Solar Installation Process Step-by-Step

Managing a solar installation from first customer call to commissioned system is, in reality, managing seven distinct phases, each with its own team, timeline, and failure modes. Most installation delays happen not because of technical problems but because of coordination gaps between phases: the structural team finishes before the electrician arrives, or the DISCOM inspection is booked before the commissioning documents are ready.

This guide covers the complete 7-Phase Solar Installation Timeline for Indian residential and small commercial systems. If you manage multiple installation crews, as most scaling EPC owners do, this is the playbook to run every project from.

The timeline varies: a well-organised EPC in Gujarat with DGVCL can complete the full cycle in 5–7 working days. An EPC in Maharashtra dealing with MSEDCL in a congested feeder zone may take 10–14 days just for DISCOM inspection and meter change. The phases are fixed; only the time within each phase varies.

Phase 1, Site Survey (Day 1, half-day)

The site survey is the first and most important phase. Every downstream decision, system size, structural design, inverter placement, cable routing, and subsidy eligibility, depends on data gathered here. A rushed 20-minute survey produces a project that bleeds cost and time in every subsequent phase.

A thorough site survey covers six categories of information. We detail all 24 check points in our solar site survey checklist, but here is the overview:

Structural: Roof type (RCC, metal, GI sheet, clay tile), roof area, roof orientation, tilt angle, age of the roof, load-bearing capacity assessment, parapet height, and accessibility for installation crew and equipment.

Electrical: Existing sanctioned load, meter rating, main distribution board (MDB) location, phase (single/three), existing cable sizing, earth resistance, and distance from solar inverter to MDB.

Shading: Photograph the roof from all four sides at solar noon. Identify shadow sources, water tanks, cell towers, neighboring buildings, trees, TV antennas. Mark shaded and unshaded areas on a roof sketch.

DISCOM: Confirm the consumer account number, meter number, DISCOM name, and feeder zone. Check whether the feeder is overloaded or net metering-capped. Some DISCOMs (MSEDCL zones in Pune, parts of BSESDELHI) have temporary moratoriums on new net metering connections in congested feeders.

Customer: Collect all documents needed for PM Surya Ghar application, Aadhaar, PAN, recent electricity bill, bank account details, and ownership proof. Getting these on Day 1 prevents a 3–5 day delay later. See the PM Surya Ghar application process guide for the full document checklist.

Commercial: Confirm system size from the sizing calculation, agree on system type (on-grid vs hybrid), confirm payment terms, and get the work order signed.

Phase 1 time estimate: 2–4 hours on-site. Add 1–2 hours for documentation and report filing.

Common Phase 1 failure: Skipping the DISCOM feeder check. This is discovered at Phase 6 (Inspection) when the DISCOM engineer flags the congested feeder, at which point you have already completed structural and electrical work.

Phase 2, Design (Day 1–2)

With site survey data in hand, the design phase produces three deliverables:

1. Solar layout drawing: Panel arrangement on the roof, row spacing, tilt angles, and shading avoidance. For a standard RCC flat roof, panels are typically installed at 10–15° tilt facing south (true south, not magnetic south). For south-facing sloped roofs, panels may be installed flush to the roof at the existing slope angle.

2. Single-line diagram (SLD): The electrical schematic showing panel strings, DC combiner box (if any), inverter, AC distribution box, bidirectional net meter, and grid connection point. The SLD is required for DISCOM application and for the DISCOM inspection.

3. Bill of materials (BOM): Complete component list with model numbers, quantities, and specifications. This triggers procurement in Phase 3. For PM Surya Ghar projects, every panel and inverter on the BOM must be on the MNRE ALMM (Approved List of Models and Manufacturers). Using a non-ALMM component disqualifies the subsidy, a costly mistake at this stage.

Phase 2 time estimate: 2–4 hours for a standard residential system. 1–2 days for complex commercial layouts.

Common Phase 2 failure: Forgetting to check ALMM status before finalising the BOM. Always verify at MNRE's official ALMM portal before ordering.

Phase 3, Procurement (Day 2–4)

Procurement is where project timelines are most often blown. If the local distributor does not have the specified panels in stock, a 3–5 day wait becomes 10+ days. Good EPC owners maintain a standard BOM with pre-negotiated stock commitments from 2–3 distributors.

Key procurement decisions:

Panels: Verify ALMM status, check wattage tolerance (only buy panels with +0/−0% or +3/−0% tolerance, never buy panels with −3% tolerance, as a 400 Wp panel could deliver 388 Wp), confirm warranty documents are available. See solar panel price trends to understand current market pricing.

Inverter: Confirm ALMM status, verify the inverter's grid frequency settings match your state DISCOM's requirements (50 Hz ± 5% in India), and ensure the warranty registration process is understood. Check solar inverter prices in India for current benchmarks.

Structure: Galvanised iron (GI) or aluminium? GI is cheaper and heavier; aluminium is lighter and more corrosion-resistant. For coastal sites (Mumbai, Chennai) or high-humidity environments, aluminium is worth the premium. Structure weight must match the roof's load capacity from Phase 1.

Cables and hardware: DC cables (4 sq mm or 6 sq mm rated for 600V DC), AC cables, MC4 connectors, earthing wire, lightning arrestor, AC/DC disconnect switches. These are often under-specified in cheap installations and cause failures within 2–3 years.

Phase 3 time estimate: 1–2 days if stock is available locally. 3–7 days if ordering from a distant distributor.

Common Phase 3 failure: Accepting substitute panels when the specified model is out of stock, without verifying the substitute's ALMM status. This has killed PM Surya Ghar subsidy applications for dozens of installers.

Phase 4, Structural Installation (Day 3–5)

Structural installation is the physical rooftop work: mounting the structure, fixing the panels, and completing the DC cabling up to the inverter. For most residential systems, this takes one full working day with a 3-person crew.

Structural checklist:

• Mark panel positions on roof with chalk line before drilling any holes
• Use stainless steel or GI fasteners, never use plain mild steel bolts on a rooftop (they rust within 2 monsoon seasons)
• Apply waterproof sealant to every drill hole, roof leaks are the #1 post-installation complaint in India
• Verify panel frame alignment with a spirit level before final torquing
• Route DC cables through conduit where exposed to walking areas or animal access
• Label each string clearly (String 1, String 2) at the inverter end before terminating

The 7-Phase Solar Installation Timeline prescribes a strict "no electrical connections until Phase 5" rule during structural work. This means no panel connections to the inverter yet, DC cables are laid and labelled but not terminated. This prevents accidental energisation during structural work, which has caused serious electrical accidents at Indian EPC sites.

Phase 4 time estimate: 4–8 hours for a standard residential 3–5 kWp system with a 3-person crew on a flat RCC roof. Sloped tile roofs take 30–50% longer.

Common Phase 4 failure: Roof leaks from improperly sealed mounting holes. Fix: use EPDM rubber gaskets under every mounting foot, plus apply butyl tape and then a surface sealant over each hole. Inspect all holes before leaving the roof.

Phase 5, Electrical Installation (Day 4–6)

Electrical installation covers everything from the inverter to the bidirectional meter and the main distribution board. This phase requires a licensed electrician, in India, any electrical installation above 5 kW requires a contractor with a valid electrical license under the Central Electricity Authority (CEA) regulations.

Electrical installation sequence:

1. Mount inverter on the designated wall (usually a shaded, ventilated indoor/covered area, never direct sun, never inside a closed cabinet without ventilation)
2. Terminate DC strings at the inverter input, verify polarity before connecting
3. Run AC cable from inverter AC output to the main DB or dedicated solar DB
4. Install AC isolator (rated for the inverter's AC output) between inverter and DB
5. Install bidirectional net meter (supplied by DISCOM, or install a temporary meter if DISCOM's is delayed)
6. Commission earthing system, verify earth resistance is ≤ 10 ohms per CEA safety regulations
7. Install surge protection device (SPD) on DC input and AC output
8. Final wiring inspection against the SLD from Phase 2

Phase 5 time estimate: 4–6 hours for a 3–5 kWp residential system. Complex systems with string combiner boxes or hybrid battery integration take 1–2 full days.

Common Phase 5 failure: Improper earthing, discovered during the DISCOM inspection in Phase 6. Fix: test earth resistance with a clamp meter before calling for inspection. If resistance is above 10 ohms, add a second earth pit.

Phase 6, DISCOM Inspection and Net Meter Installation (Day 5–14)

This phase is entirely outside the EPC's control, and it is where most residential project timelines blow up. The DISCOM must:

• Review and approve the net metering application and SLD
• Send an inspection engineer to verify the installation
• Install the bidirectional net metering device
• Update the consumer's tariff category to "prosumer"

The single most effective thing you can do to reduce Phase 6 time is to submit a clean application with all documents on Day 1. For the full benchmark analysis, see DISCOM approval time benchmarks.

What to do while waiting for DISCOM:

• Complete PM Surya Ghar application on the PM Surya Ghar National Portal, submit the installation photos, ALMM compliance certificates, and inverter commissioning report
• Run the system in "island mode" (if hybrid) or keep it de-energised (if on-grid) until DISCOM net meter is installed
• Hand the customer the commissioning report and explain what to expect during the waiting period

Phase 6 time estimate: 5–15 working days depending on DISCOM. Cannot be compressed by the EPC.

Common Phase 6 failure: DISCOM rejection due to non-ALMM components or incorrect SLD format. Fix: use DISCOM's own SLD format (most DISCOMs publish a sample SLD on their website) and verify ALMM compliance before submission.

Phase 7, Commissioning and Handover (Day 6–15, after net meter)

Once the DISCOM installs the net meter, commissioning is typically a half-day process. The goal of commissioning is to verify that the system is operating correctly, safely, and ready for the customer to hand over.

Commissioning checklist:

1. 1

   Verify DC open-circuit voltage (Voc)

   Measure Voc at the inverter DC input for each string. Compare against the expected Voc (number of panels × panel Voc). A reading more than 5% below expected indicates a wiring fault or damaged panel.

2. 2

   Power on the inverter and verify grid sync

   The inverter should auto-synchronise to grid frequency and start exporting within 60 seconds of startup. If the inverter shows "Grid Fault" or "Isolation Fault," check AC connections and earth resistance before proceeding.

3. 3

   Verify net meter is logging correctly

   Confirm the bidirectional net meter is registering import and export kWh separately. Take a timestamped photograph of the meter at commissioning, this is the zero-reading baseline for the first billing cycle.

4. 4

   Complete PM Surya Ghar disbursement documentation

   Upload the final commissioning report, net meter photo, and DISCOM approval letter to the PM Surya Ghar portal. Subsidy disbursal typically takes 30–60 days after this submission. Track the status in the portal and set a follow-up reminder for Day 45.

5. 5

   Customer handover and walkthrough

   Walk the customer through the inverter monitoring app, explain the expected generation figures by season, and show them how to read the net meter. Provide the commissioning report, warranty cards for panels and inverter, and contact details for AMC support. This conversation takes 20–30 minutes and dramatically reduces post-installation support calls.

Phase 7 time estimate: 2–4 hours on-site including customer walkthrough.

Common Phase 7 failure: Submitting PM Surya Ghar disbursement documents without the DISCOM's official commissioning certificate. Most DISCOMs issue this automatically, but in some zones (parts of MSEDCL) you must specifically request it. Forgetting this delays subsidy disbursal by 30–60 additional days.

The 7-Phase Solar Installation Timeline, summary view

Managing multiple crews, the EPC owner's coordination challenge

For Rohit, running a 12-person EPC in Surat with 3–4 active sites on any given day, the challenge is not executing any single phase, it is running 4 projects each at different phases simultaneously. A missed call about a procurement delay on Project A ripples into the structural crew's schedule for Project B.

The coordination principle that works: treat each phase transition as a formal gate, not a handshake. The design engineer does not hand off the BOM to procurement verbally, they update a shared project status log. The procurement team does not text "materials ready", they update the log. This creates a shared source of truth for where every project is, without requiring Rohit to call everyone every morning.

Common installation problems and fixes

Every EPC team will encounter these. The 7-phase timeline helps you catch them early:

Problem: Inverter shows isolation fault at startup. Root cause: DC cable insulation damaged during structural work, or a loose MC4 connector with moisture ingress. Fix: disconnect all strings and test insulation resistance of each string cable with a megohmmeter. Replace any cable showing IR below 1 MΩ.

Problem: System generates 15–20% less than projected. Root cause: shading not captured in Phase 1 survey, or panels soiled from construction dust. Fix: do a shading analysis post-installation, clean panels, and recalculate expected generation. If the gap persists after cleaning, check for underperforming panels with a thermal camera.

Problem: Net meter shows zero export even when inverter is running. Root cause: AC isolator between inverter and net meter is open, or the net meter is not configured for bidirectional reading. Fix: verify all AC isolators are closed, and ask DISCOM to confirm the net meter is in "prosumer mode."

Problem: DISCOM rejects the SLD. Root cause: SLD does not match the DISCOM's required format, or the specified inverter is not on the DISCOM's approved list. Fix: download the DISCOM's standard SLD template from their website and redo the drawing. See our guide on DISCOM approval timelines for which DISCOMs have the strictest requirements.

PM Surya Ghar documentation at each phase

The PM Surya Ghar subsidy process runs in parallel with the installation phases. Knowing exactly which documents are needed at which phase prevents the common scenario where the installation is complete but the subsidy is held up for weeks on missing paperwork.

For PM Surya Ghar eligibility and vendor registration requirements, read our dedicated guides. For the step-by-step portal submission process, see the PM Surya Ghar application process. And for understanding the subsidy amounts by system size, see PM Surya Ghar cost by system size.

The residential system sizing guide explains how to set the correct kWp before you reach Phase 2 Design, sizing errors discovered in Phase 5 or 6 are very expensive to correct.

How QuickEstimate fits

Rohit managed his 7-phase projects on WhatsApp groups and Excel sheets. Status updates were lost in group chats. The PM Surya Ghar document checklist existed in someone's head, not in a system. Customer follow-ups for post-commissioning AMC were forgotten.

• Pipeline Management, track every project through all 7 phases with a shared team dashboard; Rohit sees which projects are stuck in DISCOM inspection and which crews are available for the next structural job.
• Proposal Generator, generates the site survey report and proposal together, with PM Surya Ghar subsidy pre-calculated, so Phase 1 output becomes Phase 3 input without re-entering data.
• WhatsApp Follow-up, automated reminder at Day 45 post-commissioning prompts the customer to check their PM Surya Ghar subsidy status, and prompts Rohit's team to schedule the first AMC visit.

Start free on QuickEstimate, 10 proposals and pipeline slots per month, no card required.

What to do this week, for your EPC

1. Audit your last 5 completed projects against the 7-phase timeline. At which phase did each project lose the most time? For most EPCs, it is either Phase 3 (procurement delays) or Phase 6 (DISCOM processing). Knowing which phase is your bottleneck is the first step to fixing it.
2. Create a one-page Phase Gate Checklist for your site engineers. It should list the five must-verify items at the end of each phase before handing off to the next. Laminate it and put it in every site engineer's toolkit. This alone reduces rework calls by 40–60% in most EPC operations.
3. Pre-fill your DISCOM application forms for the three DISCOM zones you work in most often. Keep a ready template with all standard fields pre-filled; only customer-specific fields change project to project. A clean, complete application reduces Phase 6 rejections from the most common cause of delay.

Frequently asked questions

How long does a residential solar installation take in India?

A standard 3–5 kWp residential installation takes 1–2 days of physical work (Phases 4 and 5). The total time from site survey to commissioned system is 5–15 working days, with the largest variable being DISCOM inspection and net meter installation time (Phase 6). In Gujarat (DGVCL), EPCs regularly complete projects in 7–8 working days. In Maharashtra (MSEDCL), it often takes 12–18 working days.

What approvals are needed before installing solar in India?

For grid-connected (on-grid or hybrid) systems, you need DISCOM approval and net metering registration. Most DISCOMs require a net metering application with the single-line diagram, a technical feasibility approval, an inspection by their engineer, and installation of a bidirectional net meter. For PM Surya Ghar projects, additional registration on the national portal is needed. Off-grid systems typically need no DISCOM approval but may require local electrical inspector certification depending on the state.

Do I need a licensed electrician for solar installation in India?

Yes. Under CEA (Measures Relating to Safety and Electric Supply) Regulations, any electrical installation connected to the grid must be designed, installed, and tested by a licensed electrical contractor. For installations above 5 kW, the contractor must hold a valid license issued by the state electrical licensing board. Unlicensed installations can be rejected by the DISCOM and may void equipment warranties.

What is the most common reason for solar installation delays in India?

Based on feedback from Indian EPC owners, the three most common delay causes are: (1) DISCOM inspection backlog, which accounts for roughly 60% of all delays; (2) ALMM non-compliance discovered at inspection, causing the application to be rejected and resubmitted; and (3) procurement delays when specified components are out of stock. The first is mostly outside EPC control; the second and third are entirely preventable with Phase 1 and Phase 2 discipline.

Can I start generating power before the DISCOM installs the net meter?

No, for an on-grid system, you must not energise the system until the bidirectional net meter is installed and the DISCOM has completed their inspection. Operating an on-grid system without DISCOM approval violates the electricity supply agreement and the anti-islanding safety requirements. For hybrid systems with battery backup, the system can operate in island mode (serving local loads from battery + solar without exporting to grid) while waiting for the net meter.

What documents does the customer need for PM Surya Ghar subsidy?

The customer needs: Aadhaar card, PAN card, copy of latest electricity bill, bank account details (same bank as DISCOM direct-benefit-transfer), ownership proof (property tax receipt or registry copy), and a passport-size photograph. The EPC needs: ALMM compliance certificates for panels and inverter, a copy of the net metering approval from DISCOM, a commissioning report with system parameters, and installation photographs. Collect all of these in Phase 1 to avoid delays in Phase 7.

How do I handle warranty claims for solar panels and inverters?

Panel warranties in India are typically 10-year product warranty + 25-year linear performance guarantee (85% output at Year 25). Inverter warranties are 5 years standard, extendable to 10 years with an AMC. For claims, the customer files with the manufacturer using the model number, serial number, and commissioning date. The EPC should maintain a project register with all component serial numbers, this eliminates the "which inverter is on which roof?" problem when a warranty claim comes 3 years later.

How does the installation process differ for hybrid vs on-grid systems?

Phase 1–3 differences are minimal, the BOM includes a hybrid inverter and battery instead of a string inverter. Phase 4 (Structural) is identical. Phase 5 (Electrical) takes 2–4 hours longer for hybrid to accommodate battery bank installation, battery management system wiring, and backup circuit configuration. Phase 6 (DISCOM Inspection) is identical, the DISCOM inspects and registers the system the same way. Phase 7 Commissioning adds a battery charge/discharge test cycle (1–2 hours) to verify backup mode is working correctly.