Solar panel installer
invoice template

Solar installers invoice homeowners, landlords and businesses for PV systems, inverters and battery storage, usually as a complete package. Below is a ready-made solar panel installer invoice template, with worked example lines, the VAT and payment rules that apply, and the mistakes that most often delay payment.

What goes on a solar panel installer invoice

List the system size and components (4.8kWp, 12 panels, hybrid inverter, 5kWh battery), scaffolding, the DNO notification and the MCS certificate number the customer needs for export payments.

Line by line: 4.8kWp solar PV system, supplied and installed, 1 job × £5,800.00 = £5,800.00; 5kWh battery storage, supplied and installed, 1 × £2,900.00 = £2,900.00; Scaffolding, 1 × £650.00 = £650.00. The subtotal is £9,350.00. The example assumes you are not VAT registered, so there is no VAT and the total due is £9,350.00. The figures are illustrative, not a price guide, so use your own rates.

The legal minimum is the same for every trade. GOV.UK says an invoice needs a unique number, your business name and address, the customer's name and address, a description of the work, the supply date and invoice date, the amount charged, VAT if you charge it, and the total due. This template lays each of those out for solar panel installers; for the detail, read what a UK invoice must include.

Give each invoice the next number in a single sequence and never reuse one. A cancelled invoice keeps its number and is cancelled with a credit note. If you want a format that stays tidy for years, try the invoice number generator.

How solar panel installers price their work

Systems are priced as packages by kWp and components, with scaffolding and optional extras such as bird mesh and optimisers.

Keep the pricing visible. Each line should show the quantity, the unit and the rate, so the customer can match it to the quote. To set rates that cover your costs and your tax, try the day rate calculator; for materials and stock you resell, the profit margin calculator shows the margin you really make.

Agree this before you start

Agree the system design and expected generation, roof suitability, scaffolding, DNO notification, the MCS certificate, warranties for panels, inverter and installation, and a deposit.

When to send a solar panel installer invoice

Deposit at order, balance on commissioning and handover of certificates.

An invoice sent on the day tends to be paid on time; one sent weeks later tends to be paid weeks later. Email it as a PDF and keep a copy. The invoice due date calculator shows exactly when payment falls due under your terms.

VAT on solar panel installer invoices

Installing solar panels and batteries in homes is zero-rated until 31 March 2027, reverting to 5% after that. Scaffolding supplied as part of the installation takes the same rate. Commercial installations are 20%.

Once registered, solar panel installers charge 20% on most work. Two reliefs come up often: the zero rate for installing qualifying energy-saving materials in residential homes, which runs until 31 March 2027, and the zero rate for work on a new dwelling. VAT Notice 708/6 lists which materials qualify, and anything outside the list is standard-rated.

Registration is compulsory once taxable turnover in the last 12 months passes £90,000, or when you expect to pass it within the next 30 days. Check your position with the VAT registration checker; until then, see invoicing without a VAT number.

CIS: when a contractor pays you

CIS covers the installation of systems in buildings, so it applies whenever a contractor pays you for that work. The deduction comes off the labour only, at 20% when you are registered, which is why the invoice shows materials separately. HMRC's CIS 340 guide is explicit that repairing, servicing or maintaining a system, or replacing parts of one, is not an installation and falls outside the scheme. Jobs for a householder are outside CIS entirely: a homeowner is never a contractor.

Customers need your MCS certificate to apply for Smart Export Guarantee payments from their energy supplier; issue it with the invoice.

The CIS calculator shows what you receive after the deduction, and CIS invoice requirements sets out the invoice layout contractors expect.

The domestic reverse charge

When both sides are VAT registered and the job is reportable under CIS, the customer, not you, usually pays the VAT to HMRC under the domestic reverse charge. Your invoice shows the VAT that would have been due and a note that the reverse charge applies, but leaves it out of the total. End users, such as homeowners and businesses improving their own premises, pay VAT in the normal way. Check each case with the reverse charge checker and copy the invoice wording.

Working for homeowners

When the customer is a household rather than a business, consumer law sets the ground rules. A job agreed in someone's home, or by phone or online, normally carries a 14-day cancellation right under the Consumer Contracts Regulations. Starting earlier is fine when the customer asks, but record that request in writing, and bill only for work done if they later cancel.

Deposits, stages and cancellations

Deposits of 25% or more at order are common.

Ask for a deposit when you have to buy equipment for a specific customer, and invoice the balance once the system is commissioned and handed over. Small repairs are simplest paid on the day, by card or bank transfer, with the invoice sent before you leave.

Payment terms for solar panel installers

Balance on commissioning.

Between businesses, the default when nothing is agreed is 30 days from receipt of the invoice or the work, whichever comes later, and agreed terms should not normally exceed 60 days. Late business payers owe statutory interest at 8% above Bank Rate plus fixed compensation per invoice; the late payment interest calculator does the sums. Private individuals are not covered by that Act, so agree your terms with them in writing before the work starts.

Getting paid faster

Put everything the customer needs to pay on the invoice: your bank name, account name, sort code and account number, and the reference to use, normally the invoice number. Give a due date, not just "on receipt". Then follow a routine: a reminder the day after the due date, another a week later, and a firmer letter after two weeks. Most late payment is disorganisation, not refusal, and a routine fixes it. Invoice payment terms compares the common options, and the due date calculator turns them into a date.

If a customer disputes the invoice

When a customer queries an invoice, reply quickly and in writing, quote the quote or agreement, and ask them to pay the part they accept while you resolve the rest. A credit note can settle a partial dispute cleanly. Unpaid after reminders? Send a letter before action with a final date; in England and Wales, claims up to £10,000 can then go to the small claims track. Invoice disputes and small claims for an unpaid invoice have the detail.

Common solar panel installer invoicing mistakes

• Charging 20% on a home installation. Installing solar panels in a home is zero-rated until 31 March 2027.
• No MCS certificate. Without it the customer cannot claim Smart Export Guarantee payments.
• A battery added later at the wrong rate. Batteries installed in homes have been zero-rated too since February 2024.
• Leaving out the due date. "Payment due within 14 days" or a date on the invoice gives you something to chase against. Without one, business customers default to 30 days.
• Losing track of what is unpaid. Chase on the day after the due date, not a month later; the guide to chasing an unpaid invoice has the wording.

Checklist before you send it

A quick check before sending saves a chase later:

• The invoice number is the next in your sequence and has never been used.
• The customer's name and address are right, with their purchase order or reference if they use one.
• Each line shows what was done, the quantity, the unit and the rate.
• The subtotal and total add up, and VAT appears only if you are VAT registered.
• The invoice date, a due date and your bank details are on it.
• A copy is saved with your records before you press send.

Keep a copy of every invoice

Your invoices are the evidence behind the income on your tax return, so keep a copy of every one. Making Tax Digital for Income Tax makes that digital: from 6 April 2026 for qualifying income over £50,000, from April 2027 over £30,000, and from April 2028 over £20,000, with quarterly updates to HMRC. Check your start date with the MTD requirement checker.

Download the solar panel installer invoice template

Download it as a Word document for Word or Google Docs, as an Excel workbook whose totals are live formulas, or as a print-ready PDF. Prefer to fill it in on screen? The free invoice generator opens pre-filled with the example solar panel installer lines, lets you choose a template and colour, and makes a finished PDF in a minute, with nothing stored.

For the tax side of the trade, from allowable expenses to Making Tax Digital, read the self-employed solar panel installer tax guide. A TapTax account, free to start, keeps your invoices and records together and files your quarterly updates to HMRC.