A power purchase agreement is a long-term contract in which one party generates electricity and another party agrees to buy it at a price set in advance. The terms usually run 10 to 25 years, with an annual escalator of 1 to 5 percent built into the rate.1Better Buildings & Better Plants Initiative. Power Purchase Agreement Both sides sign up for the same reason: wholesale electricity prices move unpredictably, and a fixed price lets each party plan around a known number instead of the spot market. Corporate buyers signed a record 29.5 gigawatts of these contracts in the United States in 2025, and they are now the dominant tool for financing large-scale renewable generation.
How a PPA Actually Works
Strip the deal to its mechanics and it is a swap of certainty. The developer promises to deliver electricity (or its financial equivalent) for a defined number of years. The buyer promises to pay a defined price for that electricity, usually quoted per megawatt-hour, with a small annual increase to account for inflation and maintenance.1Better Buildings & Better Plants Initiative. Power Purchase Agreement
That contract is also what gets the project built. A wind farm or solar array costs tens or hundreds of millions of dollars, and no bank writes that check without proof the project will generate revenue. The PPA is the proof. The buyer’s long-term payment commitment gives lenders a predictable cash flow they can underwrite, which transforms a physical asset into something closer to a bond. The creditworthiness of the buyer, the strike price, and the length of the term all feed directly into the financing terms. A Fortune 500 offtaker or a government agency on the buyer side lowers the perceived risk, and that pushes the project’s cost of capital down.
Before power can flow, the developer also needs a separate interconnection agreement with the local utility, and that is where most projects actually slow down.2US EPA. Customer Power Purchase Agreements The U.S. interconnection queue holds over 2.6 terawatts of generation and storage capacity, with an average wait of roughly five years from application to commercial operation. A signed PPA does not get a project onto the grid; the interconnection study and queue position do. Buyers should treat this as the single largest schedule risk in the deal and expect the contract to address what happens if the grid connection takes longer than planned.
Who Is on Each Side of the Deal
The seller is usually an independent power producer or project developer. They design the facility, pull permits, line up financing, build it, and maintain it for the life of the contract. They keep ownership of the equipment and carry the performance risk.2US EPA. Customer Power Purchase Agreements
The buyer, often called the offtaker, is whoever commits to purchase the electricity. Corporations, universities, municipal utilities, government agencies, and nonprofits all sign PPAs.
There is a third party that rarely sits at the negotiating table but shapes the contract anyway: the lender. Because the developer borrows heavily against the PPA, the lending institution typically requires a consent agreement with step-in rights. If the developer defaults on its loan, the lender can take over operations and keep the PPA running rather than let the asset go dark.3World Bank PPP Knowledge Lab. Users Guide For The Power Purchase Agreement Model For Electricity Generated From Renewable Energy Facilities For a buyer, this is protection: a developer bankruptcy does not necessarily mean the lights go out.
A grid operator (either a Regional Transmission Organization or an Independent System Operator) manages the physical flow of electricity across shared infrastructure.4Energy.gov. How it Works: The Role of a Balancing Authority It is not party to the financial terms, but the contract cannot function in the real world without its cooperation.
Physical vs. Virtual Power Purchase Agreements
The biggest structural choice in any PPA is whether electricity physically changes hands or whether the deal is purely financial. These two structures look similar on paper and behave very differently in practice.
Physical PPAs
In a physical PPA, the buyer takes legal title to the electricity at a defined point. The cleanest version is behind-the-meter: the developer installs the generation (typically solar) on the buyer’s property, and the power flows directly to the buyer without touching the public grid.2US EPA. Customer Power Purchase Agreements That setup avoids transmission and distribution charges, which is a real portion of the retail electricity bill.
Larger physical deals route the power through the shared grid. For that to work, both the generator and the buyer must sit in the same power market, and physical PPAs with non-utility buyers are generally only available in competitive (deregulated) electricity markets.5US EPA. Physical PPA Meters at both ends measure what was produced and what was consumed.
Virtual PPAs
A virtual PPA, sometimes called a financial or synthetic PPA, has no physical delivery between the parties. The generator sells its electricity into the local wholesale market at whatever that market is paying. The buyer keeps buying power from its own local utility as before. The two parties then settle the gap between a predetermined strike price and the actual market price in cash.
If the market price exceeds the strike price, the seller pays the buyer the difference. If the market price falls below the strike price, the buyer pays the seller. Over the life of the contract, the buyer’s net cost sits near the strike price regardless of what wholesale markets do, and the seller gets the price floor it needed to finance the project. Because no electrons travel between the two parties, a buyer in New York can support a wind farm in Texas.
Virtual PPAs come with a particular financial wrinkle. Most contracts settle at a regional hub price, but the generator actually earns the local nodal price at its specific interconnection point. When those two prices diverge, someone absorbs the gap, usually the developer, and projects in areas prone to that divergence tend to quote higher strike prices to compensate. Comparing bids on strike price alone misses this. Look at the historical spread between the project’s node and the settlement hub.
Accounting matters too. Because a virtual PPA functions as a contract for differences, it is generally classified as a derivative under U.S. accounting standards, which means the contract is marked to market on the buyer’s balance sheet. A deal that is saving real money on electricity costs can simultaneously produce paper losses in a quarter when market prices drop. Finance teams should model that volatility before signing. Virtual PPAs are also commonly reported as swaps under Dodd-Frank, and while corporate end-users can generally rely on an exemption from clearing and margin requirements, the reporting obligations stay. Bring in counsel familiar with commodity rules early.
The Contract Terms That Matter
Every PPA, physical or virtual, is built from the same core terms. Each one deserves real negotiation because the deal lasts a decade or more.
- Term. The number of years the contract runs, usually measured from the commercial operation date rather than the signing date. Standard range is 10 to 25 years.1Better Buildings & Better Plants Initiative. Power Purchase Agreement
- Contract price. A fixed rate per megawatt-hour, typically with a 1 to 5 percent annual escalator. Some deals index to inflation instead of a fixed escalator.1Better Buildings & Better Plants Initiative. Power Purchase Agreement
- Volume. The quantity of energy the seller commits to produce, measured in megawatt-hours. Some contracts set a minimum annual output and impose penalties for shortfalls.
- Commercial operation date. The deadline for the project to begin generating. Missing it can trigger financial penalties or give the buyer the right to walk away.6World Bank PPP Knowledge Lab. Sample 1 – Standardised Synthetic PPA
- Point of delivery. Where legal responsibility for the electricity shifts from seller to buyer. For behind-the-meter projects, this is the buyer’s meter. For grid-connected projects, a specific node on the transmission system.
Curtailment
Grid operators sometimes order a plant to cut or stop production when transmission is congested or supply exceeds demand. Those curtailment events reduce output, and someone absorbs the lost revenue. The PPA should specify who. Most contracts distinguish economic curtailment (ordered when prices went negative) from reliability curtailment (ordered to prevent equipment damage or outages) and treat them differently. This clause is a frequent source of disputes, so pin down the categories and their financial consequences in the contract rather than leaving them to interpretation.
Force Majeure and Change in Law
Force majeure excuses performance when events outside a party’s control make delivery impossible. Natural disasters, wars, and government shutdowns are the usual triggers. Vague language here creates litigation risk when something unexpected happens and the parties disagree about whether it qualifies, so this is not a boilerplate clause.
A change-in-law clause covers what happens when new legislation or regulation changes the economics of the project after signing. A new tax, an emissions rule, or a revision to interconnection standards can rewrite the deal. A well-drafted clause tries to restore the affected party to the position it would have occupied without the change, usually through a price adjustment or an extension of the commercial operation deadline.
Termination and End of Term
If either party defaults and fails to cure within a specified period, the other can terminate. When the buyer triggers early termination, the payment owed to the developer is typically calculated by a formula tied to the project’s outstanding debt and the remaining contract value.7U.S. Department of Commerce CLDP. Default and Termination That number usually drops over time as debt is repaid, which reduces buyer exposure in the later years of the term.
At natural expiration, the buyer generally has three options: extend at a renegotiated rate, buy the generating system outright, or have the developer remove the equipment.1Better Buildings & Better Plants Initiative. Power Purchase Agreement The purchase option is often attractive because a fully depreciated solar array keeps producing electricity long after the original contract ends.
Risks Each Side Carries
A PPA shifts risk between the parties. It does not remove it.
- Price risk. A fixed-price PPA protects the buyer when wholesale prices rise and hurts them when prices fall. A buyer locked in at 5 cents per kilowatt-hour watching the market drop to 3 cents is overpaying for the remaining term. Virtual PPAs make this visible every month, because the buyer actually cuts a check whenever the market price sits below the strike price.
- Performance risk. If the project underproduces, the buyer gets less electricity or less financial benefit than expected. Contracts commonly include an availability guarantee requiring a minimum uptime, backed by liquidated damages against the contract price when performance slips.8OSTI.GOV. A Best Practice for Developing Availability Guarantee Language in Photovoltaic O&M Agreements
- Credit risk. A 20-year contract is only as good as the party on the other side. A developer bankruptcy can threaten supply (step-in rights help). A buyer whose credit deteriorates can threaten the developer’s ability to refinance project debt.
- Interconnection risk. With a multi-year queue, a signed contract does not guarantee power on schedule. Milestone-based adjustments tied to interconnection progress should be in the contract.
- Regulatory risk. Tax law, grid rules, and state energy policy can all change mid-contract. Change-in-law and force majeure provisions help, but only if drafted with specificity.
Tax Credits and Why They Affect Your Price
Federal tax credits are the financial engine behind competitive PPA pricing. Starting in 2025, two technology-neutral credits replaced the legacy solar and wind credits for new projects: the Clean Electricity Investment Credit and the Clean Electricity Production Credit, both available to any generating facility with a net-zero greenhouse gas emissions rate. The Investment Credit starts at 6 percent of qualified investment and scales up to 30 percent when prevailing wage and registered apprenticeship requirements are met.9Internal Revenue Service. Clean Electricity Investment Credit The Production Credit works similarly, with a 0.3 cent per kilowatt-hour base rate rising to roughly 1.5 cents when labor requirements are met.10Internal Revenue Service. Clean Electricity Production Credit
The developer, not the buyer, typically claims these credits because the developer owns the project. The Inflation Reduction Act added two mechanisms that broaden access. Tax-exempt entities (state governments, municipalities, nonprofits) can use elective pay, also called direct pay, to receive the credit as a cash refund from the IRS even though they owe no federal income tax. For-profit developers who cannot fully use the credits can transfer them to an unrelated third-party buyer for cash, selling the tax benefit at a negotiated discount.11Internal Revenue Service. Elective Pay and Transferability Both require registration with the IRS before the tax return is filed.
For a buyer, the practical point is this: tax credits reduce the developer’s cost to build, and that savings is what makes a competitive PPA price possible. When comparing bids, ask how each developer structured its credit strategy. A project qualifying for the full 30 percent credit can offer meaningfully lower pricing than one stuck at the 6 percent base rate.
Renewable Energy Certificates and Clean Energy Claims
Every megawatt-hour of renewable electricity also produces a tradable certificate called a Renewable Energy Certificate. Whoever retires that certificate gets to claim the environmental attributes of that electricity. This distinction matters: buying renewable power through a PPA does not automatically let a company call its operations “green” unless it also owns and retires the associated certificates.
REC ownership is negotiated in the PPA itself.2US EPA. Customer Power Purchase Agreements A buyer chasing the lowest possible electricity price may let the developer keep and separately sell the RECs, with that revenue used to lower the contract rate. A buyer that needs renewable energy for sustainability reporting has to take the RECs and retire them. More than one corporate buyer has signed a PPA expecting to claim clean energy on its sustainability report, only to discover the developer kept the certificates.
In a physical PPA, the RECs usually travel with the electricity as a bundled product. In a virtual PPA, the electricity goes into the wholesale market while the RECs transfer separately in an unbundled arrangement.12US EPA. Unbundle Electricity and Renewable Energy Certificates Either approach supports valid environmental claims as long as the buyer ends up retiring the certificates.
A related concept worth knowing is additionality, which asks whether the PPA actually caused new renewable capacity to be built. Buying RECs from an existing wind farm that was already operational adds no new clean energy to the grid. Signing a PPA that lets a developer finance and build a new facility does. Investors and rating agencies increasingly scrutinize this distinction when evaluating a company’s clean energy claims.
Where Power Purchase Agreements Are Legal
Not every state allows a third-party developer to sell electricity directly to an end-user. At least 29 states plus Washington, D.C. and Puerto Rico explicitly authorize third-party PPAs for solar. A handful prohibit them. Roughly a dozen more sit in a gray zone where PPAs are restricted to certain customer types, limited by system size, or simply unaddressed by existing law. The map changes as states update their energy rules, so confirming current authorization in your jurisdiction is the first step before pursuing any deal.
In states where third-party physical PPAs are prohibited, buyers still have options. A virtual PPA sidesteps the issue because no electricity is sold directly between the parties; it is a financial contract. Solar leases are also structured differently enough to comply with local rules in some states that bar PPAs. The structure of the deal, not just its label, determines whether it is permitted.