Owner's Guide

Commercial Solar RFP Checklist: What to Require From Bidders

Ferrius Energy · 2026-09-24 · 14 min read · Last reviewed September 2026

A commercial solar RFP should make every bidder price the same system, on the same assumptions, under the same contract terms. If it does not, you are not comparing bids. You are comparing sales strategies.

The short answer

A good commercial solar RFP gives bidders the site data (12 months of interval data, roof and electrical drawings, utility account details) and requires back a fixed scope: a named equipment list, a stamped design basis, a production estimate with stated losses, a schedule to Permission to Operate with interconnection milestones, warranty documents, an O&M proposal priced separately, and an incentive and tax credit position the bidder will stand behind in writing. Then level the bids on cost per watt DC, cost per kWh of year-one production, and what is excluded.

Why most solar RFPs produce bids you cannot compare

The typical first-time RFP says something like "provide a proposal for a rooftop solar system of approximately 500 kW." Five bidders respond with five different module wattages, three inverter topologies, two racking approaches, production estimates built on different weather files and loss assumptions, and exclusion lists that range from one line to two pages. The lowest price is usually the one that excluded the most.

That outcome is not the bidders' fault. When the owner does not define the scope, each contractor defines it in the way that makes its number look best. The fix is to do some of the definition work up front: give bidders the same data, require the same deliverables in the same format, and tell them how you will evaluate. The RFP does not need to be long. It needs to be specific.

Two things raise the stakes in 2026. First, the federal credit timeline under Section 48E now depends on dates that a contractor's schedule either protects or destroys, so schedule commitments are worth real money. Second, utility interconnection in New England can take longer than construction, so a bid that treats interconnection as someone else's problem is incomplete. Both belong in the RFP.

The RFP checklist, section by section

Use the table below as the skeleton of the RFP. The left half is what you give bidders. The right half is what you require back. Copy it into your own document and delete what does not apply.

Commercial solar RFP checklist. Items marked "require" should be mandatory for a bid to be considered complete.
Section	Owner provides	Bidder must provide
1. Site data	12 months of utility bills and 15-minute interval data; rate schedule; roof drawings, roof age and membrane type; single-line diagram and main switchgear photos; structural drawings if available; site plan with setbacks and no-go areas; any hosting capacity or pre-application information already obtained	Require: confirmation of which data they relied on, a list of assumptions they made where data was missing, and a site visit record
2. Technical requirements	Target size range or objective (offset, export limit, budget); preferred or prohibited equipment; roof warranty requirements; code edition in force	Require: named module, inverter, and racking models with datasheets; DC and AC capacity; layout drawing; point of interconnection; production estimate with weather source and itemized losses; structural approach; rapid shutdown method
3. Commercial terms	Your contract form, or the key terms you require (payment milestones, retainage, liquidated damages, insurance limits, bonding)	Require: lump sum price with a schedule of values; itemized exclusions; allowances stated in dollars; markup on change orders; contract exceptions listed line by line
4. Schedule	Target mechanical completion and PTO dates; any operational constraints (occupied building, shutdown windows)	Require: schedule from notice to proceed through PTO, with interconnection application, utility study, ISA, permit, and witness test milestones named; long-lead equipment dates
5. Warranties	Minimum workmanship term you require	Require: copies of actual manufacturer warranty documents, not a summary; workmanship warranty term and scope; roof penetration warranty; any installer certification a manufacturer warranty depends on
6. O&M	Whether you want O&M priced, and for how long	Require: O&M scope priced separately per year, monitoring platform and data ownership, response times, inverter replacement approach, and whether any performance or availability guarantee is offered
7. Incentives	Ownership structure (cash, loan, lease, PPA); tax appetite	Require: the incentive and tax credit assumptions in the pricing, the 48E rate assumed and why, beginning-of-construction position, prevailing wage and apprenticeship plan if at or above 1 MW AC, state program eligibility, and who carries the risk if an assumption fails

Include a pricing form. The single most useful page in any RFP is a pricing form every bidder must fill in the same way: DC kW, AC kW, year-one kWh, lump sum price, and separate lines for interconnection allowance, utility upgrade allowance, roof work, O&M per year, and optional items. Proposals that do not fill it in are incomplete.

Site Data

What bidders cannot price without

Most change orders on commercial solar trace back to something the bidder did not know at bid time. These four items prevent the majority of them.

Interval data

Monthly totals hide the load profile. Fifteen-minute interval data shows whether the system will export at midday, whether demand charges will move, and whether storage is worth quoting. Ask your utility for it before you issue the RFP.

Roof condition

Roof age, membrane type, and the manufacturer warranty status decide whether bidders need to price a re-roof, a warranty inspection, or neither. Leaving it out invites either padding or a later surprise.

Electrical drawings

The main switchgear rating and bus configuration determine where and how the system connects. A service upgrade discovered after contract is one of the most expensive surprises in the business.

Utility information

In Massachusetts, projects of 250 kW or more must request a Pre-Application Report before applying. If you already have one, share it. It tells bidders what the circuit looks like before they design to it.

Technical requirements worth being strict about

You do not need to design the system for the bidders. You do need to fix the variables that make proposals incomparable or that you will have to live with for 25 years.

Named equipment, no "or equal" without approval. Require specific module, inverter, and racking models. An "or equal" clause lets a bidder substitute after award. Allow substitution only with your written approval.
A production estimate you can audit. Require the weather data source, the software, and every loss assumption (soiling, snow, shading, mismatch, wiring, inverter, availability, degradation). If one bidder's year-one kWh is well above the others on similar equipment, the losses table will usually show why.
DC to AC ratio stated. A high ratio can raise annual energy while clipping more at peak. Neither is wrong, but you need to see it to compare.
Structural basis. Require the bidder to state whether a structural analysis of the existing roof is included in the price and who will stamp it.
Code compliance. Massachusetts enforces the 2023 National Electrical Code. Require the rapid shutdown method and equipment to be named.
Monitoring and data ownership. Require the monitoring platform to be named, the owner to hold administrator access, and the data to remain the owner's if the O&M contract ends.

Commercial terms and schedule

A commercial solar contract is a construction contract with a utility process attached. The commercial terms should reflect both halves.

Price and changes

Ask for a lump sum with a schedule of values, not a single number. Require allowances to be stated in dollars and itemized. The two allowances that most often move are utility interconnection upgrades, which are set by the utility's study rather than the contractor, and roof work. Ask each bidder to state its change order markup in the bid. It is much easier to agree to it now than after a change arrives.

Payment and retainage

Tie payments to milestones you can verify: notice to proceed, equipment delivered to site, mechanical completion, and Permission to Operate. Hold retainage until PTO and delivery of the as-built package, commissioning report, and warranty documents.

Schedule to PTO, not to mechanical completion

Many proposals show a construction schedule that ends at mechanical completion. That is not when the system starts producing value. Require the schedule to run through Permission to Operate and to name the utility milestones. Under the current Massachusetts interconnection tariff, the maximum utility time frames run from 45 business days for an Expedited project to 135 business days for a Standard project, before any group study or system modifications. A bidder that shows PTO eight weeks after contract for a 500 kW system is either assuming something it has not told you or has not looked.

Liquidated damages. If your tax credit depends on a placed-in-service date, consider schedule liquidated damages tied to the milestones the contractor controls (design, permitting submissions, procurement, construction), and a clear allocation of what happens when the utility is the cause of delay. Contractors will not accept damages for utility timelines they do not control, and they are right not to.

Warranties and O&M

Require copies of the actual manufacturer warranties for the specified equipment. Summary tables in proposals are often generous interpretations. Check whether the module or inverter warranty depends on an installer certification, and whether labor to replace a failed component is covered or only the part.

Ask for O&M to be priced separately and per year, with scope listed. NREL's Annual Technology Baseline uses a fixed O&M cost of about $21 per kW DC per year for commercial PV, covering items such as asset management, insurance, site security, cleaning, vegetation, and component failures. A bid far below that probably excludes several of those items; a bid far above it may include insurance or a performance guarantee. Either way, the scope list is what you compare. Inverters are the component most likely to need replacement during a 25 year life, so ask how the bidder handles it: an extended warranty, a reserve, or an exclusion. Our guide to commercial solar O&M cost covers what should be in that scope.

Incentives and the tax credit position

Incentive assumptions can move a proposal's economics more than the construction price does. Require each bidder to state its assumptions in writing, and to say which ones it is guaranteeing.

The 48E rate assumed. Under Section 48E the base credit is 6 percent, rising to 30 percent for net output under 1 MW AC or if prevailing wage and apprenticeship requirements are met. Require the bidder to state the AC size and, if the project is at or above 1 MW AC, its prevailing wage and apprenticeship compliance and recordkeeping plan.
The deadline position. Solar facilities that began construction on or before July 4, 2026 are not subject to the 2027 placed-in-service deadline (subject to continuity rules). Facilities beginning construction after July 4, 2026 must be placed in service by December 31, 2027. For a project being bid now, that is a hard date, and it runs through utility PTO.
Bonus adders. If a bid includes domestic content or energy community bonuses, require the supporting analysis. Treat adders without documentation as zero when leveling.
Depreciation. Commercial solar is 5-year MACRS property, and 100 percent bonus depreciation was made permanent in 2025. Whether you can use it depends on your tax position, not the contractor's.
State programs. In Massachusetts, require the bidder to state SMART 3.0 eligibility and the assumed incentive, and to confirm current program capacity with the program administrator.

For the current state of the federal credit, including the June 2026 court decision on beginning-of-construction guidance, see our Section 48E and SMART guide. Confirm your position with a tax adviser before relying on any bidder's assumptions.

How to level the bids

Leveling means adjusting each bid so it covers the same scope, then comparing. Build a spreadsheet with one column per bidder and work through these steps.

Normalize the scope. For each exclusion in one bid that is included in another, add an estimated cost. Common ones: structural analysis, roof work, utility upgrade allowance, trenching, main switchgear upgrades, permits and fees, witness testing, monitoring hardware, first-year O&M.
Compare three unit costs. Price per watt DC, price per watt AC, and price per kWh of year-one production. Per watt DC rewards oversized arrays. Per kWh rewards optimistic production estimates. You need all three.
Re-run production on common assumptions. If production estimates differ by more than a few percent on similar equipment, apply the same soiling, snow, and availability losses to every bid and see which differences remain.
Price the O&M over the term. A lower construction price with a more expensive O&M contract can cost more over 20 years.
Discount unsupported incentives. Remove any adder or state incentive the bidder has not documented.
Score schedule credibility. A schedule that names utility milestones and matches the tariff time frames is worth more than a faster one that does not.

For reference, LBNL's 2025 data update reported 2024 median installed prices of $3.2 per watt for small non-residential systems and $2.4 per watt for large non-residential systems nationally. These are medians across many markets and project types, so use them as a sanity check, not a target. Our commercial solar cost guide covers Massachusetts pricing in more detail.

Red flags in a solar proposal

"Tier 1 modules" with no model number. The model decides the warranty, the degradation rate, and the domestic content math.
No utility milestones in the schedule. The bidder has either not looked at interconnection or does not want you to.
Interconnection upgrades "by others" with no allowance. Someone pays for utility upgrades. If the bid does not say who, it is you.
A 30 percent credit on a project at or above 1 MW AC with no prevailing wage plan. Without compliance, the rate is 6 percent.
Production far above the other bids on similar equipment. Look for missing snow or soiling losses.
Long exclusion lists and short inclusion lists. Count the exclusions before you compare prices.
A workmanship warranty with no company behind it. Ask who stands behind the warranty if the entity that signed it is sold or dissolves. Our contractor vetting checklist covers how to check.
Resistance to your contract form. Exceptions are normal. A refusal to list them is not.

How we respond to an RFP

Ferrius Energy is an EPC. We engineer, procure, and build in house, so when we answer an RFP the design basis, the equipment list, and the schedule come from the people who will do the work. We fill in the owner's pricing form as issued, list our exclusions and contract exceptions line by line, and show the interconnection milestones in the schedule. If you are preparing an RFP and want a second read of the scope before it goes out, our commercial solar EPC team can review it.

Key takeaway. The RFP is where you decide whether you will be comparing systems or comparing sales pitches. Give every bidder the same data, require the same pricing form, make the schedule run to PTO, and make every incentive assumption a written commitment.

Published 2026-09-24 by Ferrius Energy LLC, a commercial solar EPC headquartered in Saugus, Massachusetts. This article is general information, not legal, tax, or engineering advice for a specific project. Incentive programs, tariffs, and federal tax rules change; confirm current requirements with your counsel, tax adviser, utility, and program administrators.

Sources

NSTAR Electric d/b/a Eversource Energy, Standards for Interconnection of Distributed Generation, M.D.P.U. No. 55G (effective August 20, 2026). eversource.com
NREL, Annual Technology Baseline 2024, Commercial PV. atb.nrel.gov
Lawrence Berkeley National Laboratory, US Distributed Solar and Storage 2025 Data Update. emp.lbl.gov
NREL, Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems, 3rd Edition. osti.gov
26 U.S.C. Section 48E, Clean Electricity Investment Credit. uscode.house.gov
26 U.S.C. Section 168, Accelerated Cost Recovery System. uscode.house.gov
IRS, Prevailing Wage and Apprenticeship Requirements. irs.gov
Massachusetts DOER, SMART 3.0 Program Details. mass.gov

Questions

Frequently asked questions

What should a commercial solar RFP include?

Seven sections: the site data you provide (interval data, roof and electrical drawings, utility details), technical requirements, commercial terms, a schedule through Permission to Operate, warranty requirements, a separately priced O&M scope, and the incentive and tax credit assumptions each bidder must state in writing. Add a single pricing form every bidder fills in the same way.

How many bidders should I invite to a solar RFP?

Three to five qualified bidders is a common range. Fewer gives you little price tension; more usually means less effort from each bidder and more leveling work for you. Prequalify on licensing, insurance, safety record, and comparable commercial projects before issuing the RFP.

How do I compare solar bids with different system sizes?

Normalize the scope first by adding an estimated cost for each exclusion, then compare price per watt DC, price per watt AC, and price per kWh of year-one production. Re-run production estimates on common loss assumptions if they differ by more than a few percent on similar equipment, and include O&M cost over the term.

Should the solar contractor be responsible for interconnection?

The contractor should prepare and manage the interconnection application and utility coordination, and its schedule should name the utility milestones. The cost of utility system modifications is set by the utility's study, so it is usually carried as an owner allowance rather than a fixed contractor price. The RFP should say which approach you expect.

What tax credit rate should a 2026 solar bid assume?

Under Section 48E the base rate is 6 percent and the 30 percent rate applies to net output under 1 MW AC or when prevailing wage and apprenticeship requirements are met. Projects beginning construction after July 4, 2026 must be placed in service by December 31, 2027. Require bidders to state the rate they assumed and why, and confirm with your tax adviser.

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