More than a third of homes share a roof or answer to an owner
Single-unit attached townhouse-style homes are 16.4 percent of Plymouth's housing stock, the highest share among the cities in this batch, and buildings of 20 or more units add another 20.2 percent. Together that is over a third of the city where a rooftop array is not a decision one household makes alone.
In a townhouse the roof structure is shared with the units beside you, so an association almost always governs what may be attached to it. Find the declaration or the association rules and read the section on exterior alterations and common elements before you commission a design. The order matters: an association can approve a system, but it is much harder to approve one that has already been designed against rules nobody read.
There is a physical dimension too. The usable roof area on your own section is often narrower than it appears from the street, and the ridge may not run the way a satellite image suggests. Ask an installer to look at the actual planes rather than quoting from imagery, and ask how they intend to handle fixings and penetrations near a party wall.
In a building of 20 or more units, the roof belongs to the building owner and the route is a written proposal covering cost, ownership of the equipment, insurance and roof replacement. That competes with other capital priorities, so expect a longer timeline than a residential quote implies.
For the 58.1 percent in detached houses, none of this applies and the decision is yours alone.
Confirm which utility serves you before accepting any credit figure
Our record does not name an electricity utility for Plymouth, so this page will not tell you who yours is. Minnesota has investor-owned utilities, municipal utilities and cooperatives, and they do not all treat customer generation the same way, so the answer changes what your exported power is worth.
Under Minnesota's net metering statute, a qualifying facility under 40 kW interconnected to a public utility may elect compensation at the average retail utility energy rate for net excess generation. That is the framework you will see quoted in general Minnesota guides, and 40 kW is far above a household system, so the size limit will not constrain you.
Whether that framework governs your service depends on which utility bills you. Read the name off your bill, then ask that utility in writing how net excess generation is compensated and at what rate, what the application process requires, what interconnection and metering cost, and whether any credit balance is reconciled or expires at a point in the year.
Then size the system against twelve months of your own kilowatt hour totals rather than against roof area. Ask your installer to model on your usage, and to state plainly what they have assumed about the export rate.
A good resource, and what erodes it
Plan on roughly 1,266 kilowatt hours a year for every kilowatt installed on a well oriented, unshaded array. That is a strong figure for Minnesota, and it is a screening number derived from irradiance data rather than a measurement from Plymouth roofs, so treat it as a ceiling.
Orientation erodes it first. A south-facing plane produces the most, east and west planes give up output, and a north plane rarely repays the hardware. On a townhouse the choice of plane may be made for you by which section of roof is yours, which is another reason to settle the ownership question before the design.
Shading erodes it most, because it removes production in the middle of the day when the array would otherwise be strongest. In an established suburb with mature trees this is not hypothetical, so ask for an assessment across the whole year rather than the afternoon of the site visit.
Check the covering age before anything is ordered. Panels outlast most roof coverings, so one within a few years of replacement should be replaced first rather than paying later to remove and reinstall the array. On a townhouse a later re-roof usually involves the association as well, which makes getting the order right worth more here than elsewhere.
The federal credit no longer applies to a purchase
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 Plymouth now cannot claim it.
The credit was large enough to carry a substantial share of a residential project, so its absence lengthens payback, raises the effective cost per kilowatt hour saved, and weakens the case for adding a battery. This is a change in the decision rather than a detail in it.
Much published material has not been updated, so a quote, guide or online calculator that still applies the credit may be out of date rather than dishonest, but the payback figure it produces is wrong. Ask any installer to show the same arithmetic with the credit removed.
Rebuild it from what remains: your own utility's compensation for net excess generation, the electricity you stop buying, and the installed cost including interconnection and metering charges. 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, which is a question for the provider and a tax advisor.