So, there is some stuff to deal with here.
Most entry level charge controller do not have a facility for limiting amps, beyond the hardcoded limit at the charge controller's rating. Yes, if you are using controllers at that end of the market, you need to replace the controller when you want to change the charge current limit.
More advanced controllers have the ability to set a current limit less than that controller's rating. However, that feature does you no good for operating daytime loads, since the available current will not be increased even if some of it is being routed off away form the battery. It does give more design flexibility and better future-proofing for the different battery configurations you might consider using.
Some controllers have relays or control signals available to connect with other equipment that may control opportunity loads. The more typical use case is for those loads to kick in when the battery is fully charged. Trying to run those loads in parallel with charging, on the assumption that there is still enough sunlight in the day to achieve both, is more thinking than the charge controller will offer.
I fully agree with the idea that the charge controller amp limit (whether it is the rating limit, or a lower one set by the user) is an effective tool to lengthen the charging day and safely over-panel the system, and builds more margin into a design than strictly limiting the PV rating to the controllers rating would allow.
Most entry level charge controller do not have a facility for limiting amps, beyond the hardcoded limit at the charge controller's rating. Yes, if you are using controllers at that end of the market, you need to replace the controller when you want to change the charge current limit.
More advanced controllers have the ability to set a current limit less than that controller's rating. However, that feature does you no good for operating daytime loads, since the available current will not be increased even if some of it is being routed off away form the battery. It does give more design flexibility and better future-proofing for the different battery configurations you might consider using.
Some controllers have relays or control signals available to connect with other equipment that may control opportunity loads. The more typical use case is for those loads to kick in when the battery is fully charged. Trying to run those loads in parallel with charging, on the assumption that there is still enough sunlight in the day to achieve both, is more thinking than the charge controller will offer.
I fully agree with the idea that the charge controller amp limit (whether it is the rating limit, or a lower one set by the user) is an effective tool to lengthen the charging day and safely over-panel the system, and builds more margin into a design than strictly limiting the PV rating to the controllers rating would allow.
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