An off grid PV system is the simplest installation in which may be in the form of DC load connected to PV modules directly, such as solar water pump etc. Unfortunately the solar radiation is variable hence the requirement of battery comes in between the PV module and DC load. If the PV modules are used for charging battery a charge controller is also used to control the charging voltage of the battery , typically the stand alone roof top system work on 12-24V DC supply and connected to a battery. Charge controller regulates the battery charging and over charging disconnection options,if we want to use ac loads such as TV, Refrigerator and other lightning appliances, it require conversion of DC to 230-240V AC electricity and system is incorporated with the inverter, which primarily responsible for two activities a) Charging of the battery , b)Discharging the battery and converting the same in to ac electricity to meet the load requirement . First green has developed some of the charge controllers which can be connected to home inverter system and the existing inverter can be used as solar inverters .
Stand alone –off grid PV rooftop systems are more popular in India, however in Europe most of the rooftop systems are grid connected PV systems . Although CERC has issued net metering guidelines which have been adopted by various states like Andhra Pradesh, Tamilnadu and Kerala ,it requires clear net metering guidelines in order to promote grid connected rooftop systems .
Rooftop systems are much more convenient to use, as they can feed electricity generated during the day to the grid through net metering and can use the same electricity in the night for the lightning and other appliances. In this case grid act as a storage option and makes it possible to use solar electricity during the night time ,there may be situations when the electricity generated from rooftop and solar PV plant is much more compared to captive requirement. The surplus electricity fed to the grid can be sold through an attractive Feed-in tariff (FIT) offered by the local utilities .Roof top solar scheme is presently being offered by Solar Energy Corporation of India and about 11.1 MW of rooftop systems have been planned in five cities in India which include Gurgaon, Jaipur, Hyderabad, Bubaneshwar, Raipur and Noida. Under this scheme a developer can install projects up to 250 Kwp capacity. Solar Energy Corporation of India is providing capital subsidy of the order of 30% and the generated power can be consumed by the rooftop owner and surplus power can be exported to grid through net metering provisions .This is for the first time ,the govt of India has initiated a 30% subsidy on grid connected roof top PV system and we believe this scheme will attract lot of roof top owners to invest in roof top solar systems.
The bidders will be selected by the final project cost they offer @ Rs. /W basis. The upper limit on project cost is Rs. 90 /W.
SECI will provide 30% of the project cost as subsidy which will be released in three installments –
- 20% after commissioning and acceptance.
- 5% at the end of 1 year of O&M period, from date of commissioning.
- 5% at the end of 2 years of O&M.
- The size of each project has to be 100-500 kW and the total capacity each bidder can apply is between 250kW – 2MW.
- Bidder has to be a corporate entity incorporated in India and engaged in Solar Power, must have a valid CST/state VAT/TIN registration.
- Experience criteria – Should have installed a minimum of 25 kW at least six months prior to techno-commercial bid opening date
- Financial criteria – annual turnover of 5 Crore/MW
- Net worth 3 Crore/MW
- Bid Bond- Rs. 6,75,000 / 250kW, valid for six months after bid deadline
- Performance security – Within 10 days of acceptance of allocation letter
- SECI charges – 3% of the 70% of project cost
- Penalty for delay – Projects have to commissioned in 6 months. Penalty will be per day basis, performance security over a period of 6 months, and project gets cancelled after 6 months
Source : MNRE
For rooftop off-grid policy ,refer the link below of First Green blog.
Supporting documents for Rooftop off-grid policy are below.
Formats for submission of Project proposal for SPV systems under Off Grid Solar Applications:-