I don't think it's a huge shock that 400W of solar panels and a 2000Wh LiPo battery could keep an RPi running indefinitely. With just trivial tuning on the RPi we're looking at a week or two just to drain the battery. The RPi's consumption and the self-discharge rate are not too dissimilar.
I think I have the gear to set up the solar panels into a controller that offers a USB output without the 2000Wh battery, and could set it up into a far more reasonable USB power bank, though I'm not sure I have one that can be charged at the same time as it discharges. It's still a day minimum for an RPi to discharge one of those with a touch of tuning, and far less than a day to recharge them.
I think I have the gear to set up the solar panels into a controller that offers a USB output without the 2000Wh battery, and could set it up into a far more reasonable USB power bank, though I'm not sure I have one that can be charged at the same time as it discharges. It's still a day minimum for an RPi to discharge one of those with a touch of tuning, and far less than a day to recharge them.