I'm ordering mppt and inverter PCBs - who wants what?


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poida

Guru

Joined: 02/02/2017
Location: Australia
Posts: 1400
Posted: 10:04am 28 Jan 2023      

for instance, the inverter board does not need to be fully populated.
You can omit the 250V cap, the two resistor and cap snubbers and you only need to build as many FETs as you need. I run my house on a 4 FET build (times 4 so that's 16 FETS in total) and that is good for well in excess of 12kW peak power. I only see about 100 Amps peak inverter current so that is approx. 5kW peak at any time.

The picoverter can have the fan control parts omitted if you are doing external fan control.
2 versions of firmware:
1 - fan controlling one fan only, based on over temp conditions of the toroid or heatsink. (I use this with my "victim" 12 FET inverter)
2 - individual fan control, one fan for heat sink, one for toroid, one of both could run depending on load and HS or toroid temps.

The LCD can be omitted but it's fun to see it work so I would want you all to build
the serial LCDs. These are easy to make. Need another nano for each LCD.

The mppt can be built with 2 FETs and 2 diodes and run perfectly well at 45 Amps
at 56V output. The capacitors need only be "enough" but more is usually better.
Maybe 4 x 450uF on the input side and 3 x 450uF on the output. Whatever you have available..

the brainboard also needs a serial LCD. It is more important to have the LCD with this controller, it tell you what the hell is happening at all times.
I would not bother with a cooling fan for the mppt, it throttles it's output as
the heatsink temp rises past a user defined setpoint. It can not overheat if you use this feature.
There are two versions of the mppt firmware.
1 - show the choke temperature and have no temperature coefficient for battery charge voltage
2 - no choke temp BUT you have the battery charge voltage tempco.
I use no. 2
This means you put a 10K NTC on a battery terminal to give battery temperature.
Electrically isolate this of course.