Solar Installation Invoice Template Australia: Panels, Inverter, STC Rebates and GST

A solar installation invoice in Australia should include your business name, ABN, CEC accreditation number, invoice number, date, customer name and property address, system size (kW), panel brand and quantity, inverter brand and model, racking, labour, the STC rebate as a negative line item, and GST. The STC rebate deduction and GST must be shown correctly — many clients use solar finance and lenders require a specific invoice format.

This guide gives solar installers a practical invoice structure, then shows how SMASH for solar installers generates the full invoice from a voice description in under 60 seconds.

The basic solar installation invoice format

1. Your business name, ABN, CEC accreditation number, and electrical contractor licence.
2. Customer name, billing address, and installation address.
3. Invoice number, invoice date, and payment due date.
4. System description: "6.6kW grid-connected solar PV system — Dee Why property".
5. Panel line items: brand, model, wattage, quantity, and unit price.
6. Inverter line item: brand, model, and price.
7. Racking / mounting system.
8. Additional components: optimisers, monitoring system, isolators.
9. Labour: crew size and days.
10. STC rebate as a negative line item.
11. GST on the post-rebate total.
12. Payment terms and payment link.

Example solar installation invoice line items

For a 6.6kW residential system:

18× LG Neon 2 370W panels @ $295 each = $5,310.00.

SolarEdge SE5000H 5kW inverter = $1,890.00.

SolarEdge P370 optimisers × 18 = $720.00.

Racking — Clenergy roof mount, 18 panels.

DC isolator, AC isolator, AC protection.

Labour — residential install, 2 crew, 1 day = $900.00.

STC rebate — 32 STCs @ $38/STC = −$1,216.00.

Subtotal pre-GST: $8,504.00.

GST (10%): $850.40.

Total: $9,354.40.

How to show STC rebates correctly

The STC rebate is a point-of-sale discount. Show it as a negative line item after the equipment and labour totals:

Small-scale Technology Certificate (STC) rebate — 32 STCs @ $38/STC = −$1,216.00.

The number of STCs depends on system size, zone, and installation year. The current STC price fluctuates — use the actual assignment price in your invoice.

GST is calculated on the post-rebate amount, not the pre-rebate total. This is the correct ATO treatment.

Sub-contract solar invoicing

When invoicing a solar company for labour-only installation:

Sub-contract installation — 10kW system, 2 crew × 2 days @ $450/crew-day = $1,800.00.

Labour only — no equipment supplied.

Client: SolarPath Pty Ltd, ABN XX XXX XXX XXX.

No STC line needed for labour-only sub-contract invoices. Your client (the solar company) handles the rebate.

Battery storage invoicing

Tesla Powerwall 2, 13.5kWh — supply and install = $10,500.00.

Gateway and installation hardware.

Labour — battery install, 4 hours @ $130/hr = $520.00.

Battery storage is often invoiced separately from the solar system — it may have different finance arrangements or be added as an upgrade after the initial install.

Frequently asked questions:

How do I show STC rebates on a solar invoice? As a negative line item after equipment and labour totals. GST is calculated on the post-rebate subtotal.

What is my CEC accreditation number? Your Clean Energy Council accreditation number. It should appear on every solar installation invoice.

Can I invoice sub-contract labour for solar companies? Yes. Labour-only invoice with crew size, days, and rate. No STC line needed.

Is the invoice format suitable for solar finance? Yes. SMASH generates a fully itemised GST-compliant invoice that meets the requirements of solar finance lenders.