A power purchase agreement is a long-term contract in which an electricity generator agrees to sell power to a buyer at a fixed price, usually for 10 to 25 years. The fixed price gives the developer enough revenue certainty to finance construction, and it shields the buyer from swings in the wholesale market. Power purchase agreements are the financial backbone of most large-scale renewable energy projects, because lenders will not fund construction without a guaranteed offtaker.
Who Signs a Power Purchase Agreement
Two parties sit at the center of every deal. The developer, or seller, designs, builds, and operates the generating facility. The developer secures permits, arranges construction, and carries the operational risk of keeping the project running for the full contract term. The offtaker, or buyer, commits to purchasing the electricity the facility produces. Offtakers are typically utilities, large corporations, or government agencies that want stable energy costs or need to meet sustainability commitments.
A third party shapes most renewable PPAs even though it never appears on the electricity bill: the tax equity investor. Renewable projects generate substantial federal tax credits, and many developers lack the tax liability to use them. Outside investors fund a large share of the project’s capital in exchange for those credits. Tax equity typically supplies one-third to two-thirds of total project financing. In a common partnership flip structure, the investor takes the vast majority of tax attributes and a smaller share of cash distributions, and the allocation reverses once the investor hits a target return. The investor holds a senior equity position ahead of the developer’s stake but stays passive in daily operations.
Wholesale electricity sales fall under the jurisdiction of the Federal Energy Regulatory Commission, which is charged with ensuring that rates for wholesale power remain just and reasonable.1Federal Energy Regulatory Commission. An Introductory Guide to Electricity Markets Regulated by the Federal Energy Regulatory Commission
Physical Power Purchase Agreements
In a physical PPA, the buyer takes legal title to the electricity at a designated point on the grid.2US EPA. Physical PPA Power flows from the project through the transmission system to the buyer’s metered facilities. The structure requires the buyer to sit within the same regional transmission organization or independent system operator territory as the project, because physical delivery across market regions introduces significant transmission complexity and cost.
The buyer handles how that power fits into its broader supply portfolio and pays for the transmission services needed to move it from the delivery point to its load. Physical PPAs suit utilities and large industrial users that already have the procurement expertise to handle scheduling, balancing, and grid logistics. For organizations without that in-house capability, the operational burden can be a dealbreaker.
Virtual Power Purchase Agreements
A virtual PPA (sometimes called a financial or synthetic PPA) is a contract for differences, and no electricity actually changes hands between the buyer and the developer.2US EPA. Physical PPA The parties agree on a fixed strike price, and the contract settles against the prevailing wholesale market price. When the market price exceeds the strike price, the developer pays the buyer the difference. When the market price falls below the strike, the buyer pays the developer. The developer still sells the actual electricity into the wholesale market on its own.
This lets a buyer in New York support a wind farm in Texas without figuring out how to move electricity across two grid regions. Virtual PPAs have driven much of the recent growth in corporate renewable procurement because they separate the environmental and financial benefits from the logistics of physical delivery.
Basis Risk
The most underappreciated risk in a virtual PPA is basis risk. Wholesale electricity prices vary by location. Each connection point on the grid (called a node) has its own price, and nodal prices are averaged into regional hub prices. Most virtual PPAs settle at the hub price, but the generator receives the local nodal price when it sells into the market. When the node and hub diverge, someone absorbs the gap. If the project’s node consistently trades below the hub, the developer takes a loss on every megawatt-hour even when the buyer’s settlement looks healthy. Developers price basis risk into the strike they quote, so projects in high-basis areas demand higher PPA prices.
Accounting Treatment
Corporate buyers should know that virtual PPAs are generally classified as derivatives under financial accounting standards. The contract sits on the balance sheet at fair value, and mark-to-market gains and losses flow through the buyer’s financial statements each reporting period. For publicly traded companies, that earnings volatility can be large enough to warrant board-level discussion before signing. Physical PPAs generally fall under lease accounting, which produces more predictable financial statement impacts.
Aggregated Power Purchase Agreements
Not every organization is large enough to sign a PPA on its own. Aggregated (or multi-buyer) PPAs pool several smaller buyers under a single contract with one project. The buyers share due diligence costs, combine their credit profiles to make the deal bankable, and each takes a proportional share of the output and environmental attributes.
These structures use either a single shared agreement where all buyers are co-parties, or multiple bilateral contracts tied to the same generating facility. Aggregated deals have opened renewable procurement to mid-sized companies, universities, and municipal governments that lack the scale to negotiate directly with a developer. The tradeoff is complexity: coordinating credit requirements, term lengths, and pricing across multiple buyers takes time and careful structuring.
Contract Term and Pricing
The contract term usually runs 10 to 25 years, matching the expected lifespan of the generating equipment and the developer’s debt repayment timeline. A longer term gives the developer a bankable revenue stream and guarantees the buyer a stable price through market cycles.
Most PPAs set a fixed price per megawatt-hour that stays constant regardless of what the wholesale market does at the time of generation. A buyer paying $45/MWh under a PPA still pays $45/MWh whether the spot market spikes to $120 or drops to $20. To account for inflation and rising maintenance costs over a multi-decade contract, many agreements include annual escalation clauses that raise the price by a negotiated percentage, often 1% to 3% per year. The escalation is locked in at signing, so neither side faces surprise adjustments.
Some contracts add price floors and ceilings to limit exposure at both extremes. A floor sets a minimum the developer will receive if wholesale prices collapse. A ceiling caps the maximum settlement price if the energy market tightens. These mechanisms matter most in virtual PPAs, where settlement swings directly with wholesale prices.
The agreement also specifies a delivery point on the grid where ownership of the electricity transfers from seller to buyer. Everything upstream of that point (generation risk, equipment failure, on-site losses) belongs to the developer. Everything downstream (transmission costs to reach the buyer’s facilities, line losses in transit) typically falls on the buyer. Where the handoff occurs has real financial consequences, so both sides negotiate the delivery point carefully.
Renewable Energy Credits and Marketing Claims
Every megawatt-hour of renewable electricity generates a separate, tradable instrument called a renewable energy certificate, or REC. RECs represent the environmental attributes of the generation, and they are legally distinct from the electricity itself.3US EPA. Renewable Energy Certificates (RECs) A PPA can bundle the RECs with the electricity so the buyer receives both, or the RECs can be unbundled and sold to a different party on the open market. Whoever owns the RECs is the party that can legally claim the renewable energy usage.
Specialized tracking systems assign each REC a unique serial number and record its creation, transfer, and retirement to prevent double counting. The Western Renewable Energy Generation Information System covers western states, and similar registries operate in other regions. Accurate tracking is essential for compliance with state renewable portfolio standards and for voluntary sustainability commitments.3US EPA. Renewable Energy Certificates (RECs)
Federal Trade Commission rules govern how companies may market their renewable energy use. Under the FTC’s Green Guides, a company that generates renewable electricity but sells all of its RECs cannot claim it uses renewable energy: the RECs carry the environmental attribute, and the claim leaves with them.4eCFR. Guides for the Use of Environmental Marketing Claims Any unqualified “made with renewable energy” claim requires that virtually all significant manufacturing processes be powered by renewable energy or matched by equivalent RECs. Companies with only partial renewable use must disclose the percentage. Sloppy REC documentation can expose a company to FTC enforcement for deceptive environmental marketing.
Performance Guarantees
PPAs allocate operational risk through detailed performance requirements. The developer typically guarantees a minimum share of expected generation, and the level varies by technology:
- Solar: around 85% of expected generation
- Wind: around 75% of expected generation
- Geothermal: around 90% of expected generation
Wind carries a lower guarantee because wind resources are inherently less predictable than solar irradiance or geothermal heat. When the developer falls short of guaranteed output, the contract imposes liquidated damages, a pre-calculated payment based on the shortfall volume multiplied by the cost of replacement power. If production drops below 50% of expected output in a single contract year, or below 65% in two consecutive years, the buyer may have grounds to declare default and terminate.
Curtailment
Grid operators sometimes order generators to reduce output when the transmission system is congested or supply exceeds demand. Curtailment means the project produces less than it could, and someone absorbs the lost revenue. In physical PPAs, the buyer typically loses both the energy and the RECs. Virtual PPAs can mitigate this through proxy generation provisions: instead of settling based on what the project actually produced, the contract settles on what it should have produced given actual weather conditions. Under proxy generation, a curtailment order does not affect the buyer’s settlement.
Force Majeure and Commercial Operation Date
Force majeure clauses excuse performance when events outside either party’s control (natural disasters, government actions, wars) make the contract impossible to fulfill. The threshold is high. Price increases and supply-chain cost overruns generally do not qualify. A court evaluating force majeure asks whether the event was genuinely unforeseeable and whether performance was impossible, not just more expensive.
Separately, the contract sets a required commercial operation date, or COD, by which the project must be fully operational and delivering power. Missing the COD triggers daily liquidated damages that compensate the buyer for the gap in generation planning. If the delay runs past a negotiated grace period, the buyer can terminate the PPA and recover damages, potentially including forfeiture of the developer’s construction security deposit.
Interconnection and Development Timing
Before a PPA project can deliver a single electron, the developer must secure a position in the grid interconnection queue and pass through a multi-stage study process. FERC Order 2023 overhauled that process to weed out speculative projects that were clogging queues nationwide.5Federal Register. Improvements to Generator Interconnection Procedures and Agreements The reforms require escalating financial commitments at each stage: a deposit to enter the queue, a commercial readiness deposit equal to 5% of assigned network upgrade costs after the cluster study, a deposit rising to 10% at the facilities study stage, and an additional 20% deposit at agreement execution. For a project assigned $10 million in network upgrade costs, the developer could have roughly $2 million tied up before construction begins.
Site control requirements run alongside the financial deposits. Developers must show 90% site control (ownership, lease, or development rights over the project land) at queue entry, and 100% by the facilities study stage.5Federal Register. Improvements to Generator Interconnection Procedures and Agreements Developers facing regulatory barriers, such as projects on public land awaiting agency approval, can post a cash deposit ranging from $500,000 to $2 million instead. The interconnection process alone can take years, which is why experienced PPA buyers build substantial timeline buffers into their procurement planning.
Federal Tax Credits and Transferability
Federal tax incentives are what keep PPA pricing competitive with fossil fuel alternatives. For facilities placed in service on or after January 1, 2025, two technology-neutral credits replaced the legacy investment tax credit and production tax credit:6US EPA. Summary of Inflation Reduction Act Provisions Related to Renewable Energy
- The Clean Electricity Investment Tax Credit under Section 48E, with a base of 6% of the qualified investment, rising to 30% for projects that meet prevailing wage and registered apprenticeship requirements. Additional bonuses of up to 10 percentage points each are available for domestic content and for siting in an energy community.7Internal Revenue Service. Clean Electricity Investment Credit
- The Clean Electricity Production Tax Credit under Section 45Y, a per-kilowatt-hour credit for electricity sold from qualifying zero-emission facilities, with a similar bonus structure. Both credits phase out as the country meets greenhouse gas reduction targets.
The Inflation Reduction Act also introduced a transferability mechanism that reshapes PPA financing. Developers who cannot use the credits themselves can sell them for cash to an unrelated buyer. The transfer must go through an IRS pre-filing registration process, and the sale must be for cash only, with no bartering or mixed consideration. Developers can split credits from one property among multiple buyers in the same tax year. One important wrinkle: if a transferred credit is later subject to recapture because the project is sold or taken out of service too early, the buyer of the credit, not the developer, bears the recapture liability.8Internal Revenue Service. Elective Pay and Transferability Frequently Asked Questions: Transferability
Early Termination and Buyout
Most PPAs let the buyer exit before the full term expires, but the timing and price are structured to protect the project’s financing. Buyout options usually do not become available until year seven of the contract or later, because tax equity investors need enough time for their credits and depreciation benefits to vest. An early buyout that disrupts those benefits would unravel the project’s financing.
When buyouts are available, the price is generally set at the fair market value of the system as assessed under IRS guidelines, so the buyer is purchasing the physical generating equipment rather than terminating a service contract. Depending on the project’s age, remaining useful life, and current energy market conditions, the buyout can range from modest for aging equipment to a substantial premium for a well-performing project in a high-price market. Some contracts also allow assignment, transferring the buyer’s obligations to a new offtaker, which can be a cheaper alternative to a full buyout if the developer consents.
Default-triggered termination works differently. If the developer misses performance guarantees, blows past the commercial operation date grace period, or breaches other material obligations, the buyer can terminate and pursue damages. The developer’s construction or operations security deposit, posted at signing, serves as a first source of recovery, and the buyer retains the right to seek additional damages beyond that amount.