Pennsylvania has an active credit market for geothermal heat pumps — but you won't find it by searching for "GRECs." The state calls them Tier II Alternative Energy Credits (AECs), and they work a bit differently from Maryland's program. As of 2026, Pennsylvania AECs trade around $26 per credit, with a $45 ACP price ceiling that the state has kept indefinitely.
The values are lower than Maryland's, but the program is real and active. This page covers how it works, what the numbers look like, and how to get started. For background on geothermal credits across all states, see our main geothermal credits guide.
Pennsylvania · 2026 market snapshot
PennsylvaniaGeothermal credits at a glance
Active market
AEPS Act 213 (signed 2004) · Tier II Alternative Energy Credits · Tracked via PJM GATS · Credits based on energy savings, not raw output
- ~$26 per credit (2026)
- $45 ACP price ceiling (indefinite)
- Savings-based measurement
- Same PJM GATS registry as Maryland
- Credit price
- ~$26
- Per AEC, 2026 market rate
- ACP ceiling
- $45/MWh
- Indefinite under AEPS Act
- Measurement
- Savings
- Energy displaced vs. conventional system
- Registry
- PJM GATS
- PA-Cert issued via PENN AEPS
Key dates
- 2004AEPS Act 213 signedCreated the Alternative Energy Portfolio Standard with Tier I and Tier II requirements
- ActiveTrading nowTier II AECs trading at ~$26 per credit through PJM GATS
- 2026$45 ACP holdsThe $45 compliance payment ceiling has remained stable — no step-down scheduled
- Ongoing10% Tier II requirementUtilities must cover 10% of retail sales with Tier II AECs indefinitely
All figures are snapshots. Credit prices are set by a market and move up and down. Every dollar figure on this page is approximate as of 2026, not a promise. Actual proceeds depend on broker fees and contract terms.
How Pennsylvania credits work
In Pennsylvania, geothermal credits are called Alternative Energy Credits (AECs) — the state’s version of what other states call GRECs. The program and the income work the same way: your geothermal system earns credits that sell on an open market.
Pennsylvania's program runs under the Alternative Energy Portfolio Standards (AEPS) Act, signed into law as Act 213 in 2004. The law requires electric suppliers to cover 10% of annual retail electric sales with Tier II AECs. Geothermal heat pumps (ground source heat pumps) are one of several qualifying technologies under Tier II.
Both Maryland and Pennsylvania base their credits on energy savings — the energy your heat pump displaces compared with a conventional system. The difference is in the details: Pennsylvania uses the PUC’s Technical Reference Manual to define deemed savings values by technology type, while Maryland uses the Climate Master Savings Calculator. One AEC equals 1,000 kilowatt-hours of energy savings.
What Pennsylvania credits are worth
As of 2026, Pennsylvania Tier II AECs trade around $26 per credit. That's lower than Maryland's ~$87 — partly because the $45 ACP ceiling is lower than Maryland's $90, and partly because Tier II encompasses a wider range of technologies (not just geothermal), which increases supply.
How many credits your system generates depends on its deemed savings under the PUC's Technical Reference Manual. The savings calculation considers what your heat pump displaces compared with a conventional system — the bigger the efficiency gap, the more credits.
One advantage: Pennsylvania's $45 ACP is indefinite. Unlike Maryland, where the ACP is stepping down from $90 to $65 over the next few years, Pennsylvania's ceiling has stayed put. That means less downward price pressure ahead — credit values aren't facing the same scheduled decline.
How to register and start earning
Pennsylvania credits are tracked through PJM GATS — the same registry Maryland uses. But PA adds its own certification step through the PENN AEPS program, which issues a PA-Cert for your system before it can generate credits.
- Register with a broker or aggregator.Most homeowners use a broker to handle the paperwork. Provide your installer's contact information and system details. Active brokers serving Pennsylvania include Flett Exchange and others listed on the PENN AEPS website. We don’t endorse any particular broker — compare fees, payment terms, and contract length before signing. Registration typically takes less than 10 minutes.
- Sign your Schedule A and customer affidavit.Your broker will email you the documentation needed to manage your facility in PJM GATS. This authorizes them to act on your behalf for credit generation and sales.
- System information is gathered.Your broker collects system specifications and an installer affidavit from your installer. This typically takes 1–3 days.
- PA certification and GATS setup.Your broker acquires your PA-Cert from the PENN AEPS program and sets up your facility in PJM GATS. This step typically takes 1–2 weeks.
- AEC payments begin.Once setup is complete, payments are typically issued quarterly. Credit pricing is available daily from brokers like Flett Exchange.
Savings-based measurement: what it means
Both Maryland and Pennsylvania measure credits based on energy savings — the difference between what your geothermal system uses and what a conventional system would have used. Maryland's PSC residential application requires output from the Climate Master Savings Calculator, and Pennsylvania's PUC Technical Reference Manual defines deemed savings values. The approach is the same; only the administrative details differ.
In practice, this means:
- Replacing an older, less efficient system earns more credits — bigger gap between old and new means more savings.
- The PUC's Technical Reference Manual sets the rules. It defines deemed savings values by technology type, so the credit calculation isn't based on your individual meter — it's based on standardized assumptions.
- One AEC = 1,000 kWh of energy savings. The number of AECs your system generates annually depends on its capacity and the applicable deemed savings factors.
How Pennsylvania compares with other states
Pennsylvania's credit market is active but lower-value than Maryland's. Here's the side-by-side:
| Maryland | Pennsylvania | Virginia | Illinois | |
|---|---|---|---|---|
| Status | Active | Active | Compliance ~2027 | Delivery 2028 |
| Credit price | ~$87 | ~$26 | ~$45 | Est. $35–50 |
| Price ceiling | $90 ACP (stepping down) | $45 ACP (indefinite) | $100 base deficiency (1%/yr increase) | N/A (contract-based) |
| Measurement | Savings-based | Savings-based | Defined by statute | Defined by statute |
| Registry | PJM GATS | PJM GATS | PJM GATS | IPA-administered |
| ACP trend | Declining ($90 → $65) | Stable ($45 indefinitely) | N/A | N/A |
The per-credit value is lower, but two things work in Pennsylvania's favor: the $45 ACP is stable (no step-down scheduled, unlike Maryland's declining ceiling), and the program has been running since 2004 with established infrastructure.
Frequently asked questions
Why are Pennsylvania credits called AECs instead of GRECs?
Pennsylvania's AEPS Act uses the term Alternative Energy Credits (AECs) for all qualifying technologies under Tier II — not just geothermal. Geothermal heat pumps are one of several qualifying technologies alongside air source heat pumps and other demand-side management systems. The credit is the same concept: your system earns credits, utilities buy them.
How much can I earn from Pennsylvania geothermal credits?
Credits trade around $26 each as of 2026. The number of credits your system generates depends on its deemed savings under the PUC Technical Reference Manual — this varies by system size and type. Your broker determines the credit count during registration. Annual income will be lower than Maryland's ~$3,567 but is still real income from a system you're already running.
15-year measure life. Under Pennsylvania's program, HVAC systems (including geothermal heat pumps) can claim savings for 15 years from the date of retrofit completion. After 15 years, the system stops generating new credits. Source: pennaeps.com.
What does "savings-based" mean?
Both Maryland and Pennsylvania base credits on energy savings. Pennsylvania's PUC Technical Reference Manual defines deemed savings values — the bigger the efficiency gap between your geothermal system and a conventional system, the more credits. You don't need to calculate it yourself.
Will the $45 ACP change?
As of 2026, no change is scheduled. The $45 alternative compliance payment has remained stable under the AEPS Act. Unlike Maryland's ACP, which is stepping down from $90 to $65, Pennsylvania's ceiling has stayed put. This provides more price stability for credit holders.
Can I earn credits if I already claimed the federal 25D tax credit?
Yes. The federal Residential Clean Energy Credit (25D) and Pennsylvania AECs are entirely separate programs. Claiming 25D never affects your eligibility for AECs. The 25D credit ended December 31, 2025, but AEC eligibility is ongoing.
Ready to start?
If you already own a geothermal system in Pennsylvania, your earning path starts with registering through a broker. The paperwork is straightforward and most brokers handle it for you. If you're still deciding on geothermal, use our planning tools below.
Plan your geothermal project
Estimate your loop size, projected costs, and available incentives — including potential credit income.
Sources and methodology
This guide uses official Pennsylvania state regulations, program documents, and verified broker information. All credit values and program parameters were verified against primary sources as of September 2026. Published amounts are reported as market figures — not guarantees. Homeowners should confirm current terms with the PA PUC or their broker before acting.
Check Your Pennsylvania Geothermal Credit Eligibility
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