Cheap China Solar Controller Failure
For a couple days been noticing higher than the 14.6 voltage,.....going to 15, and even 15.5,....I knew something was not right. The next day it was showing 16, then quickly went to 17+.......I quickl...
Forum Discussion
I believe I understand what BFL is getting at; and He can correct me if I'm wrong.
BFL has seen, first hand, increased panel temperature result in lower controller (i.e; amp) output at a given battery voltage, when using mppt vs. pwm. Perhaps it does have something to do with quality of controller? I don't know. One would have to compare mppt controllers during similar conditions to know for sure..
In the context of a relatively small, flat array, what I HAVE seen, according to a comparison chart provided by Salvo, is the minimal increase in daily haul, using mppt vs. pwm. And when compared with tracking, there is no comparison. 'Tracked pwm' greatly outshines any 'flat mppt' install. Moreover there's no reason for me to believe a 'tracked mppt' would greatly out do a 'tracked pwm', if there is little difference for a flat install; the % of increase would likely remain the same, but the figure being increased by that % would certainly be higher.
According to Salvo's chart, the mppt did much better (% wise) during the early morning / late evening hours; but at high noon, there was little, if any, difference. But even though the mppt did 50% more, morning and evening, it was outputting say 3a vs. 2a... so only an extra 1Ah. So, does this justify the added cost? I'll let the individual decide. On the other hand, a tracked mppt would likely produce considerably more Ah's than a tracked pwm.
So, now that I've stated the obvious, what about niner's question. How does mppt vs. adding another panel, fare? Well, going from 2 panels to 3 is a guaranteed 50% increase. But simply going from pwm to mppt is no where's near that, from what I can tell. So yes, the adding another panel approach seems quite reasonable.
The question for me is, at what point (i.e; at what size array) is going mppt justified?
BFL has seen, first hand, increased panel temperature result in lower controller (i.e; amp) output at a given battery voltage, when using mppt vs. pwm. Perhaps it does have something to do with quality of controller? I don't know. One would have to compare mppt controllers during similar conditions to know for sure..
In the context of a relatively small, flat array, what I HAVE seen, according to a comparison chart provided by Salvo, is the minimal increase in daily haul, using mppt vs. pwm. And when compared with tracking, there is no comparison. 'Tracked pwm' greatly outshines any 'flat mppt' install. Moreover there's no reason for me to believe a 'tracked mppt' would greatly out do a 'tracked pwm', if there is little difference for a flat install; the % of increase would likely remain the same, but the figure being increased by that % would certainly be higher.
According to Salvo's chart, the mppt did much better (% wise) during the early morning / late evening hours; but at high noon, there was little, if any, difference. But even though the mppt did 50% more, morning and evening, it was outputting say 3a vs. 2a... so only an extra 1Ah. So, does this justify the added cost? I'll let the individual decide. On the other hand, a tracked mppt would likely produce considerably more Ah's than a tracked pwm.
So, now that I've stated the obvious, what about niner's question. How does mppt vs. adding another panel, fare? Well, going from 2 panels to 3 is a guaranteed 50% increase. But simply going from pwm to mppt is no where's near that, from what I can tell. So yes, the adding another panel approach seems quite reasonable.
The question for me is, at what point (i.e; at what size array) is going mppt justified?
