Is Bangalore Climate suitable for Solar Rooftop? This is one of the big questions in Bangloreans’ mind. They are right, as Bangalore is blessed with cool climate compared to its counterparts like Chennai and Hyderabad, this question arises.
First, let us understand how Rooftop Solar works?
Solar Panels are installed on the roof of the building. When Sunlight falls on the Solar cells, they generate electricity by photovoltaic effect. And the amount of electricity generated depends on four main factors: 1. Temperature, 2. Intensity of sunlight, 3. Daily Sunlight hours, 4. Tilt angle of Solar Panels. Other things assuming to be same, we can look at the temperature effects on solar generation.
Most of us believe that very hot climate is ideal for Solar generation. But this is not true.
Generation from Solar Cells is inversely proportional to the temperature. As temperature goes above the standard test conditions, solar generation falls.
On the Solar panels we can see the efficiency parameters given. These are measured at Standard Test Conditions (STC). STC = 1000W/sq.m and 25o C. As the ambient temperature rises, the efficiency of the solar cells reduces. For every degree rise in cell temperature, the efficiency of crystalline solar silicon cells drop by 0.45%. This means, on a hot summer day the solar generation will actually be lesser compared to a cold clear winter day, other parameters being same.
A cool, Sunny day is ideal for maximum Solar generation. Solar generation also depends on the Sun light intensity (Irradiance) available at a location. Here, you can find the yearly averaged Solar Irradiance map published by National Renewable Energy Laboratory (NREL).
As you can see, Bangalore is located in the red colored area, which is the maximum solar generation belt. Based on the typical weather conditions, Tilt of Solar Panels of about 12-15 degrees to south orientation, we can expect a daily average generation of 4-5 units per kWp of installed capacity.
However, there will be seasonal variation in the Solar Generation. Here effects of all four factors listed earlier, can be seen. The following data, based on the published data by MNRE, shows the monthly variation in Solar generation for a typical 5kWp system in Bangalore, for Solar Panels with 10-15 degrees tilt with south orientation.
Here, we can clearly see that, when we optimize the annual solar generation with 10-15 degrees tilt panels, winter months show higher generation busting the myth that hot days will have the maximum generation.
In fact Bengaluru has advantage in going solar compared to other cities with hot climate.
Also, it is seen that the generation is reduced during the monsoon, as the days are cloudy with reduced light intensity available. But still the generation is almost equal to 75% of the average generation expected from the system which is shown by the green line.
Congratulations on Karnataka being emerged as the best state for setting up a roof top solar project according to the State Rooftop Solar Attractiveness Index–SARAL released by the Ministry of New and Renewable Energy (MNRE).
Now, Bangaloreans can Go Solar with confidence.
Any comments, questions, please feel free to add in the comments section. Further FAQs can be found here. and some of general technical information about Solar Rooftop can be found here. You can also use Solar Calculator, to explore the sizing of Solar Rooftop System.