Upgrades...


“This is where it gets good. And by good, I mean: Fucked.” - Ambassador To Chad
AliExpress had a sale on just as I was speccing and pricing parts for Project Harry Hart, so I tacked in a couple of choice upgrades for Tom. There’s only so much you can do with salvage and my skills aren’t up to the task of designing and building an MPPT regulator. The Tracer is a more flexible and efficient version of Brains (blue and black unit on the right). I swapped them over when the shipment arrived, having conveniently just rewired the batteries to handle more current. This also gave me a chance to play with a concept I’d seen mentioned online: using two controllers to manage separate panel strings on the same battery bank.
Quick version: it works. Brains pulls juice from my little 160w panel and pushes and extra 4-6A (when the sun is shining) to the batteries. I position the panel to catch more of the morning sun, so by the time the 2 x 250w panels get light the batteries have already gone through Bulk and Absorption charging and sitting at, or just below, Float. This mean that the batteries have stopped drawing and I have 10(ish)A of surplus current ready for the inverter to slurp.
I’ve been running 100-180w of power rough the inverter through the afternoon without touching the batteries. I can keep it going into the evening if I need to while not pushing the batteries near damage point.
Effectively I’m getting around 0.5-0.7kWh of useable energy during the day without touching the batteries. I’ve pulled another 0.5kWh after dark without going near safety margins and with current weather. Net savings for that is ~$0.20/day.
Because it’s all about the money, obviously. It does give a point of reference tho.
This weekend will likely include another fairly radical rewire to test a theory I came up with last night, and I’m considering trying to get the 160W panel up onto the roof if I can mount it securely without making too much of a mess..



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