Question: Solar

[Pat]

Hi peeps...
Opinion sought about charging from solar,,,, specifically if (when) solar drops below 1.4kWh and the car stops charging, then a few minutes later goes 1.4kWh plus and the car starts recharging.

Does this matter to the battery?

(At no time will the car hit either 0% or 100%)

Reading so much 'stuff' about this (here and lots of other places)

Opinions (with references if possible) sought.

Cheers

Pat

 

[Jomarkh]

Hi, I have just had solar installed and still playing with the Zappi settings.
They suggest setting a 100W buffer to help. Hopefully then the house battery will smooth it out.

 

[BugEyed]

In most cases it appears to be very dependent on the car and the charge point. Clearly no-one here in the UK has been able to try charging the MG4 yet so we don't know.

 

[dirk362]

In general terms, and using solar excess to charge your EV, given this is still an AC supply source it doesn't really matter. As your solar inverter only outputs AC to the house, your charger will be on that side of the supply.

As a preference what you want is to have some intelligence built into the charger that doesn't do lots of small start/stop charges because there is still an element of negotiation between charger and car, electrics have to initialise, etc.

As @Jomarkh mentioned, units like the MyEnergi Zappi 2 have settings that allow you to define the timer before it kicks in, during which the solar excess to the grid has to stay above a set minimum limit. This helps with things like clouds for a few minutes etc.
It is however important to get the threshold right for your circumstances. Some say a 100W excess for 30 seconds is enough, for others it needs to be more. You'll need to find the sweet spot for you in the 100W to 300W range. Bear in mind these are still small values in electrical terms, so you're not giving away loads of free electricity to the grid.

If you have things like a solar water heater, say the MyEnergi Eddi, you need to take that into account as well in terms of how to manage the use of your excess solar when you have some. Clearly, you have much more across March-September, but much less (indeed maybe none based on your general consumption) across October-February.

But you shouldn't be too concerned with this as car manufacturers do lots of testing of their systems to cover these sorts of situations. As the use of solar has increased in residential properties, so have the cars improved in how they work with intelligent chargers.
And at the end of the day, there is an agreed international standard and protocol/handshake between chargers and EVs, and this is all covered by that standard.

 

[Les burrows]

In most cases it appears to be very dependent on the car and the charge point. Clearly no-one here in the UK has been able to try charging the MG4 yet so we don't know.

Hi in you first point it is dependent on the charge point that is true, what its got to do with the MG4 is beyond me.

Pats question is about the car any EV I think, starting and stopping the charging when using a charger that is integrated with a solar Pv system and in doing so can it damage the batteries I think I have that right.

I tried about 18 months ago when I got my MG5 and my Zappi charger fitted , to find a way around this issue but without much success.
After speaking with MyEnergi technical, who where very helpful indeed and they talked me through the settings in my Zappi just to check all was in order.

My concern was not about the batteries being damage, but more about the relays in both the car and the charger constantly going on and off sometimes very regularly when clouds wher drifting across my solar PV array which was what I didn’t like, me thinking that can’t be doing them relays any good.

So Pat in the end I stopped using the solar only setting in the Zappi Eco called plus. Two leafs on the display, and now use and have only been using the Eco 1 leaf setting, in my Zappi as this stops this switching on and off all the time by always charging at 1.4kw or up to whatever is the maximum that the solar is producing at any time.

There’s is a full thread about this somewhere in this forum from a few months back, when I bought my Zappi January 2020, I think that it was the only one that could be set up to only use solar at that time but nowadays there is of course several you don’t say Pat which charging unit you have in you posting
Les.

 

[dirk362]

@Les burrows is absolutely right about this with the MyEnergi Zappi 2. And indeed probably other solar-aware chargers.

Things do get complicated. More so if you have a house battery off your solar, and even more so if you have a hybrid inverter and hence your battery is DC not AC.

There is no such thing as an optimal setup. You will have to think through what you want, what costs you will allow when taking power from the grid, how to manage overall load usage of house+EV, etc.

If I could go back in time before I got my solar, with what I know now, I would have had a very different system installed. Because you cannot manage everything, you have to compromise.

@Pat, if you can share what sort of system you have, we may be able to offer some more insight. That said, the manufacturer forum for your charger is more likely to give you the support that you are looking for.

 

[BugEyed]

Clearly time has mellowed the initial pain that this can cause. Early iterations of MG EVs had an issue with going to sleep which hampered stop/start charging. The main issues remaining are the manual intervention required to know when to stop charging - a 30 second break in charge early in the day with potentially good generation for the rest of the day deserves a different response to cloudy weather rolling in towards the end of the day. Currently there's no system that automates that so it requires manual intervention to prevent lots of mains charging at peak hours or depleting home battery storage. Some people create their own integrations, others resort to using a granny charger and others give up. Personally I accept the sub-optimal solution of the Eco+ option used by Les on my ProjectEV charge point and set an alarm to remind me to disconnect when the solar forecast drops off. It's right 80% of the time but can be badly wrong - one day it ran my home battery flat leaving me having to use peak rate electricity all evening and night rather than just charging the car on the off-peak.

 

[Les burrows]

Just a quick add on to my last post, a good thing about the Zappi is it comes with the myEnergi app, so that you and monitor what’s going on and control it from your phone maybe others brands are the same nowadays.
Les.

 

[dirk362]

One of the things I will be checking as part of the test drive is what settings the MG4 has for the state of charge and whether you can set AC and/or DC maximum charge %age (like you can in the Hyundai/Kia EVs). This will at least make some elements a little more set-and-forget.

I've never owned an MG EV so don't have experience with what MG have done before. That said, with the MG4 being on a totally new SAIC platform, there's no guarantee what the other MG EV models do will be applicable here anyway.

 

[AdamMGEV]

One of the things I will be checking as part of the test drive is what settings the MG4 has for the state of charge and whether you can set AC and/or DC maximum charge %age (like you can in the Hyundai/Kia EVs). This will at least make some elements a little more set-and-forget.

I've never owned an MG EV so don't have experience with what MG have done before. That said, with the MG4 being on a totally new SAIC platform, there's no guarantee what the other MG EV models do will be applicable here anyway.

The new ZS and MG5 can do that via the car and app so I assume this will do that and more

 

[BugEyed]

The new ZS and MG5 can do that via the car and app so I assume this will do that and more

Strange that none of the screen shots of the central screen have shown this yet. Are the settings in the App repeating or do they have to be set each time?