Mini-Solar V.3 – Maybe I Got It Right This Time

I’ve been working on a small battery-based photovoltaic solar-power system for the last, well, 5? 7? years- it’s been a long while. Since I first bought the modules, charge controller and small inverter I’ve been reconfiguring the parts every couple years with hope that it’ll finally “work” and be “done”… but it never has been. Until now? I’ve addressed my biggest issues with the system- location (get it out of my closet), battery size (nice big pack now), and lack of monitoring (nice new Bogart 2020).

The biggest improvement is brought by the box I built to house the batteries and system components. It lives outside the house, so I can finally get my closet back and not worry about acid spills or charging gasses.

The box is actually dual-purpose- it is designed to house the charging cord for the EV Miata so that once I park it in the driveway the charging cord will always be available.

I rewired the system (again) including a fuse and shunt for the Bogart Tri-metric meter. The charge controller and gray box are still from the very fist version of the system.

I also installed new wiring from the panels, using 8/2 tray cable. This replaces 6ga THHN in plastic conduit, which replaced exposed 8ga THHN. I added MC3 leads to the panels and soldered MC3 pigtails to the top end of the tray cable run. Either of the previous wiring solutions would probably have worked OK, but I really wanted to get rid of some of the persistent crappyness in the system. The cable is then connected to the charge controller using a SB 50 connector (and some leftover pink 6ga THHN… it’s not all gone). The 2 L 16 batteries are hooked up with a 200A class T fuse and block. 16/4 tray cable runs inside to power the Tri-metric and another run of 8/2 tray cable runs inside with a SB 50 to power loads. I made a SB-50 -> 3x powerpole pair adapter to break out the power and be able to use powerpoles for distribution.

So far I’ve just been running my computer on my old modified sine wave inverter, which makes everything buzz. I have plans for a DC-DC adapter for my laptop, as well as some direct DC hookups to other lights and things.

The Tri-metric meter is very useful for being able to tell what’s going on with the system, it’s really the confidence gained by that knowledge as well as the security of having the gassy batteries outside that makes me willing to use the system. Which I have been- in fact I’m using it right now to power my computer as I type. On a good day the panels generate far more energy than I need to run just my computer and stereo, I need to find more loads I can transfer over to the system.

It always feels good to “finish” a project (electric Miata? heh. soon, soon).