Most factory solar problems do not start on the roof. They start on the day the contract is signed, with a vague quote and promises nobody wrote down. If you run a plant in Surat, Vapi, Ahmedabad or Ankleshwar, picking the right solar EPC company for industry decides your savings for the next 25 years. This 12-point checklist shows what to ask, what a good answer sounds like, and which red flags should end the talk.
Raynex Power Solution Pvt. Ltd, a solar EPC company in Gujarat based in Surat since 2020. We built this list from the questions we wish every factory owner asked us, and every other bidder, before signing.
What Does a Solar EPC Company Do for an Industrial Project?
EPC stands for Engineering, Procurement and Construction. One company designs the plant, buys the parts, builds it and hands it over in working order. The real value is single-point responsibility. If output falls short, you have one team to call, not five vendors blaming each other.
What EPC Covers, and What It Often Leaves Out
Full solar EPC services for a factory should include:
- Site survey, load study and roof check
- Plant layout, output estimate and drawings
- Buying modules, inverters, structures and cables
- Installation, testing and start-up
- DISCOM, GEDA and electrical inspector approvals
- Handover, staff training and O&M
The gaps usually sit in the last two lines. Many quotes say “approval support” without naming who files, who follows up and who pays the fees. Get this in writing.
Why Factories Need a Different Kind of Solar EPC Company across Gujarat
A home rooftop is a small, simple job. A factory is a live site with heavy loads, HT connections, fire rules and machines that cannot stop. A Raynex team must read your load pattern, work around production and handle HT approvals. A team that mostly fits 3 kW home systems may not have that depth yet.
Gujarat also has its own rules. For HT and EHV consumers running captive solar, energy set-off is allowed only from 7 am to 6 pm on the same day, under the state’s rooftop solar rules. So a plant sized only on your monthly bill, and not on your daytime load, may make units that earn you less than you expect.
The 12-Point Checklist for Choosing a Solar EPC Company for Industry
Use these points in your first two meetings with each bidder. A good industrial solar company will answer each one with documents, not just words.
1. Proven Industrial Solar Projects of Similar Size
Any industrial solar installation company can show nice photos. Ask for three projects close to your size and roof type, with the client’s name and a contact number.
A 50 kW shop roof and a 1 MW factory are very different jobs. If you can, visit one running plant and ask the owner two things: did output match the promise, and how fast does the team fix faults? You can see our factory work on our projects page.
2. A Load Study Before Any Capacity Number
Anyone who quotes a plant size over the phone is guessing. The right size comes from 12 months of bills, your sanctioned load and your hour-by-hour daytime use.
For three-shift units, like many textile mills in Surat, the daytime share of load decides how much solar you can use directly. That number should appear in the proposal.
3. Roof Strength Checks for Metal Sheet and RCC Roofs
Panels last 25 years or more, but the roof under them may not. The EPC team should check purlin condition, sheet thickness, rust and leak points before any layout is drawn.
Mounting structures should be built to the wind load code IS 875 (Part 3). This matters on the South Gujarat coast, where monsoon winds hit hard.
4. An Honest Generation Estimate With Stated Losses
Two quotes for the same plant size can promise output 10 to 15% apart. The gap comes from assumptions about dust, heat, shade, cable loss and yearly panel ageing.
Ask for a simulation report, such as PVsyst, with every loss listed. If the losses are not shown, the number is a sales figure. We explain one often-missed loss in our guide on transformer losses in industrial solar plants.
5. ALMM-Listed Modules and Named Inverter Brands
The quote should name the exact module model and wattage, not just “Tier-1 panels.” Tier-1 is a bank rating, not a quality test. Check the model on the MNRE ALMM list yourself.
The same goes for inverters, cables, ACDB and DCDB panels. Brand and model should be fixed in the contract so parts cannot be swapped for cheaper ones later.
6. Corrosion-Ready Structures for GIDC Chemical Zones
Chemical fumes in the Vapi and Ankleshwar estates, and salty air near the coast, eat through thin coatings fast. Rust can weaken a structure within a few years.
Ask for hot-dip galvanised steel with the coating thickness stated in microns, or anodised aluminium. Also ask which nuts and bolts will be used, since cheap fasteners often rust first.
7. Clear Ownership of DISCOM, GEDA and CEI Approvals
In South Gujarat, most factories deal with DGVCL. Based on size and voltage, your plant may also need GEDA registration and drawing approval from the Chief Electrical Inspector (CEI).
Gujarat permits net metering for rooftop systems from 1 kW to 1 MW. A good solar EPC contractor in Gujarat will list each approval, who files it, who pays the fees and the expected timeline. “We will help” is not a scope.
8. Safe Work Inside a Running Factory
Your production cannot stop for weeks. Ask how the team will handle material lifting, roof access, hot work and the final shutdown for tie-in. A serious solar EPC company works under your permit-to-work system. They use safety lines on fragile roofs and plan the tie-in on a weekly off day or a planned shutdown.
9. A Performance Guarantee With a Real Remedy
Ask for a guaranteed performance ratio (PR) or yearly output in writing. Then ask what happens if the plant misses it. A real guarantee has a remedy, such as repair at the EPC’s cost or payment for lost units. A guarantee with no remedy costs the contractor nothing. Our guide on solar performance ratio explains how PR is measured.
10. O&M, Cleaning and Remote Monitoring Terms
Dust from roads and factory stacks can cut output within weeks. Ask how often panels will be cleaned, what water will be used and who pays for it. The O&M contract should state fault response time, not just the number of visits. You should also get login access to live plant data, so you can check daily output yourself.
11. A Line-by-Line BOQ and Fair Payment Milestones
A lump-sum price hides the details. Ask for a bill of quantities (BOQ) that lists modules, inverters, structure, cable sizes, earthing and lightning protection.
Recent industry buyer guides put turnkey commercial and industrial rooftop solar in India at roughly ₹40,000 to ₹50,000 per kW. A quote far below that usually means less scope, not a better deal. Payments should be tied to delivery, installation and start-up, not paid mostly upfront.
12. Local Service Reach and Financial Stability
A solar plant needs support for 25 years. Ask where the nearest service team sits and how fast they can reach your site. Check years in business, GST records and past client references. A local team often responds faster, but size alone does not prove quality. We compare both sides in our post on local vs branded solar installers.
Scoring Table: Compare Each Solar EPC Company Side by Side
Print this table and score each company from 0 to 2 on every point. A total under 16 out of 24 is a warning sign.
| # | Checkpoint | What to Ask | Good Answer | Red Flag |
|---|---|---|---|---|
| 1 | Industrial track record | Can I call three factory clients? | Names, sizes, contact numbers | Only photos, no references |
| 2 | Load study | How did you size my plant? | Based on 12 months of bills and daytime load | Size quoted on the phone |
| 3 | Roof check | Did you inspect the roof? | Written roof report, IS 875 basis | “Your roof is fine” with no visit |
| 4 | Output estimate | Which losses did you include? | PVsyst report with losses listed | One big number, no report |
| 5 | Modules and inverters | Which exact models? | Model numbers, ALMM listed | “Tier-1 panels” only |
| 6 | Structure | What coating and thickness? | Hot-dip galvanised, microns stated | “Standard GI structure” |
| 7 | Approvals | Who files DISCOM, GEDA and CEI? | Named owner and timeline | “We will support you” |
| 8 | Site safety | How will you work during production? | Permit plan and safety lines | No safety plan |
| 9 | Guarantee | What if output falls short? | PR guarantee with a remedy | Guarantee with no penalty |
| 10 | O&M | What is your fault response time? | Hours stated in contract | Visit count only |
| 11 | Pricing | Can I see a full BOQ? | Line-by-line BOQ, milestone payments | Lump sum, heavy advance |
| 12 | Local support | Where is your nearest team? | Local office, clear contact | Out-of-state, no service plan |
Industrial Rooftop Solar vs Ground Mount Solar EPC: Which Fits Your Plant?
Industrial rooftop solar uses space you already own. It has no land cost and faster approvals, but plant size is capped by roof area and roof strength.
Ground mount solar EPC suits factories with spare land or those planning a large captive plant. It allows bigger sizes, the best panel tilt and easier cleaning. The trade-off is land cost, fencing and longer approvals.
Many plants start with the roof and add ground mount later. A good EPC team will tell you which route pays back faster for your load.
5 Red Flags That Should End the Conversation
- A plant size quoted before any site visit.
- Output promised without a loss report.
- “Tier-1 panels” with no model number.
- Approvals described as “support” with no named owner.
- Most of the money due before the plant runs.
If you see even two of these, walk away. The cheapest quote often becomes the most costly plant.
How Raynex Power Solution Handles Factory Solar EPC in Gujarat
Raynex Power Solution started in Surat in July 2020. Today we build industrial rooftop solar and ground mount solar plants for factories across Gujarat, with in Ahmedabad, Ankleshwar and Vapi.
Every industrial solar project we take on follows the checklist above. We do a site and load study before quoting, share a full BOQ, file the approvals ourselves and hand over live monitoring access at start-up.
If solar does not make sense for your load or roof, we will tell you that too.
Final Word: Choose on Proof, Not Price
The right solar EPC company for industry proves its claims. It shows real projects, sizes the plant from your load, names every part and owns every approval. Use the 12-point checklist and the scoring table in your next meeting. The answers will quickly show you who has done this work before.
Planning solar for your factory in Surat, Vapi, Ahmedabad or Ankleshwar? Share your last 12 months of bills with Raynex Power Solution for a free site and load study, or get a quick figure from our solar estimate tool. Call us at +91 90332 32512 to book a visit.
Frequently Asked Questions
How much does an industrial solar project cost in Gujarat?
Most turnkey factory rooftop plants fall in the ₹40,000 to ₹50,000 per kW range. The final price depends on structure height, module choice, cable runs and HT work, so always compare line-by-line BOQs.
How long does a factory solar EPC project take?
Most industrial solar projects take 2 to 6 months, based on plant size, site work and approvals. Approvals often take longer than the build itself.
How much roof area do I need per kW?
Plan for roughly 100 square feet of shade-free roof for each kW of solar. A 500 kW plant needs about 50,000 square feet.
Do I need CEI approval for rooftop solar?
It depends on your plant size and connection voltage. HT-connected systems usually need drawing approval and inspection before start-up, and your EPC company should confirm this in the proposal.
Should I choose CAPEX or RESCO?
With CAPEX, you own the plant and keep the full savings and tax benefits. With RESCO, you pay nothing upfront but buy units at a fixed rate for 15 to 25 years, so your savings are lower.