Solar words, in plain English

These are words you will see on solar quotes, contracts and your electric bill in Rhode Island. Each one gets a short, plain meaning. Tap a number to see where it comes from.

Battery

A home battery stores power from your panels so you can use it later. The REF grant adds $5,000$5,000Extra grant for adding a home batteryOnly with a solar project that also gets the grant. The battery money has its own pot and can run out on its own. Battery projects get 18 months to finish.RI Commerce, REF Energy Storage Adder Request for Projects (v6, rev. 4/6/2026)Project Funding, 'Small Scale Program' rowVerified Oct 28, 2026 for one, but only when the solar also gets the grant.

Customer charge

A fixed charge on your electric bill each month, even if you use no power. Solar credits don't cover it: under net metering, fixed monthly charges stayCredited at the supply and delivery parts of your rate. Fixed monthly charges stay.What your solar credit coversFixed monthly charges on your bill are not covered by credits.R.I. Gen. Laws § 39-26.4-2(22)§ 39-26.4-2(22)(i)-(iv), 'Renewable net-metering credit'Verified Sep 28, 2026.

DBR registration

Registration with the Rhode Island Department of Business Regulation. Anyone selling solar here must register with the state every year.Anyone selling solar here must register with the state every year.Must solar sellers register with the state?Sales reps also need a criminal background check.R.I. Gen. Laws § 5-93-4(a); RI DBR Solar Retailers page§ 5-93-4(a); DBR page quotes it and links Bulletin 25-01 ('Required Registration Must Be Completed By August 1, 2025')Verified Sep 28, 2026 Ask to see it before you sign.

Federal solar tax credit (25D)

The federal income tax credit for home solar, from section 25D of the tax code. It is gone for systems finished after Dec 31, 2025Gone for systems finished after Dec 31, 2025Federal solar tax credit for homeowners (section 25D)A system counts as finished when it is installed, not when you sign or pay.IRS, FAQs for modification of sections 25C, 25D ... under Public Law 119-21 (FS-2025-05, Aug 21, 2025)Termination table row 25D; Q&A citing § 25D(e)(8)(A)Verified Sep 28, 2026.

Interconnection

Getting RI Energy's OK to connect a solar system to the power grid. Ask your installer who handles it and how long it takes.

Inverter

The box that changes the power your panels make into the kind your home uses. Panels make direct current (DC), and your home runs on alternating current (AC).

kW (kilowatt)

A unit of power. Solar systems are sized in kW. The more kW, the more power the panels can make at once.

kWh (kilowatt-hour)

An amount of energy. Your bill charges you by the kWh. One kW of panels in Providence makes about 1,318 kWh1,318 kWh/kW/yrabout 1,318 kWh a year per kWPower one kW of panels makes in a year in ProvidenceModeled, not measured. East or west roofs and shade make less.National Laboratory of the Rockies (formerly NREL), PVWatts v8PVWatts v8 API: lat 41.824, lon -71.413, 1 kW, south-facing (180°), 25° tilt, 14% losses, NSRDB PSM V3 TMY weatherVerified Sep 28, 2026 a year on a south roof with no shade.

Last Resort Service

The power supply RI Energy sells to homes that have not picked another supplier. What you pay for it is the supply charge on your bill.

Lease

A solar company puts panels on your roof and keeps owning them. You pay the company a set amount each month to use them. For the REF grant, leases and PPAs don't qualifyYou must own the home and the system. Leases and PPAs don't qualify.Who can get the grantYou must also own the property, and it must be in Rhode Island.RI Commerce, Renewable Energy Fund, Small-Scale Request for Projects (rev. 4/6/26)Things to know, bullet 6Verified Oct 28, 2026.

Net metering

RI Energy credits your bill for the power your panels make. Power up to what your home uses is credited at the supply and delivery parts of your rateCredited at the supply and delivery parts of your rate. Fixed monthly charges stay.What your solar credit coversFixed monthly charges on your bill are not covered by credits.R.I. Gen. Laws § 39-26.4-2(22)§ 39-26.4-2(22)(i)-(iv), 'Renewable net-metering credit'Verified Sep 28, 2026, and extra power earns the wholesale priceWholesale price, much lower than your retail rateWhat power beyond your own use earnsThe law changed in 2025. The utility's own table still lists this rate as to be determined.R.I. Gen. Laws § 39-26.4-2(8)§ 39-26.4-2(8), second paragraphVerified Sep 28, 2026. Our net metering guide has the details.

Payback

The number of years until what solar saves you adds up to what you paid for it. The estimator works yours out from your own numbers.

PPA (power purchase agreement)

A company puts panels on your roof and owns them, and you pay it for each kWh they make. For the REF grant, leases and PPAs don't qualifyYou must own the home and the system. Leases and PPAs don't qualify.Who can get the grantYou must also own the property, and it must be in Rhode Island.RI Commerce, Renewable Energy Fund, Small-Scale Request for Projects (rev. 4/6/26)Things to know, bullet 6Verified Oct 28, 2026.

REF (Renewable Energy Fund)

Rhode Island's solar grant, run by RI Commerce. It pays once for home solar you own, and the money is paid to your installer and comes off your contract priceThe grant is paid to your installer and comes off your contract price.How the grant money movesAsk to see the grant amount and what you owe after it on your contract.RI Commerce, Renewable Energy Fund, Small-Scale Request for Projects (rev. 4/6/26)Project application requirements: an executed turnkey contract, contingent on REF funding, showing total cost, the REF grant amount and the net owedVerified Oct 28, 2026. Our grant guide shows how much.

REG (Renewable Energy Growth program)

An RI Energy program that pays a set rate for each kWh your panels make, for 15 years31.55¢31.55¢ per kWh for 15 yearsREG pay rate: systems up to 15 kW, 15-year termFor the program year April 2026 to March 2027. Your rate is locked in for the full term once you enroll.RI Energy, RE Growth Solicitation and Enrollment Process Rules for Small-Scale Solar (effective 4/1/2026)Schedule 2, 'Small-Scale Solar I (>0-15 kW DC)', page 12Verified Sep 28, 2026 or 20 years28.65¢28.65¢ per kWh for 20 yearsREG pay rate: systems 15 to 25 kW, 20-year termSystem size sets the term. You don't choose it.RI Energy, RE Growth Solicitation and Enrollment Process Rules for Small-Scale Solar (effective 4/1/2026)Schedule 2, 'Small-Scale Solar II (>15-25 kW DC)', page 12Verified Sep 28, 2026 based on system size, and it replaces net meteringREG replaces net metering. You get one or the other.Does REG work with net metering?A system already on net metering can't join REG. Ask in writing who receives REG's cash part; RI Energy's documents differ on it.RI Energy, RE Growth Program Tariff for Residential Customers, RIPUC No. 2151-M (effective 4/1/2026)Sheets 6-7, project segmentation paragraphVerified Sep 28, 2026. Our REG guide explains the rates.

Renewable Energy Professional

A limited Rhode Island license to install renewable energy systems, like solar, without an electrician's license. It covers only the kind of system the holder is certified for. The state Office of Energy Resources lists who holds one.

Supply and delivery charges

Supply is what you pay for the power itself. Delivery is what you pay RI Energy to carry it to your home over its wires. Solar credits under net metering cover the per-kWh part of bothCredited at the supply and delivery parts of your rate. Fixed monthly charges stay.What your solar credit coversFixed monthly charges on your bill are not covered by credits.R.I. Gen. Laws § 39-26.4-2(22)§ 39-26.4-2(22)(i)-(iv), 'Renewable net-metering credit'Verified Sep 28, 2026.

TSRF and shade report

TSRF stands for total solar resource fraction. It scores how much sun your roof gets over a year, counting shade and the way the roof faces. The shade report from your installer shows it, and the REF grant needs 80%80%80% TSRF or higher on the shade reportHow much sun the roof must getTSRF measures how much sun your roof gets through the year. Your installer's shade report shows it.RI Commerce, Renewable Energy Fund, Small-Scale Request for Projects (rev. 4/6/26)Eligibility checklist, question 2 (the shade report must show 80% TSRF or higher); also on the Small Scale Funding FlyerVerified Oct 28, 2026 or higher.

Turnkey contract

A contract where one company does the whole job and hands you a working system for one price. The REF grant needs a signed one that shows the full price, the grant, and what you owe after it. The grant is paid to your installer and comes off your contract price.The grant is paid to your installer and comes off your contract price.How the grant money movesAsk to see the grant amount and what you owe after it on your contract.RI Commerce, Renewable Energy Fund, Small-Scale Request for Projects (rev. 4/6/26)Project application requirements: an executed turnkey contract, contingent on REF funding, showing total cost, the REF grant amount and the net owedVerified Oct 28, 2026

Wholesale price

The price power sells for on New England's grid market, before it reaches homes. Under net metering, power you make beyond what your home uses earns the wholesale priceWholesale price, much lower than your retail rateWhat power beyond your own use earnsThe law changed in 2025. The utility's own table still lists this rate as to be determined.R.I. Gen. Laws § 39-26.4-2(8)§ 39-26.4-2(8), second paragraphVerified Sep 28, 2026, which is much lower than what you pay.