relay safety, sensor, and I2C

I recently wrote and installed a service to initialize actuator power relays to a zero state. This will avoid any potential startup randomization of GPIO signals that may inadvertantly turn the relays on.

A power supply for actuator control, used in conjunction with the relay card, is on the way.
The p/s is a boost converter that will convert the battery bank's 24VDC to the 36VDC needed to run the actuator that positions the solar array.

The sensor output is recorded by a service, I've written, that records the values of A0,A1,A2,A3 and the date-time. The sensor output is sampled every 30 seconds. The functions for the sensor panels' voltages converge and diverge depending on the position of the sun and the degree of cloudiness.

A I2C multiplexor is en route from China. The device is, like most of the units I use, a breakout module. This one allows several I2C devices to communicate with the Raspberry Pi. This device elimnates the dependence on the number of access points to the I2C signal pins.
Previously, there was one set of I2C pins available on the GPIO connecot. This set was used by the RTC clock. I added a GPIO expansion module that sits on top of the Raspberry Pi. This gave me three GPIO headers to use. All I2C pins have been used. If I want to access more devices, such as sensors, I'll need to find away to expand the I2C access. This is what the I2C expander accomplishes.
The unit has connection points for several devices, each of which is selectable using address pins that can be addressed by GPIO signals.The unit can accomodate 8 devices. The units may be capable of daisychaining.