This year I had a bunch of money left over after I sold my motorcycle to my sister. The motorcycle, a 1978 Suzuki GS550, had been sitting in the garage for a season, and I had to admit that I wasn’t riding it anymore. So I sold it to my sister and have missed it ever since. 🙁

To ameliorate my loss I decided to buy some solar panels! The short version, then the details:

• Four 100W Renogy monocrystalline panels at 12V each
• Mounted on some unistrut from Menards and some tee posts
• Wired as two strands of two panels in parallel (about 20A @ 12V per wire)
• About 100 feet of two strands of 2x14AWG UF (I know it’s undersized!)
• Two VicTec 20A PWM charge controllers (one for each strand of two panels)
• Two Costco 6V deep cycle golf cart batteries, wired in series to be one 12V battery

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So I’ve had a 400W solar panel setup for almost a year now. I’ve been powering an inverter, DSL router, and some 12V LED strip lights. But now that I want to expand the system, I have to justify it by measuring its current performance and determining which parts of the system need to be expanded. Panels? Batteries? Wire gauge? Controllers? Everything?

A few years ago I bought a Raspberry PI 2 B kit that included a case, WiFi dongle, and SD card from CanaKit. Over Christmas break I searched for a PI-compatible analog to digital converter and found that the ADS1115 breakout from Adafruit was very popular. It has four single-ended (or two differential) analog inputs at 16 bits signed with a programmable gain. Very versatile, and if I later on want to measure currents by voltage drops over a small shunt resistance, it has the gain to do that. (Though I haven’t yet.)

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