Net Metering and Distributed Generation Systems

India has an ambitious Solar Energy capacity addition program of adding 100 GW by the year 2022. Out of above 40 GW is expected to be added through Roof Top Solar. Addition of 40 GW as part of Roof Top Solar in next 5-6 years is quite ambitious. Various states have announced their state specific policies for implementation of Roof Top solar programs. Net Metering policies are entwined with Roof Top solar programs. Though quite a few states have announced their programs but real work on the ground has yet to pickup. In US and some other EU countries where sunshine is abundantly available, there has been a never ending debate on practical Net Metering policies and applicable  energy tariff regime. There is a group which advocates retail tariffs while another group supports the DG to be billed as per the Utility Generation charges.The basic premise on which Net Metering works is installation of solar roof top where off grid solar power is generated. The house owners are expected to take prior permissions from Discoms and their electrical safety inspectors before they install solar powered plants in their premises. The total solar power as distributed generation as MW rating has to to be below 30% of the transformer load of the premises. This percentage keep varying based on the policies of that Discom. In case the house owner desires to increase the capacity of solar power plant then installed sanctioned load has to be raised accordingly after taking prior permission from the state authorities.

Beach umbrella in late afternoon sunlightThe islanding effect for roof top solar installations is very important as they safeguard your electrical installations. Once the grid supply is disconnected the solar roof top plant also stops generation of power. After the safety certification is completed, the bidirectional meters are installed to record both import and export of the energy.

The debate concerning rates of generated power has gone on for quite sometime. A section of experts feel that power generated from roof top solar has to be adjusted at retail power charges. That means that both inflow and outflow of energy has to be charged at the same rates. The basic logic which goes against this philosophy is that the power generated from roof top solar charged at retail power rates doesn’t take it account transmission and distribution expenses. So this kind of pricing would create some kind of push-back on tariff regime.

The strengthening of distribution network to accommodate distributed generation of power is of utmost importance. The distribution network has to be automated and should take care of extreme conditions of load throws and be able to handle volatile regulations. Distribution network should adopt IEC 61850 protocol of communication and networking to bolster its capacity to handle both inflow and outflow of power.