Solar charging allows you to charge your electric vehicle using surplus energy from your solar panels.

This feature works together with the VOOL LMC, which measures power flow at your grid connection point and adjusts charging based on available solar production.

When solar charging is active, your car will charge only when excess solar energy is available.

When you start a solar charging session:

This allows you to prioritize charging with locally generated renewable energy instead of electricity from the grid.

Solar charging must first be enabled for the site.

You can enable solar charging for the site or LMC in the VOOL portal from the LMC settings.

Once enabled:

Enable it in the VOOL portal, not directly on the LMC. Switching solar mode on from the LMC's own interface has a side effect — see If normal charging will not start on a site with solar below.

The LMC will now control charging based on available solar power.

Solar charging depends on real-time solar production. If production temporarily drops (for example due to clouds), charging may pause and resume later.

A short delay is built in before pausing or resuming charging (5 minutes by default). This prevents frequent start-stop cycles when solar production fluctuates. Because of this, charging may briefly start before the system pauses the session if no surplus energy is available.

Charging speed depends on the amount of surplus solar power available. If only a small amount of surplus energy is available, charging may run at a lower power than during normal charging.

If solar production increases, the LMC will automatically increase the charging current.

The feature operates at LMC level, meaning it affects all chargers connected to the same LMC.

Solar charging cannot run simultaneously with other charging programs such as scheduled charging or price-based charging. This limitation is temporary, and support for solar charging with other programs will be added soon.

This feature is intended for private or workplace charging sites.

For solar charging to work correctly, the LMC must measure power at the grid connection point so it can detect when energy is flowing back to the grid.

If the installation does not allow the LMC to measure solar export correctly, the feature may not work as expected.

Since charging is based on locally generated energy, solar charging sessions may appear as zero-cost sessions in the VOOL system.

The inverter is producing, the sun is out, and nothing happens. Work through these in order — the first one accounts for most cases.

There are two different limits, and both have to be satisfied:

So a three-phase charger will never start on 3 kW of surplus, however low you set your own threshold — setting a threshold below the hardware floor does not help. If your surplus hovers right at the floor, charging may also fail to start or start and stop; leave some headroom above it.

If your site has modest panels and a three-phase charger, this is usually the whole explanation.

Solar charging did not work on chargers running in Standalone mode — that is, without an LMC doing load management — before charger bundle 1.9.28. If a charger on an older bundle is in Standalone, update it. You can check and update the firmware from the charger's page in the VOOL Portal.

Solar charging is only as good as the LMC's view of your grid connection point. If the current transformers (CT clamps) are installed on the wrong cables, or facing the wrong way, the LMC reads export as import and never sees any surplus.

Tell-tale signs, all of which point at measurement rather than at solar charging itself:

Also check that the clamps cover everything between the panels and the grid. A common installation mistake is clamping only part of the incoming supply — for example leaving out a boiler room or outbuilding that the solar feed passes through — which makes the LMC's picture of the site incomplete.

Phase direction can be corrected in software by an installer without rewiring: see Reversing phase current sign.

If the car charges at full power while the inverter is producing only a fraction of that, the charger is not being controlled by solar at all. That is either out-of-date firmware (see above) or the LMC not seeing your export (see above) — not a setting in the app.

If it still will not start, send the LMC serial number, the charger serial number, your inverter model, the minimum production threshold you have set, and whether the charger is single- or three-phase. That is enough for us to tell measurement problems from configuration problems without a site visit.

This is the opposite symptom, and it catches people out: you pick Charge now at night, and nothing happens.

Normally that cannot occur. When you start any non-solar program, VOOL switches solar mode off on the LMC first, and it also switches it off when you stop a solar session. But VOOL decides whether it needs to do that from a value it remembers for 24 hours, refreshed each time solar mode is read or changed through the VOOL portal or app.

So if solar mode was turned on directly on the LMC rather than through VOOL, VOOL does not know it is on, does not switch it off, and the LMC goes on waiting for surplus that will not arrive until morning.

If a customer cannot start a normal charging session on a site that has solar enabled, and nobody can explain why, this is the first thing to check — particularly if an installer has recently been on site.

Solar charging is continuously improving. If you have feedback or ideas, we’d love to hear from you.