Configuration question from a prospective customer

Hello

I am probably going to install a Givenergy battery alongside solar and a Zappi EV charger. I use Intelligent Octopus and I'm not interested in maximising income through Flux etc - I just want to set the configuration and leave it at that until I have some special one-off requirement.

I will configure the Zappi to use excess solar during the day else do what Intelligent Octopus requests overnight. This much I can control through Zappi configuration.

But I don't want the Zappi to take power from the battery overnight because a charge towards the end of cheap rate could leave me with a depleted battery as the peak rate begins.

To support this, the Givenergy configuration I want is:

• During peak time, I want the house to use energy from solar else from the battery else from the grid
• When there is solar, use it for the house, else charge the battery, else export it
• During the cheap period (23.30 to 05.30), always get power from the grid and charge the battery to 100%. That is, set the battery to charge only, not discharge.

Is this possible?

Thanks

Steve

This will be easy to achieve. Set the inverter to eco mode and set the battery to charge at night to 100% so you can take advantage of intelligent 15p/kWh export rate. The battery will not discharge whilst charging. If you want to charge to less than 100% you can set the battery not to discharge during the car charging period.

I have an AIO and Zappi, and what you want is achievable.

The only comment to make it on the 2nd bullet point. In Eco mode the house will use solar first of all. But, the Zappi will only kick in if surplus solar is greater that 1.4kW (assuming MGL is set at 100%). So, the house will use solar, any excess will be exported to the grid until greater than 1.4kW export at which point the Zappi will start charging.

I have to say my AIO is only a month and I haven't had enough solar to confirm it works.

steve99 That is exactly how I run my system.

Pandorian The only comment to make it on the 2nd bullet point. In Eco mode the house will use solar first of all. But, the Zappi will only kick in if surplus solar is greater that 1.4kW (assuming MGL is set at 100%). So, the house will use solar, any excess will be exported to the grid until greater than 1.4kW export at which point the Zappi will start charging.

So the problem is that only high-power solar excess is suitable for the car, whereas the house battery will accept any spare solar. So it might be better to let the car have the excess solar during the middle of the day, even when the house battery has space, and then let the house battery have the "low-value" excess power after it has dropped below the car's threshold.

OTOH, since exporting will give you 15p, but it only costs 7p to charge from grid, there's no financial benefit in charging car from excess solar at all.

anthonypar

Can it be set to charge to 100% and not discharge during the cheap rate, or is the "do not discharge" setting linked in some way to not charging to 100%? That probably sounds like a stupid question when you have a Givenergy battery in front of you, but just checking!

Pandorian

Is that right about 1.4kWh? I think my Zappi will look like house load to the inverter. The Zappi can be set to charge during the day if at least a very small amount of charge (eg 50W) is being exported. When it cuts in the Zappi will take all the charge it can until that minimum is reached. But these are myenergi questions that I can check over in their forums.

Thanks all for your help. I think I will go for the Givenergy battery and hybrid inverter. If it turns out that the Zappi doesn't play as nicely as I expect, I could just replace it with a Givenergy charger later.

steve99 Can it be set to charge to 100% and not discharge during the cheap rate

Yes, whatever % you ask it to charge to overnight, once it reaches that point, it will just sit there at that level until the end of the charge period. Eg I'm currently charging to 60%, which it reached around 2am and then it idled until the end of the charge time at 4:30

steve99 Is that right about 1.4kWh?

It's a feature of the signalling protocol between chargepoint and car. The chargepoint tells the car how much current it can supply, and the minimum the protocol allows is 6A.
https://en.wikipedia.org/wiki/J1772#Control_Pilot

(It's the car that chooses how much it takes up to that limit - some cars allow the car to select less, but the chargepoint cannot offer less than 6A.)

steve99 The 1.4kW figure comes from the Zappi manual in section 10.

DD perfect. Thanks

Pandorian Ah yes of course.

I've decided to go with Givenergy. Should be installed in a few weeks. Exciting. Thanks for everyone's help.