Will-Serve Letter vs. Capacity Study: What Actually Proves a Data Center Site Has Power

Most powered land is sold on a number. "150 MW available." "Substation on site." "Utility confirmed."

Then you ask for the paper. What comes back is often a will-serve letter, an email from a utility rep, or a queue position. Each of those means something. None of them means the same thing. Buyers who treat them as equal overpay for megawatts that never show up on time.

This is how we read the documents behind a power claim.

The short answer

A will-serve letter says the utility is willing to serve the site. A capacity or facilities study says what it will take to serve it, how much, and by when. A signed service agreement says the utility has committed. Only the last one is close to a promise. Everything before it is a step in the process.

Will-serve letter

A will-serve letter is a short letter from the utility. It usually says the utility is able and willing to provide service to the parcel, subject to conditions.

What it tells you:

• The utility knows about the site and the load request.
• Service is possible in principle.
• Who the utility thinks the customer is.

What it usually does not tell you:

• A firm megawatt number that is reserved for you.
• A firm energization date.
• What upgrades are needed and who pays for them.

Most will-serve letters are conditional and non-binding. Read the conditions. Phrases like "subject to the completion of required studies," "subject to system availability," or "subject to the execution of a service agreement" mean the real answer has not been given yet.

Also check who the letter is addressed to. A letter issued to a prior owner, a broker, or a different end user does not transfer automatically. If you buy the site, you may need the utility to reissue it in your name.

Load study and system impact study

When a large load asks for service, the utility runs engineering studies. Names vary by utility and region. You will see terms like load study, system impact study, or preliminary engineering study.

These studies answer one question: can the grid carry this load at this point, and what breaks if it does?

What it tells you:

• Whether the existing substation, lines and transformers can handle the load.
• What needs to be upgraded if they cannot.
• Rough cost and timing ranges.

A completed study is a strong signal. It means the utility has spent engineering time on this specific site and load. It is still not a commitment.

Capacity study and facilities study

A facilities study goes a level deeper. It defines the specific equipment, the scope of work, the cost estimate and the construction schedule needed to serve the load.

This is often the most useful document in a data room. It turns "power is available" into a list: this many MW, at this voltage, from this substation, after these upgrades, at this estimated cost, on this timeline.

When we see a facilities study, we check three things:

1. The MW figure. Is it the same number the seller is marketing? Often it is not. A site advertised at 100 MW may show 20 MW of near-term capacity and the rest after a multi-year upgrade.
2. The schedule. What gates the energization date? A new transformer with a long lead time, a transmission upgrade, or a permit can move the date by years.
3. The cost allocation. Who pays for the upgrades? Customer-funded upgrades change the land value.

Electric service agreement

The electric service agreement, sometimes called a facilities agreement or construction agreement, is where the utility commits. It usually comes with deposits or contributions toward construction, and it sets the load, the ramp schedule and the obligations on both sides.

This is the closest thing to proof. A site with a signed service agreement and funded deposits has power that is real, subject to the schedule in the agreement.

Queue position

A queue position means the request is in line. It does not mean capacity exists.

Queue positions matter because they set priority. A site with an early position in a congested area can be worth a lot. But a queue position alone says nothing about whether the study will come back clean, how long it will take, or what the upgrades will cost. Treat it as an option, not as power.

ISA and LGIA

Interconnection service agreements and large generator interconnection agreements govern generation connecting to the grid. They matter for data center sites when power comes from on-site or co-located generation, such as a gas plant or a solar and storage project next to the load.

If a seller cites an ISA or LGIA, confirm what it covers. It may give a generator the right to inject power into the grid. That is not the same as a right to serve your load. The structure of how that generation reaches the data center needs its own review.

How the claims usually compare

Red flags we see often

• The MW number in the marketing does not appear in any utility document.
• The letter is addressed to someone other than the seller.
• The document is old and the conditions have likely changed.
• "Substation on site" with no study showing headroom on that substation.
• An energization date with no study or agreement behind it.
• A generator interconnection presented as proof of load service.

Our standard

We tie every megawatt to a utility document and confirm it with a named contact at the utility. If the paper says 20 MW, we underwrite 20 MW, and price the rest as upside that has to be earned.

That discipline is what lets us commit to offtakers on a schedule they can trust. It is also why sellers with real documentation get a faster yes from us.

If you control a site and have the documents, submit it here. We review under NDA and respond with a clear yes or no.

This article is general information about utility processes, which vary by utility, region and market. It is not legal or engineering advice.