Energy atop: Solar power virtual reality

THIRUVANANTHAPURAM: The rooftop solar project, when it was launched in 2012, was metaphorically ridiculed as an “unnecessary burden to carry on one’s head”. It was felt that the solar plant was not worth the cost; a single unit of solar power costs nearly Rs 10, considerably higher than even diesel/naphtha prices (Rs 6-7 per unit). But despite the cost, Agency for Nonconventional Energy and Rural Technology’s ambitious 10,000 Rooftop Solar project launched in 2012 virtually achieved its target. The intention was to put up 1 kW solar plants on roofs of 10,000 homes in the state, together generating 10 MW solar power. The power eventually generated came very close: 9 MW.

Emboldened, ANERT has launched two new rooftop schemes, one for expanding the non-grid solar plants and the other for grid-connected plants. “Non-grid plants continue to be popular even though the cost is higher. This is because getting grid connectivity is a laborious process involving a lot of bureaucratic red tape,” a top ANERT official said. Non-grid solar plants are standalone systems that come with financial and practical strains. The power generated will have to be consumed real-time and the excess will have to be stored in batteries with inverter. One-kW battery costs about Rs 60,000. Since a battery has only a lifespan of about 5 years, the average cost would work out to around Rs 15,000 a year. If the plant is connected to the grid, or power generated on the roof is allowed to flow into the KSEB grid, batteries can be done away with and costs reduced considerably. The domestic user can even earn money by selling power to the grid.

But KSEBL is wary. The solar power generated should adhere to certain standards before being allowed to flow into the grid. And more importantly, EB is concerned about ‘islanding’, a dangerous phenomenon where power from the solar plant keeps flowing into the EB grid even when power has been shut down. This can prove deadly for EB staff working on transformers and overhead lines. Efficient technical solutions have been found but EB continues to delay grid connectivity for solar plants. ANERT has received applications for 15 MW, and has given the sanction for 6 MW. But EB has granted grid connectivity for only 500 kW (145 rooftop plants), or just 8 percent of the sanctioned power.

“The board is so suspicious that it conducts another check even after the Electrical Inspectorate grants the ‘feasibility certificate’ for the grid-connected plant. The trouble is the time lag between these two checks is irritatingly large,” an ANERT official said. Being grid-connected is not the solution to all your power woes, either. It will take away the “uninterrupted supply” advantage of non-connected solar plants. Houses with non-connected solar plants store energy in batteries and, therefore, will remain electrified even when there is a power failure. But grid-connected houses, because they don’t have storage batteries, will plunge into darkness when there is a grid problem like any ordinary house. Doing away with batteries saves cost but then it leaves grid-connected homes vulnerable to uncertainties of the common grid.