What a proper commercial solar proposal looks like

What a rigorous commercial solar proposal should contain, why most commercial quotes fall short, and how to evaluate a proposal before committing - covering interval data analysis, load profiling, demand charge modelling and ROI assumptions.

Key findings

• Most commercial quotes are based on roof size. A proper proposal starts with 12 months of interval data and a detailed load profile.
• Demand charges can be 30 to 50% of a commercial bill. A proposal that only models consumption is incomplete.
• Savings projections without documented assumptions are meaningless - insist on the feed-in rate, self-consumption %, and degradation rate used.
• A 4 to 8 year payback is typical for well-designed commercial systems, depending on tariff, load profile and battery sizing. Shorter projections deserve scrutiny.
• Solar is depreciated rather than deducted in full. Most commercial systems cost more than the instant asset write-off threshold.

What a proper proposal must contain

1. Twelve months of interval data analysis

Your retailer provides 30-minute interval data for the past 12 months. This shows not just how much you use, but when. A designer who hasn't looked at it has not designed your system - they've estimated it.

2. A load profile and self-consumption analysis

Maps consumption against generation hour by hour across the year. For commercial sites, 60 to 80% self-consumption is achievable with correct sizing. Export-heavy designs signal a system sized for maximum generation, not maximum value.

3. Demand charge modelling

Demand charges bill on peak power draw in any 30-minute interval. Solar reduces consumption charges. A battery reduces demand charges. A proposal that ignores this is missing a significant part of the financial case.

4. Documented ROI assumptions

Feed-in tariff, electricity price escalation, panel degradation, and self-consumption % all affect the outcome. A credible proposal shows them explicitly.

5. Panel and inverter specs with warranty terms

Brand, model, rated output, warranty period - for both panels and inverters. Not generic descriptions.

6. Network connection and approvals plan

For systems above 100kW, network connection can take 8 to 12 weeks. The proposal should include a realistic timeline and confirm who handles approvals.