What shadow analysis report should an installer give for a rooftop solar plant, and what happens if shade cuts the output?
The Ministry of New and Renewable Energy (MNRE) specification says a shadow analysis report, made with an instrument such as Solar Pathfinder or professional software, should be provided for each site. Lower performance due to shadow effect shall be liable for penalty, though the guideline prints no penalty amount.
What clause 11.3 says
These are clauses from the technical specification in Annexure 3 of MNRE's guidelines for its residential rooftop solar scheme, Pradhan Mantri Surya Ghar: Muft Bijli Yojana. A factory is not bound by them, but they are a published checklist to hold a quotation against.
- The shadow analysis report with the instrument such as Solar Pathfinder or professional shadow analysis software of each site should be provided.
- The consumer should be educated to install the system only in shadow free space.
- Lower performance of the system due to shadow effect shall be liable for penalty for lower performance.
- The guideline does not say how large the penalty is or who receives it, so put both in your contract.
Related requirements
- Model agreement clause 2: the vendor's site survey includes the feasibility study of the roof, strength of the roof and shadow free area.
- Clause 3.5: the structure's inclination angle is set to take maximum insolation and complete shadow-free operation during generation hours.
- Clauses 3.9 and 3.10: adequate spacing between panel frames and rows to ease cleaning, replacement and electrical maintenance, and structures designed to allow easy replacement of any module.
- Model agreement clause 18: the performance ratio of the plant must be 75% at commissioning. Shade lowers it, since it lowers the energy for the same sunlight.
What to ask the installer for
- A report with hour by hour or month by month shade for each array, not one number for the whole roof.
- The tool used and the date of the survey. Tanks, parapet walls and nearby buildings should all appear in it.
- Which modules the report left out because of shade, and the plant size after leaving them out.
- A clause naming the penalty if measured performance is lower than the report promised.
Shade against the 75% line (example numbers)
- A plant that would just meet the 75% performance ratio with no shade
- Shade removes 5% of its output: 0.75 x (1 minus 0.05) = 0.7125, which is 71.25%
- That is below the 75% in clause 18 (vendor agreement, Annexure 2), so the shortfall comes from shade, which clause 11.3 (Annexure 3) makes liable for a penalty (amount not printed)
- With an example 5.5 kilowatt hours per square metre of sunlight a day for 30 days, a 100 kilowatt peak plant at 75% makes 100 x 5.5 x 30 x 0.75 = 12,375 kilowatt hours a month, and 5% of that is 618.75, about 619 kilowatt hours a month
The 5% shade loss, the sunlight and the plant are example numbers. The 75% and the penalty wording are MNRE's.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so the grid units you buy each month are on file before and after the plant goes live. It does not carry out shadow studies.
- Performance ratio to demand
- Does cleaning panels add to emissions
- Rooftop solar contract checklist
- Payback of rooftop solar for a factory
Last reviewed 2026-11-06. Re-check clause numbers and figures against the current version of the guidelines before you rely on them. Clause 11.3 is in Annexure 3. A penalty clause only works if it is in your signed contract.