Connecting Batteries to Store excess power

[swissdude]

Hi everyone,
I have just completed my PV install at my Swiss home. I have a Fronius Symo 12.5.3 inverter and 46 Solarworld Glass/Glass Protect modules. I currently produce about 60 to 70KWh per day
My question is this:
I am involved in the IT industry a client recently moved offices and I received a 3 Phase 20KW APC Silcon UPS including 2 battery trays as the new premises already had a UPS in place.
There are 16 Battery Shelves consisting of eight 12V 7AH Batteries, thats a total of 128 Batteries ! Is there anyway to use the UPS to store the excess power generated by the Solar inverter?
Someone said I would need to throw out the UPS and keep the batteries, get 3 Victron Multi pass inverter chargers (or 3 Sunny Island units) and connect one to each phase after my municipal meter before the grid tie inverter.
This would allow me to have greater self utilization of my power created ( we don't get a feed in tariff there is a waiting list of over 4 years )
Any clever plans ?

Many thanks
Ruedi

[Willy T]

I'd see the batteries as the biggest challenge as they are designed to be used in stand by service. Daily cycling of them will soon lead to failure. Inverter's designed for hybrid service may be a better option than the UPS as you said. There are people that use older UPS's and are happy with them.

A thought would be to see if you could sell the UPS system to someone and have a hybrid installed and new different batteries. Put a pencil to the 4 year pay back and see if you feel it's worth the trouble. Even at the end of 4 years you'll still have a stand by system in case of outages or a system you could time shift with depending on your cost of power vs your feed in.

[SunEagle]

I agree with Willy T. Those batteries are really not designed for daily or high cycles. They also may not like the charging logic from the Victron unless you can dial in the specific battery type and chemistry to match the 128 in the UPS bank.

You could use the UPS system "as is" for standby emergency power for "critical" loads but IMO do not expect to get a lot of life out of them.

[Raul]

Hi Ruedi

There is a package on EU market(Growatt) that allows a retrofit storing solution for a grid tied install . However as it has to comply with g83 it means when grid is out it will switch off . It comes as a5kw and it can be built up to your capacity needs .

[solar pete]

Hi Ruedi

There is a package on EU market(Growatt) that allows a retrofit storing solution for a grid tied install . However as it has to comply with g83 it means when grid is out it will switch off . It comes as a5kw and it can be built up to your capacity needs .

Be careful with Growatt, I know of two companies in Australia that popped up selling very cheap systems about 3 or 4 years ago now. They went bust after about 6 months, I spoke to a sparky that did some installs for them and they were using Growatt inverters and he said they had about 90% failure rate after about one month installed. No doubt things might have changed by now, they may be fine, they could be awesome now, but I can tell you we will not be using them.