Solar & battery
Solar Loan Payment Calculator
Works a solar loan payment, where dealer fees are inside the price.
Result
Low-rate solar loans usually carry a dealer fee added to the amount financed, often between 10% and 25% of the system price, which is how the advertised rate is funded. Compare the total financed amount rather than the rate. Many also reprice if an expected tax credit is not applied to the balance by a set date.
Get a Free Business AuditHow the calculation works
Principal, rate and term produce the monthly payment and the total interest over the life of the loan. The comparison that matters is the payment against the bill saving, since a loan payment exceeding the saving means the system costs money monthly regardless of how the payback is presented.
What moves the number
- Amount financed and the rate.
- Term, which trades payment against total interest.
- Any dealer fee built into the system price.
- Whether the payment steps up after an assumed credit.
Where this one goes wrong
Solar loans frequently carry a dealer fee that is built into the system price rather than disclosed as a rate, which means a low advertised rate can accompany a higher cash price, and the honest comparison is the total cost of the financed deal against the cash price elsewhere. Some structures also assume a tax credit is received and applied, with the payment stepping up if it is not, and that assumption has to be checked against whether the credit is actually available.
Before you quote
- Compare total financed cost against a cash price elsewhere.
- Ask whether a dealer fee is built into the price.
- Check whether the payment assumes a tax credit is received.
Questions
About this calculator
Why is a low-rate solar loan not always cheaper?
Because a dealer fee is frequently built into the system price rather than shown as a rate. A low advertised rate can accompany a higher cash price, so the comparison has to be the total financed cost against a cash price from elsewhere.
What is a step-up payment?
A structure where the payment assumes a tax credit is received and applied to the principal, rising if it is not. That makes the affordability of the arrangement contingent on a credit being available and usable, which has to be verified rather than assumed.
Should the payment be below the bill saving?
If it is not, the system costs money every month regardless of how the payback is presented. That comparison is the clearest test of whether a financed system makes sense, and it is frequently absent from the proposal.
The formula
standard amortisation: payment = P x i / (1 - (1 + i)^-n)
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How to use this calculator
- Amount financed ($). Enter your own figure; the page starts at $21,500.
- Interest rate (%). Enter your own figure; the page starts at 6.9%.
- Term (years). Enter your own figure; the page starts at 15.
- Dealer fee rolled in ($). Low-rate solar loans usually carry one, often 10% to 25% of the system.
- Current monthly electricity bill ($). Enter your own figure; the page starts at $168.
- Expected bill after solar ($). Enter your own figure; the page starts at $34.
The result updates as you type, so you can try a figure, see what it does to monthly payment, 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 |
|---|---|
| Amount financed | $21,500 |
| Interest rate | 6.9% |
| Term (years) | 15 |
| Dealer fee rolled in | $0 |
| Current monthly electricity bill | $168 |
| Expected bill after solar | $34 |
What comes out
| Result | Value |
|---|---|
| Monthly payment main result | $192.05 |
| Total paid over the term | $34,569 |
| Interest paid | $13,069 |
| Loan plus new bill | $226.05 |
| Against today's bill | $58.05 |
The payment plus the new bill is $226.05, which is $58.05 more than today's bill. It only comes out ahead once electricity prices rise.
How sensitive the answer is
Holding everything else steady and changing only amount financed, this is what happens to monthly payment. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Amount financed ($) | Monthly payment |
|---|---|
| $10,750 | $96.02 |
| $16,125 | $144.04 |
| $21,500 example above | $192.05 |
| $32,250 | $288.07 |
| $43,000 | $384.10 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Amount financed ($)
- A money amount, starting at $21,500.
- Interest rate (%)
- A percentage, between 0 and 40, starting at 6.9%.
- Term (years)
- A number, between 0 and 30, starting at 15.
- Dealer fee rolled in ($)
- Low-rate solar loans usually carry one, often 10% to 25% of the system.
- Current monthly electricity bill ($)
- A money amount, starting at $168.
- Expected bill after solar ($)
- A money amount, starting at $34.
What the results tell you
| Result | What it is |
|---|---|
| Monthly payment | The headline result. A money figure. |
| Total paid over the term | A money figure. |
| Interest paid | A money figure. |
| Loan plus new bill | A money figure. |
| Against today's bill | 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.
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