chargery bms8t (you can find on ebay for about 120 dollars) is the cheapest one I would recommend for solar. They got a version 4 now, with a better SOC and other updates. You need to buy the contactors seperately, I use 4 dollar 30 amp automotive relays as contactors and they work good for me. You can find relays/solonoids that can handle 200+ amps for 20 to 30 dollars. There are other bms like baltrium etc that also use contactors but those are in the 400 dollar range. I would stay away from the cheaper bms that use mosfets, I tested many of them and they don't work well with solar. The chargery has an LCD screen where you can program all the settings, over/under voltage, 1.2 amp balancing , it has audio/visual alarms, 2 temp sensors.
With contactors/relays you avoid the problem of voltage surges (since they are mechanical and completely disconnect the battery) that would occur if a bms activates. The mosfet bms when they activate, leak voltage, the charge controller reads this voltage an tries to forcibly charge the battery, but it wont accept amps this causes voltage surges. I lost many 12 volt fans, pumps, lights because of voltage surges.
On my system, I have the relay that stops the charge connected between the solar panel and controller, if the bms decides to stop the charge it basically disconnects the solar panel, this stops power going into the controller. The controller will still be connected to the battery like its suppose to be.
Picture of chargery, not shown are all the attaching wires, shunt, etc. It takes up alot of space but its worth it.
