The starting number, and what it is good for
About 1,213 kWh a year for every kW of panels is the planning figure for Dearborn. It comes from satellite irradiance data with a standard performance ratio applied, not from measured local arrays, so it belongs in the decision about whether to get quotes and not in a contract.
The site survey narrows it. Orientation determines the shape of the generating day, pitch affects both yield and how fast snow slides off, usable area is what remains after vents, stacks, chimneys and setbacks, and shade determines how much of the theoretical output you actually collect. Winter shade is the one to press on, because a low sun reaches under branches that clear the roof easily in summer.
Ask for output modelled per roof plane with the shading assumptions stated. A single whole-house number cannot tell you whether the last panels in the design are productive or decorative.
The arithmetic of inflow and outflow
Michigan replaced traditional net metering with a Distributed Generation program, and DTE's version is Rider 18, open to systems up to 550 kW. Two prices apply to your house. Inflow, the power you draw from the grid, is billed at the retail rate of the schedule Rider 18 attaches to. Outflow, the power you export, is valued at the power supply component of that same retail rate, including Power Supply Cost Recovery.
The retail rate includes delivery and other charges that the supply component does not, so the two are not equal and the difference is not small. A kilowatt-hour you consume the moment you generate it is worth the full retail rate you did not pay. The identical kilowatt-hour exported earns the narrower credit instead.
The credit itself is applied well: it offsets all electric charges at the premise except securitization charges, and any excess carries forward in an Excess Generation Bank rather than expiring at the end of the month. But no amount of favourable crediting closes the gap between the two prices, and that gap is the thing to design around.
Whether a battery belongs in the design
Storage comes up more often in Michigan quotes than in states with full retail net metering, and the reason is structural rather than promotional. Storing daytime surplus for evening use offsets power at the retail rate you would otherwise pay, instead of earning the lower distributed generation export rate. That is the whole argument, and it is a real one.
It is not automatically a good deal. Whether a battery pays depends on how much surplus your array actually produces, how much of your consumption sits outside daylight hours, and what the storage costs. A household that is home during the day and uses most of its power then has less surplus to store and less to gain.
So ask for the tradeoff to be modelled rather than asserted. An installer quoting Michigan should be reviewing the current DTE tariff schedule for your address and modelling storage against export on your own usage as part of the quote. If storage appears in a proposal without that modelling behind it, ask to see the working before you price it in.
Dearborn roofs and who decides
Single-detached houses are 73.9 percent of the 39,394 housing units here, which puts most residents in the simplest position: one owner, one roof, one electrical service, no permission needed from anyone else.
Apartments in buildings of 20 or more units are 8.9 percent of the stock. There the roof belongs to the building owner, a resident cannot commission an installation, and an array normally offsets a building account rather than an individual apartment. Single-attached row houses are 5.6 percent, and those need the roof plane, the property line and the fire separation established on site rather than from an aerial image.
Two-unit buildings are 3.7 percent, and they raise the metering question directly: an array feeds one electrical service, so it reduces one household's bill. Where the two halves are separately owned, that has to be agreed before design rather than discovered at commissioning.
The 2026 cost picture
The 30 percent federal residential tax credit under Section 25D applied through December 31, 2025 and does not cover a purchased home system placed in service after that date. In practice that means a Dearborn homeowner buying in 2026 gets nothing from it, and any quote or calculator still applying it is describing a year that has closed.
The business version of the credit under Section 48E is separate and still exists, which matters only indirectly: a lease or power purchase agreement provider may claim it and reflect part of the value in the rate they charge you. Ask what they claim and what portion reaches you, and take that to a tax advisor rather than accepting it from sales material.
For a purchase, Michigan Saves is the state's nonprofit green bank, connecting homeowners with participating credit unions for qualifying improvements including solar, battery storage and EV chargers. Rates start at 5.99 percent APR with terms up to 180 months, an authorized contractor is required, and applications go through the Michigan Saves portal. Since storage is eligible alongside the array, it is worth pricing both together if the battery modelling supports it.