A solar loan file holds three kinds of paper. The first is corporate and legal: incorporation papers, KYC and land title. The second is financial: the model, the accounts and the power purchase agreement. The third is engineering, and it is the one developers meet last.
The engineering pack is also where files collect comments. Several parties make it at different times: a yield consultant, a structural engineer, a soil agency, an EPC designer and a distribution company (DISCOM). Nobody is paid to check that their documents agree. The lender’s reviewer ends up doing that check, and files that fail it go back for another round.
This guide is for a developer or asset owner preparing a loan file in India. It covers only the engineering documents. It says what each one must contain, what a reviewer checks and which ones a design firm prepares. It does not cover promoter KYC, the financial model, the power purchase agreement (PPA) or the terms of the engineering, procurement and construction (EPC) contract.
Quick answer. The engineering pack for a solar project loan in India has nine documents. They are the DPR technical section, a P50 and P90 yield report, layout, single line diagram and structural report. The rest are the geotechnical report, bill of quantities, grid connectivity approval and the CEIG submission. We could not open a published engineering checklist from IREDA, SBI or SIDBI, so get yours in writing. Reviewers read the pack as one set, so the documents must agree.
Which solar project loan documents in India count as engineering documents?
Nine documents make up the pack. The table says what each must contain and what a reviewer checks.
One caution first. The IREDA scope we cite below names the review areas, such as energy yield, soil and foundation design, and project cost. It does not name PVsyst, a single line diagram or a STAAD report. The third column is therefore a set of consistency checks any engineer can run. It is not a published pass mark.
| # | Document | Must contain | What the reviewer checks |
|---|---|---|---|
| 1 | DPR (detailed project report) technical section | Design basis: site, DC capacity in kWp, AC capacity in kW, module and inverter models, mounting type, interconnection point, schedule | Every number matches the standalone reports. The section is written for this site, not carried over from an older project |
| 2 | Yield report with P50 and P90 | Weather data source and period, module and inverter files, a loss chain with each loss justified, P50 and P90 annual energy, degradation, the project file | Inputs against datasheets and layout. Losses against the site, especially soiling and shading. P90 is present, not only P50 |
| 3 | Layout (general arrangement) | Module count, row pitch or roof zones, inverter and transformer positions, roads, cable routes, obstructions, boundary | Module count times module rating equals the DC capacity in the yield report. Shading objects are in the model |
| 4 | Single line diagram (SLD) | Rating of every device, cable sizes, protection, earthing, metering, voltage levels, point of connection | Ratings against fault level. Inverter count and string count against the layout |
| 5 | Structural report | Code editions named, wind and seismic basis, load combinations, member checks, foundation reactions | Loads are site specific. Foundation reactions match what the soil report supports |
| 6 | Geotechnical report | Boreholes or pits, soil profile, bearing capacity, groundwater, corrosivity. Earth resistivity for the earthing design | Spacing and depth cover the array. The foundation type in the structural report follows from the soil data |
| 7 | Bill of quantities (BOQ) | Quantities by DC, AC, civil, structural, earthing and balance of system, with make and model where fixed | Quantities reconcile with layout and SLD. Major equipment outside the EPC scope is identified |
| 8 | Grid connectivity approval | Approval letter with sanctioned capacity, voltage level and point of connection, plus the interconnection study | Capacity and voltage equal those on the SLD and the PPA. The approval is valid and is an approval, not a feasibility note |
| 9 | CEIG (Chief Electrical Inspector to Government) submission | Electrical drawings, calculations and test records for the Electrical Inspector | Drawings match the SLD. Application status is documented |
The reviewer works from your set, so the order of reading matters less than the agreement between rows. The DPR guide covers how to write row 1. Our lender due-diligence guide and the independent engineer checklist cover how the review itself runs. This page is the document register those guides assume you already have.
What do IREDA, SBI and SIDBI publish about these documents?
Less than most checklists online suggest. We opened each lender’s own documents on 31 October 2026.
| Lender | Document | What it names on the engineering side |
|---|---|---|
| Indian Renewable Energy Development Agency (IREDA) | Lender’s independent engineer notice, 9 December 2022, Annexure 3 (wind, solar and hybrid terms of reference) | Review of the developer’s energy yield study plus an independent yield assessment. Site assessment including soil and proposed foundation design. Project cost estimates, including major equipment not covered in the EPC contract. Design and planning. Land, approvals, evacuation arrangement against the PPA |
| IREDA | Financing norms, Issue 33, updated to 12 June 2026, rooftop scheme chapter | Loan application with a detailed checklist on IREDA’s website. Structural load bearing, seismic and wind safety reports for every sub-project. Compliance with the CEA distributed generation regulations. IREDA’s own reviewer checks the existing shadow profile before sanction |
| State Bank of India (SBI) | World Bank rooftop program brief, August 2021 | A DPR or a technical evaluation study, and a copy of the resource study. Debt service coverage tested at P90 yield (average gross 1.20) |
| SBI | Surya Shakti solar finance page, updated 11 March 2026 | No technical document list. Rooftop or ground mount, captive loans up to ₹10 crore and other projects up to ₹50 crore. A net metering arrangement and an EPC contractor registered with MNRE or the DISCOM for the captive variant |
| Small Industries Development Bank of India (SIDBI) | Not found | We found no SIDBI-published technical checklist for rooftop or ground-mount solar loans. The SIDBI scheme sheet we could open is an energy efficiency product, which asks for a DPR vetted by SIDBI’s Energy Efficiency Cell. That is not a solar loan |
Three differences matter for your pack.
First, IREDA’s engineering text states scope, while SBI’s brief states a ratio. IREDA tells you what its reviewer covers. The SBI brief says the debt service test is run at P90. The P90 figure in row 2 may therefore be the number your lender sizes debt on. See P50, P90 and P99 explained and the P90 glossary entry.
Second, only IREDA’s rooftop scheme names a structural deliverable. It asks for load bearing, seismic and wind safety reports on every sub-project, and it says who signs them. The signatory must be a structural or civil engineer on the list of the local government, town planning or municipal authority.
Third, none of the three publishes a document-by-document engineering checklist for a solar term loan. IREDA’s rooftop scheme points to a checklist on its website, but the checklist file we tried returned a not-found error on 31 October 2026. Ask your lender for its current checklist by email and keep the reply in the file. We also did not find an MNRE template for the technical contents of a private loan file.
Bankable describes the standard a document is written to. It is never a result a lender has agreed to in advance.
How do the nine documents have to agree?
Most comments on an engineering pack are not about one weak document. They are about two documents that disagree. The check below is the one we recommend running before submission.
Illustrative example. The assumptions are ours, not data from any project. A 5 MW AC ground-mount plant has five 1,000 kW inverters. The yield report models 10,000 modules of 550 Wp, which is 5.50 MWp DC.
| Document | What it states | Value in this example |
|---|---|---|
| Yield report | Modules and DC capacity | 10,000 modules, 5.50 MWp |
| Layout | Tables and modules carried | 360 tables of 27 modules, 9,720 modules, 5.346 MWp |
| SLD | Strings | 360 strings of 27 modules |
| Structural report | Tables designed | 360 tables |
| BOQ | Modules priced | 10,000 modules |
| Connectivity approval | Sanctioned AC capacity | 5,000 kW at the stated voltage |
The layout, SLD and structural report agree with each other at 9,720 modules. The yield report and the BOQ agree with each other at 10,000. A reviewer sees two plants.
The gap is 280 modules, or 154 kWp, which is 2.8% of the modelled DC capacity. The yield report overstates energy by about the same share before any other loss, and the BOQ prices 280 modules that the layout cannot hold. One revised document would not fix this. All five need to move together.
The fix is a one-page design basis sheet with a revision number. It states DC capacity, AC capacity, module count, inverter count and the connection voltage once. Every other document quotes the sheet and its revision on its cover. When the design changes, the sheet changes first.
What goes wrong most often in the engineering pack?
These are patterns we expect a reviewer to flag, written from engineering practice. They are not statistics, and no lender has published a ranking.
- Mixed revisions. The example above. Fix: the design basis sheet.
- Yield losses left at defaults. Soiling, shading and availability are the usual ones. A loss with no stated reason invites a question. Our guide to validating a PVsyst report before a lender sees it lists the checks.
- P50 only. If your lender sizes debt at P90, a report without it is incomplete.
- A structural report with no code edition. IS 875 (Part 3): 2015, with its 2016 amendment, is the Indian wind load standard. The report must state the basic wind speed and terrain category it used. Read what reviewers accept in a STAAD report before you commission one.
- A soil report that does not match the foundation. A report with few boreholes, or none near the array, cannot support a pile design. Corrosivity data affects whether buried steel lasts the loan tenor.
- A thin SLD. No fault levels, protection settings or metering arrangement. The CEA distributed generation regulations require the applicant to prepare single line diagrams and make them available to the licensee. The SLD is also the base for row 9.
- A BOQ that does not reconcile. Quantities differ from the layout, or an item sits outside the EPC scope with nobody pricing it. IREDA’s reviewer scope names exactly this: major equipment not covered in the EPC contract.
- An approval that is not one. A feasibility letter, an approval for a different capacity, or an approval that has lapsed. Check the letter against the SLD line by line.
- Unsigned drafts. Unsigned or unrevised documents leave the reviewer unsure which version governs.
What changes between rooftop C&I and ground mount?
The nine documents stay the same. Their content shifts.
| Item | Rooftop C&I | Ground mount |
|---|---|---|
| Site evidence | Roof ownership document and roof lease with access rights, per IREDA’s rooftop scheme. Roof structural assessment | Land documents. Topographic survey. Geotechnical report with boreholes across the array |
| Structural report | Roof load bearing, seismic and wind safety for each roof, signed by an engineer on the local authority’s list (IREDA rooftop scheme). See rooftop structural certificates | Foundation and frame design from soil data and wind loads. Pile reactions tie to the geotechnical report |
| Yield and shading | Near-shading from parapets, tanks and neighbouring buildings. IREDA’s reviewer checks the existing shadow profile | Row-to-row shading, terrain, soiling, tracker or fixed tilt |
| Grid connectivity | Usually below 33 kV, where the CEA distributed generation regulations apply | Depends on voltage. Below 33 kV the same regulations apply. Above it, the transmission utility’s process applies. The CERC connectivity regulations of 7 June 2022 (as originally notified) let plants of 50 MW and above apply for central grid connectivity |
| Safety and CEIG | Roof access, fire safety and cable routing on an occupied building. IREDA’s reviewer monitors fire safety clearance | Substation, earthing and fencing. Same inspection rules |
| Minimum size in IREDA’s rooftop scheme | 1,000 kWp per application, with sub-projects of at least 20 kWp when an aggregator applies | Does not apply. The minimum belongs to the rooftop chapter only |
On the CEIG row: the CEA Safety Regulations 2023 (notified 8 June 2023) send installations above a notified voltage to the Electrical Inspector. Installations at or below it are self-certified. Generating apparatus above a capacity the government notifies is also inspected. The appropriate government notifies these thresholds, so confirm them with your state inspectorate. Regulation 121 also sets safety requirements for solar installations, including a manual disconnection switch, earthing to the relevant standard and fire detection and suppression. Inspection comes before energisation, so at sanction your file will usually hold the submitted drawings and application status, not a final approval. Our guides to CEIG approval and CEA connectivity rules cover the process by state.
Which of these documents does a design firm prepare?
Some can come from a design firm. Others only an authority, a soil agency or you can supply.
| Document | Usually prepared by |
|---|---|
| DPR technical section | The developer or its consultant, drawing on the reports below |
| Yield report with P50 and P90 | A yield or design consultant. Our reports page lists PVsyst energy simulation and shading analysis reports |
| Layout, SLD and BOQ | The EPC design team or a design firm. See how a BOQ is calculated |
| Structural report | A design firm or structural consultant, using STAAD or similar. Rooftop signatory rules apply, as above |
| Geotechnical report | A soil investigation agency does the field work and lab tests. The reports page lists geotechnical and earth resistivity reports, and scope is agreed at scoping |
| Grid connectivity approval | The DISCOM or transmission utility decides. The developer applies, and a design firm can supply the SLD and technical annexures |
| CEIG submission | The Electrical Inspectorate approves. A design firm prepares the drawings, as on our CEIG drawings page |
Heaven Designs is a design and engineering firm. We prepare documents. We do not approve them, arrange finance or review a pack for a lender, and the lender appoints its own reviewer. If you want the yield, shading, geotechnical or structural reports prepared to the register above, start at the reports page.
In what order should you assemble the pack?
Authorities set the pace for two documents, so start there.
- Apply for grid connectivity and plan the CEIG submission first. Their timelines are not yours.
- Commission the soil investigation for a ground-mount site, or the roof structural assessment for a rooftop, as soon as the site is fixed.
- Issue the design basis sheet and freeze it at revision 1.
- Build layout, then the yield report, then the SLD. The yield report needs the layout for shading.
- Run the structural report once soil data and layout are in.
- Issue the BOQ last from the final layout and SLD.
- Run the one-number check, then assemble the DPR technical section from the finished documents.
FAQ
Does a lender name PVsyst as the required tool?
None of the lender documents we opened names a simulation tool. IREDA’s scope refers to an energy yield assessment, and the SBI brief refers to a resource study. Whatever tool you use, the report needs traceable inputs, justified losses and a P90 figure. Check your lender’s own wording.
Is CEIG approval needed before the loan is sanctioned?
Inspection comes before energisation under the CEA Safety Regulations 2023, so a final approval usually does not exist at sanction. A lender can see the drawings you submitted and the status of the application. Ask your lender which stage its conditions refer to.
Who appoints the reviewer on the lender side?
For its rooftop scheme, IREDA says it engages the lender’s engineer from its own panel. Lenders set their own arrangements, so ask. For the owner’s side of the table, read our guide to the owner’s engineer for solar projects, and see owner’s engineer vs lender’s engineer for who checks what.
Can the firm that designed the plant also review it for the lender?
Not credibly. A reviewer who checks its own design is not independent, and under IREDA’s rooftop scheme IREDA selects the lender’s engineer itself. The design firm prepares documents and answers comments. The lender’s reviewer judges them.
Do small rooftop loans need the same nine documents?
Not always. IREDA’s rooftop scheme starts at 1,000 kWp per application. SBI’s Surya Shakti page lists no technical documents, so ask the branch what it needs. Even for a small loan, a yield estimate, an SLD and a structural check on the roof are the minimum a sensible reviewer will want.
Next step
Before you submit, run the one-number check across your nine documents and ask your lender for its current checklist in writing. For lender-by-lender acceptance mechanics, read our guide to how lender acceptance works in India. The IREDA glossary entry and the engineering guides in our resource center cover the terms.
If you need the yield, shading, geotechnical or structural reports prepared, see the reports page. To discuss your pack and its scope, contact us. We reply within 1 business day (company-stated), and turnaround is agreed at scoping.