Old 4kw solar + New 8kw solar and battery techy questions, monitoring and battery charging

aln230857

Hi Newbie to the forum and relatively non solar technical..

if anyone out there is techy can you answer a question.

details first.

1. I have a 2011 4kw solar array and 5kw Fronius inverter (non hybrid) and no external monitoring. This is running on the FIT tariff on a shed roof  E/W  in my garden

2. I'm having a new 7.8kw system with 6kw hybrid inverter installed on my house roof East facing and a 10.2KW battery all FOX. Plus Zappi, eddie and harvi. 

Questions:
1. can I charge the new battery with excess solar from my old 4kw system as well as from the new.
    I'm assuming the fox inverter would see this as incoming ac as if from Grid???
2. The old fronius inverter has to have a "data logger" rs323 interface installed, does anyone know if there's an easy/ cheaper way to integrate monitoring with the new system without forking out £300 for an ancient Fronius data logger upgrade. ( I suppose I could replace the Fronius with a 5kw fox string inverter )

Thanks in advance if anyone can help.
kind regards
Alan

fishfienduk

If you're using foxess equipment, you might be better off querying this group, as it deal with that equipment exclusively..very helpful I've found.

Ha.. can't post links yet.. there's a foxess Facebook group.. I suppose you can search for it..
Good luck

Heedtheadvice

Why do you need or want the data logger? If you are getting a Zappi that will give you power information.

Charging the new batteries from existing solar output will depend on the facilities of the new hybrid inverter - its ability to 'monitor' export and know it is coming from existing solar. Usually done via simple CT clamp measuring devices feeding devices.

The Zappi has such devices to be smart for EV charging and thus flexible in using the different AC energy sources (grid or existing fronts solar) but not for a battery that uses DC as its energy source ( hybrid inverter from the new solar).

Not sure why you are thinking of an Eddi. Great device but unless you can divert any excess power production to somewhere useful then there is not much point. Current thinking is that it is cheaper (as your new excess power will not be available for FIT ) that such excess can be better utilised on inport/export Tariffs. Much written on here.

I presume you are aware that such a new solar installation and batteries potentially make your grid export very big ( the sum of all the 2 solar systems and battery) and not only will the local grid power dustributor be interested it is quite likely that ( if domestic supply) your electricity main incoming cable and main fuse cannot cope!

Several things to know about and confirm  before commiting to spend!

Others with similar systems as yours under consideration and knowledge will be better placed to advise.

aln230857

thanks  yes DNO  (G99) has approved 8kw export limit overall.   Been at this since before last XMAS. waiting for installation date.  Intend on purchasing EV so along with hot tub I think I'll use most solar generated.  as far a Eddie is concerned it was recommended for heating hot water last year when I started on the whole battery and upgrade route.  Out of 7 quotes I don't think any have said its too much solar just what will fit on roof.  It is east facing so not getting sun all day?  I've upgraded to smart meter  which delayed things and  have moved to Octopus but not yet switched to any "special" tariffs unitl the new install is done. 
 Thanks for the comments and help. 

Solarchaser

I can recommend zappi and Eddi as I have them both.
As Heedtheadvice says they monitor with CT clamps, usually on solar and mains to then decide on whether to charge/heat or not.
Your hybrid system will make that more of a challenge due to it charging batteries via DC.

I'm assuming since you have been at this a while, your west facing roof is unsuitable?
I ask because with east facing you will get alot in the morning, when you don't need it so much, and then very little in the afternoon/evening when you would tend to use more.

The eddi can be set to heat your hot water tank, and then when it's hot enough, move to heating your hot tub, which may be useful.

Having a 4kw system is pretty standard for the last 15 years, but having a 5kw inverter isn't, usually you would have a 3.6kw inverter,  and these will certainly be more prevalent if you are looking for a cheap replacement. 

On a different note, there are many options for rs232 to usb conversion,  so if you are handy with python etc, I assume you could datalog with a pi or an old laptop, but either way, you myenergi gear will log all of your older system solar for you... though currently only really let's you access this month and last month unfortunately