Real Unit Economics of an Indian Solar Installer

ALMM and inverter compliance: MNRE’s current ALMM page publishes solar PV module and cell lists, not an inverter list. Verify the inverter’s exact model documents and applicable scheme or DISCOM requirements separately.

Most conversations about solar in India focus on the customer’s perspective: bill reduction, subsidy, payback period. For EPC teams looking to understand the customer’s financial framework during a commercial sale, the solar IRR and payback guide for C&I provides the financial model most C&I buyers use internally. This post is about the installer’s perspective, specifically, the unit economics of running a solar EPC business in India.

I am writing this because I spend time with EPC partners across India, and I hear the same questions repeatedly: “What should my margin be?”, “How do I think about customer acquisition cost?”, “Why am I not making money despite installing 10 systems a month?”. The answers are rarely comfortable, but they are knowable.

These are not benchmark numbers from a consulting report, they are derived from real conversations with operational solar installers in India. The ranges are honest and the uncomfortable parts are included. Installers who are formalising a scrappy operation into a repeatable one often find it worth adopting a proper solar business software stack around the same time they start taking these numbers seriously.

The direct version. A well-run residential solar EPC business in India can plan on 22–30% gross margin (an illustrative assumption). After customer acquisition cost (₹12,000–₹20,000/installation), after-sales provision (5–7% of revenue), and overhead, net operating margin is typically 5–8%. Cash is tight because the PM Surya Ghar subsidy cycle adds 60–100 days of receivables. The installers who survive long-term are the ones who understand these numbers before they become a problem.

Revenue Structure: What Installers Actually Charge

For a 3 kW residential system in 2025–26, the market-clearing price in most Indian cities is ₹1.3–1.7 lakh (after subsidy adjustment). Before subsidy, the gross system capex is approximately ₹2.0–2.4 lakh.

Breakdown of revenue components:

These are loaded costs, including the installer’s project management time, vehicle cost for site visit, and a provision for warranty work. Installers who show 30–35% margin by excluding these hidden costs are mis-measuring their profitability.

The Cost of Customer Acquisition

Customer acquisition cost (CAC) is the most underestimated line item in solar EPC unit economics. Many installers think they have a 25% gross margin business and cannot understand why they are not profitable, then discover their CAC is consuming 15–20% of project revenue. Installers running multiple acquisition channels at once usually need real lead management to see which channel’s blended CAC is actually working, rather than guessing from memory at the end of the month.

CAC by channel (residential solar, India):

Blended CAC target: For a residential-focused installer, blended CAC should not exceed ₹15,000–₹20,000 per installation. Above ₹20,000, CAC alone consumes 10–13% of a 3 kW project’s revenue, making the business mathematically difficult to sustain with a proper service team.

The most profitable acquisition channel is referrals from satisfied existing customers. Installers who invest in after-sales service quality find that referral rates improve over time, driving CAC down. This is a flywheel that takes 2–3 years to build, which is why installers who cut after-sales service to save money in year 1 end up with declining referral rates and rising CAC in year 3.

The After-Sales Cost Trap

After-sales service is where the unit economics become uncomfortable for most installers.

Consider the following common after-sales scenarios for a 5 kW residential system in the first three years:

For a 3 kW system at ₹1.8 lakh project revenue, ₹5,000–₹12,000 in after-sales cost is 2.8–6.7% of revenue. Most installers provision 0% for this in their margin calculation.

Installers who use inverter brands with strong remote diagnostic capability (where faults can be diagnosed via the monitoring app rather than a site visit) systematically have lower after-sales cost. This is one of the real reasons inverter brand quality matters to EPC profitability, beyond just the product margin.

The PM Surya Ghar Cash Cycle Problem

PM Surya Ghar Muft Bijli Yojana has been transformative for residential solar volumes in India. It has also created a cash cycle problem that is quietly strangling smaller installers.

Here is how the cash cycle works for a compliant installer:

1. Day 1: Installer quotes customer net-of-subsidy. Customer pays net-of-subsidy amount (assumed ₹1.2 lakh for a 3 kW system, with ₹78,000 subsidy outstanding).
2. Day 10–30: Installation is completed. Installer has spent the full ₹2.0 lakh cost but collected only ₹1.2 lakh.
3. Day 30–45: DISCOM inspection and commissioning certificate issued.
4. Day 45–60: Installer submits subsidy claim on PM Surya Ghar portal.
5. Day 90–130: MNRE disburses ₹78,000 to installer’s account.

Cash gap period: 60–100 days, ₹78,000 per installation.

For an installer doing 10 installations per month, this is ₹7.8 lakh in outstanding subsidy receivables at any point, money they have spent but not yet collected. This requires working capital: either from the installer’s own reserves or from short-term borrowing at 12–18% annual interest.

The working capital cost of the subsidy receivables cycle adds approximately 2–3% to the effective cost of each PM Surya Ghar installation. Installers who do not account for this discover that their PM Surya Ghar margin is lower than their non-subsidy margin, which is counterintuitive but financially accurate.

What Net Margin Actually Looks Like

Taking the numbers together for a 3 kW residential system at ₹1.8 lakh project revenue (typical market price, inclusive of subsidy):

A 5–8% net operating margin on ₹1.8 lakh is ₹9,000–₹14,000 per installation. For an installer doing 8 residential installations per month, this is ₹72,000–₹1,12,000/month of net operating income, which is a viable but not comfortable business.

The installers who build to 20–30 installations per month with a strong referral engine and low CAC, using high-quality inverters that reduce after-sales cost, move their net margin to 8–12% and build a genuinely profitable business.

The Segment Mix That Changes the Math

The single most effective way to improve EPC unit economics is to add commercial installations to a residential-heavy portfolio.

For a 30 kW commercial system at ₹15 lakh project revenue:

One 30 kW commercial installation generates the net operating income of approximately 30 residential installations. The installer’s team spends approximately 3× the time on a commercial project, not 30×. This is why EPC businesses that add commercial capability systematically outperform pure residential operations.

What This Means for How Installers Should Choose Their Inverter Brand

The inverter brand decision is not just a product quality decision, it directly affects unit economics:

Remote diagnostics reduce after-sales cost. An inverter brand with strong cloud monitoring and remote fault diagnosis means fewer site visits for common faults, for what good monitoring looks like in practice, see the solar monitoring app guide. If remote support resolves 60% of customer calls without a technician visit, the after-sales cost drops from 6% of revenue to 3–4%.

Warranty replacement process affects cash. When an inverter fails under warranty, the installer typically replaces it from their own stock and waits for the replacement unit from the manufacturer. If the replacement cycle is 30 days, the installer is carrying ₹40,000–₹80,000 of additional inventory per failure. Manufacturers with fast RMA (return merchandise authorisation) processes (replacement within 5–7 days) reduce this inventory burden; the solar inverter warranty claim guide walks through what a fast RMA process actually looks like step by step.

Brand margin varies. Premium inverter brands that support structured distributor margins allow installers to earn 12–18% margin on equipment versus 6–10% on commoditised equipment. A ₹70,000 inverter at 15% margin contributes ₹10,500 to gross profit; a ₹60,000 inverter at 7% margin contributes ₹4,200. The premium product with better margin can be better for the installer’s P&L even at higher equipment cost.

The Honest Summary

Running a solar EPC business in India is viable but not easy. The rooftop market is growing (MNRE reported 33.41 GW of grid-connected rooftop solar on 30 September 2026), and well-positioned EPC businesses can grow with it. The gross margins are real, 22–28% at project level is achievable. The challenges are in the layers below gross margin: customer acquisition cost, after-sales burden, and working capital tied up in subsidy receivables.

The installers who build durable businesses share three characteristics:

1. They measure their CAC and after-sales cost. Not as a calculation once a year, but as a rolling metric on every project, tracked through sales reports and analytics rather than reconstructed from memory at tax time.

2. They invest in after-sales quality. Because referrals are the cheapest acquisition channel, and referrals come from satisfied customers, and satisfied customers require good after-sales.

For technical references, the solar EPC bid evaluation guide and solar CAPEX vs OPEX guide cover the customer-facing financial frameworks that EPC teams use to close commercial deals.