Growatt Battery Setting Help

pcgtron

Hi all. 

Now that the days are starting to get longer, although not long enough yet, I'm looking for some advice in regards to the battery settings on a Growatt. 

Since the Solar and battery has been installed, I've been charging the battery using a cheap overnight tarrif (Intelligent Octopus) and then discharging the battery during the day. This has worked since November when it was all installed. 

Come April, I would assume that the sun will start powering the house during the day, and also charge the battery, which would then provide us with power during the hours the sun has set. This is where I think I come up with a problem. 
I'll still be charging the car overnight using Intelligent Octopus (Every day during the week), but I don't want the power for the car coming from the battery as this would drain it pretty quickly. In a perfect world, I would love the car to charge using the off peak grid prices, but the house to be powered by the battery. 

Now i've actually written this out, I don't know how this would work in practise. Is there a setting within the growatt settings that would allow this, or as the whole system is grid tied, would this actually be impossible. Will I still have to set the growatt to charge between the hours of 1130 and 0530 and just hope that there isn't much to put into it?

We have 13kw of useable battery power, so this would easily power the house should I not charge the car, but the reality is I do 20k miles per year, and the car puts in approx 30kw Monday to Friday. 

Thanks for your help if anyone knows a setting that would help

Officer_Dibble

I think if you switch the inverter to "battery first" for the whole of the Intelligent Octopus hours, that will charge the battery up to the "Max charge SOC" percentage then after that (or at the same time) draw from the grid to charge the car. On a sunny day the Max charge just needs to take you through until 10am or whatever, on a dull day you'll need it higher.

The growatt settings are a bit obscure (and it doesn't help that it sometimes takes several attempts to get them so stick) but I think that should do it.

pcgtron

Officer_Dibble said:

I think if you switch the inverter to "battery first" for the whole of the Intelligent Octopus hours, that will charge the battery up to the "Max charge SOC" percentage then after that (or at the same time) draw from the grid to charge the car. On a sunny day the Max charge just needs to take you through until 10am or whatever, on a dull day you'll need it higher.

The growatt settings are a bit obscure (and it doesn't help that it sometimes takes several attempts to get them so stick) but I think that should do it.

I think this is what it does already though. I charge the battery and charge the car at the same time during the off peak hours. 

What I'd love to be able to do is charge the car through the grid, but use the battery to power the house use in this time period. 
I don't think that would be possible, but would love to be able to do it

Officer_Dibble

Ah, I see - not sure you can do that. Though if you were drawing from the battery overnight there'd the inefficiency of going into it and back rather than drawing straight from the grid. Also if you're on a decent export tariff (eg Outgoing Octopus) you'd might as well get the battery charged overnight and export for more than it's costing you.

Solarchaser

I think for you to do this you would need the neutral from your EV charger circuit to run through the CT clamp of your growatt, this would mean the growatt wouldn't see the draw of the ev charger as it has both positive (mains draw) and negative running through the clamp essentially *blinding* it to the ev draw.

It would also mean your growatt would have no record of the EV drawing power though, so for instance your growatt may report you have used 100kwh of mains, when you have actually used 300kwh, but 200kwh were for the EV that the growatt couldn't see if that makes sense?

pcgtron

Officer_Dibble said:

Ah, I see - not sure you can do that. Though if you were drawing from the battery overnight there'd the inefficiency of going into it and back rather than drawing straight from the grid. Also if you're on a decent export tariff (eg Outgoing Octopus) you'd might as well get the battery charged overnight and export for more than it's costing you.

Can't be on a decent export tariff as I'm on intellgent which doesn't allow me to be on outgoing as well. 

pcgtron

Solarchaser said:

I think for you to do this you would need the neutral from your EV charger circuit to run through the CT clamp of your growatt, this would mean the growatt wouldn't see the draw of the ev charger as it has both positive (mains draw) and negative running through the clamp essentially *blinding* it to the ev draw.

It would also mean your growatt would have no record of the EV drawing power though, so for instance your growatt may report you have used 100kwh of mains, when you have actually used 300kwh, but 200kwh were for the EV that the growatt couldn't see if that makes sense?

Makes perfect sense, and the fact that growatt doesn't tally the figures doesn't matter to me, but to be honest that does seem like more hassle than it's worth. 

Jochi85

I have a similar situation to the original poster. The only solution I've found so far is to set the car to finish charging at 4.30am, this then leaves an hour of cheap rate electricity to finish charging the house battery. If your EV battery needs a big charge then there might not be sufficient time to charge both, but the majority of the time this works well for us.

SuzeQStan

pcgtron said:

Officer_Dibble said:

Ah, I see - not sure you can do that. Though if you were drawing from the battery overnight there'd the inefficiency of going into it and back rather than drawing straight from the grid. Also if you're on a decent export tariff (eg Outgoing Octopus) you'd might as well get the battery charged overnight and export for more than it's costing you.

Can't be on a decent export tariff as I'm on intellgent which doesn't allow me to be on outgoing as well. 

Sorry to reply to old post but yes you can be on IOG and also on Outgoing 15p per kWh. 🐙 backdated about a years worth of export I should have received when they mistakenly put me on outgoing lite (8p per kWh). I’d queried it at the time and was mistakenly advised hence the refund.