Converting my off grid solar system with transfer switch to a Hybrid Grid tie system

[alexmouris]

Greeting to all,

I would like your advice on how to convert my friends system which is off grid with battery to a Grid tied system.

Current setup.
2x540watt Sharp Panels ( limited roof space. max i can do is 3x540 !!!!!! )
Victron 100v-50a smart MPPT charger
Victron 1200VA 24v phoenix inverter
2.5KWH lifepo4 battery (eve cells with JK BMS)
Automatic transfer Switch using Hager relay.

Use case.
The offgrid system powers the fridge and the rack (router, poe switch, 2 servers, 3 Access Points) total 300-800 watt consumption
When the batteries are low, in the afternoon, the automatic transfer switch goes into Grid mode until the next morning when the sun is up again.

What i want to achieve.
1) I would like to Grid Tie the setup so that it supplies power to the rest of the house.
2) I would also like to have the batteries at a constant charge (lets say 75%) and to use them only as backup power when the grid fails (for fridge and freezer and maybe emergency lighting)
3) I would also like to not feed back to the grid because the license fees to do that in my Country are too much to worth it.


The Grid
The Grid is 3 phase 240volt 50HZ.

My concerns
1) i can not find a 3phase inverter that can provide power to the grid that works with only 3 panels. (i am normally at 110-140 volt PV input)
2) The inverter Must have a no feed to Grid function to Avoid problems with the power company.

Is this even possible?

Thank you all for your time.

 

[OffGridForGood]

What i want to achieve.
1) I would like to Grid Tie the setup so that it supplies power to the rest of the house.
2) I would also like to have the batteries at a constant charge (lets say 75%) and to use them only as backup power when the grid fails (for fridge and freezer and maybe emergency lighting)
3) I would also like to not feed back to the grid because the license fees to do that in my Country are too much to worth it.

What you want to do is grid tie - zero export.
I don't know any equpment that will do this with 3-phase.
The small system with only a few panels will not collect enough energy to run one fridge and a router, what is the point of 'conection to the rest of the house? item #1
with more loads the batteries will run down faster?
To hold the batteries at 75%, you need another energy source or more PV panels. The ones in the picture have two panels shading two below them - those lower panels are likely collecting no energy at all. Can the upper ones be moved back enough to not shade the lowers?

 

[alexmouris]

Thank you for your response.
There is equipment that does grid-tie - zero export. i found a few solutions (huawei, sma) and with 3 phase as well but they require too many panels to operate. (6+) because they need 200+ volt staring voltage to operate.

At the moment the battery depletes at around 8pm. After that it switches to Grid.
The point is to to have the battery only for backup power in case of grid black out.
Also at the moment the house is divided into 2 "power sources"
the hybrid (solar+battery+grid) that powers fridge etc
The 3 phase Grid that powers the rest of the house.
Pretty complicated at the moment.
I would like to simplify the setup so that there is 1 inverter + battery for backup + GRID.

In the picture there are only 2 PV panels. What you see below is a solar water heater. it is positioned that way:
In Winter there is no shade to the Water heater
In summer there is around 30-35% shade to the water heater.
This is done on purpose because summers in Greece are so HOT we need to shade half the water heater to protect from Overheating.

What i was thinking is add a 3rd panel perpendicular to the 2 i have already. maxing out the usable surface.

Bare in mind the roof is common space. and "fair use" only covers that space you see in the photo