Alternative Energy Credits: real money, unreliable income
Pennsylvania's Alternative Energy Portfolio Standards Act lets the owner of a certified solar system earn one Alternative Energy Credit for every 1,000 kilowatt hours generated. Those credits can be sold to utilities and suppliers that need them for compliance, which makes them a second stream of value separate from the bill savings your array produces.
Participating is a process rather than an automatic consequence of switching the system on. You register the system and connect it to the PJM Generation Attribute Tracking System through the Pennsylvania AEPS portal, either directly or through an aggregator or broker. That is administrative work rather than difficult work, but it is work, and nobody does it for you by default.
The qualification that should govern how you use the number is that AEC prices are set by supply and demand on an open market and fluctuate. They are not a tariff and they are not guaranteed. A quote that builds a fixed annual AEC figure into a payback calculation is presenting a market price as though it were a fixed rate, which is a different kind of claim.
So ask any installer who mentions AECs three things: what price they assumed, where that price came from, and what the payback looks like with the AEC line removed entirely. Then contact an aggregator to confirm current rates before you register. If a project only works with an assumed AEC price, you are underwriting a market forecast rather than buying equipment.
Retail-rate crediting, and the annual reconciliation that sets your size
Pennsylvania's PUC sets net metering at the full retail rate, and excess generation is credited kilowatt hour for kilowatt hour against your usage each billing period. That is a strong arrangement compared with the supply-only crediting new customers face in Illinois.
The detail that decides system size is the annual step. Once a year the utility reconciles any remaining banked credit at the regulated Price to Compare rate rather than at full retail. Credits you consume during the year are worth full retail; credits still banked when reconciliation arrives are worth less.
The sizing rule follows directly: build to what you actually consume across a year, so your generation is absorbed by your own usage rather than accumulating into a balance converted at the lower rate. Ask your installer to model against twelve months of your own kilowatt hour totals rather than against roof area, and to state what they assume happens at reconciliation.
Ask PPL Electric Utilities when in the year that reconciliation falls. Whether the annual settlement lands before or after winter has drawn down your summer surplus changes what a given system size is worth.
A rowhome majority, and a lot of small buildings
Single-attached rowhome-style units are 36 percent of Allentown's 49,502 housing units, against 25.9 percent single-detached. On a rowhome the constraint is usable roof area rather than sunlight, so the useful question is how many panels fit well on a narrow plane, not what the roof could theoretically produce. Ask for a layout drawing rather than a capacity figure, because a quote in kilowatts alone tells you nothing about whether those panels fit.
There is a meaningful middle here too. Buildings of 2 units are 6.4 percent and 3 to 4 units another 8.5 percent, so roughly one unit in seven sits in a small multi-unit building. Those are the hardest case in practice: the roof belongs to an owner or association, but the building is usually too small to have management that has considered solar before, so you will likely be the first to raise it. Expect the conversation to turn on the owner's economics rather than yours.
Buildings of 20 or more units are 10.7 percent, where the roof belongs to the building owner and the route is a written proposal covering cost, ownership of the equipment, insurance and roof replacement.
On any attached property, fixings, penetrations and future roof access affect the neighbouring structure, and the covering is often replaced across a row rather than unit by unit. Establish what agreements exist and check the covering age before a design is drawn, since panels outlast most coverings and replacing one afterwards means removing and reinstalling the array.
Output, and the credit that no longer applies
Plan on roughly 1,262 kilowatt hours a year for every kilowatt installed on a well oriented, unshaded array. That is a screening figure derived from irradiance data rather than a measurement from Allentown roofs, so treat it as a ceiling, and on a rowhome expect usable area to bind before irradiance does.
The 30 percent federal residential tax credit under Section 25D applied through December 31, 2025 and is not available for a purchased home system placed in service after that date. A purchase in Allentown now cannot claim it, which lengthens payback and raises the effective cost of each kilowatt hour saved.
Several widely used sources have not been updated and still carry the old text, so a quote or a guide showing the credit is not necessarily dishonest, just out of date. The payback figure that follows from it is wrong either way. Ask for the arithmetic rebuilt from what still exists: retail-rate net metering credits, whatever the reconciliation leaves you, the electricity you stop buying, and an AEC line shown separately rather than folded in.
If you take a lease or a power purchase agreement instead of buying, the provider may claim the business version of the credit under Section 48E and reflect part of that value in the rate they offer. Ask them what they claim and what reaches you, and confirm with a tax advisor rather than with the sales material.