Cheap China Solar Controller Failure

Mr.Wizard,

So what it really comes down to, is what sort of meter(s) you use? Be it Ah or Wh, it's just a different way of keeping track? Similar to using a voltmeter as opposed to an AH counter for determining soc?

Fubeca wrote:
I have a $600 controller (of course I bought it used for $200). Maybe Jim and I can get together in the summer and do some side-by-side testing. I believe we have a couple of the same panels.

Well we had better do it soon. One of the 245w systems already sold, the other is spoken for.

Then again.....

What was your peak amps for the pair this last year. With the Eco-w's mine was 34.2a.

watt hrs is power used

if you know the items plugged into the iverter used 300Whrs and the lights 23whrs
you can just add it up, you don't have to converte back and forth to amps and ampHrs amphrs*v =wattHrs and the voltage is a sliding scale on DC
a kil-a-watt meter plugged into you inverter
or better yet a Turnigy watt/power meter in the DC power line
and one in the charge line
will tell you exactly how many amp hrs and how many wat thrs

the top line of the display is "at that moment" constant monitor
second line "right" shows the current Watts (8.22a*14.78v
the second line "left" rotates thru the accumulated data, will show amp hrs, watt hrs, peak amps, peak watts

several of us have them,very handy and cost about $30 rated for 65amps
i have mine between my solar controller output and the battery bank
i get daily readings of the exact amount of solar power returned to my system
where you mount them in the circuits determines what you will read

mine measures solar power returned to the system, but not what the converter adds to the batteries, and not the exact charge into the batteries

i used to have one mounted on the inverter power input wiring
for about a year i measured daily use in amphrs and watt hrs

comparing solar watthrs and inverter watt hrs, always gave a more accurate idea of power use and charge

jrnymn7 wrote:
Mr. Wizard, I appreciate what you're saying, but I still fail to see any real advantage to thinking in terms of WattHrs?

"2.8 amps @120v is 28amps at 12v, but at 12v its recharge time
so really you are likely using 24a at 12.x volts"

... which could essentially help compensate for some of the heat losses during charging, and thus help average out overall (i.e; actual) Ah usage/replacement.

I generally run between 12.5 and 12.8 volts, so the variance in amps used in any particular situation would be rather insignificant, I would think. So, I used an average of 2.79a, as opposed to 2.81a, for 10 minutes. No big deal. It's all about averages. Likewise, if half the time the fridge is using say 42w, and the other half its using 38w, it all averages out to 40w x 24hrs for 960wh's per day.

So, how does one then figure out how to replace 960wh's ?

I knew my ears were burning at work today.

I'll go one better. I'll send them back after testing, most of them anyways. ;)

Personally I'm not upgrading for improved output, I'm doing it for the features. I'd get more power out of a extra panel/ Eco-W set up than I'd ever get spending a extra $300 on a fancy controller. Also I will be keeping the 230w/ Eco-w set up s a portable even after I mount the new panels. Come to think of it, if I could find more Schott poly's, I'd buy those.

I have a $600 controller (of course I bought it used for $200). Maybe Jim and I can get together in the summer and do some side-by-side testing. I believe we have a couple of the same panels.

If somebody wants to donate a $600 MPPT controller or even two of different brands, I will be happy to compare them this coming season with my Eco-Worthy and post the results. I would expect them to come free with all delivery and customs fees pre-paid of course. Naturally they would remain mine on completion of testing.

We almost had Jim to do that but he may have wimped out on getting a fancy controller while keeping at least one of his Eco-Ws

Performance difference is not based on just one controller. A mathematical analysis will give same results. My Blue Sky mppt controller gives same results. This white paper gives same results. mppt is on average 5% better than pwm. It doesn't matter if array voltage is high or low, it's still 5%.

mena661 wrote:
I'd like to see BFL do his testing using a higher end MPPT controller (or controllers preferably) to see if there is any real world performance difference between those and the cheap one's. Everyone here is basing their MPPT performance conclusions on ONE controller. They may not all perform the same.

Mr. Wizard, I appreciate what you're saying, but I still fail to see any real advantage to thinking in terms of WattHrs?

"2.8 amps @120v is 28amps at 12v, but at 12v its recharge time
so really you are likely using 24a at 12.x volts"

... which could essentially help compensate for some of the heat losses during charging, and thus help average out overall (i.e; actual) Ah usage/replacement.

I generally run between 12.5 and 12.8 volts, so the variance in amps used in any particular situation would be rather insignificant, I would think. So, I used an average of 2.79a, as opposed to 2.81a, for 10 minutes. No big deal. It's all about averages. Likewise, if half the time the fridge is using say 42w, and the other half its using 38w, it all averages out to 40w x 24hrs for 960wh's per day.

So, how does one then figure out how to replace 960wh's ?

BFL13 wrote:

I doubt the more expensive controllers are any "better" but one big thing is the efficiency curve and where you are on it

We don't know that because no one's tested it. It's like computers, I build my own because the DIY way has better components ie better quality. If you bought a name brand for the same price it will NOT be the same quality yet both are computers. Like you say, it depends. Some expensive items are quality and others are not. And even then, some expensive stuff is not so good and some cheap stuff is excellent. You can't just throw everything under one blanket. Evaluation is needed.

Besides "inverter creep" where amps draws rises as battery voltage drops there is how your lights dim as voltage drops, so the amps they draw goes down. It is hard to maintain a steady amps draw using lights. You have to keep turning on more lights, which makes voltage drop more which dims the lights more, etc.

Anyway on my problem not being able to run my 230w panel with my PWM controller, if the MPPT controller ever quit, smk solved that!

In another thread he mentioned you can use 24v PWM, so instead of needing two 12v panels I could use two 12v batts in series while they are being solar charged. Smk is a genius. :)