Standard Criteria for the Qualification of Solar PV Modules in the Context of Nepal
The Sun is an infinite source of energy that is pivotal for sustaining life on our planet earth. The energy from the sun can be exploited directly in the form of heat or first converted into electrical energy and then utilized. Accordingly, the solar energy is classified into solar thermal which has low level of dissemination and solar photovoltaics (PV) which is extensively used all over the world.
The solar PV can be considered the only form of electrical energy that can be generated anytime and anywhere provided sunshine is available. Nepal is blessed with solar resource as it lies at about 30◦ Northern latitude which is ideal and there are over 300 days of sunshine annually. Further the annual average solar insolation is about 5kWh/m2 per day. These conditions are perfect for harnessing solar energy for various conversion technologies.
Selection of Solar PV Modules plays a vital role in determining the fate of any project and Under the influence of Alternative Energy Promotion Centre/ Energy Sector Assistance Programme (AEPC/ESAP), Nepal Photovoltaic Quality Assurance (NEPQA) has been developed which is maintained by Renewable Energy Test Station (RETS).
SPECIFICATIONS OF SOLAR PV MODULES
The PV module must be of Crystalline Silicon (Mono Crystalline or Poly Crystalline) or Thin film Type.
IEC certificate of PV module. Model/type of PV module must be mentioned in certificate.
- The PV Module must be certified by a Certifying Body Testing Laboratory (CBTL) or National Certifying Body (NCB) enlisted in the IECEE website. The enlisted CBTL or NCB must have scope of PV Testing.
- Mono Crystalline Silicon PV module and Poly Crystalline Silicon PV module must be tested and certified according to the standard-“IEC 61215 Edition 2 2005-04 (or EN 61215 Edition 2) – Crystalline Silicon Terrestrial Photovoltaic (PV) – Design Qualification and Type Approval”.
- Thin-film PV modules must be tested and certified according to the standard – “IEC 61646 – Thin-film Terrestrial Photovoltaic (PV) Modules- Design Qualification and Type Approval”.
- A letter provided by principal PV module manufacturer in their letter head stating the warranty period for their PV module. The warranty period for the PV Module must be at least 10 years against a maximum 10% reduction and 20 years against a maximum 20% reduction of output power at STC.
- A local importer must provide a document of agreement between the local importer and the principal PV manufacturer, signed and stamped by authorized persons stating warranty period and after sales services for their PV Module. In case of local PV manufacturer, it has to provide document stating warranty period stated in clause (ii) above and after sales services for their module in their letter head signed and stamped by authorized person.
- Catalogue and technical specification of PV module.
- The following electrical parameters of the module will be tested and certified by Renewable Energy Test Station (RETS).
- Deviation of maximum power from nominal values stated by the manufacturer must be within – 5% and +20% (minus five and plus twenty) at STC. In case of Thin-film type modules, deviation of maximum power will be measured after exposing the PV modules in ambient conditions for two consecutive periods of exposure of at least 43 kWh/ m2 according to IEC 61646 10.19.
- The maximum power voltage (Vmp) of the PV modules to be used for 12V systems must be at least 17 V at STC. And for 12X, V system voltage Vmp must be at least 17X, V at STC, where X is a natural number. For systems different from 12X V, the Vmp of the module at STC must be at least 40% higher than the system voltage.
- Crystalline PV modules of 40Wp or above must have inbuilt bypass diodes. The module will be configured such that strings of maximally 20 cells are bridged by a bypass diode. The Junction box needs not be opened, if the principal PV manufacturer provides an assurance using their letter head about the existence of bypass diodes in the junction box.
- The module efficiency for crystalline module must be at least 10 % for upto 10Wp, 11% for above 10 Wp to 50 Wp, 12% for above 50 Wp to 100 Wp, and 14% for above 100 Wp.
- The module efficiency for thin film module must be at least 8% up to 100 Wp and 10% above 100Wp.
- The PV module must carry the following indelible markings: \
- Name of the manufacturer
- Model or Type No.
- Maximum rated voltage and current
- Open Circuit Voltage and Short circuit current
- Serial Number of PV Module
- For Crystalline Modules, additionally
- Nominal power in Wp
- For thin film modules, additionally
- Nominal and minimum values of maximum output power at STC (i.e., Lowest stabilized power), as specified by the manufacturer for the product type.
- Serial Number, model name and brand name must be laminated inside the glass for crystalline modules of capacity up to 100-Watt peak. For panels above 100-Watt peak mentioning of only serial number laminated inside the glass will suffice.
- Readable mentioning of serial number, model name/number and brand name is a must for thin film modules. This mentioning can be at the front of the panel or at the back by laser marking on the substrate or engraving on bus-bars.