The sun is a giant nucleic reactor in the space. The light that hits a sunflower, a window sill, or solar panel takes around 8 minutes and 20 seconds to reach the earth’s surface. It comes in the form of small chunks of energy known as photons. Before reaching the earth’s surface, a photon travels about a thousand years from the sun’s core.

Sunlight is the ultimate source of energy. Each minute earth’s surface receives more energy from the sun than its resources produce in a year. In the space, sunlight’s intensity is around 1,366 watts per square meter. As the light travels through the layers of the earth’s atmosphere, the intensity reduces to 1,120W per square meter.

Photovoltaic systems need sun light or light to generate electricity the same as plants need sunlight to produce food. Also, plants still grow when it is cloudy, but their growth slows down. When it is cloudy, the leaves on plants and trees grow smaller than during the bright sunny season. The fruiting plants still bear fruits, but they can be dwarfed or with some changes in color. The same goes for Photovoltaic cells.

Solar panels ratings adhere to the standard test conditions (STCs), i.e.:

At 25° C (77° F), a 315 W solar panel receiving 1,000 watts per square meter will produce 315 watts of electrical output. On hot sunny days, the performance of solar panels goes down with an increase in temperature. The panels reach as high as 50-65 degrees than the STCs.

Solar Panels produce electricity, even on a cloudy day. However, their output reduces. On a cloudy day, the output of a standard mono crystalline cell can be 10-25% of its typical output. It is false to say that solar panels do not produce electricity on a cloudy day, as the temperature is not responsible for energy production.

Since solar panels work best when the sun is high up in the sky, and the weather is pleasant, summer days are best for solar power. For a solar panel to provide maximum output, it must have exposure to bright and direct sunlight. Nevertheless, solar panel installations in many cloudy cities are beneficial and productive.

Rise in solar panel temperature bad for electrical output

Solar panels come with a temperature coefficient of Pmax. If a mono crystalline solar panel has a temperature coefficient of -0.5%, it will lose half of 1% of its power for every 1 degree the temperature rises. So, if:

A 315 w solar panel’s temperature rises to 65° C (149° F). Then,

Total Solar power loss:

65°C - 25°C = 40°C

40 x-0.5% = 20%

Thus, Power loss:

20% x 315 = 63W

Thus at 65°C (149°F), a 315W panel’s power is 252W.

Why choose Solar in areas with low sunlight?

Solar panel installation helps save money on utility bills. So, the higher price you pay for electricity, the more you should incline towards an alternative. Compensating the loss in power output of solar panels is possible by adapting solar accessories and local conditions. Maximum Power Point Tracking (MMPT) devices are ideal for solar systems in locations with frequent clouds. These devices maintain the productivity and performance of solar panels when the sunshine is irregular.

Using thin-film solar panels in place of mono or poly crystalline type is also a way to meet the daily energy demands of a household. The thin-film panels absorb wider-ranger of light wavelengths in comparison with mono and poly crystalline type panels. Thus, homeowners from places that receive less sunlight can benefit from thin-film panels.

Another way to increase the PV output in areas that receive less sunlight is to use more solar panels. Increasing the number of panels in a PV system will make up for the loss in power output on cloudy days. The use of charge controllers and MPPT devices will allow keeping a check on power output and maintaining panel performance during sunny days.