Adding monitoring of solar strings

[GlenB]

Hello,
Not sure which forum I should post this...

I am just getting into Home assistant, and, more specifically, ESP Home using ESP32 boards. It seems to me, one can make a WiFi-enabled sensor board to monitor each solar panel string. Measuring the voltage, current, and power over time should be fairly easy. My older inverters are very bad at WiFi monitoring!

The rub comes when you start to consider that measuring current using a clamp sensor is not very accurate, and it is expensive. I do not know if a shunt can be directly fit onto an ESP32 (differential amp with a lot of gain). Perhaps there are those folks out there who have already done this. Voltage can be done with a divider and a calibration pot. I have 11 different solar high voltage strings to monitor.

I found problems several months ago where the solar output had dropped significantly on a couple of the strings. It turns out that I had corrosion in several MC4 connectors, where I could not even get them apart! That corrosion caused a severe drop in power. Bought a bag of MC4 connectors, and cut off the bad ones, and installed new ones. Lubricated the 'O' rings with silicone grease this time. I bought some conductive grease to coat the metal conductors, but decided not to use it. Please comment if you have tried conductive grease to prevent corrosion ...

So, has anyone done this monitoring before? What sensors or components did you use? I design circuit boards, so making a bunch of these things would be straight forward.

Thanks in Advance (TIA)
GlenB K4KV
Moultrie, GA

 

[mciholas]

Doesn't your inverter tell you string voltage and current? Most do, or so I thought.

I can also monitor it with the Tigo boxes under each panel.

Mike C.

 

[wildbillpdx]

EG4 6000xp does:


So does solar assistant:

 

[GlenB]

No, my inverters are stupid and difficult to get any information. They all use different wifi applications. I have SMA, Fronius, Growatt, and SunPower inverters. The panels do have some of the information if you dig through menus. The Power is shown on the lcd if I go into
my shop and look.
I would rather be able to see it from anywhere on Home Assistant...all of them at once. Not too much to ask, right?

In theory, the perfect monitor would monitor the DC strings, AND the AC inveter output.

 

[tinyt]

No, my inverters are stupid and difficult to get any information. They all use different wifi applications. I have SMA, Fronius, Growatt, and SunPower inverters. The panels do have some of the information if you dig through menus. The Power is shown on the lcd if I go into
my shop and look.
I would rather be able to see it from anywhere on Home Assistant...all of them at once. Not too much to ask, right?

In theory, the perfect monitor would monitor the DC strings, AND the AC inveter output.

Nothing is perfect. This is what I am trying to do. Don't know when it will be finished.

This is my PV monitoring circuit board. Which right now is not being polled.

 

[meetyg]

You could try an ESP32, running ESPHome (an integration to Home Assistant) with one of these sensors:

ESPHome Docs — ESPHome

ESPHome main documentation

esphome.io

(click on Electricity in the list of sensors, if the link doesn't jump directly to it).


You will need to find the right sensor for your needs. You might need a sensor for each panel, as some of these sensors are somewhat limited in voltage. Not sure if they can handle a full string of panels.
Same goes for current, depending on the sensor.

If you want to go with a simpler route, you could use hall effect or CT based sensors, on an entire string.
Yes, these are probably less accurate, but that's a tradeoff you could choose to make.