Author Topic: solar panel mixed power  (Read 4701 times)

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thirteen

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solar panel mixed power
« on: May 06, 2016, 02:59:39 PM »
I am asking the best way to incorporate my panels together. I am about to start punching holes for my panel poles. The problem I have is that I have 9 panels 24 v 255 w each and then 3 panels 24 v 240 watts each. I wish to use four poles. These will be all in series. Originally I was going to have 9 of the 255 w panels in series coming down to my battery room.  The other three panels (240 w) are in use now.  Can I put the 3 / 240 w panels at the far end of the panels. Using them as the start point neg side  down to the batteries and then finish with the 9  / 255 w panels positive end going down to the batteries. Hopefully without losing much production.  The reason for the series is for the higher voltage. I have to go down 550 feet to the power house. I am not sure if I will lose power with the having the 240 w panels in line with the others. These panels are all the same brand and the same age but the 240 w were used for two years sitting on my wood shed.
I may lose some but I am not sure if the difference is worth buying 3 more 255 w panels. Either way I'll still have to jackhammer one more hole in the rock mother nature have given me to dig in. I thought I would ask and see what I get for an answer. 13
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Bruce S

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Re: solar panel mixed power
« Reply #1 on: May 06, 2016, 04:37:17 PM »
13
I know other more knowledgeable about this will chime in  ;D.
Basically you will have about 288VDC at the lowest panels current rating output.
So let's say for Friday's sake it will be ~ 288Vdc at ~10A . You loses at 550 feet will be dictated by wire size too.

What is the wire size you will be using and the combiner?

 Bruce S
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thirteen

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Re: solar panel mixed power
« Reply #2 on: May 06, 2016, 05:19:44 PM »
combiner box I have not bought yet that will be next month..  no 6 wire and at the highest 377 v just with the 9 / 255 at  it's top I hope to gain some with the other 3 / 240 w panels
I went to three other places and can use no 6  wire but need to stay above 270 v to make it work at its lowest. I do go down to a junction box 60 ft from the battery  bank and go to a no 4 wire  where I cross under a road and it has been known to wash out every couple of years. So I put a box there to be able to replace pipe and wire if needed when we get record runoffs. This time I put the pipe in cement along with my water supply. piping. Plus it also works as a disconnect from the panels separate from the power room.  I put the piping both conduit and water lines in a 4 in sed 40 pipe going across the road and creek so it is better protected. I also put the 4 in in a 14 in culvert over the creek to keep the water from freezing and insulated it. Once okay didn't know, second stupid, three won't be my fault. Neighbors mistake. no 1. and 2  >13
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DamonHD

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Re: solar panel mixed power
« Reply #3 on: May 07, 2016, 03:44:56 AM »
Mixing different types of panels in series, if that is what you are proposing to do, will lose you some potential power output.

If you didn't have a long cable run, and if I've read your description correctly, I'll be putting them in series in groups of 3 identical panels, and paralleling those groups up.

Rgds

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thirteen

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Re: solar panel mixed power
« Reply #4 on: May 07, 2016, 12:13:30 PM »
550 ft run is my problem. I am trying to use all of my panels in series without buying 3 more 255 w panels and selling the other three. Will I gain a little more power with the 3 / 240 watts compared to the loss of using them with the others?  My limited solar power in the winter is my problem  mid Nov. until Feb.  Estimated time would be about 3 hrs. at best.
I'm sure I can find a place for my 2 / 240 w panels. 13
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DamonHD

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Re: solar panel mixed power
« Reply #5 on: May 07, 2016, 12:31:17 PM »
Have you made sure that all panels in series will not toast your charge controller when temperatures are very low (ie panel voltage goes up as temperature goes down)?

Rgds

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thirteen

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Re: solar panel mixed power
« Reply #6 on: May 07, 2016, 11:32:16 PM »
I am getting a new one but I am also trying to find one that will also  handle a micro hydro addition. In two years I plan on putting is a micro hydro system.  I have good water during the winter but not during the summer mid June to Sept. and very little solar from mid Nov. to Feb. I'm in the middle of each so to do it easily I'll l end up with two systems. It is a $$$$ either way I hope I spelled things right I did a glasses pressure test and they did not hold up very good. 13
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southpaw

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Re: solar panel mixed power
« Reply #7 on: May 09, 2016, 09:57:35 AM »
The simple calculation for your system.
Assuming you have your panels in series using minimum 6 AWG wire and a run of 550 ft.
9X255w panels will result in 2295 watts to charge controller.

12X255w panels result in 3060 watts to charge controller.

Adding 3X240 watt panels will effectively reduce the output of all the panels in series to that of the lowest panel wattage.

Result  12X 240 watt panels result in 2880 watts to charge controller.

Using online voltage drop calculator and max voltage of 42v per panel or 502v the drop would be 2.61v or .52% which is very acceptable.

 You would gain roughly 3060-2880=180watts of power by replacing the 3 240 watt panels with 255 watt panels.
Hardly worth the effort.
Choosing the proper charge controller to maximize use of the available power is now the main concern.

Best wishes 
Kurt

thirteen

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Re: solar panel mixed power
« Reply #8 on: May 28, 2016, 02:34:52 PM »
I have found a controller that will work for my solar. Schneider Electric XM-MPPT-80- 600vdc Charge Controller. I was trying to get one that would do both solar and micro hydro but the $$$ got to much so I am going with a three way switch and do it manually when I need it. I will be able to use my controller that I have now. Outback 60 for my hydro.  I can get this for about $1400.00. I wish that included installation. I am back to my digging 4 holes in the ground for my poles. 13
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DamonHD

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Re: solar panel mixed power
« Reply #9 on: May 28, 2016, 02:47:56 PM »
Are you going to connect both hydro and solar controllers to the same battery bank permanently, or if not, why not?

Rgds

Damon
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thirteen

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Re: solar panel mixed power
« Reply #10 on: May 28, 2016, 06:38:20 PM »
yes permanent and  they will go to the same bank. 800 ah. I may go to a  bigger bank but that is the plan.
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southpaw

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Re: solar panel mixed power
« Reply #11 on: May 29, 2016, 10:27:55 AM »
Hi. It's me again.
The spec. sheet for the XM-MPPT-80 states that the max. output into a 24v battery bank is 2560W.
I don't see your bank voltage in any of your posts.
Just another thing to keep in mind, you may lose some power at maximum panel output.

Kurt

thirteen

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Re: solar panel mixed power
« Reply #12 on: May 29, 2016, 05:21:41 PM »
24 v  800 ah miss matched batteries until late this tear.
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