Solar Array Control With Photocell

Question

We did search on this topic before making this post, but this is as close as we found; Link to question from 2020: Solar Panel-Photocell Wiring ... which didn't seem to be closely enough related to this question to interpolate an answer.

Therefore here is another type of question concerning photocell control of a solar array.

We have an array of 6 100W solar panels on our condo patio that is used to charge a Li-ion power station via its XT60 charging plug. The current project is to automatically control the connection of the array to the power station. The reason for this is that if the array is left plugged in overnight while it's dark, after a certain amount of time the power station enters an undocumented sleep mode. There are no instructions for how to bring it back to life the next day, and it can take hours of plugging, unplugging and pushing buttons to get it to turn back on. Link to power station: https://www.amazon.com/gp/product/B09Y87YPFK/ Link to solar panels: https://www.amazon.com/gp/product/B09S5VBNMQ/

Manually plugging and unplugging the array into the front panel of the power station is tedious and sometimes our schedule doesn't permit it to be done in a timely manner. Thus, a lot of usable sunlight can be lost. So, we had the idea of automatically switching the positive side of the array connection to the power station.

The concept appeared to work fine when the first photocell relay was connected using the normally-open connection option on the circuit board. When the light got low enough, the array disconnected and the power station remained functional. However within a few days it overheated and failed; it was only rated for 10A and the array is pushing down around 300W or 25A @12VDC on clear days. Link to 1st relay/photocell: https://www.amazon.com/gp/product/B073XL5161/

So another relay was acquired - this time rated at 25A, and a 220V line source was run to it. Link to 2nd relay/photocell: https://www.amazon.com/gp/product/B0CZT5MPJP/

The issue with the 2nd relay was that it shipped with a normally-closed photocell, and there is not a normally-open connection option on it. So we tried getting a photocell that had NC/NO connections. Link to 3rd photocell: https://www.amazon.com/dp/B00VTVMKDY/

Once again there are no instructions and we can't figure out what the wiring diagram is telling us. The question after all that background is simple: which wires should we connect to the relay's photocell contacts to make this relay disconnect the load at sundown, and will it even work? The image below shows the schematic on the photocell, and the one after shows the schematic as listed on another message board.

Many thanks in advance for any guidance we can get.

Answer 1

As the Amazon link title states, that's a DC NPN 4 Wire NC NO Nomal Close / Open Photoelectric Sensor with a sensing range 10 - 30 cm. These are used to detect presence or absence of parts in industrial control lines.

• The unit has an infrared transmitter and a sensor to detect light reflected from the object to be sensed.
• The transmitted light is modulated (switched between bright and dim) at high frequency and the modulation is monitored by the receiver to differentiate it from background radiation.
• A pair of lenses on the front face focus the transmitter and receiver in a conical zone of interest.
• The sensor has digital outputs and so switch on and off.

The symbol on the GE YX shows a light-dependent resistor. This will give an analog change in resistance probably inversely related to the light intensity. The trigger threshold is set by the red potentiometer.

You've bought the wrong sensor.

Figure 1. A photoresistor Image source: Wikipedia.

What you're looking for will look like Figure 1 or an encapsulated version of it.