Solar Energy - Limitations

As per the Paris Agreement, India committed to increase the amount of electric power from clean energy resources to 40% by 2030. A total of 175 GW of renewable energy installed capacity was promised to be achieved by 2022, of which 100 GW is the target set for solar power alone.

• A performance analysis study by a pioneer in the power generation industry, calculated that for every megawatt of solar power capacity installed, an average output of a mere 19% is extracted.
• In a recently set up ‘the world’s largest solar power plant’ in Tamil Nadu and Gujarat is with a total capacity of 40 MW, the electricity generation of this plant is about 63.8 million units, merely at 18.2% of its total capacity. 
• For obvious reasons – night, monsoons, dust, storms – solar power is neither produced all day nor throughout the year. Thus, solar power plant's capacity utilisation factor (CUF)  will never exceed 20% of its capacity.
• The lofty cost of rooftop solar panels overrides the tangible benefit in the eyes of customers,  despite 30% subsidy. Due to the instability in solar power production, the dependence of households with rooftop solar on coal based electricity/diesel generators will persist.
• A far bigger problem is that solar power is given preference when supply exceeds demand, so thermal plants have to back down. The plant load factor (PLF) or capacity utilisation of coal-based plants was 76% six years ago, but it is now just 58%. Above 70% PLF Thermal Power Companies are profitable, at 58% they are in trouble and at 48% they would go bust.
• Solar power looks great when the sun shines, but stops at sunset, just as power demand soars to its evening peak. Much thermal power has to remain idle during the day, ready to pick up the slack when solar production suddenly stops. This forced idleness carries huge costs hidden by ostensibly cheap solar power quotations.
• Solar power appears cheaper with provision of cheap land, tax subsidies, incentives, accelerated depreciation, viability gap funding and capital equipment subsidy. Once these are all removed the picture will be different.
• The true cost of solar power (sans implicit and explicit subsidies) at Rs 6/unit without storage and Rs 8/unit with storage. A captive coal-based power station working flat out yields power at just Rs 2.50/unit, far cheaper than solar power. 
• Solar costs are falling fast. The slower we go, the more solar costs will fall. So speed is not a virtue. Raising solar targets repeatedly looks green and good, but has hidden, potentially disastrous costs.
• Both thermal and solar capacity creation must slow down. Breakneck speed for solar power will break the neck of thermal plants and banks.
• The deceiving picture of the output from a major component of renewable energy and the promise of government for 24×7 electricity for all, the idea that India’s dependence on coal based power will decrease in the near future seems naïve. 
• The government has not reduced its coal output targets and plans to raise coal output from the current 550 million tonnes to nearly a billion tonnes by 2022.
• The much advertised ten-fold increase in solar power may seem like a game-changer for the renewable energy sector. But on close examination it becomes clear that the power yield from this increased capacity on an average will be as little as 20% of the total capacity, and this will make little difference to India’s emissions.

Read 'Looming Coal Shortage'

Guaranteeing 24x7 power supply is a gigantic task. In the absence of economic batteries, solar energy suffers from its limitations. However it is very cost effective for remote villages, agriculture pump sets not serviced by regular sources of electric power. In cities and towns it could be used for water heating and for reducing electricity bills. Much of power demand for commercial, domestic and street lighting occurs during evening and night hours and has to be met from non-solar resources only. With all its limitations, still solar power could be used to reduce power demand during day time hours. The higher the solar power generation the higher would be stand by sources of power thus efficiency of power sector gets reduced translating into higher tariffs apart from creating power system operational issues. Therefore, solar power can never replace conventional resources of power fully and at best it could meet 20-25% power demand.