Control Settings

Greetings Givenergy and users of the products.
I have a Gen2 Inverter, with Solar panels and battery. It has been running for two years and broadly works to my expectation. We are on a flexible tariff so I juggle the settings to minimise my electric costs.
For the first year we did not own an EV car, and I found that the 'Settings' options on the control panel were reasonably sufficient to drive the system.
The main aim is to ensure the battery is filled to at least 50% before the expensive period of 4PM to 7PM.
During the winter, a timed charge overnight works is best, but ensuring the battery is still charged by 4PM is a gamble.
During the summer, the ECO mode generally ensures the battery is charged by 4PM.
So the control settings generally worked out.
However, this year, we now own an EV car, and charging the car is a nightmare of juggling the inverter settings against the need to keep the car charged. My wife decides when to charge her car, and I need to power up a PC and change the Givenergy settings to stop the EV car from flattening the Givenergy battery.
Generally, in the winter we charge the car overnight when the electric tariff is low. The Givenergy battery is exhausted and there is no solar, so the car charges from the grid. But setting a timed charge on the Givenergy battery is tricky: If the Givenergy battery is set for a timed charge, later on the EV charger might come on, and exhaust the Givenergy battery first and then charge from the grid. A solution might be to charge the car first and then the Givenergy battery.
When the Summer comes round, the Sun will help power the house, and put excess into the battery. But using the car EV charger during the day will exhaust the Givenergy battery leaving no battery power by 4PM.
Juggling the Settings controls to try to keep on top of this is a trial and I am hoping that Givenergy can look into this and come up with a cleverer Settings control panel.
Proposal
(1) The timed charge option is duplicated.
Charge option one is used overnight, and is selected when overnight Energy cost is low.
A further option should ensure that the battery charge is preserved and not used until say 6AM.
Charge option two is used during the day, to ensure the Givenergy battery has at least 50% charge by 4PM.
(2) Battery options.
If the battery could have a timed minimum charge setting this might keep the battery charge for when it is needed.
Setting 7% minimum between 4PM and 7PM and 40% minimum at all other times might work out.
This could ensure the battery has useful charge during the expensive period, without needing so much supervision.

Hope this provokes a discussion, and Givenergy gives some thought to these issues!

You could get on tariffs like Intelligent Octopus Go for import at 7p per kWh and Octopus Fixed Outgoing at 15p per kWh. Then overnight from 23:30 to 05:30 charge your car and house battery and run the house load. During the day solar will keep the battery topped up for the daytime and evening load. Whilst the battery is full then any excess solar power will be exported. At this time of year and onwards til autumn you are likely to make money this way. IOG can also give you off peak rates for half hour slots that Octopus may provide. There are other similar tariffs such as Eon Drive from other providers.
Setting inverter to Eco mode and a charge slot for the off peak period for the house battery plus a scheduled charge for the EV should let you largely set and forget.

mike_bcd what model of EV / chargepoint do you have? And which tariff are on on that makes 4pm expensive?
How flexible is your wife in choosing when to charge? Are we talking what hour of day, or which days of week?

Hi there DD, and thanks for getting back so promptly.
The tariff is the flexible octopus. It can be very cheap if it is windy overnight, or sunny during the day.
The tariff rises at 4PM to say x4 rate and reduces again at 7PM.
Lately when we have had dull calm days, the 4PM rate has approached £1 per unit!
Most of the time it is much cheaper than that. The export tariff is always half the import tariff.
Now we have an EV car it would be better to always dump the excess Solar into the car if possible.
What I am looking for from Givenergy is a way of keeping the battery charge for when I really need it.
The control settings are currently far too primitive when matched to an EV charger, although seemed sufficient before.
Currently we are using a basic EV charger. I will buy something posher when I better understand the requirement.
A posher EV charger ( I already have the power and network cable installed ) would suck the Givenergy battery dry in minutes if it was allowed to contribute to the EV charger demand.
The car has a timer system built in, so I can live with this setup for now.
With basic charging to the car it takes about 2kW. Add in my house load and office load, on a sunny afternoon 50% power will be from the grid ( or being sucked from the Givenergy battery ) and 50% from the Solar.
The Givenergy battery 5.2 ( its really 2.6KW ) if charged fully overnight would quickly deplete during the day and nothing would be left by 4PM if the sun didnt shine. I want a way to preserve say 50% until 4PM.
If on the other hand I did fully charge the Givenergy battery overnight and the sun did shine I would be fully charged and would need to export the excess or plug in the car! An overnight charge to 50% is a good compromise.
Note I work from home in an Electronics design studio, so my day time demand will be much higher than somebody going to work every day and coming home in the evening. My network server also means I need 300W overnight.
One option would be a bigger Givenergy battery. But the control system still needs to preserve the juice until its needed..
Look forward to further posts! M.

mike_bcd Mike, you say you are on “flexible octopus”, that isn’t a tariff name! I’m guessing from your description of it that you are on Agile Octopus.

Agile has not been particularly good for most of this year, its been relatively expensive overnight (18p overnight), about the same in the day, and then about 40-45p in the evening peak with a few exceptional £1 periods in January when it was very cold and calm.

It sounds like you are also on the Agile export tariff which pays a variable export rate based upon supply and demand.

Then you describe the problems of your battery discharging to your EV.

There’s several things going on here, so try to cover them all.

Firstly there is very close to zero chance that GivEnergy will make any big changes to your Gen 2 inverter firmware. The inverter doesn’t have as much memory as the newer inverters an so limited expansion capability.
Plus all the new feature development is going on the newer kit.

But the good news is that to solve your battery discharging into the EV problem you just need to get a bit of rewiring done, which could be as simple as moving the CT clamp for your inverter which you can do yourself.

Been covered several times before but basically you need to have your inverter and car charger arranged like this:

Grid supply —— Electricity meter —— CT clamp for EV charger & EV charger connection —— CT clamp for inverter — House wiring including inverter

Basically you need things arranging so that the inverter CT clamp cannot “see” the EV load. Worst case its an hour or two of an electrician’s time to rearrange things to look like this.

Next, in terms of your tariff, you don’t mention your battery size and whether you do a forced discharge/export during the peak period to get the better export rate, but in most cases even if you do, you are on the wrong export tariff.
You are much better off changing to the Fixed Outgoing tariff which pays 15p/kWh all the time so once your batteries are full in the summer you’ll be getting 15p whereas at the moment you are getting less than this, and only getting a better rate if you do a peak period export.

Several choices as to import tariff. You could stay on Agile and hopefully as the summer comes the overnight agile rates will drop (I was on agile for 16 months and am hoping this happens). Or you could go onto one of the EV tariffs which give you a longer and cheaper overnight charge rate, but during the day its more expensive than Agile.

geoffreycoan there is a flexible octopus tariff - it's what Octopus call their price cap tariffs e.g. SVR.

But yeah it sounds more like agile + agile outgoing.

mike_bcd 2kW charging suggests a 3-pin (granny) charger, so can't easily hide it from the battery. Might be possible if, for example, that's plugged in in the garage, and that has a separate consumer unit
Perhaps consider Go tariff with fixed export. Fixed cheap overnight hours, and doesn't have the peak 4pm rate. But daytime power is probably a bit higher.

What I've done to stop my EV draining the battery instead of charging from the grid overnight, is to reduce the battery's maximum discharge to say 1000w, i.e. below the minimum needed for the EV battery to charge.
I do this at bedtime when there will be no other load on the battery and of course you need to remember to increase the maximum discharge wattage again in the morning.

John_Bennion while 1kW isn't enough to charge the car on its own, it presumably still contributes 1kW towards whatever the car is consuming?
Why not charge battery at same time as car, while power is cheap?

DD Why not charge battery at same time as car, while power is cheap?

I do.

But if the the time for cheap power isn't for an hour or two, it prevents the battery being drained in the mean time.

John_Bennion the obvious next question is why don't you wait until power is cheap before charging the car?
And if the cheap period hasn't yet started, maybe it does make sense to drain the battery, when it will be able to be recharged soon?

hello All, Geoffrey,
thanks for your comments. I did mean 'flexible octopus'. Its not very economic currently, but I guess other tariffs have gone up as well. The tariff is pretty flat today, with a peak 4-7PM.
If Givenergy would look at blocking the battery usage over specific times I would appreciate it. My first post is one solution if there is enough firmware space in the Gen-2.
The idea of isolating the CAR charger feed from the metering is a good one. I looked at the block diagram left by the installer, and it is not helpful, as it is totally generic, so I looked at the installation myself, and came up with the two block diagrams I have attached. ( Possibly!)
The existing installation has a CT clamp on the live tail outside the consumer unit so it always monitors grid import/export.
The ECA2 meter is monitoring the Gen-2 current in/out.
To isolate the CAR charger current from the EM115 CT clamp needs a fair amount of rework.
Inside the consumer unit, the live bus bar needs to be isolated from the Car Charger breaker, and the Live bus bar taken via a 60A ( minimum) jumper cable to the main breaker. The EM115 CT clamp is moved to measure the current in this jumper cable. There is limited space inside the Consumer unit, but it should be possible.
Its better explained on the attached block diagram.
This looks like a fix to me : do you agree?
Cheers, Mike.

mike_bcd I did mean 'flexible octopus'. Its not very economic currently, but I guess other tariffs have gone up as well. The tariff is pretty flat today, with a peak 4-7PM.

Flexible octopus is their SVT tariff, so either single unit price, or eco 7 with a day rate and a night rate. It doesn't have a 4pm to 7pm peak rate.

Hi all, I can't make the 'upload' mechanism work, Tried the 'my media' instead.
Mike

mike_bcd yes, very messy if they have installed everything in a single consumer unit. I thought installers tended to use separate mini-CU to avoid disturbing existing kit (and therefore being responsible for it). I have separate mini-cu for each of GE, EV and heat pump, using Henley blocks to split the tails.

DD
Hi DD. Something wrong with my brain wiring. I wrote 'flexible' when I meant to write 'agile' !!!!

Sorry for the confusion. M.

mike_bcd have you considered an EV tariff, like Go ? With a relatively small battery, you can't store much overnight to cover daytime use. So it depends a bit how much your EV uses, and how much you can shift overnight (eg washing machine, dishwasher). Before I had battery, I was probably using more overnight than daytime, so av. unit price would have been around 15p. Unfortunately daytime import prices are about to go up.
I did try solar charging EV, but it was frustrating when clouds passed over. That was back when Go export rates more or less matched overnight import rate. These days, much simpler to just import overnight and export all solar.