Measuring Sunpower Amps

[Vern2]

Don't have panels yet. Want to measure each panel while system is in production. I'm only looking for consistent readings. Install company said, It can't be done. Panel arrays are in series, so all panels measure 5 amps. I got one of these 336 fluke. I don't want to turn off system or do any wiring to measure amps. How can it be done and what kind of tools?

Monitoring system http://www.theenergydetective.com/store
This product is now in back order 3 to 6 weeks delays. I ordered mine last week and I did get notice it's been shipped. I'm moving the above system to permanent link on the net. I did not order any monitoring devices. It comes with a gateway that plugs into your router(wi-fi). Plus no wiring and it even appears in your browser, Mac, Linnex, window.

Sunpower will be running their monitoring system.

Google Power will be hooked up also.

Progress link http://www.enichesoftware.com/solar/index.htm

Vern

[Mike90250]

I got one of these 336 fluke. I don't want to turn off system or do any wiring to measure amps. How can it be done and what kind of tools?

Are you comfortable dealing with lethal voltages and current? One error, and you are dead, with your family planning your funeral. If you are asking this question, you likely are not ready to do the following dangerous steps.

Does your Fluke have a DC clamp on amps setting?

You can, if you are expecting only 5 A, create a short circuit at each panel, unless they are wired with MC connectors (which are self-locking)

To measure amps, at system voltage, of ALL panels in series, would be like shorting a 400V power supply. Only 5 amps per string, but a heck of an ARC !
If you do it in the J-box, it will leave a big burn mark, and not be good on your meter leads.

Best is to buy or lease a Clamp-On Dc Amp meter for a day, and test each string

Is your system Actually Running, inverting and feeding the grid ? Doesn't the inverter have a display which shows all states (it may be slowly scrolling)

If inverter is not running, it's much harder, you have to get current flow going, which means a short. Do you have DC breakers in a combiner box?
If so switch them all off, install series ampmeter, and switch one breaker back on, record, OFF, next breaker on....

[Vern2]

Fluke is a DC-AC Amp clamp meter. http://www.tequipment.net/FlukeClampMeter336.html

The panels are coming with the new MC4 connectors. You need a tool to release clip connectors.

With At&t I'm a licensed DC Power systems tech, I had to have that license to do my real job. PBX (Switch installer). I retired with 33 years because I had a stroke. I installed AT&T end offices. I've installed more power system... Giant Battery backup systems. I know what big black burn marks look like. I really don't like making them. You actually have to watch out for flying liquid copper. I only did it once.

The install company, I think was leading me to believe. When panels are wired in series all you get is 5 amps. So no actual panel output, only a series array amp reading. Or is that the reading I'm looking for? And he doesn't know what he talking about.

Big DC stuff does not leave black marks, I could not find any copper. It might have vaporized. Just a hole in the bus bar 3/4 inch 1/4 to 3/8 deep. It was out of sight once I put all the sheet metal around the contactor area. Can't remember how big that system was. 1 to 2 hundred amps. I think I was moving a 2 ott power cable to fire up another bus bar for more DC breakers. I was working late at night by myself.

AT&T uses positive grounding, not a stranger to this.

Thank Mike

Vern

[Vern2]

I think I figured it out. The only way, is look at the voltage of each panel. If I suspect a problem.

By the way my TED just arrived. I ordered the TED 5000-SG. No 6 week back order for me. http://www.theenergydetective.com/store

Vern

[Mike90250]

Do they have any breakers in the DC path ?

Otherwise there IS one way. At night, short the panels, and when the sun rises, current will start to flow, and you can measure it. And you have to wait ALL day. If you open the circuit in light, you have the 500V arc welder (at 5 amps)

[Vern2]

Panels wire #10 to two combiner boxes(sub panels) with breakers to put two groups of arrays into. (40 - 230k panels 9.2k) Arrays will be 8 rows of 5 panels. See Drawings, http://www.enichesoftware.com/solar/index.htm All 5 panels will be adjusted(tilt) at one time, no info on how many legs in group, I asked. Then bus bar from combiner boxes to two 5,000 SMAs. #6 wire, 55 feet to 200 amp powerbox in conduit. I think two phase and a ground 3 wires. That connects to 50 or 60 amp breaker, no info yet, I asked. They are charging me $1,250 for eng drawings and calculations, unseen so far. I asked for a copy. What am I leaving out. NO DRAWING YET.

[newenergy]

I don't get why you can't measure amps with the clamp on meter. You don't have to disconnect anything. The amps on any one module will necessarily be the same as for that whole string.

BTW, I don't see why you need to disconnect any MC4s, but it's easy to do with a needle nose and not really hard to do with your finger nails.

[Vern2]

I don't get why you can't measure amps with the clamp on meter. You don't have to disconnect anything. The amps on any one module will necessarily be the same as for that whole string.

BTW, I don't see why you need to disconnect any MC4s, but it's easy to do with a needle nose and not really hard to do with your finger nails.

You are right.

I'm just trying to move from panel to panel and measure that panels performance. I'm told with a DC clamp meter I will only get an array total of amps not an individual panels performance.

So if thats right, I've got to compare arrays to one another. If there's a difference, I can figure there's an under performing panel in the array group. Now I'm back to the same problem, which one.

Vern

[Mike90250]

I've got to compare arrays to one another. If there's a difference, I can figure there's an under performing panel in the array group. Now I'm back to the same problem, which one.

Vern

Nobody said it would be easy

[newenergy]

Current is charge (electrons) per time. The flow of charge through a circuit is like water down a river. As long as the section you are talking about has no tributaries (no parallel paths) the current must be the same at all points. That's the way it is in a string of modules. So, it's not that you can't measure current differences within a string, it's that there are no current differences within a string.

It could be that reading the voltage of each module would give you the answer you want. I think something could be rigged up to do this safely.

[Vern2]

Thanks Mike.

If I rig up something, I can move from panel to panel measuring open voltage. I don't think a small load while measuring will make a differents.

I here +-5, +-10 percent on panel quality. What are we buying? How do our panels fit into that quality range. Is it just a pig in the poke.

It seems like the only test is, is the panel dead or not. I don't think all panels are born equal.

Vern

[Mike90250]

It seems like the only test is, is the panel dead or not. I don't think all panels are born equal.

Vern

Generally, panels are "graded at the factory." That's why all the 180, 185, 190, 195, 200, 205W panels are the same size. They came off the same line, and performed differently at test time. Some Mfg's rate 5%, some 10%

After they leave the factory, they all age pretty much the same, about -1 or 2 % each year. Just the nature of the Silicon crystal, it slowly degrades in sunlight.

A large drop in power is usually a crack or intermittent electrical connection.

http://en.wikipedia.org/wiki/Photovoltaics