional AC.

Here is a table displaying the energy and cost savings of an Enovatek Solar Hybrid Air Conditioning System in comparison to a conventional air conditioner.


Air Conditioner

Daily Energy Savings (kWh)

Annual Energy Savings (kWh)

% Energy Savings

Annual Savings Cost (SGD)

Enovatek Solar Hybrid (sunny day)





Enovatek Solar Hybrid (cloudy day)





Enovatek Solar Hybrid (rainy day)






Conclusion: There are significant savings in both energy and cost with Enovatek’s Solar Hybrid Air Conditioning System no matter the weather — sunny, cloudy, or rainy.

A return on investment (ROI) calculation, based on the generated savings per month for one unit, proves that it takes only 1 ½ years for Enovatek’s system to pay for itself.

Monthly savings per AC unit on electricity equalling $134 is possible. That is a 56% reduction per month.

Enovatek Solar Hybrid Air Conditioning System Reduces Carbon Dioxide Emissions and Offsets Carbon

Singapore Polytechnic has taken several green initiatives in the past decade, beginning with winning the President’s Award for the Environment in 2010. Retrofitting SP’s campus with our solar hybrid AC system upholds the school’s commitment to sustainability for a livable planet.

Here is a table that illustrates the reduction in carbon emissions brought about by using our solar AC units instead of conventional machines. Also shown is the carbon offset, expressed as the equivalent number of trees planted. SP earns this offset because of our solar hybrid air conditioning system. (Carbon offset is a way to nullify your carbon footprint by planting trees which absorb the equivalent amount of carbon dioxide that you produce.)


Air Conditioner

Carbon Emissions Reduction (Kg/yr.)

Carbon Offset (Equivalent number of trees planted)

Enovatek Solar Hybrid (sunny day)



Enovatek Solar Hybrid (cloudy day)



Enovatek Solar Hybrid (rainy day)



Be Envionrmentally Intelligent with Enovatek

Learn more about Enovatek’s Solar Hybrid Air Conditioning System