On-Site Solar PV: When the Math Works
A behind-the-meter solar decision hinges on your rate, your load, and how you own the system. This guide is the framework to run those numbers before you sign a vendor pro forma.
Who this is for
- ■Plant managers, facility managers, CFOs, and operations executives with a solar proposal on the desk
- ■Manufacturers, breweries, food processors, and warehouses paying meaningful demand charges
- ■K-12 districts, municipalities, and nonprofits evaluating direct pay or a PPA
- ■Operators spending five, six, or seven figures a month on electricity
- ■Anyone whose vendor pro forma uses a blended rate that ignores their tariff
Should we invest in on-site solar PV to cut operational costs and improve resilience for this specific facility?
On-site solar means the system is tied directly to your facility's electrical system, on the roof, in the parking lot, or on the ground. Production offsets your grid purchases in real time. When your panels produce more than you're consuming, excess flows to the grid. In states with net metering legislation, you receive a bill credit for that export. In states without it, or where net metering has been reduced, the economics are different, and that distinction matters enormously.
The C&I band, by size and timeline
| Segment | System size | Install timeline |
|---|---|---|
| Residential | 1 kW | 1 months |
| C&I | 30 kW | 2 months |
| Utility-scale | 1 MW | 12 months |
C&I spans a wide band, from 30 kW on the small end to several megawatts on the large end. A small church or synagogue project runs around 50 kW. A large school runs 300 kW to 400 kW. Install timelines run 2 months to 6 months, versus 1 months to 2 months for residential and 12 months to 24 months for utility-scale.
30%of this guide, read. The rest of it is below.
- 02 The mechanism Rate compression: why the vendor number is often wrong
Here is the honest objection to run before anything else. Commercial energy rates per kilowatt-hour are typically lower than residential in most U.S. markets. Per EIA data, the average U.S. residential rate in February of that year was 13.3 ¢/kWh, while the commercial rate was 11.9 ¢/kWh. PV Magazine has put the C&I discount at 15% or more versus residential.
Residential vs commercial energy rateLower headline commercial rates compress the per-kilowatt-hour savings from solar, which pushes payback out. But that is only half the picture. Demand charges often make the effective all-in rate comparable or higher depending on your load factor. The savings margin a vendor models against a simple blended rate can be misleading. If a vendor's pro forma doesn't account for your specific tariff, your energy rate per kilowatt-hour, your demand rate per kilowatt, and your load factor, the payback number they're showing you is probably wrong.
This is where it gets interesting for manufacturers, breweries, food processors, and anyone paying significant demand charges. Demand charges are billed on your peak kilowatt draw, typically measured over a 15 minutes interval. Battery storage discharges during those peak windows, reducing the demand your meter registers, and the charge drops directly. That is peak shaving, and for operations where demand charges represent 30% to 50% of the total bill, it is often the single highest-value application of storage.
ApplicationPeak shaving
Discharge during your peak interval to lower the demand charge that lands on your bill.ApplicationEnergy arbitrage
Store power when rates are low, use or export when rates are high, capture the spread.ApplicationBackup power
Protect against downtime and equipment damage during grid outages.Policy pressureThe regulatory note you have to track
California restructured its net metering framework in 2,023, replacing retail-rate export credits with time-differentiated avoided-cost values that reduced midday export compensation by roughly 75%. That restructuring primarily affected residential customers, but the policy direction is what matters. Similar reviews are underway in other states. If your state goes the same direction, a solar-only system becomes materially less attractive, and solar-plus-storage becomes the more defensible configuration.
- 03 What it does to you Where storage restructures the math
This is where it gets interesting for manufacturers, breweries, food processors, and anyone paying significant demand charges. Demand charges are billed on your peak kilowatt draw, typically measured over a 15 minutes interval. Battery storage discharges during those peak windows, reducing the demand your meter registers, and the charge drops directly. That is peak shaving, and for operations where demand charges represent 30% to 50% of the total bill, it is often the single highest-value application of storage.
ApplicationPeak shaving
Discharge during your peak interval to lower the demand charge that lands on your bill.ApplicationEnergy arbitrage
Store power when rates are low, use or export when rates are high, capture the spread.ApplicationBackup power
Protect against downtime and equipment damage during grid outages.Policy pressureThe regulatory note you have to track
California restructured its net metering framework in 2,023, replacing retail-rate export credits with time-differentiated avoided-cost values that reduced midday export compensation by roughly 75%. That restructuring primarily affected residential customers, but the policy direction is what matters. Similar reviews are underway in other states. If your state goes the same direction, a solar-only system becomes materially less attractive, and solar-plus-storage becomes the more defensible configuration.
Path What you get What you carry Direct ownership (cash or loan) Full control, ITC and MACRS access, power essentially free after payoff Upfront capital, maintenance and monitoring responsibility PPA or lease No upfront capital, no maintenance burden, fixed or escalating rate Higher long-term cost than owning, no direct tax benefit ESPC Project financed against realized energy savings, ESCO designs and installs ESCO holds performance risk, you pay from the savings stream For K-12 districts, municipalities, and nonprofits carrying no tax liability, the Investment Tax Credit has historically been inaccessible directly. That has changed. The Inflation Reduction Act created elective pay, often called direct pay, under Section 6,417, which allows tax-exempt entities to receive the ITC as a cash payment from the IRS rather than a tax offset. Third-party PPA structures are still available as an alternative. The mechanics matter. Get them right before you sign.
If you lease your buildingOne more structural issue
If you lease your facility, you likely face the split incentive problem. The building owner makes the solar decision, but you pay the utility bill. That misalignment has held back more projects than financing ever has.
- 04 The trap Ownership structure and the split incentive
Path What you get What you carry Direct ownership (cash or loan) Full control, ITC and MACRS access, power essentially free after payoff Upfront capital, maintenance and monitoring responsibility PPA or lease No upfront capital, no maintenance burden, fixed or escalating rate Higher long-term cost than owning, no direct tax benefit ESPC Project financed against realized energy savings, ESCO designs and installs ESCO holds performance risk, you pay from the savings stream For K-12 districts, municipalities, and nonprofits carrying no tax liability, the Investment Tax Credit has historically been inaccessible directly. That has changed. The Inflation Reduction Act created elective pay, often called direct pay, under Section 6,417, which allows tax-exempt entities to receive the ITC as a cash payment from the IRS rather than a tax offset. Third-party PPA structures are still available as an alternative. The mechanics matter. Get them right before you sign.
If you lease your buildingOne more structural issue
If you lease your facility, you likely face the split incentive problem. The building owner makes the solar decision, but you pay the utility bill. That misalignment has held back more projects than financing ever has.
Solar can be an excellent long-term investment for the right operation. But right operation is doing a lot of work in that sentence, and the only way to know if you are it is to look at your own bills. Systems typically last 25 years or more, so the decision compounds either way, in your favor or against you.
- 1 Pull twelve months of interval data and the current tariff sheet. Not a summary bill, the interval data.
- 2 Compute your true all-in cost per kilowatt-hour, separating the energy rate and the demand rate.
- 3 Confirm your state's current net metering or net billing rules, and get the vendor to model both a hold and a reduction case.
- 4 Quantify demand charges as a share of your total bill. That number tells you whether storage belongs in the project.
- 5 Match the ownership structure to your capital position and tax situation. Direct pay if tax-exempt, direct ownership if you have appetite, PPA or ESPC if capital is the constraint.
- 6 Rerun the payback against your actual tariff before signing anything.
- 05 Your leverage The diligence that saves you from a bad pro forma
Solar can be an excellent long-term investment for the right operation. But right operation is doing a lot of work in that sentence, and the only way to know if you are it is to look at your own bills. Systems typically last 25 years or more, so the decision compounds either way, in your favor or against you.
- 1 Pull twelve months of interval data and the current tariff sheet. Not a summary bill, the interval data.
- 2 Compute your true all-in cost per kilowatt-hour, separating the energy rate and the demand rate.
- 3 Confirm your state's current net metering or net billing rules, and get the vendor to model both a hold and a reduction case.
- 4 Quantify demand charges as a share of your total bill. That number tells you whether storage belongs in the project.
- 5 Match the ownership structure to your capital position and tax situation. Direct pay if tax-exempt, direct ownership if you have appetite, PPA or ESPC if capital is the constraint.
- 6 Rerun the payback against your actual tariff before signing anything.
When on-site solar is worth acting on, and when it is not
✓ Move forward when- Your commercial electricity rates are relatively high and demand charges are meaningful
- Your state's net metering or net billing policy provides workable export compensation
- You own the building, or you have an owner aligned with your utility spend
- You have capital appetite for direct ownership, or you're tax-exempt and can use elective pay
- Your load profile lines up with daytime generation, or storage covers the gap
✗ Hold off when- Your all-in commercial rate is low and demand charges are a small share of the bill
- The vendor pro forma assumes retail-rate net metering and your state is reviewing that
- You lease the facility and the split incentive has not been resolved with the owner
- You're a tax-exempt entity and no one on the deal team can explain elective pay
- The pro forma uses a blended rate and no one has rerun it against your actual tariff
- Decision matrix
When on-site solar is worth acting on, and when it is not
✓ Move forward when- Your commercial electricity rates are relatively high and demand charges are meaningful
- Your state's net metering or net billing policy provides workable export compensation
- You own the building, or you have an owner aligned with your utility spend
- You have capital appetite for direct ownership, or you're tax-exempt and can use elective pay
- Your load profile lines up with daytime generation, or storage covers the gap
✗ Hold off when- Your all-in commercial rate is low and demand charges are a small share of the bill
- The vendor pro forma assumes retail-rate net metering and your state is reviewing that
- You lease the facility and the split incentive has not been resolved with the owner
- You're a tax-exempt entity and no one on the deal team can explain elective pay
- The pro forma uses a blended rate and no one has rerun it against your actual tariff
Questions for your morning huddle- What is our current all-in cost per kilowatt-hour, energy and demand components separately, and does the vendor model reflect it?
- What is our state's current net metering or net billing policy, and has the model been stress-tested against a reduction in export compensation?
- If we're pairing storage, what share of our bill is demand charges, and what does peak shaving actually save on our specific rate structure?
- If we're tax-exempt, are we using elective pay under Section 6417 to receive the ITC as a cash payment, or going through a third-party PPA, and does our advisor know the difference?
The one thing to rememberWhether a solar project pencils depends on your rate, your load, and your ownership structure. A vendor pro forma that uses a blended rate and assumes retail-rate net metering is not a decision document, it is a sales document.
Before you sign anything, pull twelve months of interval data, separate your energy rate from your demand rate, and have the pro forma rerun against your actual tariff and against a stress case where export compensation is reduced.
Know if the numbers actually pencil out before you sign anything.
A written second opinion on the project in front of you, whether that is a rate change, new equipment, or a renewable installation.
- 01A short call, to figure out quickly whether we can actually be helpful. If we can't, we'll say so on the spot.
- 02We pull the data, your bills, your rate structure, vendor proposals, project specs.
- 03You get the verdict in writing: whether the payback will materialize, and the opportunities or risks nobody has raised.
Get a Blueprint at blueprint.tac-nrg.com Free for Indiana-based operations spending five figures or more a month on electricity. No obligation. You keep the write-up either way. - The one thing to remember
Whether a solar project pencils depends on your rate, your load, and your ownership structure. A vendor pro forma that uses a blended rate and assumes retail-rate net metering is not a decision document, it is a sales document.
Before you sign anything, pull twelve months of interval data, separate your energy rate from your demand rate, and have the pro forma rerun against your actual tariff and against a stress case where export compensation is reduced.
The Energy Decision BlueprintKnow if the numbers actually pencil out before you sign anything.
A written second opinion on the project in front of you, whether that is a rate change, new equipment, or a renewable installation.
- 01A short call, to figure out quickly whether we can actually be helpful. If we can't, we'll say so on the spot.
- 02We pull the data, your bills, your rate structure, vendor proposals, project specs.
- 03You get the verdict in writing: whether the payback will materialize, and the opportunities or risks nobody has raised.
Get a Blueprint at blueprint.tac-nrg.com Free for Indiana-based operations spending five figures or more a month on electricity. No obligation. You keep the write-up either way.does on-site solar make sense for my manufacturing plant
It depends on your specific rate, your load profile, and how you own the system. Commercial rates are typically lower than residential, around 15% or more below, which compresses savings per kilowatt-hour. But demand charges often run 30% to 50% of an industrial bill, and pairing storage for peak shaving can restructure the value significantly. Run the numbers against your actual tariff, not a blended rate.
how long is a commercial solar install
C&I installation timelines typically run 2 months to 6 months, versus 1 months to 2 months for residential and 12 months to 24 months for utility-scale projects. Permitting complexity and system size drive most of the variance.
what is behind-the-meter solar
Behind-the-meter means the solar system is wired directly to your facility's electrical system, on your side of the utility meter. Production offsets grid purchases in real time. When output exceeds your consumption at that moment, excess flows to the grid, and in states with net metering you get a bill credit for that export.
can a school or municipality get the solar tax credit
Yes. Historically the ITC was inaccessible to entities without tax liability, but the Inflation Reduction Act created elective pay under Section 6,417. Tax-exempt entities including K-12 districts, municipalities, and nonprofits can now receive the ITC as a direct cash payment from the IRS rather than a tax offset. A third-party PPA is still available as an alternative if direct pay does not fit.
how long is a commercial solar install
C&I installation timelines typically run 2 months to 6 months, versus 1 months to 2 months for residential and 12 months to 24 months for utility-scale projects. Permitting complexity and system size drive most of the variance.
what is behind-the-meter solar
Behind-the-meter means the solar system is wired directly to your facility's electrical system, on your side of the utility meter. Production offsets grid purchases in real time. When output exceeds your consumption at that moment, excess flows to the grid, and in states with net metering you get a bill credit for that export.
can a school or municipality get the solar tax credit
Yes. Historically the ITC was inaccessible to entities without tax liability, but the Inflation Reduction Act created elective pay under Section 6,417. Tax-exempt entities including K-12 districts, municipalities, and nonprofits can now receive the ITC as a direct cash payment from the IRS rather than a tax offset. A third-party PPA is still available as an alternative if direct pay does not fit.
how does NEM 3 affect commercial solar economics
California restructured its net metering framework in 2,023, cutting midday export compensation by roughly 75%. It primarily affected residential customers, but the policy direction matters. If other states move the same way, solar-only economics weaken and solar-plus-storage, where you self-consume rather than export, becomes the more defensible configuration.
how big is a typical commercial solar project
Commercial PV systems typically start around 30 kW and scale to several megawatts. Small church and synagogue projects run around 50 kW. Large schools run 300 kW to 400 kW. Manufacturing sites vary widely depending on roof area, ground availability, and load.
- Behind-the-meter
- A system wired on the customer side of the utility meter, so production offsets purchases before it touches the grid.
- Net metering
- A policy where exported solar energy earns a bill credit, often at or near retail rates, applied against future consumption.
- Net billing
- A policy where exported energy is compensated at a lower avoided-cost value rather than the full retail rate.
- Demand charge
- A utility charge based on the highest kilowatt draw during a billing period, typically measured over a fifteen-minute interval.
- Peak shaving
- Discharging a battery during the demand-billing interval to lower the peak kilowatt reading the meter records.
- Power Purchase Agreement
- A contract where a developer owns the system on your property and you buy the power it produces at a set rate over a set term.
- ESPC
- Energy Savings Performance Contract. An ESCO designs, installs, and finances the project, and the customer pays over time from realized energy savings.
- Elective pay
- An IRA Section 6417 mechanism that lets tax-exempt entities receive the Investment Tax Credit as a direct cash payment from the IRS.
- Split incentive
- The misalignment when the party paying the utility bill is not the party deciding whether to install the solar system.