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Nickel-Iron technology Off Grid Solar Power

Q7: Off Grid - wiring solar panels

Strip wire ends, tape red positive and green negative identification to all wires.

This design has three wires for each of three MPTT solar controllers, rated at 30amps each.

This means the panels are parallel wired and series wired, to make 36V 5A, into two series array of 72V 5A, as this allow more voltage about float charging voltage of 27.4 volts.( more the 10 volts above float voltage is required). Next the array is paralleled , this makes 72V 10 A.

This power (72V, 10A) is fed into the MPPT and we get 26 amps at 27 volts. Nothing is wasted.

Please do not touch 72 Volts DC (@ 10 Amps) as this voltage and current can kill you.

To reduce dangers, each solar panel is wrapped in a blanket during installation.

Blankets and sheets remove power source from panels.

Anderson plugs are cut and removed, to reduce costs. These panels are second hand.

On the roof, color coded each wire, placed in conduit, with vermin wire each ends, and hard plastic elbow into the roof conduit.

Why all this trouble? Vermin. Mice eat wires, and wire short cause fire.

Cables are rated for 60VDC, but I am using 72VDC in them, is OK according to solar panel installers.

Keep wires dry, in conduit and all should be OK. Use double insulated wire if possible.

Notice the small brackets with 4 fixing holes each for mounting panels to the purlins, using metal self tapping screws. (Red arrows)

Also notice blankets keep solar panels from working.

On my first 3 day trial, this system delivered only little amps (5 and 7) not enough.In emails to my Battery Supplier, I was told I needed at least 60 amps daily as a bulk charge. Just a learning experience.

So I removed the entire array, and learned to test each solar panel, using multimeter tester, also comes with ammeter tester. When testing current on a solar panel, you short the panel, so make your test quickly, under 5 seconds.

On the left are the brand new Trina-Solar Panels (370 Watt, 10 Amps), they are wired two in series and two in parallel.

On the right are the older, 8 yr old Zeus-Apollo (200 Watt, 4.8 Amps), these six are 45Volts and are all wired in parallel.

Now at last on a sunny day, I get 60 amps charging, 30 amps from each MPTT. I decided to name one MPTT system "Trina" and the other MPTT system "Zeus", after the solar panel manufacturers.

Next we continue building the invertor panel wiring.

Ni-Fe battery technology

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