New French wood 2 storey Garage, PV & electrics installation.A 3.7kW Photovoltaic PV, and its electrics installation, that will join my other 14kW of PV here that is also collecting the sun light.
These are UpToDate, Dec 2020, LONGI 370w split monocrystalline PV panels, each panel is 1760mm x 1040mm and 35mm thick. Each has a maximum output of 40.5vdc at 9.1amps. I call these Longi panels medium quality, makers like LG and Panasonic etc i call top brand panels.
Firstly, SAFETY, if your not sure then please!, please! ask a competent qualified person.
This electrics installation is for France and complies to the French regulations, which after all these years I actually like. The earth system here is a 1.5m rod bashed into the ground and linked to the distribution fuse boxes with a earth 16mm/2 cable. MCB’s here are 2 pole, so both N & L are protected, in France we do not use a common Neutral bond/bus bar, nor do we bond the Neutral to the Earth.
For this installation on the south side of the new garage slate roof, I have 2off used/second-hand 1700W SMA Grid Tied Inverters, GTI’s. These will feed into the OzInverter created 240vac Mini Grid. Therefore, I have split the 10off PV panels into 2 strings of 5 panels each, and those 5 panels will give a maximum of 202.5vdc at 9.1amps into each GTI.
The 2 GTI inverters will convert the 202.5vdc into 240vac and this will feed back into the OzInverter MINI GRID that is connected to all the 8 buildings here.
If the electricity being created by the PV is not being used around the buildings, then any excess will back feed through the OzInverter and re-charge the batteries. If the batteries are fully charged then the AC voltage will rise slightly by a few volts and shut the SMA GTI inverters down.
Please note, it is very important for the life and longevity of your batteries, that they MUST NOT BE OVERCHARGED.
So setting the GTI shut down voltage is specialised for each GTI, as its location for voltage drop/droop, and its own internal settings do vary. Dc battery voltage Comparator circuits can also be used to operate a relay at the GTI to shut it down. Another method is redirection circuit or specialised battery controllers that sends excess power to Dump Loads or other uses like underfloor heating or swimming pool heater etc.
Costs so far, the 10off Longi PV panels with transport fees, tax etc, $1920 or 1600 euros, 2off SMA 1700 used GTI’s, total $204 or 170 euros.
The 10off LONGI Mono PV panels.

The hardware electric boxes and wire channelling/trunking and 2off GTI inverters gets installed. That white board is plasterboard over a 18mm plywood support back board, it is a wooden garage, and those GTI's inverters are 30kg each!