How it works

The whole idea in one sentence: the surplus solar you currently sell to the grid for a few cents a unit is worth far more in your car's battery — so ChargeSense puts it there instead, automatically.

Which charger this is for

ChargeSense is for a Tesla charged from a third-party (non-Sigenergy) charger: a Tesla Wall Connector, the Tesla mobile connectorplugged into an ordinary socket, or any other brand of charger. None of them know anything about your solar, and your Sigenergy system can't control any of them — so we control the car instead, over Tesla's own API. That makes whatever charger you already have solar-aware, with nothing new on the wall. (Sigenergy's own AC charger already does this natively with the inverter — it doesn't need us.)

The problem with charging "when the sun's out"

Your solar goes to your house first, then your home battery, and whatever is left is exported. That surplus moves constantly: a cloud, the kettle, the dishwasher finishing. If you just plug the car in, it charges at full power and pulls the difference from the grid — you pay retail for what you could have used for free.

ChargeSense reads your Sigenergy system every 30 seconds and matches the car's charging rate to your actual surplus, right now: up when the sun comes out, down when the oven goes on, paused when there's nothing spare, resumed when there is. Your house and home battery always get first call — we only ever use what was heading to the grid.

What we need, and why

  • A mySigen login — to read your solar, battery and grid numbers. That's all it's used for, and it's stored encrypted. Please make us a separate View Only account rather than handing over your own — see below, it saves you a real annoyance.
  • Tesla authorisation — you sign in on Tesla's own website, so we never see your Tesla password. Tesla grants us charging control and charge status only: we can start, stop and set the charging rate, and read the battery level. We cannot unlock, drive, or locate your car — and we deliberately never collect its location.
  • A virtual key — you approve it in your Tesla app. It lets our commands be cryptographically signed, which is how Tesla knows they're really from you. You can revoke it from the car at any time.

Make us our own mySigen account

Give ChargeSense its own mySigen account. Sigenergy allows one active session per account, so if you hand over the login you use on your phone, we become a second sign-in and the mySigen app will periodically sign you out. It looks like a bug in your app; it isn't, and it isn't something we can fix from our side.

In the mySigen app: Settings → System Settings → System Share → Invite

  1. Email — a second address you control. If your provider supports plus-addressing (Gmail, Outlook and iCloud do), youremail+chargesense@gmail.com works and needs no new mailbox.
  2. Sharing permissionsView Only. We only ever read your numbers; this makes it impossible for us to change your system even by accident.
  3. Sharing durationNo Expiration. Any other duration silently cuts ChargeSense off on a date you won't remember, and it looks like a broken app rather than an expired share.

Submit, then open the invite email and set a password. That email and password are what you enter here. You can revoke our access at any time without changing your own login.

Which Sigenergy mode to run

We've tested against Self Consumption mode, and that's what we suggest during the beta. Modes that make their own battery decisions — Sigen AI especially — change how much surplus is left for the car, and may produce different results. That isn't a fault, it just isn't characterised yet. If you run a different mode, please tell us what you see; that feedback is the point of a beta.

One question we'll ask you

During setup we ask where your car charger is wired. It matters more than it sounds: it decides whether your Sigenergy system can see the car or not, and therefore whether the export figure we read is the true surplus or one that shrinks the moment we start charging.

Upstream of the sensors

mySigen shows no change at all when the car charges.

Gridmeter🚗what Sigenergy sees☀️solar🔋battery🏠house

The car is outside the dashed box, so export stays honest while it charges. We can point the car straight at your surplus — full solar-following.

Behind the inverter

mySigen counts the car as household usage. Always true for a portable charger in a normal socket.

Gridmeterwhat Sigenergy sees☀️solar🔋battery🏠house🚗

The car is inside the dashed box: the moment it charges, your export appears to vanish. Following it naively would chase its own tail, so we don't — schedules and force charge work, and solar-following waits for the closed-loop version.

Don't know? Say so — that's the honest answer for most people, and we work it out for you. Solar-following stays off until we're sure it will behave; schedules and force charge work from day one either way.

What you control

  • Solar — follow the sun. The normal mode.
  • Force charge — charge now, at the rate you choose, sun or not. For the night before a road trip.
  • Schedules — a nightly window (say 23:00–02:00 on a cheap tariff) with its own charging rate and its own battery limit.
  • Separate battery limits — e.g. 80% on solar but only 60% overnight. These are set on the car itself, so the car enforces them even if we disappear.
  • Stop / off — hand control straight back to the car.

Plugging in at home

When you plug in, the car normally starts charging immediately at full power. ChargeSense pauses that within seconds, so your kWh wait for sunshine or your schedule instead of pouring in from the grid. If you actually wanted to charge right away, one tap on Force Charge does it. Superchargers and other DC fast charging are never touched — road trips are none of our business.

Your first sunny day

Plug in, then leave it. Expect charging to begin once your export passes a small threshold and to stay off entirely on a dull day. Watch the dashboard: the flow diagram shows the sun going into the house and the surplus going into the car, and the amps will step up and down through the day. That's it working — a car that charges in bursts and idles under clouds is doing exactly what you asked. If you need a guaranteed full battery, use a schedule or force charge; that's what they're for.

Keep it on your phone

There's no app store download. The dashboard installs straight from the browser and then opens like any other app — its own icon, full screen, no address bar, straight to your dashboard:

  • iPhone / iPad — in Safari, tap the Share button (the square with the arrow), scroll down, and tap Add to Home Screen.
  • Android — in Chrome, tap the menu and choose Install app (some phones say Add to Home screen).

You stay signed in, so it's one tap to see what the car is doing. It's the same dashboard either way — nothing is stored on the phone, and uninstalling the icon changes nothing about your charging.

What it costs

Nothing, while we're in beta. We intend to charge a small monthly fee once it leaves beta, and you'll hear about it with plenty of warning — no surprise billing, ever.

Still curious?

Email contact@chargesense.app — a real person who built this reads it. Or request early access.