We said as soon as our local town got an EV charger we would buy an electric car. In September, a charger was installed, so we carried through and bought a car.
Our car has two and a half times the battery capacity as our house, so we needed a smart charger – one that could be set to only charge on excess solar. Most of these say they won’t work offgrid.
Zappi (myenergi), assured me it would work, so we bought one. (I think I did find an alternate but it was more expensive and not quite as well featured.)
And it works brilliantly (except for the internet connection fault).
It’s a standard install for a smart charger except that the Zappi’s CT clamp is on the battery feed rather than the normal electricity grid feed (we’re AC coupled). So it tries to minimse import and export, as you would to the grid
It has three modes:
- Fast: charge the car at 7kW (you can get higher rated ones). Not a good option for us, at this rate our battery would be dead in under 4 hours and we’d have only added 30% to the car.
- Eco++: charge the car with excess solar. If the Zappi sees power being exported to the batteries, it diverts the power to the car.
- Eco +: charge the car with excess solar, diverting from the batteries, but set a minimum car charge rate to ensure the charging is not shutdown if available solar power drops below 1.3 kW (or other setting).
The problem with Eco+ is that if we had no excess power we could use up to 5% of our battery capacity an hour. It’s OK and there are times when we do use it – cloudy day, AC and other heavy users intermittently running. It was also our fallback operating mode if eco++ didn’t work easily/well.
We really want to be using Eco++, but we also want to charge the batteries first. And that’s the problem with offgrid solar and smart chargers. With batteries fully charged, the solar panels just produce enough power to meet the load. The Zappi can’t detect that there is any excess power available, since nothing is being exported to the full batteries. So it won’t run.
Myenergi told us to run it in Fast for a second and then switch to eco ++. It works a treat. In Fast, it pulls 7kW from whereever it can get it – batteries and solar. So now the solar panels have ramped up to meet the new load, or as much of it as they can, with the rest coming from the battery. With the switch to eco ++, there is a drop in load, but the Zappi can detect that excess power is available before the system ramps back to balance. Once it knows there is some power available it adjusts demand until it balances with the available power to ensure no import or export from the battery. It shuts down when there is not enough power to meet the minimum car charge rate, so no risk of it running overnight if we forget to turn it off the way there is with Eco+. And it will start automatically in the morning, since the batteries are depleted.
It works exactly as we were told. Brilliant. We’ve only had it installed for a couple of months, but it’s great for charging the car. We hardly ever charge in town now, although in winter we might need to.
There was a problem with the install – it’s supposed to have been plugged into an ethernet cable (we have terrible wifi at the shed) so we can remote control and monitor the charging but there was a fault in the unit, and although it works perfectly, it can’t connect to the internet, so no remote control.
Still waiting on a replacement unit, although I suspect that’s the busy installer’s fault rather than Zappi. We got our solar installers to supply and install the unit, and we don’t want to hassle them if we don’t have to – if we have a real problem, then we want rapid response, but for this we’re happy to just slot in. We can see enough on the Sunny Portal and car to know what’s going on – we just have to walk outside to change the settings. Definitely a first world problem.
Oh, and they haven’t billed us yet, coz the jobs not complete.
Off Grid Living - Building the Dream 