Solar installers design and install photovoltaic systems on homes and small commercial buildings, and many also add battery storage, EV charger circuits, and system repairs. Invoices usually cover equipment, labor, permitting, and interconnection work, often split into milestone payments because jobs run for weeks. Solo installers and small crews also bill for service calls, panel removal and reinstall for roof work, and monitoring or troubleshooting.
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Most residential solar is priced per watt of installed system capacity (price per watt DC), which bundles panels, inverters, racking, labor, and overhead into one number. Small installers often show this as a flat contract price with line items behind it, then bill in milestones: a deposit at signing, a payment when equipment is delivered or installation starts, and a final payment after installation or after the utility grants permission to operate. Add-ons such as batteries, main panel upgrades, trenching, roof reinforcement, and critters guards are priced separately as flat fees or per unit. Service work such as inverter swaps, panel cleaning, and troubleshooting is billed hourly or per visit, usually with a minimum trip charge, and parts are billed at cost plus markup. Permit and interconnection fees are either built into the price or passed through at cost, and the invoice should say which.
| Service | Priced | Typical range |
|---|---|---|
| Residential rooftop system, installed | per watt DC | $2.50-3.80 |
| Battery storage installation (labor and equipment, single unit) | flat fee | $9,000-16,000 |
| Main service panel upgrade | flat fee | $1,800-4,500 |
| Solar panel removal and reinstall for roof work | per panel | $150-300 |
| Service call / troubleshooting | per hour | $100-175 |
| Inverter replacement (labor only) | flat fee | $500-1,200 |
| Permit and interconnection handling | flat fee | $500-1,500 |
| Panel cleaning and system inspection | per visit | $150-400 |
Typical US ranges. Rates vary by region, experience, and job size.
| Description | Qty | Rate | Amount |
|---|---|---|---|
| Milestone 2 of 3: Equipment delivered and install started, 7.6 kW rooftop system (19 x 400 W panels, string inverter, rail racking) | 7600 watt DC | $1.20 | $9,120.00 |
| Main service panel upgrade, 100A to 200A | 1 flat fee | $2,400.00 | $2,400.00 |
| Permit and utility interconnection application handling | 1 flat fee | $850.00 | $850.00 |
| Roof penetration sealing upgrade (additional flashing on 2 rafter sections, change order #1) | 1 flat fee | $420.00 | $420.00 |
| Conduit trenching, 40 ft to detached garage meter location | 40 linear ft | $18.00 | $720.00 |
| Total | $13,510.00 | ||
Notes: Milestone 1 deposit of $6,000 received at signing. Milestone 3 is due upon utility Permission to Operate. Payment due within 7 days of invoice date. Change order #1 approved by homeowner on the install date. Late balances accrue 1.5% per month. Equipment warranties and workmanship warranty details are in the signed contract.
Ties the invoice to the contract and permit, and gives the customer a record for warranty claims and incentive paperwork.
Progress billing is common, and the customer needs to see what has been paid and what remains.
Many states require a contractor license number on contracts and invoices, and lenders and utilities often ask for it.
Documents that the work was permitted and inspected, and helps resolve delays on Permission to Operate.
Roof repairs, panel upgrades, and trenching surprises are the most common sources of billing disputes.
Makes clear what is a real fee versus your markup, and helps if the customer is claiming costs for incentives or financing.
Lender-funded jobs often release payment on milestones, and the invoice must match the lender's draw requirements.
Residential solar contracts commonly take a deposit of 10 to 30 percent at signing, with a further payment at equipment delivery or install start, and the balance at final inspection or Permission to Operate. Some states limit deposit size on home improvement contracts, so check your local rules. Net 7 to net 14 is typical for milestone invoices, and final payments are often due on completion. Customers pay by check, ACH, or card, and card fees on a five-figure invoice can be significant, so many installers pass them on or prefer ACH. If a customer is using a loan, expect payment from the lender after you submit completion documents, which can take several days. Late fees of 1 to 1.5 percent per month are common if stated in the contract.
Tie payments to signing, equipment delivery, install completion, and inspection sign-off. Avoid making your final payment depend only on utility Permission to Operate unless the contract says so, because utility delays can hold your cash for weeks.
Rafters that need sistering, a panel that cannot take the backfeed, or extra trenching all change the price. Get a signed or emailed approval, then show it as its own line on the invoice.
Customers compare quotes by price per watt. Listing system size and the effective rate makes your price easy to check and cuts down on questions.
Panels, inverters, and batteries are expensive to order. Collect the equipment milestone before you place the order, especially on custom or backordered items.
Include the inspection sign-off, as-built details, warranty documents, and monitoring setup instructions. A customer who has everything in hand is more likely to pay promptly.
Most installers quote a total price and show the price per watt, then list add-ons separately. Itemizing every component can invite line-by-line haggling, but you should itemize anything outside the base scope, such as panel upgrades, trenching, and batteries.
Match the invoice to the lender's milestone schedule and use the borrower's name and the loan reference if the lender requires it. Lenders often release funds after specific documents such as a signed completion certificate or permit sign-off, so confirm those requirements before you invoice.
It varies by state. Some states exempt residential solar equipment or installations, others tax materials, and some treat it differently for commercial customers. Check with your state revenue department or a tax professional, and show any tax or exemption on the invoice.
The customer claims any federal or state tax credit on their own return, and you generally cannot guarantee eligibility. It helps to provide an itemized invoice with system size, cost, and date placed in service so they have what their tax preparer needs.
This is why contracts should define the final payment trigger clearly. If the contract ties final payment to completed installation and passed inspection, you can invoice then. If it is tied to Permission to Operate, document your submissions and follow up with the utility on the customer's behalf.
Send a Solar Installer estimate for approval, then turn it into an invoice when the work is done.
Solar Installer estimate template