Possible new installation

Hi all. First post.

I have a surveyor coming today to look at a 4.something solar array, 5.2 kW battery, hybrid inverter and Zappi EV charge point. I'm keen to have a 'set and forget' system where the battery and car charge at night on Go (whenever the bloody smart meter gets fitted) and during the day the solar feeds the house, keeps the battery topped for the evening and any excess goes to the car. My question is with this system will it be possible for the Zappi to determine where the energy from the hybrid inverter is coming from? I don't want the sun to go down, the battery to come on line but discharge into the Zappi/car because it thinks its excess solar.

Thanks,

73henny Hello! I assume that you won't be able to fully charge the car within the 4 hours of Go at night and this is why you'd like to top up the car during the day? This is definitely possible with the Zappi but it will charge at a slower rate obviously, and the surplus needs to be at least a constant 1400w. The Zappi charge won't go under 1400w (unless your car itself slows down the charge, at the end of the charge for example).

The Zappi won't be able to detect what is battery and what is solar with a hybrid inverter, it will see it as solar + battery combined.

But there are settings within the Zappi which you can get to stop it from using any energy from the battery (myself and others have tried and tested and it works). The Zappi has different settings called Eco+, Eco and Fast.

For what you want you'd have it always on Eco+ at 100% MGL (Minimum Green Level) with a minimum export maintained of either 50w or 100w. This would make sure that it wouldn't start charging unless there was a minimum of 1450w or 1500w depending on the minimum export you'd set it at, and will keep a small export going to keep it from eating up the battery. Then it would charge at least at 1400w speed or higher if your surplus increases.

Then you just create a schedule to boost everyday between 00:30 and 04:30 and that will charge at full speed during the Go hours.

Many thanks for your reply. If I understand correctly when the settings you suggest are applied the inverter is only exporting once the battery is full and the Zappi then charges if it sees an export of 1450 or 1500w?
What happens then when the sun goes down? Doesn't the battery 'take over' and the Zappi then think there is excess coming from the inverter? Similarly what stops the battery exporting back to the grid?
Apologies for the questions - very new to this but keen to get it as close to right as possible. Surveyor arriving today and I'd like to be as informed as I can be. Still unsure if the loft is or isn't a good place for the inverter too.

73henny Many thanks for your reply. If I understand correctly when the settings you suggest are applied the inverter is only exporting once the battery is full and the Zappi then charges if it sees an export of 1450 or 1500w?

That's correct.

And if you want to "boost charge" at a higher speed than 1400w without taking anything from the grid you can set the battery to export and the car will start charging from both the panels and the battery. I use this often when I know that the battery will be able to recharge throughout the rest of the day.

73henny What happens then when the sun goes down? Doesn't the battery 'take over' and the Zappi then think there is excess coming from the inverter? Similarly what stops the battery exporting back to the grid?

The Zappi can't detect what is battery what is solar, but it can detect if there is export going to the grid, that's what it uses to identify export correctly. It will stop if all export stops.

No problem about the questions, we've all taken a bit of time to understand what work best for us!

So the surveyor has been. He thinks the Zappi can determine whether its battery or solar being supplied from the inverter.
Looks a straightforward installation though.
I still have some questions however. It is disappointing that with Octopus go you can't have their SEG tariff and similarly it seems having a battery makes the SEG a lot more complicated. How do I stop the battery discharging to the grid? I don't understand why when there is little house load the battery doesn't just discharge at its maximum rate to the grid?

I’ve been through this and going AC coupled instead of hybrid.

Zappi can tell for the AC coupled batteries but not for hybrids. The work around mentioned above does sound like it does the job though.

73henny you can definitely have SEG with octopus go (pays 4.5p). You just can't have their Agile Export tariff.

You can apply for the basic SEG here, once you have your DNO letter of approval and the MCS certificate for your installation: https://octopus.energy/help-and-faqs/categories/tariffs/seg-tariff/

The Zappi definitely can't read what's solar whats battery from a hybrid inverter, but the workaround I mentioned works. It can detect from AC couple inverters as mentioned above.

If your bothered about the 0.5p difference you can also try SO Energy - Theirs pays 5p.
Worked well as essentially net metering for me (on 5p/15p tariff still) but come September i'll have a delta again.

As for how it doesn't discharge - the CT clamp monitors essentially flow direction - normally always aiming to have 0 flow inbound to save money by either using PV energy or Battery or both.
If it sees it going out to the grid (and you've not asked it to) then it stops the battery discharging until it goes back to 0 flow.
When battery is full and PV is covering house loads then the inverter ups the voltage slightly above the grid voltage and the excess flows out.

73henny As Huntzie has said you definitely CAN have the SEG with Octopus whilst on their Octopus Go tariff as I have it in the same scenario since mid February this year. Mine is currently exporting at 4.1pence per unit fixed until Feb 2022. Its not going to make me rich but with the current weather it is a helpful credit on my energy bill to set against the increase in prices for units that I am buying from the grid

Can you be on Octopus Fixed export (7.5p) and "Go"?

wilfleek I don't believe so.

Octopus Go and Octopus seg work fine together. Though you are limited to the 4.1p kw seg. But thats fine, thanks to the battery most of the usage is at 5.5p for me and so export off sets the usage and standing charge and even some of the juice needed for my ev.

wilfleek No, I should have said that you can't be on their Outgoing Tariffs, that includes Agile and Fixed.

wilfleek No, they wont pay you a profit. That would be bad business 😄

THALL To be fair if you're in the new Octopus Go which costs 7.5p, it wouldn't be a profit on the Outgoing Fixed! If you were to fill up your battery at night and export that, that is... would still be a slightly better deal to export your free solar.

Huntzie True. I did not think of the new rates before posting.

BTW my fix is to February 2023 - just not sure what date it is at the moment as doing year end accounts for 2021 and month end accounts for 2022. I just know that it is today!

I do wish GE would release their new charger and hopefully put an end to compatibility issues!