Solar Array Help – I

So I’ve got my 20x 260W Monocrystaline glory… I’m dreaming up a mounting system in SolidWorks, but I’m running into a different problem.

Charge Controller.

In series, my string would have an Open Circuit Voltage of 766V. That not only exceeds the wire insulation rating, but have you ever seen an MPPT charge controller with that input rating? Yeah…

I obviously need some way to run these suckers in parallel. A few smaller charge controllers that link and synchronize output? With noting but salesmanship, and nothing technical about how they work, I’m at an impasse.

I considered making my own, but I encounter a similar problem. I’m not using the traditional (stupid) Pb+H2SO4 Cells. I’m using LiFePO4. As long as it never tops-off, and only bulk charges below top-off voltage, any old charger will still do. I intend to bottom-balance the pack and then never fill it all the way to avoid unbalancing it; which is the death of LiFePO4 packs. So, I’ll never reach the top-off charge portion of the LiFePO4 charge curve, and never risk overcharging some cells while undercharging others until Bad Things. The unanswered question remains, how to assure the charge controllers work together.

I can’t just run parallel sets because the unequal wire lengths will cause slight voltage variations. One long High Voltage string is the best option, but an unavailable option…

Is a charge controller a kind of DC to DC converter? If so, how is it achieved? I have this handy-dandy Raspberry Pi sitting here. I can haz MOSFET? PWM into a bigass capacitor and monitor current load to suit? How do we trade Amps for Volts keeping Watts constant? A giant multi-tapped transformer? No answers, all kept secret. Even the DIY projects fail to explain. “Just blindly follow these steps and copy the code.” No thanks. I will have understanding. I am not a stupid monkey. My only holdup is that knowledge is kept secret to force consumerism… Painfully inadequate consumerism that fails to deliver a suitable product, as usual…

The conventional voltage regulator that simply throws away the “extra” as heat is obviously a hugely wasteful and unacceptable way to go. I even considered adjustable high-wattage power supplies, as in the Zero S DC Charger idea. That’s a lot of money to spend on a guess that may not work. I need information, answers, but as is usually the problem, the people calling themselves experts are in fact clueless, too.

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