Its just a fucking plug, how hard can it be?
– Everyone
Look, I realise this is probably one of the most boring subjects, but this is my website, let me moan godamnit.
Problem Statement
I have a second hand Electric Car, I have a house, I have solar panels and a house battery. Yes, that makes me both rich and posh, don’t worry, I do feel the appropriate level of guilt and self loathing.
What am I trying to do? Charge my car from solar panels, and/or when the grid is cheap. Why am I writing this? Because its too fucking hard. That’s why.
Here is a longarsed rant about why its hard for a non-technical person to have an electric car at home, and make savings on running it.
Glossary
- EV: Electric Car
- Plug: The thing that connects a car to the grid to enable charging
- Zappi: The make of socket that connects my car to the mains in my house
- The Grid: the source of electricity, provided by large generation companies or municipal power stations.
Problem 1: integrating Solar
I chose a Zappi 2, because it has the ability to integrate with both the panels and the battery to “optimally” charge. The wording is vague on the website, but it does have the ability to charge using only “spare” electricity from the solar panels.
The Zappi has a some current clamps to measure the output of the of the panels, this allows it to regulate the amount of charge going into to car. One of the things that isn’t obvious is that the minimum power you can deliver to a car is 1.4kw.
This is fine, because my charger is intelligent™ and can see that the power output from the solar panels have dropped and stop charging. Where its less intelligent is there is no ability to top up with grid power. You either have solar power, or grid.
Also if you leave the car in over night, it’ll use the grid to charge up your car, regardless of what you tell it to do. They call it “boosting”
Now you can use “blending” to top up the solar power with grid power. Its simple, you just adjust the slider
Its a nice idea, however it has never worked. You can slide it all you want, its still never going to mix grid and solar. The best part is, as soon as the sun goes in, the charge stops. So its stop-start stop-start all the time. Fucking great. There is no hysteresis, no way to buffer using the grid.
*update*: this is because I have it in “eco+” mode. In eco mode it might do what I want. I need to experiment further.
Problem 2: Managing the house battery
The house battery, which was manufactured by everyone’s favourite space bellend, doesn’t talk to the Zappi. So if you charge the car, you stand a very good chance of draining your battery in 2 hours.
If you want to make sure you keep your house battery in one piece, then you need to either be good at programming, or cry.
Problem 3: The API
Zappi has an API. Its shit. It was very unreliable, which given that its not actually doing very much is impressive. There is no local API, so you can’t poll the device in “real time” you have to go through their gateway and in incur a 10 second penalty.
The documentation for the API doesn’t exist, but there is someone who’s done a load of work to make it useable to the rest of us. There is no local API, readonly or otherwise. I wouldn’t mind so much about the lack of local API, if the real API was actually fast, documented or had some uptime.
Now, the problem is, to make the charger useful, we need to control it. So we need to fuck with the shitty infra. This does not spark joy. What does spark joy is that someone has made a Home Assistant integration. Its surprisingly stable, and handles the crappy API really well.
But why should anyone normal care about the API ? Well it drives the app. The shitty shitty app.
Problem 4: That Fucking App
Have a look at this screenshot:
Are the changes I’ve just made being synchronised to the actual charger? You don’t know! because the app is just great. Well that’s not really true, because when you start up the app it spends 10 seconds with a spinner telling you its connected.
The App is also a marvel of UX fuckery. For example, how do you set the priority of the car over charging the battery?
Step one: wait for the app to load
Step Two: drag the car
Step Three: Wait
Any action takes about ten seconds to sync. It is time that I love spending. Fortunately for me, I have home assistant to automate all of that shit for me. However, if you’re a normal person, who isn’t a professional infra engineer, you’re fucked.
Problem 5: Charging in daytime
Now, if you have a Phd in solar power, you might already know that solar panels produce the most power when the sun is shining. It may shock you to further assert that when the sun is shining at its peak, is when it tends to be hot.
If you want to charge your car using solar panels, you might be charging when it warm. The Zappi is having none of that shit. If its warm, you’re getting 1.4kw of power, regardless of what mode you have it in.
Needless to say, this is a pain in the bollocks. In the installation manual, it says that if the device gets warm, it’ll throttle the power back. What it doesn’t tell you, is that you really need to install the device in the shade.
Considering this device is a relay, current clamp, CAN bus and plug, it really shouldn’t be getting hot through resistance. However, it does. The net result: most of my solar juice goes to the grid, not the car.
Problem 6: getting cheap rates
Now this isn’t unique to the Zappi. If you are with a fancy electricity supplier, you can request to get variable rate tariff. If the wind is blowing then you might get paid to charge your car. If its not windy, and everyone is making tea, it’s going to cost you >50p a kWh.
The price will change every 30 minutes, and there are APIs that publish the price a day in advance. With some “automation”, Home Assistant its perfectly possible to set a price point so that the car only charges when its below a certain price.
But that shouldn’t really be that hard. Why is it not possible to have that built into the charging app? (don’t answer that, I know why.)
Conclusions:
Having an Electric Car is great. If I had more solar panels, and a better fucking plug, it would be almost zero cost to run.
Even with a shit plug, its great great fun to drive, and surprisingly convenient, even if you are charging on the motorway (that bit is not cheap though.)
Yes, some people complain that Electric cars are boring to drive, they either have not driven a modern car, or don’t like having 100% power instantly. Beating a £85k Audi in a small family hatchback is immense fun, as is spanking boy racers.
But, at the moment its too fucking hard to have a working, simple to use, solar panel aware charging system at home. For that, I blame Zappi.