Solar Photovoltaic Power for Urban Households We are on days where in everything which we need cannot be made without power supply. And given rising electricity bills, increasing load-shedding by the local power distribution company, rising diesel prices for DG sets, and call for green power development, alternatives need to be explored. The solution is at hand - power for households can now be produced with a rooftop solar photovoltaic (PV) plant. A 1 kilo watt (kw) peak solar photovoltaic plant (crystalline silicon type) generates around 5 unit s power each day in India depending on the sun light intensity. What s more, the solar silicon prices are steadily falling making the PV systems affordable, at least to middle/high income urban households. The table-1 below gives an idea regarding the electricity consumption by a middle/high income household at different cities in India and the percentage electricity bill savings made after installation of the 1kWp solar PV plant. Table 1 Percentage energy savings achievable with 1 kwp roof top solar PV system: Power consumption by a Power supply obtained % Savings for City middle/high income from 1kWp solar roof urban household top plant households in Yearly kwh /day kwh/year kwh / day kwh/year electricity bills average Delhi 12 4380 5 1825 42% Bangalore 6 2190 5 1825 83% Chennai 16 5840 5 1825 31% Mumbai 16 5840 5 1825 31% Kolkata 10 3650 5 1825 50% Hyderabad 12 4380 5 1825 42% Ahmadabad 12 4380 5 1825 42%
And households can own roof top solar PV plant at a price less than a Maruti Alto car, without disconnecting oneself from the grid power. The technology persists.germany and Japan were the early experimenters of these systems. They are using it since 1994.Such systems are popular in Queensland and Victorian areas of Australia. Canada s Ontario, British Columbia, New Brunswick states also running them successfully. In USA except for Tennessee, South Dakota and Mississippi, all other states are encouraged to own solar roof top systems. In European Union solar roof top homes are common at Germany, Denmark and Italy. Three configuration options are available based on customer requirement: PV system which is standalone i.e. not interconnected to any grid power line Solar PV system interconnected with existing grid power supply line and using battery storage with 5 hours backup. Solar PV system interconnected with existing grid power supply line and not using any battery back-up
A) Roof-top area required In general a 1-kilowatt home solar system would consists of about 10-12 solar panels depending on their watt peak rating and require about 100 square feet (10ft x 10ft) of roof area for the installation. However, safety and security of panels and PV systems is a big concern and needs to be thoroughly examined by the owner, before installation. B. Cost implication Solar PV only has capital cost and very less operating cost. For the different option configurations, costs are presented below. The government subsidy scheme is also mentioned. Table 2: Nutshell of the Option Configurations Option Configuration Cost for 1 kwp system in Rs. Main Components Features and Scheme/Incentive Use separately from existing grid power OPTION 1: PV system which is standalone not interconnected to any grid power line Rs. 2 Lakh. Solar panels, Battery & Stand alone inverter. line. Load (appliances) cannot be increased. Not flexible. 30% installation cost is subsidized by central government.
Option Configuration Cost for 1 kwp system in Rs. Main Components Features and Scheme/Incentive Significant savings in the electricity bills. Load (appliances) OPTION 2: Solar panels, can be increased. Very flexible. Solar PV system interconnected with existing grid power supply line using battery storage with 5 hours backup. Rs. 2.5 Lakh Battery which would last for 5 hours & Utility grid active with stand alone mode inverter. When grid power fails, power available for running small appliances However, no guidelines/schemes are available from the government for household grid interface systems yet. Significant savings in electricity bills Load (appliances) OPTION 3: can be increased. Very flexible. Solar PV system interconnected with existing grid power supply line using no Rs. 1.74 Lakh Solar panels &Grid Tied or utility interactive inverter. Not of use when grid power fails. However, no battery back-up guidelines/schemes are available from the government for household grid interface systems yet.
OPTION 1: Stand Alone Systems Essentially a standalone system means it is completely separated from the existing grid power line and it is powered solely by the solar PV system. And these systems are currently being used such as solar lanterns, small panels with one or two CFLs, computer power supply and remote households. Stand Alone Systems - Flow Diagram: Key features: Used separately from existing grid power line. Load (appliances) cannot be increased. Not flexible.
OPTION 2: Interconnected with grid line with further 5 hours battery backup. Essentially it is a solar PV system interconnected with existing grid power supply line with 5 hour battery back-up. And the advantage of the system is that it can power home even during blackouts. Grid connected roof top solar PV system with 5 hours battery backup - Flow Diagram: Key Features Significant savings in the electricity bills. Load (appliances) can be increased. Very flexible. When grid power fails, power still available for 5 hours for running small appliances
OPTION 3: Interconnected with existing grid line using no battery back-up With Grid connected roof top solar PV system a home can be interconnected to the electrical grid line and distribute the combined grid and PV power to the house. But the PV system does not supply power when there is no grid power as there is no separate battery back-up system. Grid connected roof top solar PV system without battery - Flow Diagram: Key features: Significant savings in electricity bills Load (appliances) can be increased. Very flexible. Not of use when grid power fails.
It was reported from Mr. W. Duke Christopher Daniel, Deputy General Manager (Solar Division), Tamil Nadu Energy Development Agency (TEDA) that since there are no guidelines available from CERC with regard to the Grid interactive roof top solar PV system as a nodal agency of MNRE they could not propagate such grid interactive systems for household level. Unfortunately even when such technologies persist there has been no policies/ guidelines released so far by CERC or MNRE, India. The policies /guidelines are still at their draft stage. In the present Indian scenario Electromagnetic compatibility (EMC) regulations do not exist for 230V grid lines. With more strict guidelines & EMC regulations, grid interactive inverters can operate with their optimal efficiencies. By Soundaram Ramanathan Intern, Centre for Science and Environment (CSE)
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