[Steve N]

All being well we'll have solar PV + battery installed early next month, hopefully coinciding with the arrival of a Kona. I was all set to order a Zappi to get the most out of the "free" electricity on days when I'm working from home and at weekends. But now I've stumbled on the EmonEVSE.

From the limited information available, it appears to have pretty much no user experience at the charger itself, but does have a pretty comprehensive web-based UI and wifi with firmware updates out of the box. It doesn't have the straightforward modes of the Zappi, but does an option for consuming excess PV generation.

Most interestingly, it open source and has a bunch of software features ready to work with out of the box. As a software engineer for a living, this is pretty interesting to me!

Does anyone have any experience of the Emon? It's a little more expensive than the Zappi, but then it does have wifi connectivity out of the box, which the Zappi doesn't seem to?

 

[Aragorn]

I use an EmonESP + EmonTX Sheild + EmonCMS for logging my energy consumption. Its a pretty comprehensive system, but does have a bit of a learning curve and isnt quite "plug and play". I wouldnt imagine a software engineer would have any issues with it, but Joe Public might.

That EmonEVSE looks like a ready-to-go packaged up version of the openEVSE system, which should be pretty good, and its OLEV approved so you can use the grant for it.

The other option is to retrofit the OpenEVSE controller into a Rolec or similar unit. The controller is pretty cheap, and uses a standard ESP8266 module for the Wifi. The software is all open source etc too.

 

[leafmonster]

tell me more aragorn
where do i buy and connect these items?

 

[Aragorn]

If you mean the energy monitoring stuff, theres a number of options.

The simplest is to purchase an EmonTX:
emonTx V3 - Electricity Monitoring Transmitter

That unit has four CT inputs, a voltage sense, and does all the measuring/calculating etc and outputs over RF.

The RF transmisison is then picked up by either an EmonBase, or an EmonPi. Those are kinda expensive, so instead you can use something like a WiMOS D1 Mini or other compatible ESP8266 units, and connect the serial output from the EmonTX, to the ESP8266, which deals with the Wifi part for only a few quid instead.

As a cheaper option than the EmonTX, you can buy something called an EmonTX Arduino Shield. This is a semi-DIY PCB that sits on top of a standard Arduino, and does the same stuff as the normal EmonTX, but without the fancy case etc. That means its much cheaper.
emonTx Arduino Shield SMT

You'll also need CT's for each thing you want to measure. I have three CT's one measuring the car charger, and the other two measuring the two halves of the main DB in the house.

EmonCMS is a software package. You can either use their hosted version at emoncms.org, or you can host your own (which is what the EmonPi does) I host my own on a server i already have at home.

 

[modeller]

I have an emonPi and Tx for energy monitoring. One of the unique capabilities is automation using node-red (part of Pi). You'll be able to easily setup custom rules for charging your car incorporating information from wherever using MQTT/http etc. Integrating twitter (for notification) is a doddle.
Node-red is great fun (and was incidentally developed by IBM UK Hursley)

 

[Aceshigh]

The Zappi should be plug and play and is marketed as a commercial solution over the emonEVSE which others have already suggested requires some technical knowledge to extract the most from.

Be aware the Zappi has a Comms problem when used with multiple other MyEnergi products; apparently it is a known problem with a fix due "soon". All well and good being told this after purchase.

There is also a potential problem when combined with battery storage that I have requested support with; my LEAF will charge from the PowerWall at 3.3kW when the Zappi is on fast mode but when the PowerWall hands over to the grid (at Economy 7 times) I have had the charge rate drop to 2.3kW in one instance and stop charging altogether in a second.

 

[Aragorn]

The zappi does seem to have a lot of issues despite being "plug and play". I do wonder if the EmonEVSE is actually a better choice, given the open nature of the hardware and software that it runs...

 

[Steve N]

The other option is to retrofit the OpenEVSE controller into a Rolec or similar unit. The controller is pretty cheap, and uses a standard ESP8266 module for the Wifi. The software is all open source etc too.

Ahh, that's very interesting. We currently have a Polar branded charger installed by the previous owner for their Zoe. If it's possible to bolt on the OpenEVSE controller and get 7kW from that, then that's probably my cheapest and most flexible route forward, thanks.

 

[Aragorn]

I dont know what the insides of a Polar unit will look like. The older podpoints had separate components like the Rolec for instance, and so a controller swap would be fairly easy. Later units had an all in one PCB instead.
I suspect the Polar units might all have a single board PCB.

 

[championc]

Hi @Aragorn , what solution did you eventually go with ? I already have SolarPV and Batteries. I was originally leaning towards the Zappi because know that you can add several Harvi units in order to monitor the battery aspect of the SolarPV and therefore prioritize charging of the Car over the Batteries, while pulling nothing from the grid.

My inverters are 2 x 3kw Sofar units - 1 x 3000TL Standard Inverter and 1 x ME3000SP Storage Inverter.