The term “merchant battery” (or merchant BESS)1 refers to a giant, grid-connected rechargeable battery that operates like an independent, market-driven “power trader.”
Unlike under a regulated utility contract, or a long-term power purchase agreement (PPA), a merchant battery operator doesn’t have an agreement in place with a utility or customer guaranteeing steady income.
Instead, the owner of the system uses the battery to buy electricity from the wholesale market when prices are low (often when solar or wind is flooding the grid), store it, and sell it later when prices are high (during peak demand).
A merchant battery can also be used to earn extra money by providing quick grid-stabilization services, such as frequency regulation or reserves.
How Are Merchant Batteries Developed and How Do They Make Money?
A merchant battery developer, like a real estate or solar project developer, seeks to capitalize on market opportunity.
They harness intellectual energy, investment capital (which may be a combination of public or private)2, state and federal financial incentives – if any – and market forces, such as the demand for grid stabilization and lower cost energy, to bring their project ideas to life.
A merchant battery developer identifies opportunistic geographic locations where a battery system can be installed to address grid instability which may exist due to weather or market forces.
The BESS system they build uses energy management software to buy and/or sell electricity according to an algorithm that may be proprietary or off-the-shelf.
The software buys electricity at low prices and sells at high prices. The goal is to make a profit while helping the grid handle the ups and downs of supply and demand and renewable energy.
The owner of the merchant system may hire a third party to manage the BESS or they may do it themselves.
Unlike a long-term, fixed contract to provide energy or energy services to an offtaker, a merchant battery model isn’t a very predictable source of revenue.
As such, merchant batteries carry more investment risk because wholesale energy prices can swing unpredictably.
However, such market-based systems offer greater potential profit and return on investment opportunities than projects locked into stable, lower-return contracts.
Hypothetical Investment: Merchant Battery Project
The following is a hypothetical example of a 100 MW/200 MWh merchant battery project in Texas.
- BESS Project Size: 100 MW power capacity with 2 hours of storage (200 MWh energy capacity/utility-scale battery).
- Project Investment: $45-70 million in capital expenditures (capex), or roughly $125 per kWh of storage capacity. This includes battery equipment, power conversion system (PCS), balance of system by EPC/contractor, and soft costs and grid interconnection.3
- Battery Useful Life: Approximately 15 years, with gradual performance degradation (typically 1–2% per year).
- Annual operating costs (maintenance, insurance, etc.): Approximately $1–2 million per year.4
- Location: Texas/ERCOT… But can really be any market with high renewable penetration and price volatility (e.g., parts of California, Europe, or India), where daily price spreads between cheap and expensive electricity are significant.5
Revenue Sources:
A merchant battery makes money mainly through energy arbitrage (buy low, sell high), as well as ancillary services6 and/or demand response programs.
The battery system charges mid-day when solar production in Texas is peaking… This peak energy production may push wholesale electricity prices down, say to $15/MWh, or pricing could even go negative in some situations. 7
The BESS then discharges later in the evening when prices are much higher, perhaps hitting $80–150+/MWh, because of the reduction in solar production and simultaneous spike in demand from people coming home after work, turning on the AC in their homes, etc.
Potential Investment Returns:
Texas has experienced an influx of BESS installations to take advantage of the opportunities there which has reduced the potential returns for merchant battery developers…
However, it’s still a great market if the details are right:
- Conservative: $25,000-$35,000/MW per year. Mild seasons without major grid emergencies and low natural gas prices. Could generate $2.5 million-$3.5 million annually.
- Middle/Average: $50,000-$70,000/MW per year. Typical hot summer with localized price spikes, predictable transmission congestion and winter cold snaps. Could generate annual gross revenue of $5-7 million.
- Aggressive: $80,000-$120,000/MW per year. If the market experiences extreme weather with regular grid emergencies the merchant battery of this size could generate annual gross revenue of $9-12 million.
If a market has growing renewable energy and frequent price spikes, the battery developer may be able to capture big profits during extreme weather events (e.g., heatwaves or calm wind days).
Falling battery costs make the math more attractive every year.
Summary
Merchant battery projects are high-risk, potentially high-reward plays that bet on the continued growth of renewable energy and the volatility of the energy markets.
In contrast to a contracted battery (with a fixed revenue deal), merchant BESS is not a “set it and forget it” investment like a traditional power plant with a long-term contract. And such systems require smart software, market expertise, and ongoing optimization.
A contracted battery with a PPA/offtaker is safer and easier to finance with cheap debt, but the returns are lower and there’s less upside.
Merchant developers are seeking hybrid models that include some contracted BESS revenue for stability while keeping merchant exposure for extra profit when not obligated to their offtaker.
Merchant projects vary widely by region, so you should always run detailed, site-specific financial models before committing any capital…
However, if it works, a merchant battery system could provide you with attractive returns while accelerating the clean energy transition.
Footnotes
- Battery energy storage system
- Unlike with fixed, predictable revenue streams from PPAs, lenders may decline to finance merchant battery systems because cash flows may fail to appear.
- Costs for turnkey BESS projects outside high-tariff regions have fallen to around this level.
- Insurance costs can vary due to siting and risk management practices. Reach out to Rob for best practices to reduce total cost of risk.
- Texas may be ideal for a 2 hour battery, whereas a market like California/CAISO may be better suited for a 4 hour battery (i.e. 400 MWh) because of the "Duck Curve" associated with its relatively predictable level of solar production.
- Services required to maintain the reliability and stability of the electrical grid, such as frequency control, balancing supply and demand, voltage regulation, etc.
- Wind power is also abundant in Texas and could cause similar, even more unpredictable peaks or valleys in energy production that creates opportunities for the merchant battery.
