Solar and home charging (UK)

[kempez]

Hi All

I have a PodPoint Solo installed at my house and I also have a Solar PV installation with 10 kW of batteries. It's a 3kW inverter but I have around 6.5 kW of power that can come in via the panels. I also have an Octopus EV tariff - 40p (ish) per kW in the day and 9p between 00:30 and 04:30.

Ideally I'd like to be able to plug my car in and tell the charger to use whatever solar is available and vary the charge according to that, so it costs me £0 when there's enough sun.

I use the MyPorsche App to set the preferred time of charging - 00:30 to 04:30. This works fine as long as I'm not too ambitious with the amount I want it to be charged on a per-charge basis

My question is: does anyone have a less 'dumb' charger than my PodPoint and if so: does it work well?

I want to know if I should switch my charger out (at a cost), or stick with what I have

Now we also have a Volvo XC90 T8 hybrid that only charges at 3kW and I do plug this in in the day which works 'OK' with the batteries etc but sometimes consumes electricity on dull days etc, which is highly annoying

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[bn8959]

I've been thinking about this loads too, and I'm not sure if there is a good solution. I don't yet have my Taycan, so haven't been able to work this out, but these are my thoughts.

I have 6kWp of panels, a 3.6kW inverter and a myEnergi Zappi EVSE. I also have a Tesla PowerWall, but the battery is irrelevant in this context, as it's wired in a way where it would never send power to the car - the Zappi is wired grid side of the PowerWall.

There are some challenges I think in the way the Taycan charging logic works, which isn't going to play well with pure solar charging. Things to note - you need a minimum of 1.4kW going into the car to charge, the standard doesn't allow for charging at any lower rate. Also, the standard has no way for the EVSE to see the SoC of the car - so the EVSE is going to be unable to stop itself when the car reaches a certain charge level (eg 80%).

I see the options are:

(1) EVSE in dumb mode
In the Zappi this is called 'Fast' mode. Use profiles and timers in the car as normal.
Pros - Car will charge itself as per timers, and get to the desired charge level (eg 80%) at the desired time, and wont over-charge.
Cons - Car will pull full 7.4kW when it wants. If you set your scheduled timings correctly, then this should happen during the low tariff rate (ie overnight), but it could technically exceed the window if it wants - but no use for pure solar charging at all.

(2) EVSE in full control - car set to Direct Charging
Pros - The Zappi would fully control the charge rate of the car. The car will sit there waiting for any available energy to charge. If you set the Zappi to Eco+ mode, then it will only charge when the sun is out and generating more than 1.4kW, or in Eco mode it can top up to 1.4kW so you can have a 'partially green charge. You can use schedule boosts in the Zappi to allow the car to charge at full rate during exact times (ie your cheap night rate), so no risk of charging at peak rates.
Cons - No way to stop the car charging to 100% - you'd have to monitor it and unplug it, or set the EVSE to Stop mode if you dont want it to charge all the way to 100% (inherent behaviour of Direct Charging mode).

(3) EVSE in control, but still having timers enabled
This is the unknown one. The challenge - get all the benefits from (2) above but only charge to, say, 80%. If you enabled the charging profiles from (1), how is it going to behave? There could be problems. For example, the car may want to charge, but the EVSE may say 'no power available as not enough sun' - will the car then throw a charging error and give up, or will it politely wait for the EVSE to allow it to start? Also, as you set in the profile a charge level and a time for it to be ready by (only way to set the car to charge to 80% for example), it's only going to charge when it wants to so its ready at the right time - so you are sat there in glorious sun and your PV is throwing out 3.6kW and the EVSE is say 'yep, go ahead, have 3.6kW', but the car will likely say 'nah, I don't need to start charging until 1am thanks very much'.

So I think the only way to get close to the ideal behaviour would be to set the car to Direct Charging mode when you want it to charge from the sun - so it will always pull whatever the EVSE will allow. But you'd have to (a) remember to turn off Direct Charging at the end of the day, so the car will then revert to its timer to finish off, and (b) keep an eye on the SoC so it doesn't charge above your desired max charge from the sun.
Or maybe have multiple timers, telling the car you want it 80% by midday AND 80% by 5pm AND 80% by 7am - that way there are more targets for the car to hit and therefore it's more likely to want to pull power from the EVSE at the right time?

I could be wrong, as I haven't been able to test - maybe someone else can confirm my thinking?

 

[kempez]

I don’t mind setting the car into Direct Charging. It really doesn’t like the EVSE telling it it cannot charge and throws up a red error. I’m happy to monitor it tbh. I don’t plug my car in a whole load, only when I need it, so it’s likely to be a while until it’s charged to 100% anyway.

Thanks for the response. If anyone has a decent charger (like your Zappi), and their Taycan, feedback is appreciated

Currently setting the car to charge overnight works absolutely fine as long as you don’t ask it to charge more than circa 40% in one go, or it uses premium time rate electricity. I’m happy to manage this, but I really want to be getting my ‘free’ charging when the sun is giving me enough juice to charge the car!

 

[bn8959]

Im hopefully borrowing a Taycan from my OPC next Wednesday and will test it out - you never know, I might even have my own Taycan next week (unlikely though!).

 

[kempez]

`either way, if you can update that would be great.

And good luck/enjoy your new car. They really are special

 

[Jin]

me Taycan is a few months off still but been reading in prep!

I've recently had the Myenergi Zappi and Libbi installed and the plan is to move to Octopus Intelligent (OI) when the car arrives.

Looks like Myenergi and Octopus are close to releasing changes to Zappi to allow the EVSE to control the charging. OI looks like it will add its own charge schedules when Octopus feels the need to.. i.e. extra sunny or windy day or they have excess energy they can offload.. this means you can get a charge at the cheap rate outside the usual 11.30-5.30 window.

they've published a few articles now talking about the different set ups possible with Zappi: https://support.myenergi.com/hc/en-gb/articles/18470101583377-Zappi-Intelligent-Octopus


OI also throws up potential issues with people who have battery storage too... given the different brands of battery and EVSE.. there's a chance that OI could 'drain' your battery into the car during its charging schedule. having the battery and EVSE as one brand has made this easier for me as I can directly tell my battery not to provide power to Zappi demand.


but as I say.. all theory right now!

 

[bn8959]

Yep, OI throws yet more complication and setup options in to the mix.
I plan to move to OI.
OI will use the cars Timers by setting them on your behalf via the Porsche API. This isn’t going to play nice with trickle charging via solar and would need your EVSE to be in dumb mode. Or if integrating to the EVSE instead of the car, then you have other challenges.

it would be SO much easier if the Taycan had a simple option of setting a max charge level. Then you could easily leave everything to the EVSE. (Except for morning preconditioning).

 

[gramorris]

Yeah I'm going to have the problem of managing the battery so it doesn't transfer to the car. I'm not expecting to push solar to the car as summer export rates are higher than import on Octopus Flux and in winter I'll use any solar on the house (heat pump). So my starting plan is just to charge the car during the tariff low rates and I'll probably do that from the car rather than the EVSE.

I am running Home Assistant too to try and pull it all together. No car yet though so all theory.

 

[inv]

I am on Intelligent Octopus with solar and battery. Over the past year I managed to set up my system to match the charge rate with the solar quite nicely (The EV charger is terrible, would not recommend). Since Octopus increased the export rate to 15p/kWh a couple of weeks ago it now makes no financial sense to charge in the day any more. All charging happens during the night period now at 7.5p/kWh.

During the night the house battery is now charged to 100% meaning that all excess solar is exported during the day.

 

[Jin]

Yeah I'm going to have the problem of managing the battery so it doesn't transfer to the car. I'm not expecting to push solar to the car as summer export rates are higher than import on Octopus Flux and in winter I'll use any solar on the house (heat pump). So my starting plan is just to charge the car during the tariff low rates and I'll probably do that from the car rather than the EVSE.

I am running Home Assistant too to try and pull it all together. No car yet though so all theory.

home assistant did seem to be the way to manage it will if you have different battery, solar, EVSE etc


if you're a Zappi user, the myenergi forums had a lot of info there too for people in similar positions with battery drain

 

[AlexMaxX]

Maximizing solar power for your EV charging is a smart move. Switching to a smarter charger could definitely help optimize that. There are chargers out there that sync with solar production, adjusting the charge rate based on available sunlight. It might be worth exploring options like those to sync better with your solar system and tariff. But yeah, balancing cost and functionality is key here. Understanding solar electricity pros and cons, especially in relation to EV charging, can give you a clearer picture to make that call.

 

[bn8959]

Yep, and Zappi is very very good at that. However, Octopus Intelligent tariff gives you 6 hours of 7.5p/Kwh overnight plus 15p/Kwh for export. So it’s better to export your solar and charge overnight currently. Plus, it can give you extra hours at the low rate to charge. Yesterday I got the 7.5p rate between 18:30 and 08:00.
I have a Tesla Powerwall too, so 99% of my use can be on the low rate

I’ve wired my Zappi to be ‘grid side’ of the Powerwall - so the battery will never be used to charge the car.

use yesterday according to Powerwall:

Grid use according to Zappi:

 

[W1NGE]

Hi All

I have a PodPoint Solo installed at my house and I also have a Solar PV installation with 10 kW of batteries. It's a 3kW inverter but I have around 6.5 kW of power that can come in via the panels. I also have an Octopus EV tariff - 40p (ish) per kW in the day and 9p between 00:30 and 04:30.

Ideally I'd like to be able to plug my car in and tell the charger to use whatever solar is available and vary the charge according to that, so it costs me £0 when there's enough sun.

I use the MyPorsche App to set the preferred time of charging - 00:30 to 04:30. This works fine as long as I'm not too ambitious with the amount I want it to be charged on a per-charge basis

My question is: does anyone have a less 'dumb' charger than my PodPoint and if so: does it work well?

I want to know if I should switch my charger out (at a cost), or stick with what I have

Now we also have a Volvo XC90 T8 hybrid that only charges at 3kW and I do plug this in in the day which works 'OK' with the batteries etc but sometimes consumes electricity on dull days etc, which is highly annoying

Have you considered using a Home Energy Manager (HEM) to manage this mix of solar, grid and pricing? Porsche provide one.

 

[kempez]

Have you considered using a Home Energy Manager (HEM) to manage this mix of solar, grid and pricing? Porsche provide one.

No but it looks interesting. It would be nice to have something that was clever enough to efficiently manage everything and had an intuitive interface

 

[gramorris]

No but it looks interesting. It would be nice to have something that was clever enough to efficiently manage everything and had an intuitive interface

I’m still of the view that the easiest way to manage it at the moment is to be on an export tariff that pays more than your off peak import. You can then charge off peak only and export freely during the day. This is the greenest and cheapest solution too.

My experience is that any device in the system is individually intelligent but collectively they’re dumb and spend a lot of time competing with each other.

Fortunately I don’t have to worry about it now until April but stopping an ‘intelligent’ EVSE sucking power from an equally ‘intelligent’ domestic battery is a problem. It’s a problem for which I don’t have long enough cables to accommodate all the CT clamps needed to solve.

Then chuck ‘intelligent’ Octopus in to the mix

life’s too short

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