Solar Controllers--Don't be a Sucker! :(
Just got to say it again, how it is we are sitting here for five months off grid on solar with no problems at all (third season on solar like this), using the non-programmable, non-MPPT, solar control...
Forum Discussion
Because of all the variables I don't think a real or meaningful comparison can be made.
Variables include:
1. Solar insolation which includes tilt and alignment, time of day, atmospheric conditions, cloud effect, etc.
2. Battery SOC
3. Other electrical demands on the system
4. Ambient temperature and panel temperature
5. Systemic differences such as wiring resistance, different panels
I'm sure there are more. Unless a test could be made with identical panels under the same conditions with all system variables the same, it is all a matter of conjecture.
It goes without saying (but I'll say it anyway) that panel production is at max during MPPT phase. However daily solar production is only equal to the amount of power used or the maximum the system can produce. As a means of testing the system I have tried to force production higher by loading up electrical demand until I see negative flow from the batteries, ensuring instantaneous maximum panel production. Some people take advantage of the extra power available by diversion loads after the batteries are charged.
The real comparison is not so much peak amps, but daily total power (that's watts!) production. If a certain selection of 12-volt panels and a PWM controller get the job done for someone, then that is good enough, no need to look further. For others there are more factors involved and the choice becomes harder. I suspect that there are many with a cobbled together system, that if they had it to do over would go with 24-volt panels and an MPPT controller, not to disparage those that make do with what they have.
I have only used my system for a season and a half with mostly good (solar) weather and relatively low demand. I'm still exploring to understand the full capabilities of my system. I have on occasion seen peak watts high enough to trigger the 30-amp max of the Rogue controller.
Variables include:
1. Solar insolation which includes tilt and alignment, time of day, atmospheric conditions, cloud effect, etc.
2. Battery SOC
3. Other electrical demands on the system
4. Ambient temperature and panel temperature
5. Systemic differences such as wiring resistance, different panels
I'm sure there are more. Unless a test could be made with identical panels under the same conditions with all system variables the same, it is all a matter of conjecture.
It goes without saying (but I'll say it anyway) that panel production is at max during MPPT phase. However daily solar production is only equal to the amount of power used or the maximum the system can produce. As a means of testing the system I have tried to force production higher by loading up electrical demand until I see negative flow from the batteries, ensuring instantaneous maximum panel production. Some people take advantage of the extra power available by diversion loads after the batteries are charged.
The real comparison is not so much peak amps, but daily total power (that's watts!) production. If a certain selection of 12-volt panels and a PWM controller get the job done for someone, then that is good enough, no need to look further. For others there are more factors involved and the choice becomes harder. I suspect that there are many with a cobbled together system, that if they had it to do over would go with 24-volt panels and an MPPT controller, not to disparage those that make do with what they have.
I have only used my system for a season and a half with mostly good (solar) weather and relatively low demand. I'm still exploring to understand the full capabilities of my system. I have on occasion seen peak watts high enough to trigger the 30-amp max of the Rogue controller.
