COMPARISION BETWEEN A GROSS METERING AND A NET METERING & IT’S IMPORTANCE
There is an important distinction between net and gross metering for residential solar systems in India. Currently, however, almost all new systems are installed with a net metering setup. In the past, most states offered a kind of generous tariff incentive for solar energy. The rates paid under these programs were quite high often 2-3 times higher than those currently in force for the power system. This meant that all solar homes receiving them would benefit the most by sending their solar into the grid which was done under Gross metering. For Instance we can take of Gandhinagar, Gujrat were the tariff was Rs 12/kWh for generation unit.
Now, the generation cost of rooftop solar is falling year after year while the retail supply tariffs of consumers are increasing which leads to the lesser Gross metering tariff and new metering system i.e.; Net metering. Traditionally electricity great was designed to work unidirectional and with larger penetration of solar rooftop system the rule of same have changed and electricity systems are now to adopt the reverse flow of electricity generated from the consumers to the Grid. This is done by two methods:
A net-meter (bi-directional meter) is used for measuring the export of excess energy from the solar system and import of energy from the grid. When the power consumption bill is generated, if the export of solar energy exceeds the import of energy from the grid, the consumer gets credits for the excess energy injected into the grid. This can be carried forward to the next month or reimbursed at a rate provided by the state authority.
gross-metering, all the electricity generated by the solar rooftop system is exported to the grid and energy required for consumption is imported from the grid. The consumers are paid a feed-in-tariff decided by the respective state nodal agencies for the electricity injected into the grid. Allow gross metering capacity higher than connected load of consumer.
|Only excess energy is exported to the grid||All of the Solar Energy generated is injected to the grid|
|Consists of a bi-directional meter that measures both – the import and export of energy||Separate meters for measuring solar energy export and import from the grid|
|One bill is generated which will give a measure of both total imported and exported energy. Difference between both import and export is taken and payment is based on the net of import or export||One bill for the consumption of electricity from the grid which has to be paid by the consumer to the utility provider and one bill for energy injected to the grid which will be paid to the customer.|
|Return is dependent on what is the savings on electricity bill due to the installation of the solar system. As the cost of energy increases savings will also increase||Return from solar energy is fixed for 25 years as all the energy generated is exported and the PPA is for 25years. The savings is lesser as there is a hike in utility rate in the range of 3-5% every year.|
Financial Comparison of NET Metering and Gross Metering in recent situation with three different month data:
Financial implication to Discom for Rooftop Solar system under NET metering
|Month||Discom unit consume (A)||Total Solar Generation (B)||Net Energy Units [C=A-B)||Net monthly Payment by Discom(B* @ APPC Rate Rs 4.25/ KWh)||Net monthly Payment by Consumer to Discom|
Net amount received by DISCOM is = Rs. 3563
Financial implication to Discom for Rooftop Solar system under Gross metering
|Month||Discom unit consume (A)||Bill Amount paid by consumer to Discom (C=A*Tariff Rate@ 7.50/ KWh)||Total Solar Generation (B)||Bill Amount to be paid to consumer(D=B* @ APPC Rate Rs 4.25/ KWh)||Net monthly Payment by Discom||Net monthly Payment by Consumer to Discom (C-D)|
Net amount received by DISCOM is = Rs. 13938