How to Analyse a Renewable Energy (Solar/Wind) Stock

In FY26, Adani Green Energy earned an EBITDA margin of 91.2% (Inve data, Q4 FY26) — a number that looks like a software company, not a power plant. And yet the same year, the same company lost between ₹1,300 crore and ₹1,500 crore of EBITDA it should have earned, because it had built solar and wind capacity faster than the grid could carry the power away. As management put it on the Q4 FY26 call: "the mistake that we do not want to repeat going forward is to have capacities coming up and then evacuation not being sufficiently available" (Adani Green Q4 FY26 concall). (Illustration of how to read the numbers, not a view on the stock.)

That sentence is the whole sector in miniature. A renewable energy business has almost no fuel cost — the sun and wind are free — so once a plant is built and contracted, the economics look astonishing: 90%-plus margins, twenty-year cash flows, near-zero variable cost. But the entire risk sits before that point and at the edges of it: the borrowed money you sank into the asset, whether you can actually sell the power at a fixed price or are dumped into a volatile spot market, whether the grid can evacuate what you generate, and — for the equipment makers — whether the order book converts into deliveries on time.

This is how to analyse a renewable energy stock the way an infrastructure analyst does: the GW-denominated numbers that decide the outcome, where they hide (almost always in the investor deck and the concall, not the income statement), why a fat margin can still be a poor business, and the one distinction that changes every metric — whether you are looking at an asset owner (an IPP) or an asset-light equipment maker (a wind OEM or solar manufacturer).

A boundary first: this is the renewables-economics guide, distinct from the regulated/thermal world in how to analyse a power utility. A regulated utility earns a fixed return on equity set by a regulator; a renewable IPP lives or dies on contracted tariffs, capital cost, and execution. Different animal, different metrics.

What actually drives the economics of a renewable energy company?

Picture a toll bridge that costs a fortune to build with borrowed money, then collects a fixed toll for twenty-five years with almost no running cost. That is a contracted renewable plant. The whole game is: how cheaply did you build it, how cheaply did you fund it, and is the toll actually fixed — or does it float with a spot market you don't control?

Three consequences fall out of that picture, and they govern everything.

The cost of capital is the business. Because fuel is free and operating costs are tiny, a renewable plant's economics are almost entirely the spread between the tariff it earns and the interest it pays on the debt that built it. A 1% move in the cost of debt can swing project returns as much as a big move in tariff. This is why renewables behave like bond proxies — and why a rising-rate environment hurts them more than almost any other sector.

A contracted megawatt and a merchant megawatt are not the same asset. A plant selling under a long-term Power Purchase Agreement (PPA) has a fixed, bankable tariff for 20–25 years. The same plant selling into the merchant (spot) market earns whatever the grid pays that hour — which can be half the contracted rate. Adani Green's contracted new-solar tariff guidance was ₹2.60/unit (Inve data, Q4 FY26), but its merchant solar realisation in Q3 FY26 was just ₹2.20/unit, and its merchant wind realisation fell from ₹4.15/unit in Q3 FY25 to ₹3.50/unit in Q3 FY26 (Inve data). Same electrons, wildly different cash flow.

Commissioning is the bottleneck, not order-winning. It is easy to announce a 50 GW vision. It is hard to pour foundations, get modules, build transmission lines, and energise the plant before the grid is ready. The gap between signed capacity and operating capacity is where the value — and the disappointment — lives. Adani Green had 28 GW of capacity "already signed up" but only 19.3 GW actually operational at FY26-end (Adani Green Q4 FY26 concall).

Hold those three — cost of capital, contracted-vs-merchant, commissioning pace — and the metrics below stop being a list and become one story.

The metrics that matter — and where they hide

Here is the uncomfortable part for anyone used to reading a P&L: almost none of the numbers that decide a renewable investment are on the income statement. Order book in GW, operating vs under-construction capacity, PLF/CUF, the PPA-vs-merchant split, cost of debt, book-to-bill — these live in the investor presentation and get quoted on the call, denominated in gigawatts and rupees-per-unit. The income statement gives you revenue and EBITDA; it does not tell you whether the megawatts are contracted or merchant, built or still on a slide, and those distinctions are the entire investment.

Order book / pipeline (GW)

The signed-but-not-yet-built capacity — your future revenue, denominated in gigawatts. It matters because a renewable company's growth is visible years ahead: you can see the runway in the order book before it shows in earnings. Where to find it: the deck and the call, almost never the financials. Adani Green carried 28 GW signed against 19.3 GW operating (Adani Green Q4 FY26 concall) — roughly nine years of its current annual build rate already locked. Other listed pure-play IPPs whose pipelines you can line up the same way include NTPC Green, Acme Solar and JSW Energy. For the equipment side, Suzlon reported a 6.4 GW order book in Q3 FY26 (Inve data, Q3 FY26) and Inox Wind 3.2 GW (Inve data, Q3 FY26). What "good" looks like: a long, contracted order book with visible execution — not a vision-slide number with no PPAs behind it.

Commissioned vs under-construction capacity

The split between what is actually generating cash today and what is still a construction project. This is the single most-missed distinction by retail investors, who read "28 GW" and value all of it. Only the operating capacity earns; the under-construction portion is a cash outflow until it energises. Where to find it: the deck's capacity bridge. Adani Green's own breakdown of its operating book is instructive — of its operating capacity, "9.7 gigawatts of operating capacity is going 100% under PPAs", "5.3 gigawatts… as infirm" (interim merchant), and "4.2 gigawatts are pure merchant" (Adani Green Q4 FY26 concall). Read that and you realise even the operating fleet is only partly contracted.

PLF / CUF (plant load factor / capacity utilisation factor)

How much of a plant's nameplate capacity it actually generates over a year — the renewable equivalent of a factory's utilisation. A 1 GW solar plant doesn't make 1 GW around the clock; the sun sets. CUF tells you the real output. It matters because two plants of identical size can earn very different revenue depending on resource quality and uptime. Where to find it: the investor deck, almost never the results. Adani Green's Khavda complex ran a solar CUF around 27% and wind CUF of roughly 29–30% (Adani Green Q4 FY26 concall). The number to watch isn't the absolute CUF — it's set partly by geography — but whether availability stays high and CUF holds or improves as the fleet ages. A falling CUF on a maturing fleet is a quiet warning about module degradation or O&M.

PPA tariff vs merchant realisation

The contracted price versus the spot price — and the gap between them is your risk gauge. A plant 100% on long-term PPAs has bond-like, predictable cash flows; a plant heavily merchant is a price-taker exposed to grid economics. Where to find it: the call, in rupees per unit. The Adani Green spread above (₹2.60 contracted vs ₹2.20 merchant solar; merchant wind falling year-on-year) is the entire argument for why contracted cash flows deserve a premium and merchant exposure a discount. What "good" looks like: management committing the new book to PPAs — Adani Green guided "more than 90% of new capacities tied up in long-term PPAs" (Adani Green Q4 FY26 concall). The catch: a guidance that the next tranche will be contracted does nothing for the merchant megawatts already bleeding today.

Commissioning / execution pace

How fast signed capacity actually becomes operating capacity — measured in GW added per year. This is where ambition meets the grid. Where to find it: the call, as an annual run-rate. Adani Green added 5.1 GW in FY26 and guided 4.5 GW for FY27 (Inve data, Q4 FY26) — a deliberate slowdown, with management capping execution "at a number of about between 4.5 to 5 gigawatts, looking at the transmission and evacuation constraints" (Adani Green Q4 FY26 concall). That is a company learning the hard lesson that building ahead of the grid destroys value.

Debt and cost of capital

The survival-and-returns metric for any asset owner. Because the asset is built on borrowed money and earns a thin, fixed spread, the level and the rate of debt decide whether equity holders see a return at all. Where to find it: the balance sheet for the level, the call for the rate and refinancing plans. KPI Green Energy ran a debt-to-equity of about 1.5x in Q3 FY26 while committing it would "not cross 2:1" (Inve data and KPI Green Q3 FY26 concall). For the asset-light names the question flips entirely — Suzlon ran a net cash position of ₹1,556 crore at Dec 2025 (Inve data, Q3 FY26), because an OEM doesn't carry the plants on its own balance sheet.

For wind OEMs: order book and deliveries

An equipment maker is a different business — it doesn't own plants, it sells turbines. Here the metrics are order book, deliveries (MW shipped), and book-to-bill (orders won ÷ revenue billed). Where to find it: the deck. Suzlon delivered 1,625 MW in 9M FY26 with a book-to-bill of 1.9x (Inve data, Q3 FY26) — meaning it won nearly twice the orders it billed, a sign of a filling pipeline. Inox Wind guided FY26 execution of 1,200 MW+ and FY27 of 2,000 MW (Inox Wind concalls). The OEM risk isn't tariff or grid — it's conversion: turning a fat order book into shipped, paid-for turbines on a working-capital cycle that can stretch for months.

How do you value a renewable energy company?

This is where most retail investors go wrong, and the error is treating an IPP and an OEM with the same yardstick.

For an asset owner (IPP), P/E is close to useless. A renewable IPP loads up depreciation and interest on assets built with borrowed money, so reported net profit is small and erratic even when the plant is gushing cash. Adani Green trades at a P/E of 138 with a price-to-book of 12.7x and an ROE of just 11.4% (Screener.in, FY26) — numbers that look insane on an earnings or book basis. But the business runs a 91.2% EBITDA margin (Inve data, Q4 FY26): the cash is real, it's just buried under depreciation and finance cost that P/E can't see through.

So value an IPP on EV/EBITDA and a DCF of contracted cash flows. Enterprise value captures the debt that P/E ignores; EBITDA captures the cash before that debt's depreciation/interest distorts it. Better still, build a discounted-cash-flow model on the contracted PPA cash flows — twenty-five years of fixed tariff, discounted at the cost of capital — and value the merchant portion separately, at a discount, because it isn't bankable. The discipline: never value an under-construction megawatt the same as an operating, contracted one. One earns; one consumes cash and carries execution risk.

For a wind OEM, P/E against the order book works far better. An equipment maker has a normal cost structure and a normal margin — Suzlon ran a ~17–18% EBITDA margin (Inve data, TTM) — so earnings mean something. Suzlon's P/E of 24.9 with an ROE of 40.6% (Screener.in, FY26) describes a genuinely profitable, asset-light business. Here the question is whether the order book and book-to-bill justify the multiple — is the P/E being paid for visible, converting orders, or for hope? A 6.4 GW order book at 1.9x book-to-bill (Inve data, Q3 FY26) is real forward revenue; a P/E paid for an order book that won't convert on time is a trap.

The owner's frame for an IPP: don't ask "what's the P/E?" Ask "what is the contracted cash flow over the next twenty years, what does it cost to fund the assets that produce it, and what am I paying today for that discounted stream?"

A worked case: Adani Green and the grid that wasn't ready

The cleanest way to feel why commissioning ahead of the grid is the renewable-specific risk is to watch a company that did exactly that, then said so on the record. (Illustration, not a view on the stock; figures as reported by the company.)

The headline economics are spectacular. FY26 EBITDA of ₹10,865 crore at a 91.2% margin, operating capacity up to 19.3 GW, 28 GW signed, a 50 GW-by-2030 vision reiterated (Inve data and Adani Green Q4 FY26 concall). On paper, the toll bridge is collecting.

But read the same call for what didn't hold. Management quantified, plainly, the cost of building faster than the grid: "we've lost about INR 500 crores of EBITDA in the past year on account of curtailment… the loss would be in the range of somewhere between INR 800 crores to INR1,000 crores" on under-realised merchant power, "a total of somewhere between INR1,300 crores to INR1,500 crores of EBITDA in the past year" (Adani Green Q4 FY26 concall). Curtailment means the plant generated power the grid couldn't take. That is a renewable-specific failure mode with no equivalent in a thermal plant.

And the guidance record shows the strain. The FY27 capacity-addition target was revised down from 10 GW to a 4.5 GW range (Inve data); a commitment to commission 3.5 GWh of battery storage in FY26 was recorded as missed (Inve data); an earlier FY27 revenue guidance of ₹17,000–18,000 crore was simply never mentioned again — guidance that quietly went silent (Inve data). A net-debt range commitment of "4x to 5x" run-rate EBITDA also stopped being repeated (Inve data). None of this means management misled anyone — much of it is an honest, public reckoning with the evacuation lesson. But the texture matters: a glittering margin sitting on top of missed commissioning, dropped revenue guidance, and ₹1,300-crore-plus of curtailment loss is a very different read from the headline 91.2%.

You only see that pattern by tracking each commitment against the quarter it was made — which is the job of Promise Tracker, and the kind of thing no one reconstructs by re-reading four transcripts by hand.

Red flags specific to a renewable energy company

• Capacity built ahead of evacuation. A commissioned plant with no transmission line is a stranded asset earning nothing. Curtailment and "infirm" power are the tell — Adani Green's ₹1,300–1,500 crore FY26 loss (Adani Green Q4 FY26 concall) is what this looks like in rupees.
• A vision number with no PPAs behind it. "50 GW by 2030" is free to say. Ask how much is signed, how much is operating, and how much of the new book is contracted versus merchant.
• Heavy merchant exposure dressed up as growth. Merchant megawatts inflate capacity headlines but earn a volatile, often-halved tariff. The Adani Green merchant-wind drop from ₹4.15/unit in Q3 FY25 to ₹3.50/unit in Q3 FY26 (Inve data) shows how fast that cash can move.
• Rising cost of debt on a thin-spread asset. Because returns are mostly tariff-minus-interest, a refinancing at a higher rate can quietly erase project equity returns. Watch the cost of debt and the debt-to-equity trend, especially for IPPs scaling fast.
• For OEMs: an order book that won't convert. A 3 GW order book is worthless if working-capital days are blowing out and turbines aren't shipping. Inox Wind's net-working-capital target of 120 days was recorded as missed (Inve data) — conversion is the OEM's real risk, not order-winning.
• Valuing an IPP on P/E, or an OEM on EBITDA-margin alone. The two are different businesses; a single yardstick across both will mis-price at least one.

Frequently asked questions

A repeatable workflow

1. Decide what you're holding. Asset owner (IPP) or asset-light maker (OEM/manufacturer)? Every metric below changes with the answer.
2. Split the capacity. Operating-and-contracted vs operating-merchant vs under-construction. Only the first is a bankable cash flow.
3. Read the tariffs. PPA vs merchant realisation in ₹/unit — the gap is your risk gauge.
4. Check the build pace and the grid. GW added per year, and whether evacuation/transmission can carry it. Curtailment is the red flag.
5. Stress the cost of capital. Debt level and rate for an IPP; working capital and conversion for an OEM.
6. Value on the right yardstick. EV/EBITDA and contracted-cash-flow DCF for an IPP; P/E against a converting order book for an OEM.
7. Audit the guidance. Check capacity-addition, PPA-tie-up and order-book commitments against what actually happened next.

Inve's KPI Screener lines up order book, operating capacity, CUF, tariffs and margins across renewable companies — value, trend and a data-confidence flag per number — so the GW-hunt takes minutes, not an afternoon of PDF-mining. For the regulated/thermal cousin read in a completely different shape, see how to analyse a power utility; for another capital-heavy, cost-of-funds-driven business, how to analyse an NBFC.

Where this lens can be wrong. The strongest case against everything above is that the contracted-cash-flow framing assumes the contracts hold — and in renewables, they don't always. PPAs can be renegotiated or stranded when a counterparty distribution company (discom) refuses to honour a high old tariff; states have tried to claw back signed agreements; transmission delays can leave a "contracted" plant unable to deliver. So a DCF on a 25-year PPA can be precise and still wrong if the off-taker's credit or the grid fails. Equally, the cost-of-capital argument cuts both ways: India's renewable build-out is a multi-decade tailwind, and a low-cost, well-funded developer commissioning into a strengthening grid can compound for years — the merchant volatility and curtailment that look like flaws today may be transitional as transmission catches up. The honest claim is narrower than it looks: reading contracted-vs-merchant, CUF, build pace and cost of capital lowers your odds of overpaying for an under-contracted, over-levered, grid-constrained developer. It does not tell you whether the off-taker pays, when the grid catches up, or what interest rates do next.

The owner's question to sit with before buying any renewable stock: over the next twenty years — not this quarter's margin — how much of this company's capacity is genuinely contracted and connected, what does it cost to fund the assets behind that cash flow, and is management building at a pace the grid can actually carry? If the thesis leans on a 50 GW vision slide and a 91% margin while the commissioning slips and the merchant tariff halves, you have read the headline, not the business.

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