Bringing my new system on-line

[MichaelK!]

For several years, my meager 400 watt solar system supplied a bit of power at my cabin. But, a long-term goal of mine was to design and build a much larger system capable of powering my 240VAC well pump. This would reduce fuel consumption on the homestead significantly.

Using a clamp meter I determined that the 1.5hp pump was using 10 amps to run. This Fluke meter also has "in-rush" capability, and measured that starting amperage at 37-38 amps (500 mSec). That means I needed a substantial inverter to supply that much power. I selected Schneider's XM6848 120/240VAC inverter that has up to 12kw of surge (5 seconds).

I coupled this to 15-300watt Renogy panels, wired three in series per array, a 3S5P configuration. The 115VDC from each array was funneled through a combiner box which feeds a Midnight 200 charge controller. The Midnight charges a bank of 8 L-16 batteries wired in series for 48V. I created ground arrays, made out of welded unistruts. Each array sits on a 3.5" pipe sunk 4' into concrete. A 4" pipe slips over the 3.5", with the frame attached. This allows the arrays to track both left to right, and can also be adjusted for seasonal position changes.

image_10177.jpg The frame fits over a single steel pipe sunk in 48" of concrete, which allows the array to track the sun left and right. The horizontal stabilizers at the bottom also allow for season angle changes. Here is the array with the panels installed.
image_10178.jpg
Though I did most of the wiring myself, my BIL is a retired electrician, so I had him inspect my work.

Last month we flipped the breaker to start the well pump, and the XM powered it up with ease. I'm now in the performance qualification phase of the system. My rule of thumb is to run the pump only while the panels are capable of making >2400 watts of power. This happens after about 9:30 in the morning. If the arrays are swung over to face SE, the batteries are mostly charged by then. By noon though, there's enough excess power to bring the batteries up to float. I position the arrays manually to track the sun when maximal power is needed. On days I'm not pumping I just lock the arrays facing south and forget about them.

[sensij]

For those interested, here is a thread started back in 2015 when the OP was earlier in the design stage:

https://www.solarpaneltalk.com/forum...pumping-design

Glad to see it coming together so nicely!

[Saggys]

Nice design on the ground mounts, did your BIL help with that? Us electricians love to use unistrut.

[J.P.M.]

For several years, my meager 400 watt solar system supplied a bit of power at my cabin. But, a long-term goal of mine was to design and build a much larger system capable of powering my 240VAC well pump. This would reduce fuel consumption on the homestead significantly.

Using a clamp meter I determined that the 1.5hp pump was using 10 amps to run. This Fluke meter also has "in-rush" capability, and measured that starting amperage at 37-38 amps (500 mSec). That means I needed a substantial inverter to supply that much power. I selected Schneider's XM6848 120/240VAC inverter that has up to 12kw of surge (5 seconds).

I coupled this to 15-300watt Renogy panels, wired three in series per array, a 3S5P configuration. The 115VDC from each array was funneled through a combiner box which feeds a Midnight 200 charge controller. The Midnight charges a bank of 8 L-16 batteries wired in series for 48V. I created ground arrays, made out of welded unistruts. Each array sits on a 3.5" pipe sunk 4' into concrete. A 4" pipe slips over the 3.5", with the frame attached. This allows the arrays to track both left to right, and can also be adjusted for seasonal position changes.

image_10177.jpg The frame fits over a single steel pipe sunk in 48" of concrete, which allows the array to track the sun left and right. The horizontal stabilizers at the bottom also allow for season angle changes. Here is the array with the panels installed.
image_10178.jpg
Though I did most of the wiring myself, my BIL is a retired electrician, so I had him inspect my work.

Last month we flipped the breaker to start the well pump, and the XM powered it up with ease. I'm now in the performance qualification phase of the system. My rule of thumb is to run the pump only while the panels are capable of making >2400 watts of power. This happens after about 9:30 in the morning. If the arrays are swung over to face SE, the batteries are mostly charged by then. By noon though, there's enough excess power to bring the batteries up to float. I position the arrays manually to track the sun when maximal power is needed. On days I'm not pumping I just lock the arrays facing south and forget about them.

If I correctly understand what's been done, how is the 4" pipe that's sleeved to the 3.5" pipe in such a way so that wind uplift doesn't take the panels ? Gravity is holding them down but the vertical component of the resultant wind vector on the panels could exert more upward force than gravity. Maybe I'm missing something.

[MichaelK!]

If I correctly understand what's been done, how is the 4" pipe that's sleeved to the 3.5" pipe in such a way so that wind uplift doesn't take the panels ? Gravity is holding them down but the vertical component of the resultant wind vector on the panels could exert more upward force than gravity. Maybe I'm missing something.

Yes, I am concerned about the wind too. If you look carefully at the empty frame picture you can see locking T-bolts I positioned about 1/3 of the way up from the bottom. Basicly, I drilled and tapped the 4" pipe, then welded a 3/8" nut on top of the hole. This lets me screw in a T-bolt that I made from a 6" piece of rebar with a 3/8" bolt welded in the middle. This lets me position the array, then lock it down by tightening the T-bolts. We'll see what happens this winter when the big storms blow through.

To answer Saggys, I found a cheap source of unistruts on Craigslist, and I decided to make the frames out of them. This is actually my fourth generation frame. The first was a little less substantial and welds cracked just as I was dropping the frame into place. I simply started added more and more reinforcements till I reached the 4'th generation design you see now. I did plagerize some ideas from commercial products I saw on the internet, so maybe I should keep that quiet. All the welding was done by the time the BIL showed up. I had a little MIG welder and I basicly taught myself how to weld with this project. By the time I was finished with frame #5, it started to look like I knew what I was doing.

[AzRoute66]

I notice you added three more panels. Was that just because the Midnight 200 CC would take them, or was there another calculation or experience involved?

One of the other posters you referenced in your research, bbuddy, had to turn off his house breaker before starting the pump. What is your pre-ignition checklist?

You were hoping for three hours of pumping per day in the summer. What has worked and not worked as far as schedule? What do you see the 'routine' being when you are well and truly satisfied with the system?

[J.P.M.]

Yes, I am concerned about the wind too. If you look carefully at the empty frame picture you can see locking T-bolts I positioned about 1/3 of the way up from the bottom. Basicly, I drilled and tapped the 4" pipe, then welded a 3/8" nut on top of the hole. This lets me screw in a T-bolt that I made from a 6" piece of rebar with a 3/8" bolt welded in the middle. This lets me position the array, then lock it down by tightening the T-bolts. We'll see what happens this winter when the big storms blow through.

Thank you. I think I understand. Myopia made me not pay attention to the locking mechanism.

I got that the 3 1/2 " pipe butts up to the support frame. I was confused by your statement that "the frame ...allows the array to track the sun left to right" and took that to mean the 4" pipe was free to rotate about the 3 1/2 " pipe and thus track the sun via some as yet to be added arrangement.

FWIW, and no more than back of envelope stuff, a very cursory view of the system makes me SWAG that a design wind speed of, say, 90 M.P.H, and a 30 deg. tilt would produce uplift on each 3 1/2" post of something like 400 - 600 lbf. or so. I appreciate that most wind loading will be less, but if that or something like it is the resultant design wind uplift, that's a fair amount of force to be resisted by a 3/8 " bolt in what is mostly a system that relies on bolt face to pipe friction to resist wind induced uplift, especially if that and lesser loads will be cyclic or occasional as is the nature of wind loadings.

Take what you may want of the above. Scrap the rest.

[MichaelK!]

I notice you added three more panels. Was that just because the Midnight 200 CC would take them, or was there another calculation or experience involved?

One of the other posters you referenced in your research, bbuddy, had to turn off his house breaker before starting the pump. What is your pre-ignition checklist?

You were hoping for three hours of pumping per day in the summer. What has worked and not worked as far as schedule? What do you see the 'routine' being when you are well and truly satisfied with the system?

I added more panels because at least in part, the numbers you see presented about this panel or that panel are just numbers printed on a piece of paper (or computer screen). I have become more educated in terms of what to really expect during the operation of my first-generation solar system and typically derate every panel I see by 20%. I'm starting to think that any solar company that doesn't post their NOCT numbers should be guilty of fraud! If you go by the "on paper" 4500 watts of my system, I am overpaneled. In reality, these brand-new Renogy panels never exceed ~3600 watts, which works out to be 80%. I test this at noon by turning on heavy items like my toaster oven and rice cooker that are all steady induction loads, then check what is coming into the charge controller by both the digital screen and my hand-held clamp meter.

In terms of the checklist, it's only whether or not the panels are producing more the 2400watts at the moment I flip on the switch. This is at about 9:30am in October. Maybe the batteries stop charging after 9:30, but as the sun gets higher in the sky, I am still floating them by about 11am. If I rotate the arrays to the west as the day goes by, I can continue pumping till about 3:30 before power levels drop below 2400W. My next experiment will be to determine just how much battery depletion I can tolerate by running the batteries after 3:30 by checking the specific gravity of the battery cells. Maybe 5:00pm? The leaves are starting to fall off of my trees, so I will be suspending irrigation in the near future, Winter-time water use drops dramaticly.

The pump load on the XM doesn't appear to be more than 25% of total capacity, but I really haven't tried pushing things too hard yet. When we replace the gas refrigerator with an electric one (maybe next May) our daily loads will start ratcheting up. I might have all the subtle nuances of my new system worked out by then.

[MichaelK!]

I appreciate that most wind loading will be less, but if that or something like it is the resultant design wind uplift, that's a fair amount of force to be resisted by a 3/8 " bolt in what is mostly a system that relies on bolt face to pipe friction to resist wind induced uplift, especially if that and lesser loads will be cyclic or occasional as is the nature of wind loadings.

I took things one step further actually. Once I drilled out the 4" pipes, I took a slightly small drillbit that didn't hit the threads and cut a little "dimple" in the face of the 3.5" pipe. I ground down the end of the T-bolts to snuggle into this "dimple". I'm hoping that depression is enough to withstand any reasonable wind force I'm likely to experience. Winter is coming, and I will find out.

[J.P.M.]

I took things one step further actually. Once I drilled out the 4" pipes, I took a slightly small drillbit that didn't hit the threads and cut a little "dimple" in the face of the 3.5" pipe. I ground down the end of the T-bolts to snuggle into this "dimple". I'm hoping that depression is enough to withstand any reasonable wind force I'm likely to experience. Winter is coming, and I will find out.

Thank you. I think I understand. If so, that would mean one dimple for each azimuth change ?

[MichaelK!]

Thank you. I think I understand. If so, that would mean one dimple for each azimuth change ?

No, just due south. There was some effort involved, and didn't want to spend the whole day drilling. My reasoning is that securing the panels down is for rough weather, and most likely I will never need to be pumping water during a storm. We are only lock the arrays down when we leave to go home, and I would never, ever consider letting the pump run without myself being physically present.

[AzRoute66]

My next experiment will be to determine just how much battery depletion I can tolerate by running the batteries after 3:30 by checking the specific gravity of the battery cells. Maybe 5:00pm?

I would suggest that you install an energy meter on your battery bank. These work by putting a shunt in series off the negative lead of the battery bank. The numbers you get from it can form an approximation of the State of Charge in the batteries. While specific gravity is THE measure, I think you will find that the Watt-Hours indicated by the meter will correlate close enough that over time you will be able to estimate real time battery reserve very closely without popping a lot of battery caps to do it.

[J.P.M.]

Thank you. I think I understand. If so, that would mean one dimple for each azimuth change ?

No, just due south. There was some effort involved, and didn't want to spend the whole day drilling. My reasoning is that securing the panels down is for rough weather, and most likely I will never need to be pumping water during a storm. We are only lock the arrays down when we leave to go home, and I would never, ever consider letting the pump run without myself being physically present.

So how often will the panel's azimuth be adjusted ? I guess I need more clarification on your statement that the array can (will ?) be tracking the sun left to right which implies daily or more often azimuth adjustments. I'm not trying to bust your onions, just understand whether or not you plan on azimuth tracking, and respectfully suggest that the hold down method for wind might need some consideration.

[MichaelK!]

Basicly, I cut three inverted V notches in the bottom of the 4" pipe, and screwed a 3/8" bolt into the 3.5" post, pointing due north. Each cut is 30 degrees east or west of south. As I rotate the array left or right by hand, it lifts slightly out of the notch, then drops into the next notch. Once it lands in the V, it is quite stable and doesn't move at all. I didn't bother going more than 30 degrees, because I thought shading would start be to a problem. So far it's working exactly as I expected it to do. I have no intention what so ever to motorize this.

In the morning, I swing the arrays to east of south, though the panels are not perpendicular to the sun till about 10AM. At around 11AM, I swing the arrays over to the south V. Then at about 1PM, I do it one more time, swinging to the west. So far, this stratege is letting me pump from about 9:30AM till about 3:30 pm.

[J.P.M.]

Basicly, I cut three inverted V notches in the bottom of the 4" pipe, and screwed a 3/8" bolt into the 3.5" post, pointing due north. Each cut is 30 degrees east or west of south. As I rotate the array left or right by hand, it lifts slightly out of the notch, then drops into the next notch. Once it lands in the V, it is quite stable and doesn't move at all. I didn't bother going more than 30 degrees, because I thought shading would start be to a problem. So far it's working exactly as I expected it to do. I have no intention what so ever to motorize this.

In the morning, I swing the arrays to east of south, though the panels are not perpendicular to the sun till about 10AM. At around 11AM, I swing the arrays over to the south V. Then at about 1PM, I do it one more time, swinging to the west. So far, this stratege is letting me pump from about 9:30AM till about 3:30 pm.

Thank you for the clarification. When you wrote "track the sun", I took that to mean the azimuth was continuously adjustable, not incrementally or stepwise adjustable.

Not a knock, and I hated it when other engineers pulled the same crap as I'm about to pull on you, but I might have used sch. 80, 3 1/2" pipe and put a continuous 3/32" or 1/8" groove around its circumference at the same elevation as the 3 dimples and get continuous azimuthal adjustment. FWIW, I probably couldn't have done as well as you have done.