My Monday started with a missed call from an installer. He was standing in front of a customer who wanted a backup generator with solar panels—and he had a Champion generator inverter model picked out. The installer asked, which Growatt inverter do I need to make this work?
I am not an electrical engineer. I'm the operations-and-procurement person at a 26-person solar installation company. Since 2020, I've ordered roughly 200 inverters—maybe 180, I'd have to check—and I've seen what happens when technical specs are left to the last person who gets the email.
The surface problem: backup generator with solar panels sounds simple
When someone searches generator vs generator inverter, they are usually comparing a conventional generator to an inverter generator. That is a useful comparison for portable power. Champion's inverter generators, for example, produce cleaner power and run quieter than many open-frame units. But once you add solar panels, the comparison changes. You are no longer choosing between two generators. You are choosing between two system architectures—and most buyers do not realize that until after the invoice.
Most people think: grid goes down, generator runs, solar panels keep producing. That is true in a very narrow sense and false in every other. A grid-tied Growatt PV inverter—or any other string inverter—must disconnect when the grid fails. That is code. It prevents backfeeding electricity into lines being worked on. So while the generator runs, your solar panels are off. You have paid for both and you are still burning fuel.
This is the surface problem: a solar-plus-generator system works only if the generator can pick up critical loads, charge batteries, and communicate with an inverter that allows generator input. That is not a Champion versus Growatt question. It is a what-is-my-inverter-doing-during-an-outage question.
The deeper cause: architecture, not brand
The phrase generator vs generator inverter is actually the clue. A generator-inverter is still a generator. It burns fuel to create AC power. A solar inverter is a power management device: it converts DC from panels, controls battery charging, and can operate with or without the grid. They are not the same job.
So which inverter do I actually order? For a customer whose main goal is backup, I usually reach for Growatt's off-grid or hybrid series, not a pure grid-tie string inverter. A pure Growatt PV inverter is built to feed the grid and monitor production. That is great for net metering, but it does not make an outage livable. The Growatt 12kw off grid inverter is a different animal: it manages PV, battery, and AC input in one box. That distinction is the real reason people end up angry after searching generator vs generator inverter—they buy a solar inverter that was never designed to work with a generator.
For an off-grid or backup install, I want an inverter that can accept AC input from a generator and use it to charge the battery bank. That is what a Growatt 12kw off grid inverter does in many installations: PV during the day, batteries at night, and a generator as an AC input to recharge when solar is insufficient. The generator does not power the house directly; it recharges the battery bank, and the inverter converts stored DC to clean AC. That architecture avoids the solar-panels-turn-off problem.
According to Growatt's published SPF 12000T DVM manual (current as of January 2025), the AC input terminals can accept either grid or generator power. Confirm your exact model before ordering, because the generator-input feature is model-specific.
I can only speak to the system designs we have installed. We mostly use Growatt's 12kW off-grid model with a battery bank. If you are setting up three-phase commercial loads, the calculus changes. For residential and small commercial, this layout is what finally made backup generator with solar panels work without a second mortgage.
What nobody shows you on the invoice
We have had customers bring a Champion generator inverter to a job site. There is real value in that—inverter generators are reliable and their output is clean enough for modern electronics. But the purchase price is not the project cost. You need a transfer switch, proper grounding, fuel storage, a maintainer for the starter battery, and an inverter that can actually accept its input. The most frustrating part is watching these show up as extras during installation.
I have learned to ask what is NOT included before asking the price. That is a mindset I stole from our finance team. The same logic applies to solar equipment. In my first year of purchasing, I made the classic rookie mistake: I chose the lowest-priced Growatt inverter listing I could find and approved it without checking freight, mounting hardware, and whether the manual was in a language our installer could use. The vendor's photo looked great; the spec sheet did not match. Our installer could not configure it, so we reworked the whole order. That mistake cost us about $2,800 in labor and one very unhappy customer. (This was back in 2022; we do not order that way anymore.)
A backup generator quote is the same story with a different cover. The hidden list usually looks like:
- Transfer switch and wiring labor
- Generator maintenance—oil, filters, fuel stabilizer
- Battery maintainer for the generator's starter
- Integration with your solar inverter, if it supports generator input
- Permit and inspection fees (we see $150 to $850 in our region, but that varies)
That is why I do not trust low upfront prices. It is not because I dislike savings. It is because hidden add-ons make it impossible to compare two quotes. If a vendor lists all the fees at the top—even when the total looks higher—it usually costs less in the end.
The cost of starting from the generator
The expensive version of this problem goes like this: someone buys a generator first, then tries to add solar around it. They buy a Growatt PV inverter that is not generator-compatible. The first cloudy night, the generator runs, the inverter sits idle, and the battery is not charged. The customer calls us back. The rework requires a different inverter or an external battery charger. That second invoice is what nobody budgets for.
For a typical off-grid home here, the sensible starting point is the inverter and battery bank. A Growatt 12kw off grid inverter gives the system a brain; the generator becomes a supporting player that charges batteries during long cloudy stretches. That is the opposite of a backup generator with solar panels. It is a solar panel system with a generator as backup—which is a much better sentence to write on a proposal.
What actually works (short version)
If you are comparing generator vs generator inverter, the answer depends on where the generator sits in the system. For solar backup, put the inverter in charge. The order that worked for us:
- A Growatt hybrid or off-grid inverter that can charge batteries from both PV and AC input.
- A battery bank sized for overnight loads.
- A Champion generator inverter (or similar) as AC input for long cloudy periods.
- A transfer switch only if you want a direct generator bypass—many designs do not need it.
This worked for us because our projects are mostly residential and small commercial with predictable loads. If you are designing for pump systems, industrial equipment, or anything with high inrush current, the calculus is different. Talk to an engineer, not a procurement person like me.
The real question was never generator vs generator inverter. It is which device is the center of the backup power system. If you want solar panels to keep working during an outage, make the Growatt inverter the center. The generator then does what it does best: provide the long-run fuel when the sun is not out.
