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The solar energy can be used for captive consumption or exported to the grid. The electrical energy (DC) or the solar power generated by the solar PV modules during the sunshine hours is stored in the batteries for use, as and when required. The energy stored in the batteries is converted into 230V AC mains using an inverter. This energy automatically synchronises with the grid and gets injected into it.

Installation by integrators
Many solar system installers and owners have had good experience in anchoring the panel structures. This has to be done scientificallyand with care. It is possible to have non-anchored installation systems but these need to be very carefully designed to with-stand heavy winds. Such systems are designed to connect the solar power system to a roof using weights, rather than fasteners that must be anchored to the roof.

Solar installation companies, often called integrators, can complete a small rooftop project within a few weeks. Before signing a contract with an integrator, evaluate the roof for solar installation with respect to:

Roof condition. The roof should be in a good state prior to solar installation. If it needs significantrepair or replacement, get this done before installing the solar array.

Space availability. Solar power projects work best on flat roofs without obstructions.

Weight load. Some roofs are not designed to hold much additional weight. Ascertain the acceptable weight you can add to your roof before signing a contract.

Investments involved
Of all the components of a solar PV plant, solar module accounts for the biggest cost—it can be 70 per cent of the total project cost. The cost per watt is currently Rs 130-150 ex-factory. The investment primarily depends upon the size of the power plant, which varies from a small kilowatt to multi-megawatt plant. At present, good-quality off-grid rooftop solar power plants can be installed at a cost of Rs 250,000 per kW.

Under the National Solar Mission policy, the benchmark price for an off-grid system is Rs 270,000 per kW peak. For a grid-connected system, it is Rs 190,000 per kW peak. The government also provides a 30 per cent subsidy on the benchmark price. Installation costs would differ in case of remote installations and poor site conditions.

Economic advantages
The total investment per kW in a small power plant, for example, 10kW, will be the same if not less than in a large 5MW plant. It is therefore viable to go for small grid-fed plants owned by small privately-owned utilities. A buying rate of Rs 17 or 18 per unit of electricity from such plants will attract thousands of small investors like a magnet. In most areas in India, solar power can then be a fiscallysound investment that reduces electricity payments immediately, as well as hedges the small solar plant owners against local utility price increases.

If solar power is fed into a small city grid like Miraj, Ratnagiri or Ratlam, all consumers in that area will get cleaner uninterrupted power from the local copper grid. The high impedance of the local grid helps power to remain local, improving the local power quality. That’s why all other countries in the world allow solar plant owners to feed power into the local grid at the low voltage end.

It therefore makes sense to set up a solar rooftop plant in cities or towns facing severe electricity shortages. Today, the cost of generating electricity using a diesel generation (DG) set is in the range of Rs 20-22 per unit, whereas generating solar power costs only Rs 13-15 per unit.

Based on the current prices and assuming that one takes advantage of the 80 per cent depreciation permitted on such investments, in the firstyear the cost of power per unit (kWh) from a well-maintained solar plant will be less than Rs 8 per watt for a plant of any capacity between 5 kW and 1 MW. Thus solar rooftop installation is a good investment option considering both tangible and intangible benefits.

[stextbox id=”info” caption=”Eligibility criteria for project proponent”]

While the government is yet to announce the policy for rooftop grid-connected power plants, it has laid down certain guidelines for rooftop PV and other small solar power plants connected to distribution networks at voltage levels below 33 kV. Hereinafter, the programme is referred to as Rooftop PV & Small Solar Power Generation Programme (RPSSGP).

Technical criteria. The project schemes that propose to deploy PV modules and inverter systems are considered to be technically qualified and eligible for participation in the RPSSGP scheme only if these comply with relevant IEC/BIS standards and/or applicable standards as specified by the Central Electricity Authority (CEA). For solar PV projects to be selected under this scheme, it is mandatory that these are based on crystalline silicon technology and use modules manufactured in India. There will be no mandatory domestic content requirement for projects based on other technologies. For solar thermal technology, it is mandatory that the technology is demonstrated and such projects should be operational for one year. Project proponents should submit documentary evidence and an undertaking in this regard along with their applications to the competent authority in the state.

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