How to read AMPs from Solar Panel??

[Dunner]

Originally Posted by rbertalotto

I think I might have a defective panel....Voltage will get up wards of 30-35 volts, depending on the sun exposure. Does this sound correct for a 120W panel?

If you can prove the panel was bad, "right out of the box", email the seller; he might send you a new one at no charge. I had that happen to me with an ampmeter. Actually, his meter wasn't bad, but his schematic would have released ALL the smoke I paid for. I sent him the correct schematic and without asking, he thanked me with a new meter and shunt. They usually do this to keep their approval rating high.

[camaraderie]

Originally Posted by vsheetz

Help me understand if I am not correct here. If you are monitoring only the battery side of the controller, you will only get an idea of what the panels are generating when in bulk charge mode - when the controller is passing power directly through to the panels. At other times just monitoring the battery side does not tell you panel output. For example it can be mid-day full sun and I know my panels are generating upwards of 30a, but the charge mode is absorption and flowing maybe 3a to the batteries.

Assuming there is no load on the batteries, you are monitoring what is being delivered to them AFTER regulation. If the batteries are getting a bulk charge (depleted batteries) then that is what you are getting from your solar SYSTEM. What you are getting OUT of your solar panel is another matter entirely since most solar panels put out 17.9 DC volts or so (a 100 watt panel would be 17.9 volts x 5.6 amps at full output). Your regulator may be throwing away the extra power above the charge rate (14.4V or so in bulk) and generating heat. Or ...if you have an MPPT type regulator you may get an improvement on that of up to about 30% recovery.
It seems to me that there is little value in understanding what your panel is putting out... it is what your SYSTEM is putting in that determines how well you are doing vs. the theoretical maximum during bulk charging. Your present meter set up tells you this. If it is no where close to maxing out...(more than a third less amps)...you might wanna measure panel output once to insure the cells are working properly and that you are not getting ANY shading on your cells...even ONE cell in the shade can cut output of the panel in half. Assuming the panel is working properly...the only ways to get more output are:
Panel orientation to the sun...maximize the perpendicular ray "hit time"
Change to a better regulator
Get more panels.
In general...expected output on a sunny day with a standard regulator and flat mounted panels with good air circulation...should be 1/4 of the wattage in amp hours per day. 100 watt panel gives on average 25 amp hours. MPPT...might get ya low 30amp range.

[vsheetz]

Originally Posted by camaraderie

Assuming there is no load on the batteries, you are monitoring what is being delivered to them AFTER regulation. If the batteries are getting a bulk charge (depleted batteries) then that is what you are getting from your solar SYSTEM. What you are getting OUT of your solar panel is another matter entirely since most solar panels put out 17.9 DC volts or so (a 100 watt panel would be 17.9 volts x 5.6 amps at full output). Your regulator may be throwing away the extra power above the charge rate (14.4V or so in bulk) and generating heat. Or ...if you have an MPPT type regulator you may get an improvement on that of up to about 30% recovery.
It seems to me that there is little value in understanding what your panel is putting out... it is what your SYSTEM is putting in that determines how well you are doing vs. the theoretical maximum during bulk charging. Your present meter set up tells you this. If it is no where close to maxing out...(more than a third less amps)...you might wanna measure panel output once to insure the cells are working properly and that you are not getting ANY shading on your cells...even ONE cell in the shade can cut output of the panel in half. Assuming the panel is working properly...the only ways to get more output are:
Panel orientation to the sun...maximize the perpendicular ray "hit time"
Change to a better regulator
Get more panels.
In general...expected output on a sunny day with a standard regulator and flat mounted panels with good air circulation...should be 1/4 of the wattage in amp hours per day. 100 watt panel gives on average 25 amp hours. MPPT...might get ya low 30amp range.

Trying to figure out why you quoted me here...?

[rbertalotto]

Are you testing the panel when the battery is charged and you're plugged into shore power? The controller may not be flowing any current because its seeing the battery charger voltage and it thinks the battery is charged.

The meter is between the panel and the CC......Would a fully charged battery affect this reading? I would think it would read current from the panel regardless of the battery's condition...No?

vsheetz...Not sure why that quote popped up...sorry for the confusion.

[camaraderie]

Originally Posted by vsheetz

Trying to figure out why you quoted me here...?

So am I!!
I was trying to respond to the OP and decided to drive you nuts instead! Sorry for the fumble thumbs!
**********************

As a separate aside to the thread...Wouldn't a simple disconnect switch for the panels be a LOT easier way to evaluate what they are doing. Example...with panels off...battery V = 12.5 and current =2 amps draw. With panel switch on...it reads 14.4 and 4 amps input. You know the panels are working in bulk mode and input is 6 amps. Easy and no cascade of monitors required.

[bdosborn]

Originally Posted by rbertalotto

The meter is between the panel and the CC......Would a fully charged battery affect this reading? I would think it would read current from the panel regardless of the battery's condition...No?

Nope, the controller will disconnect the panel from the battery. There would be voltage present but no current flow.

Bruce

[bdosborn]

Originally Posted by camaraderie

As a separate aside to the thread...Wouldn't a simple disconnect switch for the panels be a LOT easier way to evaluate what they are doing. Example...with panels off...battery V = 12.5 and current =2 amps draw. With panel switch on...it reads 14.4 and 4 amps input. You know the panels are working in bulk mode and input is 6 amps. Easy and no cascade of monitors required.

Yeah but with my luck I would forget to turn the switch on for some reason. You can easily argue this either way, it all comes down to what you think you need for information on your system. Me, I like gauges, I've got them all over the truck too.
Bruce

[rbertalotto]

Nope, the controller will disconnect the panel from the battery.

I understand this, but this disconnect is after the CC. My meter is connected before the CC. Right off the wires coming from the panel.

[bdosborn]

It sound like you're trying to figure out if the meter will ever read 0 amps when it's in the circuit between the panel and the charge controller. The answer is yes, but it depends on several things. Are you plugged into shore power? Are your batteries charged? What kind of charge controller do you have? Good luck with your trouble shooting. Bruce

[bukzin]

Originally Posted by bdosborn

How about a Turnigy meter?


Operating voltage: 4.8~60V (0V with optional auxiliary battery)
Measures;
0~130A, resolution 0.01A
0~60V, resolution 0.01V
0~6554W, resolution 0.1W
0~65Ah, resolution 0.001Ah
0~6554Wh, resolution 0.1Wh
Screen: 16x2, backlit LCD display
Size: 85x42x25mm
Weight: 82g

Turnigy 130A Watt Meter and Power Analyzer

Bruce

Here is a YouTube review of that meter.

http://m.youtube.com/watch?v=kfs4Bs3H7gw