Check what each solar quote includes
A lower headline price can still leave you unsure what is included. Check design, assumptions, costs and warranty terms in each written proposal.
The Quote Normalisation Checklist
Comparing solar quotes is notoriously difficult. Installers often use different assumptions for energy generation, different quality tiers of equipment, and different warranty structures. To compare them fairly, you must normalise the data.
1. Verify the Generation Assumptions
Are they assuming perfect south-facing orientation? Ensure all quotes are using the same shading, pitch, and angle metrics—ideally the official MCS standard calculation framework. If one quote claims 20% higher generation than the others using the same panel wattage, check their math.
2. Hardware Tiering
Not all panels with the same power rating have the same specification. Compare the proposed model's dimensions, efficiency and written performance warranty, including exclusions and the route to a claim.
3. The Inverter Strategy
Ask which inverter is proposed, what it does, and how it may work with future storage. On shaded roofs, ask whether module-level electronics are appropriate and what they add to cost and maintenance.
4. Battery Sizing Logic
Ask how battery capacity and power rating were chosen for your usage and tariff, especially during low-generation months. Check whether backup power is included if that matters to you.