01Standard and certification
Flat-plate collector specifications are covered by the IS 12933 family. BIS listings now show 2025 revisions for Part 1 requirements and Part 2 components, while the 2024 Solar Thermal Quality Control Order and certification pages must be checked for the applicable implementation status. Ask for a valid licence scope, test reports and exact model mapping—an IS number printed in a brochure is not enough.
- Verify licence status on BIS, not only a dealer statement
- Match collector size and model to the certificate
- Keep approved data sheet in the handover file
02FPC versus ETC
FPC has a metallic absorber, riser/header circuit, insulation and glazing. It is mechanically robust and well suited to multiple-collector arrays and indirect loops. ETC offers a lower entry cost and easy tube replacement, but glass exposure and scaling pattern differ. Neither technology is universally superior; pressure, water and maintainability control the decision.
03Model architecture
Domestic FPC systems commonly use integral thermosiphon storage. Commercial systems may use separate insulated tanks, forced-circulation pumps, differential temperature controllers, plate or coil heat exchangers, recirculation and backup. A 100 LPD-per-collector shortcut is only preliminary; use certified aperture and performance data for final quantity.
- Non-pressurised domestic
- Pressurised domestic
- Commercial forced circulation
- Solar + heat-pump hybrid
04Installation sequence
Survey and shade study come first, followed by structural support, collector alignment, hydraulic headers, storage, valves, insulation, controls and safe drain/vent arrangements. Flush debris, hydro-test the circuit, verify direction of non-return valves, prove pump interlocks, measure temperature rise and train the operator before sign-off.
05Subsidy reality
Residential rooftop-PV subsidy and solar-water-heater incentives are different programmes. Do not reduce an FPC quotation by a presumed subsidy. Confirm a current notified scheme, customer category, empanelment and portal process in writing before counting any benefit.
Planning table
Compare before requesting a quote
| Capacity | Preliminary collectors | Roof allowance | Planning price |
|---|
| 200 LPD | About 2 | ≈4–5 m² plus access | ₹70,000–₹1,05,000 |
| 500 LPD | About 4–5 | ≈10–12 m² plus access | ₹1,65,000–₹2,40,000 |
| 1,000 LPD | Certified aperture design | Project layout | Engineered quote |
| 2,500+ LPD | Performance-based field | Structural/hydraulic design | Turnkey quote |
Indicative ranges are planning aids for Patna, not quotations. Capacity, pressure, tank metallurgy, roof work, piping, controls, GST, transport, electrical work and warranty can change the signed price.
