Solar & battery
Solar Proposal Calculator
Builds a proposal, where the assumptions shown decide whether the customer was told the truth.
Result
A planning estimate, not a quote. Access, the age of the equipment, what is found once it is opened up and local labour rates all move the real figure, sometimes a long way.
Get a Free Business AuditHow the calculation works
System size, production estimate, cost, any incentives, financing and projected savings, assembled into the figures a customer sees. Every one of those rests on assumptions, and a proposal that presents results without them is presenting a sales figure rather than an estimate.
What moves the number
- Production estimate and the derate assumed.
- Export credit terms under the actual tariff.
- Rate escalation assumed in the savings projection.
- Which incentives are claimed and their availability.
Where this one goes wrong
The assumptions that make a proposal optimistic are a high rate escalation, full retail credit for exports, a production estimate without realistic losses, and an incentive that may not be available to that customer. Each is individually defensible and together they produce a proposal the system cannot meet. State every assumption on the page and show a conservative case, because the customer who feels misled is the one who leaves the review that costs ten sales.
Before you quote
- State every assumption on the proposal itself.
- Use the customer's actual tariff for export credit.
- Verify incentive availability for that customer before claiming it.
Questions
About this calculator
What makes a solar proposal misleading?
A high rate escalation, full retail credit for exports, a production estimate without realistic losses, and an incentive that may not be available. Each is individually defensible and together they produce a proposal the system cannot meet.
Should assumptions be on the proposal?
Yes, on the page rather than in a footnote, along with a conservative case. The customer who later feels misled is the one who writes the review that costs ten sales, and stating the assumptions is cheaper than that.
Can an incentive be shown as a certainty?
Not responsibly. Federal availability has been amended by legislation and depends on the provision and the placed-in-service date, and a credit requires tax liability to use. Showing it as conditional, with the customer directed to their tax professional, is the honest presentation.
The formula
total = hours x people x rate + parts + call-out, then sales tax
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How to use this calculator
- Hours on site (h). Enter your own figure; the page starts at 32 h.
- People needed. Enter your own figure; the page starts at 1.
- Labour rate charged ($). Enter your own figure; the page starts at $105.
- Parts and materials ($). Enter your own figure; the page starts at $12,500.
- Call-out or diagnostic fee ($). Enter your own figure; the page starts at $95.
- Sales tax (%). Leave at zero if you are quoting before tax.
The result updates as you type, so you can try a figure, see what it does to estimated total, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Hours on site | 32 h |
| People needed | 1 |
| Labour rate charged | $105 |
| Parts and materials | $12,500 |
| Call-out or diagnostic fee | $95 |
| Sales tax | 0% |
What comes out
| Result | Value |
|---|---|
| Estimated total main result | $15,955 |
| Labour | $3,360 |
| Before tax | $15,955 |
| Sales tax | $0 |
About $15,955: $3,360 of labour, $12,500 of parts and a $95 call-out.
How sensitive the answer is
Holding everything else steady and changing only labour rate charged, this is what happens to estimated total. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Labour rate charged ($) | Estimated total |
|---|---|
| $53 | $14,291 |
| $79 | $15,123 |
| $105 example above | $15,955 |
| $158 | $17,651 |
| $210 | $19,315 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Hours on site (h)
- Measured in h, between 0 and 400, starting at 32 h.
- People needed
- A number, between 0 and 40, starting at 1.
- Labour rate charged ($)
- A money amount, starting at $105.
- Parts and materials ($)
- A money amount, starting at $12,500.
- Call-out or diagnostic fee ($)
- A money amount, starting at $95.
- Sales tax (%)
- Leave at zero if you are quoting before tax.
What the results tell you
| Result | What it is |
|---|---|
| Estimated total | The headline result. A money figure. |
| Labour | A money figure. |
| Before tax | A money figure. |
| Sales tax | A money figure. |
A design still needs a site visit
Output and sizing figures use the assumptions you enter, not measured irradiance, shading or roof orientation at your address. Real production depends on all three, plus inverter behaviour and local interconnection rules.
Estimating is the easy part
The jobs you never hear about cost more than the ones you mis-measure. BDEVY builds the marketing, systems and automation that bring them in.