managing battery inverter output.

Heedtheadvice

I realise that there are Battery Management Systems but I could be wrong that they only control input?

I am currently planning and installing extra solar generation capacity (about 2.5kWp max) following purchase of an electric vehicle (phev) and Zappi. At many times there is sufficient spring to autumn excess to charge the car. Quite often those excess periods do not correspond to car charge demand times so I plan to install, following DNO approval, storage capacity to time shift for vehicle and household purposes.

Now it would be a justifiable comment that cheap(er) night time power could be utilised (I am on a fixed contract for some time so not currently desired!) and there is no guarantee cheaper tarrifs times will stay. I prefer some independance. Also justifiable is that it is not currently financially a good move to install batteries but I want to optimise my own generation.

So down to the question specifics! What battery output choices are there to control the battery inverter to only discharge storage batteries when car or household demand justifies it i.e. minimise import. I already have the Zappi configured to take priority over an Immersun diverter (which would also take priority over battery charging except when minimum charge levels on storage battery needs maintaining). The Immersun still has the control relay output available (normally triggered when there is unused excess generation) but that is just on/off rather than real excess level unlike the voltage controlled outputs.

I presume a similar system to the Zappi for car charging might be available where one can configure to charge when there is excess without importing (Eco+ setting) might be available on a battery output inverter?

QrizB

Heedtheadvice said:

I realise that there are Battery Management Systems but I could be wrong that they only control input?

...

What battery output choices are there to control the battery inverter to only discharge storage batteries when car or household demand justifies it i.e. minimise import.

Pretty much any AC-coupled battery inverter will have this ability. My Sofar certainly does (and it's been described as "old technology" around these parts).

I can't comment directly re. DC-coupled batteries but if they sense the incoming mains I would expect them to be able to work similarly.

Heedtheadvice

Crikey, you're on the ball tonight @QrizB !! Under 11 minutes!!

I am only considering AC charging source.

Good to know the availability of the control. Thanks

QrizB

I just happened to be here now; I'd been away for a while before that!

Most of the battery storage inverters have their manuals online, so you can have a good poke around in the options before even speaking to an installer.

Heedtheadvice

So I gather you are happy with your Sofar.

 Can you or anyone else suggest which of the competition I should investigate too?

QrizB

Lux products are very popular on this forum, and I don't mean the soap

Solarchaser

QrizB said:

Heedtheadvice said:

I realise that there are Battery Management Systems but I could be wrong that they only control input?

...

What battery output choices are there to control the battery inverter to only discharge storage batteries when car or household demand justifies it i.e. minimise import.

Pretty much any AC-coupled battery inverter will have this ability. My Sofar certainly does (and it's been described as "old technology" around these parts).

I can't comment directly re. DC-coupled batteries but if they sense the incoming mains I would expect them to be able to work similarly.

Sorry buddy.
I didn't mean the sofar is obsolete, just comparatively the lux has a higher charge and discharge rate, and the app is able to instruct the inverter vs the sofar only able to receive information. 

I loved my sofar, it was a good inverter!

Solarchaser

The lux is a good system, I like it.
There is also the GivEnergy systems which are quite new and their batteries are comparatively cheaper than pylontech... or have been.

Heedtheadvice

Thanks for the extra posts @Solarchaser . Will certainly have a look at lux too.

I hope you can help with some associated questions.

I assume that you are in the SP Eergy Networks area given your location. How did you get on with the extra DNO approval to get G99 type A agreement. Did you have an installer do it on your behalf or yourself? Was it easy to do, what was the cost and how long did it take?

 Any further info would be most welcome.

Solarchaser

I am indeed in Southern Scotland and so SP energy networks. 
I called them about adding to my existing array and batteries,  and the lad said "Southern Scotland is already red for renewables, so little chance you will be approved and will be around £400 to apply"

So I didn't bother applying.....

Heedtheadvice

Ah!

Thanks for the post.