SOLAR PV INTEGRATION: ISSUES & CHALLENGES with NET METERING A.K. Bohra Chief Executive Officer NESCO, WESCO & SOUTHCO Central Service Office, Bhubaneswar
DISTRIBUTED RENEWABLE ENERGY GENERATION With the involvement of improved technology, upgraded equipments and compatible codes, the distributed renewable energy generation is gaining popularity in today s competitive power generation Harnessing of Renewable source of Energy is also important from the Environmental point of view and has to go a long way Among the various Renewable source of Energy, Solar Energy Generation is gaining more popularity because of its easy installation, cleanliness, zero fuel cost and maximum availability of Solar irradiance; resulting in generation at competitive rates with Grid supply
DISTRIBUTED RENEWABLE ENERGY GENERATION Across the Globe, distributed generation through Roof Top Solar PV Panel is encouraged due to the following major advantages ; Help utility to reduced stress on Grid, Peak Demand, T&D loss; being located at the Load centre Real time demand side management reduces burden on conventional generation Reduce Power Bill, provides Backup Power & use of spare roof area Earn revenue through Export of Power to the Grid Reduce emission of pollutants through community support Mass scale integration of power generated through Rooftop Solar PV panels needs implementation of Micro Grid with smart features However, certain issues are associated with such integration with Utility Grid
ISSUES WITH DISTRIBUTED GENERATION INTEGRATION Metering and Energy Accounting Interconnection Arrangements Commercial Settlement Process Applicability of Regulatory Instruments
Metering and Energy Accounting Metering arrangements for Rooftop Solar PV projects in use across the Globe are; Gross metering and Net metering Gross Metering : The entire energy generated by Rooftop Solar PV system is fed directly into the Grid and the system owner is benefited by feed-in-tariff based on sale of power to the utility Net Metering : The excess/surplus is either sold to or banked with the utility, thus, combine elements of captive consumption and exchange of power with the utility
Metering and Energy Accounting
Metering and Energy Accounting For installation of small Rooftop Solar PV panel by Domestic consumers connected to the utility Grid, effective Net metering is essential and therefore in this presentation focus is laid on the issues and challenges with Net Metering
What is Net Metering? A billing methodology that allows customers with self generation to net the amount of electricity that they generate against the amount that they use from the Grid A relatively simple method for utilities to measure the amount of electricity to bill where generation does not typically follow a customer s demand usage (such as with small wind and solar generation) Usually requires the use of a single meter that spins backward when customers are generating more than they are consuming or two meters; a system use meter and an excess generation meter
What is Net Metering? Typically results in customers receiving applicable retail rate of the amount of energy that is netted, which acts as an incentive for small renewable generation to develop Since last one year, many States initiated steps towards conceptualizing and implementing net metering policies in India As per information, States that have announced net metering policies in India are Andhra Pradesh, Tamil Nadu and Uttarakhand. Delhi and Maharashtra are in the process of coming up with policies for their respective states
Net Metering Concept
Net Metering Schema
Issues with Net Metering & Energy Accounting Non availability of standard, model for Net metering schemes Absence of standard Net meter specifications, specifically with respect to 1 Ph. connections Code of practices for use of different class of import, export meters and generation meter Lack of clarity on role of different entities in bilateral/ tripartite arrangements in project developed by owner/ third party Improper definition of Net metered consumer related to coverage of self-owned and/or third party developed projects Non availability of provisions towards TOD settlements as to how to align energy settlement under Net metering with the existing framework
Issues with Interconnection When a consumer is privileged to export surplus power to the Grid, issues related to the point of connectivity, level of voltage of interconnection, limit of power export & most importantly the safety concerns comes into the picture While the draft CEA Technical standards for connectivity of distributed generation resources regulation 2012 recognizes the issues in interconnectivity but has left on licensee to address the same as evident from below; The licensee shall carry out the inter-connection study to determine: (a) the point of inter-connection, required interconnection facilities and modifications required on the existing electricity system, if any, to accommodate the interconnection,
Issues with Interconnection (b) the maximum net capacity of the distributed generation resource at a particular location for single-phase and three phase generators connected to a shared single-phase system or three phase system respectively, based on the configuration of the electricity system and imbalance in the power flows that distributed generation resource may cause, (c) likely impact, if any, on the quality of service to consumers connected to the electricity system and measures to mitigate the same, (d) additional measures to ensure safety of the equipment and personnel.
Issues with Interconnection Contrary to above, international codes like NEC, IEEE 1547 & UL 1741 takes care of the following: Reliable Power Grid Operation Protection Against Faults Power Quality Impact on Utility Monitoring and Switching Equipment Testing facilities and Quality Assurance While NEC, IEEE & UL Codes specifies electrical interconnectivity standards, Meter specifications, size of project and network, testing etc., ANSI specifies the product specification of inverter, its installation and safety Connectivity of distributed generation at the medium and low voltage still need clarity in US due to overlapping legislative provisions to overcome safety hazards
Safety Hazard Overlapping Provisions
Issues with Interconnection Safety Concern Initially power systems were designed to support only one way power flow from the point of generation through a transmission system to distribution level loads These systems were not originally intended to accommodate the back feed of power from distributed generations at the distribution level The introduction of backup flow of power from local generation causes serious threat to the safety and thus needs attention
Issues with Interconnection Safety Concern For the safe system operations of an interconnected distribution generation following is important: Self islanding in the event of Grid faults i.e. protection from distribution system faults Auto cut-off from Grid in the event of internal PV system breakdown ; Cease to feed power to Grid Prevention of feeding power to Grid in the event of Grid fault/system Break down Protection to People (Public & Utility workers) and Property Protection from abnormal Voltage & Frequency levels Protection while synchronization with Grid Protection against injection of Harmonics, DC supply & Flicker etc. to the Grid
Issues with Interconnection Safety Concern Earlier to prevent reverse power flow, an equipment called Utility External Disconnection Switch (UEDS) being utilized by many states in US which was required to be operated before taking up work by a line worker on line Due to non practicability of operations in large distribution generation network and looking to the introduction of Meters having inbuilt disconnect switch & supply imbalance sensing device, use of such device is now not necessary The necessity of having disconnection arrangement lockable and visible Break Separation have been dispensed with in the amended National Electric Code (NEC) due to these features incorporated in the Inverter of Solar PV system
Issues with Interconnection Safety Concern In Indian context, these are important and need to be incorporated Besides above, provisions exists in Germany, US and other advanced Countries related to various product specifications, connections and testing (at the time of installation, commissioning & periodical) need to be replicated in Indian standards Some indigenous manufacturers provides equipments not confirming to such Standards to save cost which cause hazards There is a need for capacity building of Utility Officials who are neither aware nor trained about the testing to be carried out on Solar PV system equipments and frequency of such testing
Commercial Settlement Issues The overall viability as well as ownership patterns adopted for development of Net metered roof top solar projects mainly depends upon applicable charges and commercial arrangements Implementation of net metering based roof top solar system will require clarity on the energy accounting & Commercial settlement for electricity consumed from such system as well as excess energy injected into the Grid
Commercial Settlement Issues Commercial settlement in net metering depends upon: Definition of eligible consumer Generation capacity limits Interconnection voltage Energy Accounting Net metering settlement period Restrictions on level of overall or local Grid penetration Renewable Purchase Obligation (RPO) Application of other charges & incentives (fixed charge, connectivity charge, TOD, ABT, GBI) etc. Forum of Regulators (FOR) though addressed these issues but are yet to be incorporated in the Codes
Applicability of Regulatory Instruments As stated in the foregoing slides, there is lot of Regulatory infirmity, affecting propagation of Net metering projects in India International experience shows that propagation of various business models of rooftop Solar segment has a very high reliance on the policy and regulatory framework Non availability of clearly defined technical standards and guidelines for Grid connectivity, metering, safety and security etc. are major barriers in implementation of such projects
Applicability of Regulatory Instruments Current Regulatory framework also lack in addressing the charges related to wheeling, open access, Cross subsidy etc. Indian standards for installation & testing etc. is must in line with international equipment standards issued by International Electro technical Commission (IEC) Need is to have a code like IEEE 1547 which provides guidelines for technical requirements, design, construction, commissioning, acceptance testing, O&M and performance requirements for interconnecting local electric power sources to a bulk power transmission grid
Applicability of Regulatory Instruments Standards and Codes available like CERC model guidelines for Rooftop Solar Grid interactive system based on Net metering and CEA technical standards for connectivity of the distributed resources regulations 2012 etc. are still under draft form and not bringing adequate clarity However few States like Tamil Nadu & Gujarat have taken initiative and propose amendment in regulations covering Net metering, LT connectivity etc. The main technology constraint lies with the specification of meters which necessarily has to be export import type smart meter with disconnection facility from remote
Applicability of Regulatory Instruments Odisha scenario : Govt. of Odisha has formed a Company to promote, develop, implement, operate & maintain renewable energy projects namely GEDCOL (Green Energy Development Corporation of Odisha Ltd.) Dept. of Science & Technology has published a draft Solar Policy for the State with a target of adding 135 MW Solar Energy capacity by 2015-16 OERC yet to give detailed Scheme, associated metering arrangement & commercial mechanism between Consumer, DISCOM & GRIDCO
Applicability of Regulatory Instruments The status of policy framework & regulatory provisions in various States is as under: Tamil Nadu: Commercial arrangements : Cap for injecting excess energy to the grid, will be 90% of the electricity consumption by the eligible consumer at the end of a settlement period (annually) Grid penetration restrictions : Restricted to 30% of the distribution transformer capacity on the basis of first come first served Metering : Two meters have to be installed, first for measuring solar power generation and the second for the import/export measurement
Highlights of various State s Policies Uttarakhand: The roof owner of residential/commercial/ industrial/institutional/government establishments are eligible to set up Solar Power Plant within 300W to 100 kw with battery backup and up to 500 KW without battery backup Can work on net metering basis wherein the beneficiary pays to the utility on net meter reading basis only, alternatively two meters can also be installed to measure the export and import of power separately Punjab: Capacity range allowed 1 KW and 500 KW. The maximum capacity of the Roof Top Solar PV system shall not be more than 80% of the Sanctioned Connected Load. Injection of power from the rooftop solar PV system shall not be more than 90% of the consumption from the licensee s supply by the consumer in a year
Highlights of various State s Policies Andhra Pradesh: Net Metering permitted for 3 Phase only. Consumers can avail Government of AP subsidy and MNRE subsidy through New and Renewable Energy Development Corporation Andhra Pradesh Ltd (NREDCAP) A single bi-directional meter should be installed for export and import energy measurement. DISCOMs shall accord approvals on a first come first serve basis for Solar Net Metering till the Solar installed Capacity reaches 50% of the closest upstream Distribution transformer s rated capacity Delhi: Delhi Electricity Regulatory Commission (DERC) has released a draft net metering policy. Most of the policy details are similar to the Tamil Nadu net-metering policy. The final policy will be announced after getting the inputs of all the stakeholders Maharashtra: Maharashtra Electricity Regulatory Commission (MERC) has instructed for formation of a Working Committee which will come up with a draft policy
Conclusion Once the Indian Standards, Codes, Regulations are put in place, it will open a big market for Indian Entrepreneurs to venture in to the Field of Net Metered Solar PV generating equipments and integration with Grid The product, service may include following: Solar PV Panels, Batteries and accessories Inverters with protective devices confirming to Standards Smart Energy Meter with export, import features and disconnection facility Erection, Commissioning works as per Codes Lab testing and site testing of equipments as per provisions I.T. enabled services for Meter reading, billing, accounting, Load dispatching & demand side management and isolation of generation on demand from line worker etc.
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