$265,000 vs. $40,500: The Math on Financing a Grid-Independent Solar System
TL;DR: A household with a ~$600/month electricity bill will hand over roughly $265,000 to the utility over 20 years — and own nothing. That same payment redirected to a HELOC pays off a $30,000 grid-independent solar system in about five years, with a total 20-year cost of ~$40,500 to ~$54,000. We ran the numbers (and you can too with the Solar Payback Calculator below).
A homeowner reached out to us: they’re on the grid and drive an EV, with a daily usage of about 60-65 kWh in March, before air conditioning enters the chat. They want to finance a grid-independent solar system with a Home Equity Line of Credit (HELOC), structured to keep the monthly payment manageable but ultimately enable them to own the system within a reasonable timeline.
That’s a smart move because they’re asking the right question. Most people wonder, “Can I afford to go solar?” But the better question is, “Should I keep paying Edison and own nothing at the end?” Let’s do the math.
You're already making a payment. The question is, what does the money go toward?
Every month, money leaves your bank account and goes to Edison. You get electricity in return (hopefully, if there isn’t an outage), but no equity. We’ve been conditioned to take that arrangement lying down — you get what you get, and you don’t get upset.
When you spend several hundred to a thousand (or more) a month on electricity, you're already carrying a significant recurring payment. The only question is: what’s that money ultimately getting you? What if it doesn’t go to a utility company but buys you a system for generating almost-free* power after a few years?
A HELOC (or other loans) repoints that same money you’d pay a power company toward an asset you'll own. The payment doesn't change much, if at all. What changes is where it goes and what it builds.
The math, with an EV and mostly propane appliances
Take the scenario above, where a household draws 60–65 kWh per day for home loads plus daily EV charging. The home load in this case is on the lower end since these folks have most of their heat-generating appliances (e.g., water heater, clothes dryer, stove) on propane.
At an average blended rate of $0.50/kWh, the tab runs about $950/month. (Actual SCE rates vary by plan and time of use; $0.50/kWh is a reasonable working average for many rural areas.)
Let’s assume you purchase a $50,000 grid-independent solar system, financed with a HELOC at 7.5%. And you redirect the monthly $950 payment to the lender instead of the power company.
You will own the system in ~5.3 years. Afterwards, you get almost-free* electricity for as long as you own and live on the property. Meanwhile, if you stay on the grid, that bill won't stay flat. SCE documented an 83% rate increase over the past 10 years, equivalent to a 6% annual rate escalation.
Here's what the 20-year picture looks like:
| Year | Cumulative — Utility | Cumulative — Solar |
|---|---|---|
| 1 | $11,400 | $11,400 |
| 3 | $36,300 | $34,200 |
| 5 | $64,300 | $57,000 |
| ~5.3 paid off | ~$68,000 | ~$60,800 |
| 7 | $95,700 | $61,400 |
| 10 | $150,300 | $62,200 |
| 15 | $265,300 | $63,700 |
| 20 | $419,400 | ~$65,200 |
The math, no EV but a few more electrical appliances
Let’s look at a slightly different scenario: you don’t have an EV, but do have some electric heavy-hitter appliances. A household drawing 40 kWh/day runs about $600/month at the same average rate of $0.50/kWh. A properly sized grid-independent system for that load comes in closer to ~$30,000 (actual cost depends on your site conditions, terrain, load profile, usage patterns, etc.).
If you take out a loan at 7.5%, you’re looking at a ~5-year payoff timeline.
| Year | Cumulative — Utility | Cumulative — Solar |
|---|---|---|
| 1 | $7,200 | $7,200 |
| 3 | $22,500 | $21,600 |
| 5 paid off | $40,600 | $36,000 |
| 7 | $60,400 | $36,600 |
| 10 | $94,900 | $37,500 |
| 15 | $167,600 | $39,000 |
| 20 | $264,900 | ~$40,500 |
*The “almost-free” caveat
After the solar system is paid off, you should expect a ~$300/year fee to maintain the grid connection as backup. Most folks will also benefit from our post-implementation proactive remote monitoring/troubleshooting service (currently priced at $300/year) to help prevent costly failures and extend equipment lifespan.
Then, you should set aside ~$5,000 to $7,000 to replace the batteries at around year 10 and maybe another few thousand to replace/repair components over the system’s lifespan.
The good news is that solar still comes out ahead by a huge margin if we assume these post-payoff ongoing costs:
$300/yr connection fee
$300/yr monitoring
$6,000 battery replacement
$3,000 components (spread over lifespan)
The EV scenario above would have a total solar cost of ~$78,600 (vs. $419,400 paid to Edison). The no-EV scenario above would have a total solar cost of ~$54,000 (vs. $264,900 paid to Edison).
The numbers here are estimates — your mileage may vary. However, the difference is so substantial that we feel rather comfortable saying you’ll come out ahead by investing in grid-independent solar.
These are actually conservative numbers
The 60 kWh number was recorded in March. A rural property in Kern County in July is a different animal. Air conditioning alone can push daily consumption way past what we see in spring — and every additional kilowatt-hour goes on Edison's tab, compounding at 6% a year.
The $419,000 or $264,900 figure isn't a worst-case number — it’s on the conservative side.
Moreover, we aren’t just talking about electricity bills saved. A resilient energy infrastructure helps boost the value of rural properties, giving you an edge if you put your home on the market. For example, on average, homes with solar sell for 6.9% more than those without. That’s $20,700 on a $300,000 property — essentially pure profits after you’ve paid off your loan.
[Calculator] What’s your solar payback timeline?
| Year | Cumulative — Utility | Cumulative — Solar |
|---|
A few considerations in our calculations
This math works because the money is already leaving your pocket. If you're currently paying a monthly electricity bill, redirecting the payment to a HELOC/loan isn't a new burden. You’re repointing an existing expense toward an asset you'll own.
A few things must be true for the arrangement to pencil out:
The system must be sized right. An undersized system that still requires significant grid purchases doesn't deliver what the tables above show. Set the foundation with a detailed, accurate load analysis.
Loan terms matter. A 7.5% interest rate is used here as a current benchmark for HELOC. Your actual rate affects the payoff timeline and total interest. Use our calculator to get a general idea and work with your lender to see the full financial picture.
This is arithmetic, not financial advice. There may be tax considerations depending on your situation. Talk to your advisor.
The question isn't whether you can afford it
You can afford the monthly payment, because you’re already doing it. The question is: do you want to pay for electricity without building equity?
If you're spending a good chunk of change on electricity, you're already funding a significant asset. Right now, it belongs to the utility. But why should it?
Let’s talk about what grid-independent solar looks like for your property.
