what is the error?
60.304 Error ModManager.cpp:1294: Error while running setup for entity prototype "advanced-solar-panel-rampant-arsenal" (solar-panel): next_upgrade target (solar-panel-2) must have the same grid alignment (bounding boxes aren't compatible or tile_width/tile_height aren't compatible).
and the accumulator too
60.485 Error ModManager.cpp:1294: Error while running setup for entity prototype "advanced-accumulator-rampant-arsenal" (accumulator): next_upgrade target (large-accumulator) must have the same grid alignment (bounding boxes aren't compatible or tile_width/tile_height aren't compatible).
The problem seems to be that you copy the next_upgrade over into the adv. panel from bobs panel, but give the panel a new size, so the old upgrade can't fit anymore. The vanilla panel had no upgrade, so that wasn't a problem.
I just added .next_upgrade = "" for those 2 entities and it is loading fine again. I guess any mod that adds upgrades to the solar-panel will break the same way.