Upgrade of electrics to 24V

The MPPT controller for the solar-battery system can only handle solar voltage of up to 80V. Since my solar panels are connected in series, this voltage will be exceeded. Currently the three panels produce an idle voltage of 66V. If I would connect the 4th panel, the voltage could be 88V.

This is in the 12V mode. If the controller would operate in the 24V mode, a max voltage of 160V would be accepted.

Therefore I decided to upgrade my system to 24V. 

And I went for a real upgrade: two LiFePO4 batteries from Amazon. LiFePO4 is supposed to be very safe, no fire hazard. Is currently the standard for RV and camper batteries.

Most of the 12V equipment can also operate on 24V: refrigerator, circuit breaker panel. The invertor needed to be replaced: I had a spare 24V inverter from my experiments with the solar system of my home.

The batteries arrive:

Each has a capacity of 100Ah. Together they have about 5 kWh capacity.

Connecting them in parallel.

The inverter.

Inverter connected to the battery.

Affixing the manual circuit breaker and the battery volt meter.

Batteries are connected.

Circuit breaker panel is connected.

Refrigerator is operating on 24V (25.6V).

Current temporary wiring of the internal battery-powered electrics.

The UK-circuit checker shows "missing ground" when connected to the inverter.

The 230V fuse panel, operated with converter voltage.

Settings of the selector switches: lower left switch:  1 = from extern power, 2 = from inverter; upper right switch: 1 = regular polarity, 2 = switched polarity (phase is on other line).

Power from solar panels when solar is connected to controller: 38.9V

Power from solar panels without connection to controller: idle voltage = 66.2V.