Generator and Solar System: How Do They Work Together?

Yes, a generator can be connected to the same system where a solar plant and a battery operate — hybrid inverters have a separate, specially marked input for exactly this. But a generator, a battery, and solar panels play completely different roles in a system, and most of the confusion comes from the fact that these three things sound similar but work differently.

Generator, battery, and “generator that charges from electricity” — three different things

A generator (diesel or petrol, including the Marsun line) produces electricity by burning fuel while it runs — as long as there’s fuel, the generator works.

A battery connected to a hybrid inverter doesn’t produce electricity, it stores it: it’s charged from the solar panels or the grid through the inverter itself, and later gives that same energy back through it. Once the battery is drained, it gives nothing until it’s charged again.

And what people call a “generator that charges from electricity” is technically not a generator at all — it’s a portable power station: a battery pack with its own inverter that charges from an outlet or solar and later releases the stored energy through its own sockets. Its limit is set not by a fuel supply but by battery capacity. Some manufacturers call these units a “solar generator” — that’s marketing, not a technical term: the device doesn’t produce energy, it only stores it.

In short: a generator produces; a battery stores and releases through an inverter; a power station stores and releases on its own. Hybrid Energy sells these two products — diesel and petrol generators and batteries for hybrid systems — as separate but compatible parts of one system.

How a generator is physically connected to a hybrid inverter

Hybrid inverters (Deye, Solis) have a separate “GEN” terminal block next to the “Grid” and “Load” inputs — a physical input, isolated from the grid, dedicated to the generator.

The same physical port can be set in software as a generator input, as a “smart load” output, or as an AC-coupled input for an additional grid-tied inverter — only one function is active at a time. If set incorrectly, Solis warns that an incorrect setting can make the system malfunction or damage the generator.

Once the GEN port is set as a generator input, the generator simultaneously charges the battery and powers the load, as long as its capacity allows. In the system, the generator switches on last: solar is used first, then the battery or the grid, and the generator only starts if that’s not enough. Solis notes an important limitation: through the GEN port, the generator powers only the backup line, not the whole house — for powering the whole house, the manufacturer recommends an ATS.

Such a GEN port exists, for example, on the 10 kW hybrid inverters Deye 1 949 € and Solis 1 449 €. A grid-tied inverter, e.g. Deye 499 €, doesn’t have one — it only works with the grid, without a battery.

Automatic start and generator power

The inverter can start the generator automatically based on the battery’s state of charge (SOC) — the menu sets when to start and when to stop. But it doesn’t turn the engine itself: it only opens or closes a dry contact signal, sending a “start” / “stop” command. The actual start is carried out by the generator’s own control unit (often called an ATS/AMF controller) — without it, the generator can’t accept the command, and the system then only works in manual mode.

The power rule is simple: the generator’s power, connected through the GEN port, must not exceed the inverter’s rated power — that’s a ceiling, not a minimum. You can set the exact generator power in the inverter, and if the load plus battery charging would exceed it, the inverter draws the missing part from the battery so the generator isn’t overloaded. Manufacturer documentation doesn’t give an exact minimum ratio of “generator kW per kW of charging power.”

GEN port or ATS — when to use which

• GEN port on the inverter. The generator is controlled by the inverter’s own logic (auto-start by SOC, power limiting), but it only powers the backup line. Suits a single inverter.
• ATS (automatic transfer switch). The generator is connected on the grid or whole-house side, and switching happens in a separate panel, not by the inverter’s logic. Needed for several inverters running in parallel, or when you need to power the whole house.

When connected via ATS on the grid side, you additionally need a current transformer (CT) or a smart meter.

The most common mistakes when connecting a generator

• Wrong port setting in the app. The manufacturer warns this can cause a system fault or damage the generator.
• Confusion between GEN port functions. The port can be a generator input, a “smart load” output, or an AC-coupled input — the wrong mode means the generator won’t start.
• Generator power set too high. Exceeding the inverter’s or port’s rating means the manufacturer doesn’t guarantee correct operation.
• Generator without an automatic start unit. Without it, the generator can’t accept the inverter’s start command — leaving only manual start.

When a battery is enough, and when you need a generator

In the system, the generator switches on last: solar is used first, then the battery or the grid. So the question isn’t “is a generator good” but how long the house needs to hold out without the grid — that’s what determines where it makes sense to put your money.

Outages are rare and last a few hours. A battery handles that job, and in that case it makes more sense to invest in bigger battery capacity rather than a generator: no fuel, no maintenance, and no outdoor space needed.

You need reserves for days at a time, the load is large, or the property has motor-driven equipment. For that kind of use, battery capacity would end up unreasonably expensive — that’s where a generator pays off, since its runtime is limited only by fuel.

The same hybrid inverter with a GEN input combines both options: you can start with a battery and add a generator later without redoing anything. We help you calculate which path is cheaper for your specific home before you buy.

Frequently asked questions

Can a generator be connected directly to a hybrid inverter? Yes, Deye and Solis hybrid inverters have a dedicated separate GEN port for this.

Are a generator and a battery the same thing? No. A generator produces electricity by burning fuel; a battery only stores it and releases it through an inverter — they’re two different devices.

What does “a generator that charges from electricity” mean? It’s a colloquial name for a portable power station — a unit with its own inverter that doesn’t produce energy itself, only stores it from the grid or solar and releases it through its own sockets.

Does the inverter start the generator automatically? It only sends a start/stop signal based on battery charge — the engine itself is started by the generator’s own control unit.

When do you need an ATS instead of a GEN port? When the generator needs to power the whole house, not just the backup line, or when several inverters are running in parallel.