Growatt WW and an Octopus heat pump

beebop

Hi there,
We have recently had a 9KW Daiken heat pump and hot water tank installed by Octopus. We also have an EV with an OHME charger and Growatt 3600 Hybrid inverter and 7Kw of batteries. Our current tariff is Octopus Intelligent Go and our WW account is configured as follows:
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Our hot water tank charges itself between 1am-3am and it seems to be discharging the battery. Assuming we change change the water heating timing to say 12am, is it possible to use WW to only charge the batteries after say 2am so that the batteries stay charged until morning?

MrMessy

beebop Is there a reason you want to "Hold charge" your battery, rather than just allowing it to charge to full during the default IOG period?

Most people with this sort of set-up, myself included, need all the battery capacity they can muster over winter.
Charge to 100% overnight, charge from solar, charge in any smart charging slots.
More is more.😁

KristianS

MrMessy I have the same thought. I am not sure why in this case @beebop you have enabled 'Hold Charge' set to ON. There are other use cases where I can see the value in holding charge, but not in the instance you describe above. But maybe I am missing something

beebop

I find the wording of this section very confusing and its not well explained what 'Hold Charge' actually means. I want teh batteries to be charged overnight but then not to discharge when the EV is connected and charging.

Installing the heat pump has increased our use of electricity up to a rough average of 40kwh per day inc charging two cars. Will need to do some sums to see how many batteries our Growatt 3600 inverter can handle and whether the cost of the extra batteries is worth it.

admin

beebop Hold in this context really means it will set a battery charge for the current SOC at the start of the EV charge for IOG.

The idea is that you will roughly end up on the same SOC at the end of your EV charging session. If you don't want that, simply set Hold to off, and you can select a target SOC to charge to.

johalareewi

On the Agile scheduler, HOLD CHARGE will send commands to the inverter to limit battery discharge to a set rate (like 500W) so that the battery can provide enough juice to run the home base load forcing any extra to come from solar or the grid. This effectively stops the solar battery charging the EV.

I imagine HOLD on IOG scheduler does something similar?
Although it looks like you can't set a discharge lrate.
The text saying the battery will not charge or discharge seems a bit wrong because AFAIK, when the EV is charging on a cheap slot, WW will set battery to charge at the cheap rate. You only want battery discharge stopped (not charge).

If your inverter has an option to show the remote commands log, you can see exactly what WW is doing.

Also, the WW HOLD feature on Agile has been broken lately. Maybe IOG HOLD is too?