First, the reassuring part
A rising bill on a solar home is usually not a broken system. Hardware failure is the least common cause on this list, and it is the one people jump to first — partly because, since SunPower's shutdown, most owners lost the dashboard that would have ruled it out.
There are six realistic causes. They stack, which is why a bill sometimes jumps more than any single one of them explains.
The six causes, most to least common
1. Your utility raised rates
The dullest answer and frequently the right one. Retail electricity rates have moved sharply in several states, and a solar home is not insulated from that — you still buy power at night and in winter. Same production, same usage, bigger bill.
Check the per-kWh rate on this year's bill against last year's. It is the fastest thing on this list to rule in or out.
2. True-up timing
Many net-metered accounts settle annually rather than monthly. Your monthly statements look tiny — sometimes negative — while credits build up, and then one true-up bill reconciles the year. A big true-up is usually not a sudden new problem; it is a small year-long gap arriving in one envelope.
3. Time-of-use windows
Under time-of-use pricing, when you use power matters as much as how much. Solar produces at midday; households consume most in the evening. If your plan pays you less for what you export at noon than it charges you for what you buy at 7pm, you can send out plenty of energy and still owe money.
This trips people up most after a plan change or a move onto a newer tariff, because production and consumption did not change at all — only the prices attached to each hour did.
4. You are simply using more
An EV is the big one — charging a car can add more load than a whole house used before. Heat pumps, a new air conditioner, a hot tub, a home office, or another person in the house all do the same thing more quietly. A system sized for your 2019 consumption does not cover your 2026 consumption.
5. Panel degradation
Panels lose output slowly — a fraction of a percent a year is normal and expected. Over a decade that is real, but it is gradual, and it does not produce a sudden jump. If your bill changed abruptly, degradation is not the explanation.
6. An actual fault
Least common, but not rare enough to ignore: a failed microinverter, a string that has dropped out, a gateway that stopped reporting. The problem is the size of the signal. One dead panel in thirty is about 3% of production — invisible against weather variation on a monthly bill, invisible at the meter, and capable of running for years.
This is the one cause you genuinely cannot diagnose from a bill. It needs per-panel data.
How to work out which one is yours
- Compare year over year, never month over month. Solar output swings enormously with season and weather. June against May tells you nothing; June against last June tells you a lot.
- Separate production from consumption. If production held steady and the bill rose, the cause is rates, usage or timing — not your panels. If production fell with comparable weather, look at the system.
- Check the rate itself. Pull the per-kWh price and any fixed charges off both bills. Rate changes are invisible in kWh terms and account for a surprising share of "my bill went up" cases.
- Then, and only then, look at individual panels. If production really has dropped, per-panel output tells you whether it is one dead unit, one shaded string, or the whole array.
Most owners get stuck at step 2, because after SunPower's shutdown they no longer have production history to compare against — which is precisely what makes an ordinary rate increase feel like a broken system.
Getting the data to answer it
Your utility can give you your consumption: most large utilities offer a Green Button export or an interval-usage download covering the last 12 months. That is free, and it is the fastest way to see whether your usage grew.
Production is the harder half now. Your PVS gateway still records it locally — it does not need anyone's cloud to know what your panels are doing — so any tool that reads the gateway on your own network can show it to you. If you are technical, the open-source Home Assistant integrations do this for free.
⚠️ One honest limitation whichever route you take: whole-home consumption only works if CT clamps were fitted at installation. Plenty of systems never got them, and after the bankruptcy that is difficult to remedy. Without them you can see production but not household usage.
Where WattHacker fits
The WattHacker monitor is a small box that plugs into your existing SunPower PVS6 gateway on your own home network and reads it directly. It doesn't rely on SunPower's or SunStrong's servers, because for owners like you those are either gone or behind a paywall. No technician, no electrician, no rewiring — you plug it in yourself.
- The monitor is $50 once (list $100), with a 30-day money-back guarantee.
- Free to see your panel data, forever — every panel, live, no subscription and no card on file.
- An optional premium plan at $6/mo (billed annually) adds the memory: full history kept for good, year-over-year comparison, and alerts told to you in dollars.
- Built by an electrification superfan who wants to help others use their solar smarter, lower their utility bills, and clean up the planet. Who's behind it.
Common questions
Why is my electric bill going up if I have solar panels?
Most often it is not the panels. The common causes are utility rate increases, annual true-up timing, time-of-use pricing that values the power you export less than the power you buy back in the evening, more household consumption than last year (an EV, a heat pump, air conditioning), gradual panel degradation, and — least often — an actual equipment fault. They can stack, which is why bills sometimes jump more than any single cause explains.
How do I tell whether my solar system is underperforming or my usage went up?
Compare production against the same month last year, not against last month — season and weather swamp month-to-month comparisons. If production is roughly flat year over year and your bill still rose, the cause is on the consumption or rate side, not the panels. If production dropped year over year with similar weather, look at the system.
What is a solar true-up bill?
On net metering, many utilities settle up once a year rather than every month. Monthly statements can look small or even negative while credits accumulate, then a single annual true-up bill reconciles the whole year. A large true-up is often not a new problem — it is twelve months of a small gap arriving at once.
Does a dead solar panel show up on my bill?
Rarely in any obvious way. One failed microinverter in a 30-panel array is roughly 3% of production. That is invisible against normal weather variation on a monthly bill, which is why panel-level faults can run for years unnoticed. It takes per-panel data to see it.
See your own panels, live.
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