Solar panel installation, starting with your roof

What is solar panel installation?

A residential solar installation puts a grid-tied array on your roof and ties it into your electrical service through an inverter and a new AC disconnect. The physical work is usually one to three days; the permitting, utility interconnection approval and final inspection around it typically take considerably longer than the install itself. Two decisions made before any of that determine whether the project is worth doing: the remaining life of your roof, and whether you buy the system or sign a long-term contract for the power it makes.

Signs you need solar panel installation

• Your roof is newly replaced, or has well over a decade of life left - this is the ideal moment to go solar, and the reason people who wait end up paying twice
• You have a large, mostly unshaded south, west or east-facing roof plane with few vents, chimneys or dormers breaking it up
• Your electricity bill is consistently high and driven by usage you cannot easily reduce - a pool pump, a well, electric heat, an EV, a home office running all day
• You already have or are planning electric appliances, a heat pump or an EV, so your consumption is going up rather than down
• You plan to stay in the house long enough for a 20-to-25-year asset to make sense
• Your utility has been raising rates and you want to fix part of your energy cost rather than ride the increases
• You are already replacing the roof, so the mounting work and the roofing work can be sequenced together instead of fighting each other

Seeing something not on this list? Browse solar problems by symptom →

How solar panel installation actually works

1. 1

   Roof condition and remaining life - the first conversation, not the last

   A solar array is a 20-to-25-year commitment bolted to a roof covering that may not last that long. If your roof has fewer than roughly ten good years left, the honest sequence is roof first, panels second. Removing and re-setting an existing array so a roofer can work underneath is a real, separately quoted cost, and it is money you spend for nothing but access.

   Watch forA salesperson who declares your roof "fine for solar" from a satellite image or a walk around the outside. Get an independent opinion from a roofer who is not being paid by the solar sale. Also ask, in writing, who removes and re-installs the array if the roof needs work later, and at whose expense.

2. 2

   Shading, orientation and a real production estimate

   The site assessment measures how much sun each roof plane actually gets across the year, allowing for trees, neighbouring buildings, chimneys and the way the array will self-shade in winter. The output is an annual production estimate in kilowatt-hours, which is the number every financial claim in the proposal rests on.

   Watch forA production estimate with no shade measurement behind it, or one that quietly assumes trees will be removed. Ask which software produced it, what shading data went in, and whether the estimate is guaranteed. If a proposal promises savings, the production number under it should be contractually backed, not aspirational.

3. 3

   System design and sizing against your actual usage

   Sizing works backwards from twelve months of your own utility bills, not from your roof area. An array much larger than your consumption may produce power you export for far less than you pay to import it, depending entirely on what your utility does with exported energy.

   Watch forBeing sized to fill the roof rather than to match your bill. Ask directly what your utility currently pays for exported power and how long that arrangement is guaranteed for new systems - net-metering and buyback terms vary by state and by utility, and several have changed them. Get the answer from the utility, not only from the installer.

4. 4

   Ownership structure - cash, loan, lease or PPA

   Buying outright with cash or a loan means you own the equipment and you are the party who claims any tax credit you qualify for. A lease or a power purchase agreement means a third party owns the hardware on your roof; they take the incentives, and you pay them monthly for the system or for the power it produces, usually for twenty years or more.

   Watch forThe escalator clause. Many lease and PPA contracts raise your payment by a fixed percentage every year for the life of the agreement, on the assumption that utility rates will rise faster. If they do not, the deal inverts. Find the escalator, read what it does in year fifteen, and price the total contract, not the first monthly payment.

5. 5

   Permitting, interconnection and utility approval

   Your installer files a building and electrical permit with the local authority and an interconnection application with your utility. The utility reviews whether your service and the local circuit can accept the export, and issues permission to operate. The array cannot legally be switched on before that permission arrives.

   Watch forTimelines quoted as though permitting were instant. Ask who files, who pays the fees, what happens to your deposit if the utility rejects or delays the application, and whether the contract lets you walk away if approval takes beyond a stated date.

6. 6

   Mounting, flashing and roof penetrations

   Racking is lagged into the rafters and each penetration is flashed and sealed. This is roofing work performed by an electrical contractor, and it is where the long-term risk on your house lives - dozens of new holes in a weatherproof surface.

   Watch forSealant-only penetrations with no metal flashing worked into the shingle courses. Sealant is a maintenance item; flashing is a roof detail. Ask what flashing system is used, and confirm your roof warranty survives the installation - some manufacturer warranties are affected by third-party penetrations.

7. 7

   Electrical work, inverters and the interconnection point

   Panels are wired into strings or fitted with microinverters or optimisers, then connected through a new disconnect into your service panel. Older or fully loaded panels sometimes need a main-breaker change or a service upgrade to accept the backfeed.

   Watch forA panel upgrade appearing as a change order on install day. A competent installer opens your service panel during the site visit and tells you then. Also ask where the rapid-shutdown device is and whether the design uses string inverters, optimisers or microinverters, because that choice decides how future repairs and expansions work.

8. 8

   Inspection, permission to operate, and monitoring handover

   The local inspector signs off the electrical and structural work, the utility swaps or reprograms the meter if needed, and permission to operate is granted. You should be handed monitoring access, a wiring and layout diagram, the equipment serial numbers and every warranty document.

   Watch forBeing left without monitoring logins or without knowing what normal production looks like for your system in each season. Without a baseline you will not notice a failed string or a dead microinverter for months, and quiet underproduction is the most common way owners lose money on a working-looking array.

What does solar panel installation cost?

Residential solar is priced per watt, so the total tracks system size, roof complexity, equipment tier and any electrical upgrades. Incentives, financing structure and what your utility pays for exported power change the real number enormously - confirm the current federal and state position before you sign anything.

See the full solar panel installation cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →

Solar tools and calculators → Size a system against your own usage before you look at any proposal.