steve, the problem is that shore power
chargers and solar
chargers use different protocols for regulating, and integrating the output from the two would be problematic at best. So now they need to deisgn and build a new charge controller, which will raise the price
, and then build different versions of it to suit the 100-200-400-1000 watt markets, again raising the price
As best I can see, the problem is that there's no easy way to integrate the different charging
schemes, and if you logically extend that to include wingens as well, the engineering guys will probably say "Oh sure we can do that" while the marketing
guys run crying "MAMA!!" because they're job is going to become so much harder.
If you just want a raw charge controller (instead of MPPT) from the solar, and can settle for a dumb brute-force shore charger that has no fancy regulation either, sure, you can just run 'em together. But as soon as you go beyond crude, now the voltage from even a dumb solar charger is going to trip the shore power
charger and tell it "battery voltage is high" and that's going to shut down or go into float mode.
Catch-22, too many cooks spoil the soup. One system to integrate and regulate them all? That's gonna price you out of the market.