Signing a Rooftop Solar PPA? 12 Clauses to Check Before You Sign

Published Nov 2, 2026Updated Nov 3, 2026

OPEX/RESCOGuides

A rooftop solar PPA (Power Purchase Agreement) is the contract that turns "zero upfront cost" into real savings, or into a long-term headache. You will live with it for many years, so the fine print matters more than the headline tariff.

This guide walks through the 12 clauses that matter most, in plain language, for owners, CFOs and plant heads of Indian factories, hospitals, hotels and institutions.

What is a rooftop solar PPA?

A rooftop solar PPA is a long-term contract in which a solar developer installs and owns a plant on your roof, and you buy the power it produces at an agreed per-unit tariff.

This is the heart of the OPEX model, also called RESCO (Renewable Energy Service Company). The developer funds, builds, owns and maintains the plant. You pay only for the units (kWh) you use, usually at a rate below your grid tariff. The alternative is CAPEX, where you buy the plant outright.

In India, most rooftop capacity is still bought on CAPEX. Mercom India reports that the CAPEX model accounted for 84% of rooftop additions in Q2 2026, though much of that market is residential (Mercom India). For C&I (commercial and industrial) buyers who want to keep capital for their core business, the PPA is the main alternative.

How long does a solar PPA usually last?

Typically 15 to 25 years. Law firm King Stubb & Kasiva notes that PPA terms "often" range from 15 to 25 years (KS&K).

That is longer than most leases, loans or vendor contracts your company signs. Treat it like a long-term infrastructure decision, not a purchase order.

Which clauses matter most in a rooftop solar PPA?

Twelve clauses decide most of the value and risk: tariff, tenure, minimum offtake, deemed generation, performance, O&M, roof, insurance, change in law, payment security, early exit and end-of-term transfer.

Here they are one by one.

1. Tariff: fixed, escalating or indexed?

The tariff can be "a fixed rate, an escalating rate, or a rate linked to specific indices" (KS&K). A fixed tariff gives certainty. An escalating one starts lower but rises each year. Ask the developer to show the tariff for every year of the contract, side by side with your expected grid tariff, so you can see your savings over the full term.

2. Tenure and lock-in

Check the total term and the lock-in period. During a lock-in, neither party can exit "without incurring penalties" (KS&K). Match the tenure to how long you expect to stay in that building. A 25-year PPA on a leased warehouse with 8 years left is a mismatch.

3. Minimum offtake (take-or-pay)

Many PPAs set a minimum quantity of power you must buy each year. The sale and purchase clause specifies "any minimum or maximum thresholds" (KS&K). Ask: what happens if your plant shuts for a month, runs one shift instead of two, or you cut load? Can surplus units be exported under net metering instead?

4. Deemed generation

Deemed generation means you pay for power the plant could have produced but did not, because of a reason on your side, such as a shutdown or roof work. It is a fair clause when the cause is truly yours. Make sure it is narrow: it should not apply to grid outages you do not control, or to the developer's own faults.

5. Performance guarantee

The plant should promise a minimum annual generation, with compensation if it falls short. Look at how it is measured. A high availability number can hide long outages in peak sunshine hours. Ask for a generation-based guarantee, adjusted for actual sunlight, and access to a live monitoring portal.

6. O&M (Operations and Maintenance)

Under OPEX, the developer should carry O&M for the full term. The contract should spell out cleaning frequency, response times for faults, spare parts, inverter replacement and who pays for each. Vague promises like "best efforts" are not enough.

7. Roof access, leaks and repairs

Your roof is the developer's site for many years. The PPA should cover safe access rules, who fixes leaks caused by the installation, and what happens if you need to repair or replace the roof. Ask who pays for removing and re-installing panels, and whether you owe deemed generation during that time.

8. Insurance

The plant should be insured against fire, storm, theft and damage, plus third-party liability. Confirm who holds the policy (usually the developer under OPEX), what it covers, and that your building and people are protected too.

9. Change in law

Rules change often. A change-in-law clause "typically includes provisions for adjusting tariffs or other terms" when laws change (KS&K). This is not theoretical. In Q3 2026 alone, Karnataka expanded net metering to 1 MW across consumer categories and Gujarat cut green energy banking charges to ₹1 per kWh (Mercom India). In October 2026, Bihar's electricity regulator published a draft proposing a 500 kWp cap on net metering and paying for year-end surplus at 50% of the feed-in tariff (SolarQuarter). Ask: if net metering or banking rules change, who bears the cost, and can the tariff move?

10. Payment terms and security

Check the billing cycle, due dates, late payment interest and any security the developer asks for, such as a deposit, bank guarantee or LC (Letter of Credit). These are normal, but the amount should be reasonable for your credit profile.

11. Early exit and buyout

Life happens: you may sell the business, move the plant or want to own the system. The PPA should state when you can buy out the plant and how the price is calculated, usually through a schedule of termination values by year. Ask for that table in the contract, not "to be agreed later". The termination compensation clause "outlines the compensation due to the affected party" (KS&K), so read it from both sides: what you owe if you exit, and what the developer owes if it defaults.

12. End of term: who owns the plant?

Some rooftop PPAs transfer the plant to you at the end of the term. Others require the developer to remove it. Confirm the plant's expected condition at handover, any testing, and that warranties and documents pass to you.

How do I compare two PPA offers fairly?

Compare total savings over the full contract, not just the year-one tariff.

Question	Why it matters
What is the tariff in year 1, 10 and 20?	A low starting rate with high escalation can cost more overall.
What generation is guaranteed?	A cheap tariff on low output saves less.
What is the minimum offtake?	Shows your exposure if operations slow down.
What is the buyout schedule?	Shows your flexibility if plans change.
Who handles approvals and net metering?	Delays at the discom (electricity distribution company) delay your savings.
How many plants does the developer run, and for how long?	You are signing up for a long relationship; track record counts.

What are common red flags in a rooftop solar PPA?

Watch out for blank schedules, one-sided penalties and vague performance promises.

Buyout values or tariff tables marked "to be finalised".
Deemed generation that applies even to grid outages.
No generation guarantee, or one with no compensation.
Penalties only on the buyer, nothing on the developer.
No clear owner for discom approvals and net metering paperwork.
No mention of roof leak responsibility.

Should I involve my legal and finance teams?

Yes. A PPA is a long-term financial commitment and deserves the same review as a loan or a lease.

Your finance team should model savings over the full term under a few grid tariff scenarios. Your legal team should review the exit, change-in-law and liability clauses. A good developer will welcome this, answer questions in writing and share a clear tariff and buyout schedule upfront.

FAQ

What is the difference between a PPA and RESCO?

RESCO is the business model where a developer owns and runs the plant. The PPA is the contract that sets the terms of that arrangement, including tariff, tenure and responsibilities.

Can I exit a rooftop solar PPA early?

Usually yes, by paying a termination or buyout amount set out in the contract. Make sure the PPA includes a clear year-wise schedule.

Who maintains the plant under a PPA?

Under the OPEX/RESCO model, the developer maintains the plant for the full term, including cleaning, repairs and monitoring.

What happens to the solar plant at the end of the PPA?

It depends on the contract. Some rooftop PPAs transfer ownership to the buyer at the end of the term; others require the developer to remove it.

Is a PPA better than buying the plant on CAPEX?

It depends on your priorities. CAPEX can give higher long-term savings if you have capital and want to manage the asset. A PPA gives savings with zero upfront cost and no maintenance burden.

About SustVest

SustVest (SolarGridX Ventures Pvt Ltd) is a CRISIL Top-10 rooftop solar developer in India, ranked #5 for 2026, running 80+ distributed solar plants (around 30 MW) across 13 states for factories, hospitals, hotels, tea estates and institutions. Under our OPEX/RESCO model, we fund, build, own and maintain your rooftop plant while you pay a lower per-unit tariff with zero upfront cost. Want a clear, plain-language PPA? Start at sustvest.com.