1
“Show me the generation forecast built on MY last 12 months of usage.”National averages flatter the sale. Your smart-meter data tells the truth.
2
“Who designs this system — an engineer, or you?”If the person sizing your system is paid on commission, that's not design, it's sales.
3
“What's the payback WITHOUT assuming I export at import prices?”The single most common trick in the industry. Watch their face.
4
“Size the battery to my overnight usage — show the calculation.”Oversized batteries are where quotes hide their fattest margin.
5
“Is the inverter matched to this array, or am I paying for expansion I haven't ordered?”“Future-proofing” is often just present-billing.
6
“What exactly does the workmanship warranty cover, and for how long?”Panel warranties are long. Workmanship warranties are where problems actually happen.
7
“Is scaffolding a fixed line or a provisional sum?”Provisional sums grow. Fixed lines don't.
8
“What happens to my export payments if I switch electricity supplier?”Some export tariffs quietly require you to stay put.
9
“What did you consider before this system — and why did insulation lose?”Fabric first. If they never considered it, they weren't designing for you.
10
“If I say no today, does the price change?”A real price survives a week's thought. A pressure price was never real.
And before any of it: run the 5:1 Rule for a fortnight — the cheapest kilowatt is the one you stop wasting.