Will a dual post breaker diminish output using a single series array?

[showme]

I've just completed installing a grundforss sqflex pump and something is weird here. I have it wired direct (no batteries) to a series of (6) Evergreen Solar 120w panels. It was late afternoon when I finally got it wired and operational. The panels are on a temporary stationary ground mount I made. I can't remember what degree they're mounted, but it's basically winter position, not facing up to the summer alignment.

I've got them running through an old(er) Outback breaker box with a dual post 125a breaker that was in it, which came with a wind generator set up I bought used. So, I've got 720w of panels but the CU200 controller was showing 250w coming in at the time shown above. It was pumping a good 5.5gpm through the 6gpm Grundfoss even at .25kw, and I haven't made it back down to the property today to check in in mid day sun, but I was just wondering if running the panels through a double breaker instead of a single could affect the power coming out of that breaker? I realize I may get back down there tomorrow and get full power out of the array, but it made me think about something I'd never considered before. Thanks for any help on this. Lee

 

[OzSolar]

Sounds like a fun project!

250W from a 720W rated array later in the day from an array with an angle optimized for winter sounds in the range of normal to me.

What do you mean by a dual post breaker? Are you talking about a panel mount breaker? You might check to make sure it's under the array's voltage.

 

[Ozark Tinkering]

I've just completed installing a grundforss sqflex pump and something is weird here. I have it wired direct (no batteries) to a series of (6) Evergreen Solar 120w panels. It was late afternoon when I finally got it wired and operational. The panels are on a temporary stationary ground mount I made. I can't remember what degree they're mounted, but it's basically winter position, not facing up to the summer alignment.

I've got them running through an old(er) Outback breaker box with a dual post 125a breaker that was in it, which came with a wind generator set up I bought used. So, I've got 720w of panels but the CU200 controller was showing 250w coming in at the time shown above. It was pumping a good 5.5gpm through the 6gpm Grundfoss even at .25kw, and I haven't made it back down to the property today to check in in mid day sun, but I was just wondering if running the panels through a double breaker instead of a single could affect the power coming out of that breaker? I realize I may get back down there tomorrow and get full power out of the array, but it made me think about something I'd never considered before. Thanks for any help on this. Lee

Using a single pole of a 2 pole breaker will not have any affect on the amount of current it allows to pass through. The circuit will be protect at nameplate rating of the breaker. A 2 pole breaker is essentially 2 single pole breakers mechanically tied to each other so that if one pole sees an over-current event, both poles open. If you have a low output problem in the scenario you described, that ain't it.

 

[JoeHam]

I use C65H-DC dual pole breakers on all panel setups. Handy as a disconnect switch also.

Never had a problem, agree with Ozark.

Here is one example :

https://www.amazon.com/Delaman-Circuit-Low-Voltage-Miniature-Switch16A/dp/B081RY3NJ9/

 

[Quattrohead]

Use Chtaixi brand breakers, they are good quality and work as expected.

CHTAIXI: 12V-110V DC

DC Miniature Circuit Breaker TXC65Z-60 Curve B 1P

www.amazon.com

 

[Mattb4]

Simple answer is yes. Though if the quality of the breaker contacts are good than the amount of resistance is negligible. To understand why you need to get into breaker, fuse theory and design. With a intro to conductive metals and the effects of oxidation/corrosion. Interesting fact of copper conductivity is it is reduced by oxidation whereas silver conductivity increases.

Suffice to say every single break in your conductor between source and load increases the resistance.

Another interesting fact is breakers have a lifetime based on usage and their ability to handle arcs.

 

[showme]

Thanks, everybody! I'm going back down there today (rained all day yesterday), but I'm pretty sure it's a Midnite Solar breaker. The breaker that was in there originally was pretty dirty, so I took it out and stuck in the new MS breaker I had. I used the box since it wasn't being used for anything else and I had it laying around from the old Whisper 400 set up I'd acquired a few years back when I bought my Xantrex power panel set.

I was fairly sure it was the sun/panel angles that were the culprit, but I'm still a novice at this.

OzSolar, I meant double pole, not post. I'm a geezer. I forget sometimes.

Ozark Tinkering (like the name), that's what I wanted to hear!

Thanks again, folks, and I'll report back after I re-check everything in full sun. As I said, it was still pumping out almost 6gpm at the .25 kw level, so I'm not unhappy with what it's doing. I should have just gotten down there earlier in the day and tried it out at mid day. It will be interesting to find out if it actually raises the gpm when the sun is direct. But for a 6gpm pump, I say it's doing pretty good at low wattage. And these pumps are designed to work with 30-300vdc, a very wide range. That's another thing I didn't get done that day, which is putting a meter on it and see what's coming out of the panels and then the breaker. BTW, I'm using the breaker mainly as a shut off switch for the system. Since it's straight solar with no batts or generator (no grid power to the 43 acres it sits on), it only pumps when the sun shines, and I'll be shutting it down by that breaker when it's not in use, for awhile anywyay. Thanks again, guys! Lee

 

[showme]

Matt- thanks for that information. I agree I need to educate myself on breakers. Per the effects of metal oxidation, I'm a retired Ironworker and a welder of 40 years, with classes in metallurgy under my belt. I'm fascinated by the different stages that different metals go through, from heating and burning all the way through rust and oxidation. In my early days, I was always perplexed by aluminum welding, as it would "turn to water" when I attempted to weld it. That's until I remembered that the skin (oxidation) on the surface melts at a much higher temp than the base metal. Sand blasting or "clean grinding" solved the problem, but it sure had me scratching my head the first few times I tried it. Thanks!

 

[OzSolar]

I was fairly sure it was the sun/panel angles that were the culprit, but I'm still a novice at this.

OzSolar, I meant double pole, not post. I'm a geezer. I forget sometimes.

We're all learning! It's a pretty common for folks to assume that a solar panel will produce it's rated watts. The reality is that about the most you'll ever see it do in real world conditions is somewhere between 80% and 90% and then for just a few hours a day when the sun angle is just right.

What is the voltage of your array? Is it less than the rating on the breaker? I think you're right on the edge.

 

[Ozark Tinkering]

@showme ...hope you didn't catch any of that water that hit St. Louis yesterday. We've been in a heat wave and severe drought just a couple hundred miles away. We're supposed to get some badly needed rain in the next few days and a break from the heat.

 

[showme]

No, OT, we're about an hour south of STL, but parts of it really got it. Our son and his family live in the Webster Groves section, but it didn't seem to affect them. Our son's ex (mon of our grandkids) lives closer in to the ciity proper, but they were ok too. I heard they got 8" in a matter of hours. Lots of damage. I read in the Post Dispatch today that parts of Metro Link (public transportation) may be down for weeks due to damage of some of it's equipment. Thanks for your concern, though!

 

[showme]

Went back down to the property yesterday and re-checked the numbers at about 12:30. The sun is nearly straight up and i would guess the panels are at about 60 degrees. Still getting .25kw, exactly, once it powers up the controller.

I checked the voltage coming off the series and it read 106.2. This seems right, since the Vp is 17.6 on these panels.

Evergreen Solar 120w panels-
Pp- 120w
Vp- 17.6v
Ip 6.82A
Voc 21.5v
Isc 7.68A

What am I missing here, anwyay?

 

[Ozark Tinkering]

Here's the thing about pumps and motors...an electric motor is really dumb and will pull the current needed to maintain the rpm it was wound at the factory to rotate at. It's only imperative is to keep going and will consume as much power as is available to continue to turn. Even to the point of self destruction. The hp necessary for the pump pushing or lifting water to pump the water will be affected by how much head of water above the (submersible) pump there is or in the case of a shallow well pump, the amount of lift. So if you have a submersible pump rated at 6gpm and the effort in hp required to move the water is only 1/3hp then the motor will only develop that much hp because all the motor knows is what rpm it was wound to rotate at. It's all math. Your panels are rated to produce more than the motor needs to accomplish its only task, maintain rpm.
You stated that it was pumping at least 5.5gpm at .25kW and the pump is rated for 6gpm. Seems like all is well and you have more solar capacity than needed for the task. If you had a battery you could probably suck the rest of the potential from those panels and you would see the current rise but that motor is using everything it needs to get the job done already.
I worked on the Robert E. Lee Jr. dinner boat back in 2000 (working vacation) when the river flooded and I had my 5th wheel set up in Cahokia. I wonder how bad the flooding was there in Cahokia yesterday?View attachment 104389

 

[OzSolar]

What am I missing here, anwyay?

Have you looked at the pump curve for your pump? I suspect the answers are there.

 

[showme]

OT- thank you for that information and explanation. I know very little about the actual workings of pumps, and this grundfoss is way beyond my knowledge in the electronics and motors. I know it's a helical design and what that means. All you had to do was use the 'math' word for me to realize one of the reasons I have trouble with it. Although I consider myself a reasonably intelligent person, higher math has always been tough for me. I took some renewable energy classes in a program at San Juan Community college in Farmington, New Mexico about 15 years ago, for one semester. They consisted of Electrical Math, DC control electronics and a physics class, among others. The physics class was easier for me than the two other classes, which were heavy in math. I had no idea how much math electrical engineering is made up of! My head was spinning daily. It was really neat, and interesting, but also depressing seeing all these kids around me sailing right through the work while I struggled to comprehend what I was reading. (Same thing happened in an Excel computer class I took there. I couldn't keep up, so I decided I didn't need Excel for solar, so I bailed on that class.) Did great in physics, though! I was just born without the 'math gene', I guess.
Ah, the Robert E. Lee! I remember going up to the river front as a kid (and a teenager, and an adult to take our kids), and we use to take day cruises on the Lee, the Admiral, and also tour the old Santa Maria replica and a naval ship that was docked there. As a teen, my friends and I would go on the night "party cruises" on the Admiral and have a fantastic time. Later, we discovered the venues just north on the landing (Mississippi Nights, Muddy Waters, etc). Also the Arch and the museum under it. A lot of fun! Until a flood comes along and things start floating down river, anyway.

OzSolar- Pump curve?? Seems I saw a diagram somewhere, but how would that help me here? Let me know. I'm listening! Lee

 

[OzSolar]

OzSolar- Pump curve?? Seems I saw a diagram somewhere, but how would that help me here? Let me know. I'm listening! Lee

We can use a pump curve to determine several things like how much flow we can get at a certain wattage and static water level.

What pump do you have and what is your static level?

Below is a pump curve for Grundfos helical rotor pump but I just guessed a model number so don't assume it's your pump.

Look for that red dot I put on the 15' curve. It's saying that you get 6 GPM with around 80 watts of power from a water source at a 15' static level.

Now look for the blue dot on the 130' curve. 5.5 GPM needs 250 watts.

 

[showme]

Thanks, Oz! Mine is an SQFlex 6gpm pump. The bore hole is 180' deep, but I installed the pump at 165'. The driller said they hit water at 170', but since it apparently hit an artesian vein, the static hovers around ground level to a little over (6-8", but ground level in summer). My gpm measurements were not precise, but pretty close. I used a plastic 50 gallon barrel to get the 10 minute fill time. Since I was holding the stop watch, hose and milk jug when I measured the individual gpm, it was as close as I could get. But after a few tries, it seemed to be 11 seconds per gallon. Also, since the barrel is blue I wasn't able to see 'through' it, I think I actually timed it to closer to 55 gallons. But if it will pump like that at 250w, that's not too bad. And this is a temporary set up until we get the house built, which will probably be next Spring, now, so after that we'll have it on the full set up of new LG Neon panels, not the 6 Evergreens. Thanks for the diagram, too. Visuals are good!

 

[OzSolar]

Thanks, Oz! Mine is an SQFlex 6gpm pump. The bore hole is 180' deep, but I installed the pump at 165'. The driller said they hit water at 170', but since it apparently hit an artesian vein, the static hovers around ground level to a little over (6-8", but ground level in summer).

You're most welcome! Well we appear to have answered your question. The most your pump will do is 6GPM and at that static level it needs ~250 watts. Looks like all is good!

Ultimately it's going into a pressure tank? At that point you will will 2.31 feet of head for each PSI your pressure tank is set at. EG: 50 PSI x 2.31 = ~116ft At that point your pump will need ~400 watts and deliver just under 6 GPM.

 

[Ozark Tinkering]

I'm no engineer nor have I ever played one on television.
In another life however I was an electrician that ran the maintenance shop in a couple of power houses and worked very close with the head millwright at both plants where I learned the physics of pumping water and how those same physics affect electrical motor driver of the pump. All of our pump motors had minimum 115% duty cycles and our plant manager liked to get the most out of them in many cases. We ran many of our motors @>100% so the pumps would perform the work we need done. The current of the motor can be raised and lowered to a certain degree on a centrifugal pump by throttling the output valve. The more flow the more amps. Conversely the less flow the less amps. Throttling is done on the discharge side. If you throttle the suction side you will cavitate the pump.
That working vacation on the Robert E. Lee was a hoot. 3 days after I took that call the river rose way up on the grassy bank below the arch. They were turning it into a dinner boat steak house with a brick bbg in the kitchen (which I thought at the time was kinda dumb) and my project was installing the exterior lighting around all the decks. The only way to get to work while the river was flooded was to park about 1/2 mile away and walk to a grassy spot below the arch where we had a 20' jon boat tied off and the 13 year old son of the brick mason the built the bbq was the operator that pulled the boat and it cargo across the water til we got to the part of the access ramp to the boat wasn't submerged. That lasted about 2 weeks. It was a blast! We got it done just in time for the 4th of July, 2000 fireworks display they put on every year across the river from the arch and had it lit up for the event. The investors invited us( the workers and our families) to have dinner on the boat that night plus we had dedicated parking at the river's edge (which had receded by then) and we had ring side seating on the upper deck of that boat while 10,000 other viewers crammed in below the arch and swatted mosquitos.
Best 4th of July show ever!
@OzSolar excellent work!