Myenergi Zappi Electric Vehicle Charger Review

My Myenergi Zappi smart EV charger was installed on 17^th October 2022 as part of my smart home solar energy project.

Zappi is a smart EV charger with a difference. It can operate as a standard home car charger, using power from the grid but, it also has optional charging modes which can use 100% green energy generated from your own home solar PV system or wind turbine. The Zappi charger is not the cheapest available but, I bought one because my goal is to charge our CUPRA Born using only free electricity and as much solar energy as possible. When under the intelligent control of my contextual smart home, it will also be a zero touch user experience for myself and my family. We simply just need to plug our CUPRA Born in and my smart home will do the rest.

We have purchased our first EV, a CUPRA Born on the 6^th August 2022. This EV charger will mostly be used to charge this vehicle but, it will also be used to charge our guest's cars too.

Note: I have assumed that my Zappi charger will not charge the car using stored energy from my Tesla Powerwall, simply because it is not rated to deliver more than 5kW and this is also not a use case I require.

Charging Modes

Zappi features 3 charging modes and it also has a 'Stop' mode:

Eco

This mode uses a mixture of both green energy and energy imported from the grid. This minimises the use of grid power, taking advantage of cheaper rates overnight, but it can also charge using 100% green energy. Essentially giving you the ability to charge up your car for free! The charging power is continuously adjusted in response to changes in generation or power being used elsewhere in the home. If the surplus generation drops below 1.4kw some power will be drawn from the grid to top it back up.

Eco+

This mode is very similar to eco charging in that it can utilise power from the grid or your own power source. However the charge power is continuously adjusted in response to changes in generation or power consumption elsewhere in the home. Your electric car charging will pause if there is too much-imported power, continuing only when there is surplus free power available.

Fast

In this mode, your vehicle will be charged at maximum power. This power can come from a renewable energy source or from the grid.

If you don't have solar panels or wind generation, Zappi will charge just like an ordinary Mode 3 charging point. The charging modes are described in more detail here.

ECO+ Mode & Minimum Green Level (MGL)

On a cloudy day I might want the charge to start even if there is less than 6A (~1.4kW) available as surplus from the local generation. With a Minimum Green Level (MGL) set at 100%, Zappi will stop the charge if the surplus generation drops below 1.4kW. By reducing MGL, Zappi will allow some power to be drawn from the grid to top up the generation if needed. For example, with the MGL set at 50%, Zappi will keep charging the EV until the surplus generation drops below 700W.

Features

The main features advertised by myenergi for the Zappi charger are:

• At certain hours 'time of use energy tariffs' are significantly cheaper. With Zappi, you can use the 'boost timer' option to start charging at times with the lowest rates.
• Zappi is claimed to be the only EV charger with built-in PEN fault technology. This improves safety and eliminates the need to install additional earth rods.
• Zappi works in harmony with your Solar PV or wind generation, meaning you can charge your car using green energy for free. If you haven't got a renewable energy source at home, Zappi works just like any other charger in 'fast mode'.
• The myenergi app allows you to access and control your devices from anywhere in the world. Visual graphs allow you to monitor your import/export information all in one place.
• A 5-digit pin code is a security feature integrated into this smart electric car charging point, should you wish to use it. It prevents people from changing your settings or using your solar EV charger without permission or tampering.

The Zappi charger uses CT clamps to monitor solar power generation and house load, to enable it to know how much power is available to charge an EV.

Support

As well as having our excellent technical support team on hand to answer any of your questions and queries, Zappi also comes with a 3-year warranty. Once your myenergi Zappi has been installed, please register your individual products to take full advance of the 3-year warranty support.

Installation

The Zappi charger requires a network connection. I had already installed an 8-port switch in my garage for other smart home and solar kit. Initially, the installer couldn't get the Wi-Fi to work with my BT Whole Home Wi-Fi disks. The WPS function just didn't seem to work. The issue seemed to be the older software version installed. Without a network connection, there is no way to update it though. I then spotted it had an Ethernet port and MAC address, so he ran an Ethernet cable. This worked first time and I updated the software.

In Use

The first thing to say is that the cable is plenty long enough to allow cars to be charged on both sides of my drive.

The Zappi security is good. I've set up a PIN to secure the physical unit outside from unauthorised use. We only really use the app to unlock our Zappi though and enable charging, which is very easy to do.

According to the EV charging standard, the minimum charging current is 6A (approximately 1.4kW) so if you have less than 1.4kW of surplus generation the extra power has to be taken from the mains. This is where my smart home energy management project comes in, because my contextual smart home can disable charging if there isn't 1.4kW spare.

To put this into context, my Cupra Born has a 54kWh battery. To charge it up using a 7kWh charger takes:

• 6.9 hours from 10%
• 6.2 hours from 20%
• 5.4 hours from 30%
• 4.6 hours from 40%
• 3.9 hours from 50%
• 3.1 hours from 60%
• 2.3 hours from 70%
• 1.5 hours from 80%
• 0.8 hours from 90%

If the Zappi charger could on only provide 3kWh it would take:

• 16.2 hours from 10%
• 14.4 hours from 20%
• 12.6 hours from 30%
• 10.8 hours from 40%
• 9.0 hours from 50%
• 7.2 hours from 60%
• 5.4 hours from 70%
• 3.6 hours from 80%
• 1.8 hours from 90%

If there is only 1.4kW available then it will take several days to charge an EV but that is fine, as it will be on our drive and plugged in most of the time.

App

This photo doesn't really do it justice but the myenergi app has a nice moving graphic, clearly showing where energy is coming from and where it is going.

The app allows control of charging but it's not what I would call intuitive. I had to read the manual before I fully understood what was going on.

Scheduling

The only way that I can see to enable scheduling is to use the Boost mode. I would typically do this if I wanted to charge my CUPRA Born overnight, using the Octopus Go 7.5p rate from 00:30 to 04:30. This is called 'Boost Timer' and it only works in Eco and Eco+ modes.

Examples

October 2024

In October 2024, I moved us over to the Intelligent Octopus Go tariff. My calculations showed that we could save over £500 by moving on to this tariff. Between 05:30 - 23:30 the cost is 26.72p per kWh and between 23:30 - 05:30 the cost is 7p per kWh. There is a flat export rate at 15p per kWh. The standing charge is 48.79p per day.

This tariff allows you to 'bump charge' in emergencies and you would then typically pay 26.72p per kWh to charge your EV. In my case it would also use any available solar energy being generated, so it wouuld actually work out cheaper but, I would also lose export revenue.

22^nd January 2023

The week ending Sunday 22^nd January 2023 was an amazing week for solar production, with 123.5kWh over the seven days 😮 That's a daily average of 17.6kWh over winter!

Despite all the other things using power in out home (heating, washing machine, tumble dryer, etc.), our Zappi put 48.1kWh of energy into our CUPRA Born.

22^nd October 2022

Did a test of the Zappi today, to see how much solar energy generated could be put into our CUPRA Born. The Zappi was in Eco+ mode with an MGL of 100%. Of the 24.9kWh generated, 18kWh was put into the car, which is really impressive. You can see a lot more detail about this charging session in my blog.

Summary

In the middle of 2023, we moved over to the Octopus Flux tariff. This tariff means that it makes more financial sense to charge our CUPRA Born overnight and to export all our solar energy. The Zappi still makes a lot of sense though. Not only is it a brilliant, reliable charger with a great app but, we can also charge our EV through a power cut and using solar energy gives us more cheap charging time to ensure we get to 100% if we need it for a trip the following day.

It took me a few days to monitor my Zappi charger working before I really started to trust it. I was confident that it would work well on consistently sunny days but, less so when it came to mixed days. I now just trust it to do it's thing and it really is a case of just plugging the car in and letting the charger use solar energy when it can.

• Zappi obviously works best if you can leave your car on the drive during sunny days and we actively target these days.
• The larger your solar array, the better Zappi works. This is because it needs at least 1.4kW of free power to start charging and ideally a 'buffer' to ensure it carries on charging without interruption.
• The more consistent the sunshine, the more energy Zappi is going to put into your EV. As a rule of thumb, I only bother to plug our CUPRA Born in if my Solcast forecast for the day is greater than 10kWh. If it is over 20kWh, then I would make an effort to ensure the car is left plugged in for as much of the day as possible.

Note that I'm only using the Eco+ mode with a MGL of 100%. It still uses tiny amounts from the grid but this has always been less than 5% of the energy put into the car. On more consistent sunny days, this is less than 1%.

I'm still investigating the unofficial API, to see what is possible. It's a real shame that there is no published and local API to this charger. It would make it truly brilliant.

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Further Reading

My Projects

• Smart home energy modelling project
• Smart home energy management project
• Tesla Backup Gateway smart home integration project
• Energy data analysis & savings for 2022
• AC current transformer sensor

My Reviews

• CUPRA Born V2 review