Getting three quotes is good advice. The problem is that they rarely list the same things, so you end up comparing a total number without knowing what’s inside it. Here’s how to make them comparable.
- An itemised quote with brand and model of each part.
- Panel wattage, quantity and string layout.
- Cable sizes, breaker types and SPDs listed separately.
- Structure material, height and warranty on workmanship.
Step 1: Ask for itemised quotes
A single line saying “10kW solar system, complete” isn’t a quote, it’s a guess. Ask each installer to list every major item with brand and model.
Step 2: Put them in a simple table
| Item | What to compare |
|---|---|
| Panels | Brand, model, wattage, quantity, PERC or N-type, warranty |
| Inverter | Brand, model, kW, hybrid or on-grid, MPPTs, warranty |
| Battery | Type, kWh, voltage, cycle rating, warranty |
| Structure | Steel or aluminium, galvanised or painted, height, raised or flush |
| DC cable | Size (4mm² / 6mm²), brand, length |
| Protection | DC breaker, AC breaker, SPDs, fuses |
| Earthing | Dedicated earth pit included or not |
| Labour and transport | Included or extra |
| Net billing paperwork | Included or extra |
| After-sales | Workmanship warranty, free visits, response time |
Step 3: Find the gaps
Usually the cheaper quote is lighter in one of these areas: thinner cables, no SPD, a basic painted steel structure, no earthing, fewer panels than the “kW” suggests, or a cheaper inverter model with similar branding.
Step 4: Check the panel maths
Multiply panel wattage by quantity. A “10kW system” with 16 panels of 580W is actually 9.28kW of panels. That may be fine, but it should be clear.
Step 5: Ask about after-sales
Who comes if the inverter shows a fault in two years? Do they charge a visit fee? Do they help with warranty claims? A slightly higher quote from someone who’ll actually answer the phone is often the better deal.
Red flags
- Pressure to pay full amount upfront before any equipment arrives
- No model numbers, just “Tier 1 panels” or “best inverter”
- Very quick quote without asking about your load or roof
- Promises of exact savings without seeing your bill
For current price ranges, see our solar system price guide. And before any quote, run your appliances through the load calculator so you know the size you actually need.
Got quotes you can’t compare?
Send them to us. We’ll help you line them up and point out what’s missing.