Written by Harsha Kamak & Vigneshwar RK
Nov 20, 2019 • 3 min read
‘Is it worth going Solar in Bangalore given its cool, cloudy weather?‘ is one of the most common questions from Bangaloreans, only next to ‘Why is the airport so far?’ and ‘Why won’t the traffic move?’
People tend to believe that places with hotter climates like Chennai or Goa are ideal for using solar, which is amongst the many misconceptions about solar. In reality, solar photovoltaic (PV) systems work better at moderate temperatures.
To know why Bangalore is one of the ideal places to go solar, let’s first understand how solar PV works.
When sunlight hits the solar PV panels, the sun’s energy converts into electricity, which in turn powers homes, apartments, offices, schools, and more. The amount of electricity generated depends on multiple factors:
2. Intensity and angle of sunlight
3. Daily sunlight hours
4. Solar panel type
5. Inverter technology
6. Shading (by obstructions)
Now, let’s focus on temperature and how it affects solar PV generation in theory and how that translates into a practical scenario.
Solar panels operate at a higher temperature than their surroundings because the panel glass traps the heat of the sun, akin to what happens in a greenhouse. For instance, in a surrounding temperature of 25°C, the solar panel temperature is close to 45°C. The power generation efficiency reduces once the panel temperature rises beyond an optimum of 45°C.
A 1°C rise in panel temperature leads to a reduction in efficiency of around 0.45%. The phenomenon is known as the temperature derating factor.
The power generation efficiency of solar panels generation also depends upon the panel type. For instance, monocrystalline solar panels, apart from their higher efficiency, handle temperature changes better than polycrystalline solar panels.
Here is an analysis of solar generation data of a 96.2-kilowatt power rooftop solar system installed by us.
• First apartment in Bangalore to use solar for 100% of their community area
• Second best performing SolarEdge installation in India
Let’s dive into the season-wise analysis of solar power generation from Brigade Petunia, for the last 12 months.
Summers in Bangalore last from April to June, with April and May being the hottest months of the year. The temperature soars up to as high as 33-34°C, with panel temperatures reaching more than 55°C. As a result, the efficiency of the solar panels is affected because of the temperature derating factor. Therefore, the generation is low when compared to March, despite receiving a similar duration of sunlight.
Winters in Bangalore last from December to February, with January being the coldest. Contrary to popular belief, this works excellently for the solar panels. As we can see from the graph, the solar production peaks in January. We experience this because the temperature is closest to the optimal operating temperature of the panels, 45°C. So, as far as Bangalore is concerned – colder the weather, the better.
Though Bangalore gets intermittent rainfall throughout the year, July to September receive the most. The generation is consistently lower throughout this monsoon season. Solar panels cannot produce as much electricity under cloudy conditions, and their output can reduce to 30% in overcast conditions. The primary reason for this reduction is because of the lower intensity of sunlight due to cloud cover. Despite this reason, the system produces atleast 10 MWh of electricity in a month.
Bangalore is one of the ideal cities in India to go solar in. All-in-all, the moderate temperatures year-round and availability of 280 days of good sunlight, combine to make Bangalore an excellent place for using solar power.