Can you add support for update planner? - it is just these lines of code:

1 new file - prototypes/entity/base-entity-updates.lua: (required by data.lua)
data.raw["accumulator"]["accumulator"].fast_replaceable_group = "accumulator"
data.raw["accumulator"]["accumulator"].next_upgrade = "advanced-accumulator"
data.raw["solar-panel"]["solar-panel"].fast_replaceable_group = "solar-panel"
data.raw["solar-panel"]["solar-panel"].next_upgrade = "advanced-solar"

edits of existing files: add at line after after "minable = ..."

prototypes/entity/advanced-accumulator.lua:
fast_replaceable_group = "accumulator",
next_upgrade = "elite-accumulator",

prototypes/entity/advanced-solar.lua:
fast_replaceable_group = "solar-panel",
next_upgrade = "elite-solar",

prototypes/entity/elite-accumulator.lua:
fast_replaceable_group = "accumulator",
next_upgrade = "ultimate-accumulator",

prototypes/entity/elite-solar.lua:
fast_replaceable_group = "solar-panel",
next_upgrade = "ultimate-solar",

prototypes/entity/ultimate-accumulator.lua:
fast_replaceable_group = "accumulator",

prototypes/entity/ultimate-solar.lua:
fast_replaceable_group = "solar-panel",

done and tested.

Just updated to this and had the following error.

Mods to disable:Failed to load mods: Error while running setup for entity prototype "solar-panel" (solar-panel): next_upgrade target (advanced-solar) must have the same fast_replaceable_group ( != solar-panel).

Do you have other mods that edit solar panels or that have other modded solar panels?
I could not replicate the issue.

It is working now, with new Base update.