Hi, if you add the mod for the first time, it will take some time until all machines start their maintenance cycle. Solar panels and accumulators do also need some more time, if the "Cycle time multiplier" is set to something >1 (3 by default). The effects will also be aplied to all existing entities on the map.
The second part of your question is a request to add a "disable replacement" option, right? To just use the maintenance functions, but without needing to replace the machines?