Solar panel installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What solar panel installation is

Solar panel installation mounts panels on a roof or a ground rack, wires them to an inverter, and connects the inverter to the home's electrical panel. The work also includes the permits and the utility connection that let the system run safely and legally. It is a large electrical and structural job, and it often involves an engineer's review of the roof and the panel.

Signs you need it

  • Your electric bills are high and you want to offset part of your usage with on-site generation
  • Your roof is in good shape and faces a direction that gets good sun for most of the day
  • You are planning a roof replacement and want the panels installed while the roof is open
  • You want backup power or battery storage with the system, and the home's wiring can support it
  • Your home has a service panel with room for a new breaker, or can be upgraded to take one
  • You are looking at a ground-mount system on land that has the space and the sun

What the pro does

  • Survey the roof or ground site, including the roof structure, the panel's capacity and the service entrance
  • Plan the array layout, the inverter location and the wire run, and prepare the permit and utility interconnection documents
  • Mount the racking and panels with flashing and attachment that matches the roof structure and the load
  • Install the inverter and the disconnects, and run the DC and AC wiring with the correct conductor sizes and protection
  • Connect the system to the home's panel through a dedicated breaker, and install the rapid-shutdown equipment and labeling where the rules call for them
  • Schedule the inspection and the utility interconnection, and commission the system with a documented test before it runs

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • System size and the number of panels, which set the racking, wiring and inverter needs
  • Roof type, pitch, age and the structural condition, including any reinforcement needed
  • Whether a panel upgrade or a sub-panel is required to take the system's breaker
  • Inverter type, such as string or microinverter, and whether battery storage is included
  • Distance from the array to the inverter and to the panel, which changes the wire size and run
  • Permit, engineering review, utility interconnection and inspection requirements

What a written quote should spell out

  • System size, panel model and inverter type, with the rated output
  • Roof attachment method and the structural review performed
  • Panel connection, breaker size and any panel upgrade needed
  • Permit, engineering and utility interconnection responsibility
  • Monitoring setup and the commissioning test documented at handoff

Questions to ask before you hire

  • Has the roof structure been checked, and who signed off on the attachment method?
  • Will my panel need an upgrade, and what does that change in the quote?
  • Who handles the utility interconnection application, and how long does it take?
  • How is the rapid-shutdown system set up, and where is the switch?
  • Which inverter type will you use, and how does it affect shading and monitoring?
  • What happens to the system if the roof needs repair in the future?

Red flags

  • Mounts panels without checking the roof structure or the attachment method
  • Connects the system to the panel without a load calculation or a breaker check
  • Says the utility will approve the system without an application
  • Skips the rapid-shutdown, labeling or grounding required for the system
  • Quotes a system without a site survey or a shade analysis

What you can do yourself

Researching panel types, planning roof shading, and cleaning panels from the ground with a soft brush and water are reasonable. Mounting racking, working on the roof edge, and connecting wire to the home's electrical panel are dangerous and need a licensed contractor. A solar system carries live DC voltage even when the grid is off, so do not work on the wiring yourself.

Licenses and permits

Solar installation is commonly done by licensed electrical contractors, often with a roofing or structural license for the mounting work, and a permit with inspection is often required. The utility also has rules for connection. Check with your state or local licensing agency, building department and utility for the requirements that apply.

Solar panel installation questions

Can the roof hold the panels?

It depends on the roof's structure, age and pitch. A site survey and an engineering review of the attachment method answer the question. A solar installer should not mount panels without that check.

Will my home need a panel upgrade for solar?

Sometimes. The panel must have room for the system's breaker and the load must be calculated. The installer checks this during the survey and shows the result before you sign.

Does solar work during a power outage?

A grid-tied system shuts down during an outage for safety, unless it is paired with a battery and a backup design. Ask the installer how the system will behave in an outage and what equipment that needs.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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