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Discussion Starter #1
All,

Current Car: Vauxhall Ampera

House: 4Kw of Solar, 19.2KWh of house batteries

Electricity Supplier: Octopus Go

New Car: Kia eNiro (eventually – probably next year when / if it arrives)


I currently have an old chargepoint, non tethered, capable of 32Amps - Polar/Chargemaster which works still. So at the very least I will need to change the cable. I also have an OHME cable that I don’t use and which again, if I buy another, would need changing (I don’t use it as it doesn’t really communicate with the Ampera properly).

As I will briefly own 2 EV’s I can order a second charge point at a discount, probably replacing the first so I thought I would ask here – which one is the smartest.

I have both solar and batteries so any sunshine charges the house batteries first and should then charge the car if any left over. Car should charge normally during the 4 hours cheap rate up to a %SOC that I set (somewhere). Alternatively, if I switch to Octopus Agile (maybe) then I would like the charger to take that into account. Essentially I want to be able to control the charge from the charger, meaning that I can leave the car to accept charge at all times – so if I go elsewhere and charge (either Granny or other charger) I don’t have to override settings

Anyone got any suggestions?
 

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It think the Zappi will do most of what you want, except for varying output to follow Octopus Agile. There may be ways of doing this but it may require some work.

I have a Zappi and am happy with it, would get another. Someone on another thread was looking at SolarEdge EV chargers, which could be another option, particularly if you have SolarEdge inverter and/or batteries
 

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Zappi. Or the Andersen EV if you want one that looks neater
 
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Benefit for me of the Zappi is that if you have more than one device (solar, battery, Eddi hot water diverter, 1 or 2 Zappi) you can prioritise what uses solar / grid when, and whether any excess solar is used by the battery, the car(s), the Eddi....
 

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Discussion Starter #9
Been looking further into this.
If I use a zappi then I will need:
1 * Zappi
2 * Extra CT Clamps (+1 with the zappi = 3 total)
1 * Hub
I may need 1-2 Harvi's depending on whether I can hardwire the CT clamps - which seems a better plan anyway

This way I can
1. Charge the car on Octopus Go at the cheap rate using Boost
2. Push solar to house batteries as a priority and prevent the house batteries charging the car
3. If house batteries are full and > 1.4Kw is available from solar AND car is less than max set SOC then push surplus solar to car otherwise push to grid.

Also, assuming 100% efficiency (for the sake of the maths)
Octopus Go = 4 hours. EVSE is 7KW = 28KWh/day into the car batteries = 2.3 overnight charges to fully charge the 64KWh (0-100%, which is hopefully unlikely) battery which given I am retired and don't use the car every day is fine.
Also, I do use a lot of electricity so the number of days where:
1. House Batteries are full
2. Suplus Solar > 1.4KW (1.4KW is minimum to activate Zappi apparently)
is fairly limited so is probably not worth worrying too much about
This sort of event tends to happen high summer and during that time I tend to turn on the AC anyway and I do love me some "free" Airconditioning

Also zappi are looking at integrating Octopus Agile in a future update should I want to go that way.
 

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Benefit for me of the Zappi is that if you have more than one device (solar, battery, Eddi hot water diverter, 1 or 2 Zappi) you can prioritise what uses solar / grid when, and whether any excess solar is used by the battery, the car(s), the Eddi....
If you don't have anything more complex than an EV to charge - is the Zappi still worth it ?
 

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If you don't have anything more complex than an EV to charge - is the Zappi still worth it ?
Load control could be useful. Which is the Zappi monitors total load demand of your house and then scales down the EV charging output according to the settings you set.

e.g. your house main fuse may be 80A, you could set Zappi to "only total demand below 70". If your EV is charging at 32A and you then turn on a bunch of stuff round the house (oven, kettle, power shower, etc.) - Zappi will scale down the EV bit.

I'd love a Zappi, but the cable management is just poor (nothing beats the Andersen for this feature). Maybe if I wait long enough Zappi will release something better!
 
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Load control could be useful. Which is the Zappi monitors total load demand of your house and then scales down the EV charging output according to the settings you set.

e.g. your house main fuse may be 80A, you could set Zappi to "only total demand below 70". If your EV is charging at 32A and you then turn on a bunch of stuff round the house (oven, kettle, power shower, etc.) - Zappi will scale down the EV bit.

I'd love a Zappi, but the cable management is just poor (nothing beats the Andersen for this feature). Maybe if I wait long enough Zappi will release something better!
Thanks !
 

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Discussion Starter #13
I have been thinking - which is a dangerous activity in and of itself.
Current Situation:
I have a significant quantity of batteries connected to the house (19+KWh) that I charge overnight off Octopus Go. If the batteries are flat in the evening (poor solar or I use a lot) then I cannot charge the batteries fully as Octopus Go is only 4 hours (I suppose I could switch to Go Faster at 5.5p rather than 5p). Essentially I use a load of power at night charging the car AND the house batteries and import mostly very little during the day. I do however use quite a lot (Base load of 1.0KW (ish) due to computer equipment running 24*7) before any optional use.

Note that the EVSE is inside a locked garage

As things stand worrying about solar power charging the car is not a major worry as any solar goes to the batteries and its a corner case where the batteries are full during the day (it does happen but only on really good solar days) so as long as I stick to Octopus Go then the Zappi is a luxury as the only rules I would be working under is "only charge car during 00:30-04:30" the divert 1.4+Kw to car during the day requires a good solar day and for the batteries in the car to be discharged AND the solar house batteries to be full. What I actually need is a charger I can remotely control, so I can force a charge to the car if I need to for some reason. Potentially I could do this with a Ohme and a 32Amp Commando socket rather than a full blown EVSE.

A lot cheaper (in fact I could continue with the Chargemaster and the current Ohme (with a new end on it), other than the simple issue that the charge point will need to move a bit from where it is due to the charging point on the new car being different). Note that the battery inverter does 3.6KW so (ignoring losses) 4*3.6=14.4KWh into the batteries overnight. Actually Go Faster is looking good even at the slightly increased price, in particular over winter when solar is low. Currently my average price for electricity last month is 5.51p. I think I shall ask to switch tomorrow for the next 6 months

I have been looking carefully at Octopus Agile but as far as I can tell based on my gut feeling maths electricity would cost more as its rarely down below 5.51p seeming to hover around the 7-9p as its cheaper rates (more work required to confirm my gut feeling). And whilst the -ve pricing would from time to time be nice its not something I can rely on. So as I have already invested in a fairly large quantity of batteries Agile seems expensive. I could have spent less on batteries and then offset power to cover the expensive points - but I have too much battery capacity for that to be sensible when I can get power at 5 / 5.5p

Conclusion seems to be go cheap. If I need a new EVSE then a cheaper remote control unit would be enough, rather than a Zappi or just use an Ohme cable and a 32Amp Commando. The Zappi would give me extra options, but only in a corner case which isn't worth paying too much attention to. A few days a year does not make a significant difference overall. All I actually need to do is limit the charge time (unless overridden) to the Octopus Go times.
 
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