Should they stop listing panel wattage as a specification for SCC?

[Vigo]

I still think something is missing here.

Panels' maximum power point, the only place they hit their watt rating, relies on them being hooked to a load that allows them to operate somewhere in the upper half of their voltage range.

A PWM charge controller does not step down voltage from the panel to something appropriate for the battery. It simply shorts the two things togehter. So when you operate a higher voltage panel on a PWM scc hooked to a lower voltage battery and the SCC hooks them together, the battery is going to (HOPEFULLY!!) pull the solar panels output voltage down to whatever the SCC is set to as a charge voltage. At that voltage level, even at the maximum current the panel is capable of producing, it will be nowhere near the actual max watts rating of the panel.

So the SCC has a 'max input voltage' in terms of not blowing itself up, but it also has a 'max productive input voltage' when hooked to 12v, 24v etc because while you can hook a higher voltage panel to it, it is going to make a fraction of its rated wattage when pulled down to half or less of its 'rated' mpp voltage, so going higher is pointless and just going to make people have shitty power output from their big panels, and POSSIBLY damaged batteries since for example, a bms on a 12v lithium battery might not like having 70v pwm'd into it, for however short a duty cycle.

 

[Mattb4]

I still think something is missing here.

Panels' maximum power point, the only place they hit their watt rating, relies on them being hooked to a load that allows them to operate somewhere in the upper half of their voltage range.

A PWM charge controller does not step down voltage from the panel to something appropriate for the battery. It simply shorts the two things togehter. So when you operate a higher voltage panel on a PWM scc hooked to a lower voltage battery and the SCC hooks them together, the battery is going to (HOPEFULLY!!) pull the solar panels output voltage down to whatever the SCC is set to as a charge voltage. At that voltage level, even at the maximum current the panel is capable of producing, it will be nowhere near the actual max watts rating of the panel.

So the SCC has a 'max input voltage' in terms of not blowing itself up, but it also has a 'max productive input voltage' when hooked to 12v, 24v etc because while you can hook a higher voltage panel to it, it is going to make a fraction of its rated wattage when pulled down to half or less of its 'rated' mpp voltage, so going higher is pointless and just going to make people have shitty power output from their big panels, and POSSIBLY damaged batteries since for example, a bms on a 12v lithium battery might not like having 70v pwm'd into it, for however short a duty cycle.

Batteries are complicated as loads. Different battery chemistries toss in complications. Such as the reason standard engine alternators can overheat when trying to charge a lithium battery. The lithium battery accepts the full amperage that the alternator can deliver but the alternator does not control the engines rpm therefore it lacks sufficient fan speed to keep it cool at a high amperage rate. Works good for a lead acid battery though because of its charging characteristics.

In the case of a PWM SCC panel and a lithium battery setup I am not sure how it would effect the demand from a solar panel. It is a good question.