Sunplug
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Charge your cars on surplus solar
Smart solar
charging
Sunplug watches what your panels are producing and what your house is using, then charges your cars with whatever is left over — following the sun through cloud and shade, minute by minute, so you buy less electricity and export less of your own.
Free while in beta.
How it works
Connect your solar
Sign in with your inverter's maker, or run a small agent on your own network for readings every thirty seconds instead of every five minutes. If your brand is not listed, send the numbers yourself — there is a documented API, and it takes ChargeHQ's own meter fields, so an existing bridge changes its address rather than its arithmetic.
Connect your cars
Tesla and Volvo sign in with their own accounts, handled in the app — a Tesla is driven directly, a Volvo reports its battery while your charger sets the current. Everything else goes through the wallbox over OCPP, which nearly every serious charger speaks — so the make of your car stops mattering.
Set what you want
A floor to reach overnight, a target for the sun to chase, and how much home battery to keep back. Then leave it alone. Boost when you are in a hurry; set a departure time when you are not. (Some features are only available with Tesla currently).
Tesla owners
Your Tesla needs nothing but the app.
Sunplug talks to your car directly, so there is no wallbox to configure and nothing to install in the garage. It sets the charging current amp by amp as the sun changes, and because it can see the battery it knows when to stop.
It knows the state of charge
Charge to 80% on sun and no further, but keep a floor of 45% for the morning. Sunplug tops up overnight only if the sun did not get there.
Three cars, one supply
Up to three cars share whatever surplus there is, inside the limit your wiring allows. Name the one that goes first, or let Sunplug work out which needs it most.
Leaving at seven?
Set a departure time and a target. Sunplug works backwards and starts only as late as it needs to, using sun first and cheap hours after.
It stays in charge
Change the rate in the Tesla app and Sunplug notices, backs off, and tells you — rather than silently fighting you over the same setting.
A slider for every car Sunplug can see inside: blue is what the grid guarantees overnight, amber how much further the sun may take it.
Nearly every model, including most of the ones other tools dropped. Model 3, Model Y, and both Model S and Model X — pre-refresh cars included. Those older S and X use Tesla's legacy command path rather than the signed commands newer cars need, and Sunplug speaks both. Mine is a 2020 X, which is rather how I noticed. The one exception: pre-2018 S and X don't support Tesla's Fleet Telemetry, so those specific cars aren't covered yet.
Volvo owners
Your Volvo, read by Volvo and charged by your wallbox.
Sign in once with your Volvo account and Sunplug can see what the socket cannot: how full the battery is, whether the car is plugged in, and the charge limit you set in the car. That is the number that turns surplus charging into charging to a target.
Volvo publish no command that starts, stops or throttles charging — so the current is set at your wallbox instead. A Volvo Wallbox comes with the same sign-in and needs no second password; an OCPP charger, a go-e or an Easee works just as well. A Volvo on a plain socket cannot be managed by anyone, and Sunplug says so rather than letting you find out.
- Battery level and plug state
- The car's own charge limit
- Volvo Wallbox, from 6 A
- One sign-in for both
Every other car
The same, for more brands.
Supported today: any car on one of the smart chargers below — it charges on surplus exactly like a Tesla, everything except the state of charge. The socket meters what went in and how much came off your own roof; what it cannot see is how full the battery is.
The car APIs on the roadmap add that missing number, and with it the full experience: charge to a target, ready-by times, live state in the app. When an API exists, we will do our best to integrate it with Sunplug.
Sun when there is sun. Off-peak when there is not.
A cloud passes and the surplus drops. Sunplug eases the charge rate down rather than stopping, waits to see whether the sun comes back, and only gives up when it is clear it has gone. When it returns, it ramps back up.
That waiting is deliberate. Every stop and start cycles a mechanical contactor inside your charger, and those have a finite life. Chasing every dip would cost you a wallbox to save a few pennies of electricity.
Some days the sun simply does not show, and you still need the car in the morning. Set charge windows for your cheap hours and a floor to reach by dawn, and Sunplug fills the gap from the grid — and on the hours you would rather not buy at all, it can be told not to bother.
Dynamic electricity pricing support on the roadmap.
You can see exactly what it did.
Every decision the engine makes is recorded with the reason for it. How much of your charging came from the sun rather than the grid, what it saved against charging off-peak instead, and where the energy actually went — day, month or year.
The savings figure is deliberately conservative: it compares against what you would have paid charging overnight at your off-peak rate, not against peak. Less impressive, more honest.
Sunplug Agent
Your solar, read every 30 seconds.
A Raspberry Pi on your network, set up from your phone. Nothing exposed.
Does it work with your kit?
Solar
Reading production, house use and battery.
- Enphase — locally with the agent, every thirty seconds
- Fronius — locally in seconds, over the inverter's own API
- SolarEdge — locally over Modbus with the agent, battery included
- Sungrow — locally over Modbus with the agent, or one-click cloud
- SolaX — locally with the agent, or minute-fresh cloud
- GoodWe — locally with the agent, or five-minute cloud
- LuxPower — read through its own Wi-Fi dongle with the agent, battery included
- Solis — one-click sign-in on SolisCloud's own page
- APsystems — ECU read locally; ECU-C sees the house itself, others need a meter
- SMA — read locally with the agent; pair a Shelly to see the house
- KOSTAL — read locally with the agent, with its own meter for the house
- Hoymiles — DTU-Pro or OpenDTU with the agent; pair a meter to see the house
- Victron — GX device read locally with the agent, whole site included
- Tesla Powerwall — through the Tesla connection your cars already use
- Shelly meters — pairs with any inverter that cannot see the house
- Push API — send your own readings, from a script or Node-RED
Cars & chargers
Setting the rate, not just switching on and off.
- Tesla — directly, every model except pre-2018 S and X
- Volvo — battery and plug state from the car, current set at the charger
- Volvo Wallbox — same sign-in as the car
- go-e — locally, no account
- Easee — through Easee's cloud, and their app keeps working
- Wallbox, Zaptec, ABB, Alfen, Keba, Vestel — over OCPP
- Any OCPP 1.6 wallbox — and so any car
- BMW & Mini, Ford, Hyundai / Kia / Genesis, Mercedes, VW Group — car APIs on the roadmap
Controlling the charger rather than the car is why the make of your car does not matter. The limit is applied at the socket.
The car APIs above add the one thing the socket cannot see — the battery percentage. A smart charger still sets the amps; with both together, those brands get the full experience Tesla gets today: charge to a target, ready-by times, live state in the app.
On the roadmap for solar: Huawei — read on your own network rather than through a cloud, the same way SMA and KOSTAL are today.
Setup guides for each of these — what you need, how long it takes, and what usually goes wrong. Not sure? Ask me and I will tell you honestly whether yours works today.