Combining Solar Panel Strings facing different directions - Virtual Tracking

littleharbor2

Funny how that happens when your system is well designed.

Dave Angelini

Are you down there? There is a rocket launch coming up the 30th of a Delta Heavy out of Vandenberg that should be great to see down baja way. It is the last of the class and the largest thrust in the world right now. 21 million pounds. I was in Vandenberg Wednesday when they scrubbed it for the 4th time in a week. Bummer!

Your friends tracker is a Zome. They are mostly used for water pumping on farms and ranches because they need no electricity to track.
I use them very occasionally and their strong points in simplicity and reliability are great. Their downfall for offgrid is they do not go back to east until the next morning when the sun warms the gas, they miss early sun. In baja they are fine but in colder climes this is an issue with the design. They also are not really a dual axis as their track does not change in height. It is an approximation. Still for Offgrid they are fine. It is harder to get alot of solar on them also.

littleharbor2

Dave Angelini said:

Are you down there? There is a rocket launch coming up the 30th of a Delta Heavy out of Vandenberg that should be great to see down baja way. It is the last of the class and the largest thrust in the world right now. 21 million pounds. I was in Vandenberg Wednesday when they scrubbed it for the 4th time in a week. Bummer!

Your friends tracker is a Zome. They are mostly used for water pumping on farms and ranches because they need no electricity to track.
I use them very occasionally and their strong points in simplicity and reliability are great. Their downfall for offgrid is they do not go back to east until the next morning when the sun warms the gas, they miss early sun. In baja they are fine but in colder climes this is an issue with the design. They also are not really a dual axis as their track does not change in height. It is an approximation. Still for Offgrid they are fine. It is harder to get alot of solar on them also.

I will be down there starting on the 27th. I was on top of Catalina Island for the Wednesday launch attempt. Great place to watch as well. Perfectly clear skies.  One thing for sure, Baja is a great place to watch satellites and shooting stars/meteor showers.

Funny, I was chatting with my neighbor one morning and all at once the whole rack of panels flopped over from west to east and started it's business day.  I may be wrong but it seems he has 8 (I think) , 125 watt 12 volt panels on it. I'll take another look this coming week.

Dave Angelini

I bet Cat would be fine. My Brother in Law does launch and space weather and so we were at the balloon shop a few miles from the pad.
Double bummer on the scrub.

We have a very nice view up here and if you can, log into Nasa and get the space station schedule e-mail to your lat /lon. Satellites are great but nothing is as good as the solar panels reflecting when the station goes over your place. It can be a 6 minute show.

Save me some dorado

mike95490

Except for Iridium Flares !  Visible in daytime even, as bright as aircraft landing lights !!
Use the link below, plug in your location.   Very bright reflection from flat antenna array, but the new generation of sats have  different antenna, and don't show well
 The ground track is tiny, only a couple miles across, so they are not always visible from everywhere.   Change the location from LA, to wherever you are viewing from.

https://www.heavens-above.com/IridiumFlares.aspx?lat=34.0522&lng=-118.2437&loc=Los+Angeles&alt=87&tz=PST

Brandont12

Hello- I have 1 HQST 40a MPPT & 4 panels total:

2 Canadian Solar 400w (52.3 VOC & 9.9 ISC)

2 REC 370W (44.1 VOC & 10.55 ISC)

Due to space constraints, I will need to have 2 panels facing West and 2 panels facing South. Im in Northern hemisphere. Being they are facing different orientations, I want to lose the least amount of production. I already know due to the panel types being different, I will lose some production due to VOC dropping to lowest in series or ISC dropping to lowest in parallel. I know that the best way to do this is to have panels of the same orientation on its own MPPT.

However if I were to want to remain with just the one MPPT what is the next best way to wire these panels? Can I Just parallel all 4 panels together? Thanks for taking the time to read this. Your help is much appreciated, Happy New year!

BB.

With the MPPT controller you have, and living in a cool climate (New York area?), you are really stuck placing the panels all in parallel. The controller's maximum Solar panel input voltage is only 100 VDC, and your panel's Voc (voltage open circuiting at room temperature) is already 52.3 volts--Which will only rise as the panels are exposed to cold/sub freezing weather (two of these panels in series is 104.6 volts at 25C/77F). Assuming this is your controller:

https://hqsolarpower.com/40a-mppt-solar-charge-controller-with-parallel-charging-bluetooth/

Another question is what is your battery bank voltage? If it is 12 volts, then all of the panels in parallel will work OK for that setup.

REC 370 Watt panels, Vmp~37.4 Volts
https://es-media-prod.s3.amazonaws.com/media/components/panels/spec-sheets/ds_rec_alpha_series_rev_d_ul_web_en.pdf

If this is a 24 volt battery bank, the REC 370 Watt panels are a bit of a low Vmp voltage during summer heat (Vmp and Voc voltage fall as the panels get hot in full sun and warm weather). They will work OK in parallel, but may not be the most efficient under full summer sun as Vmp falls.

If this is a 48 volt battery bank, these panels+controller will not work (all parallel, Vmp array is too low, any series/parallel combination, the Voc array is too high).

The last issue is that the too sets of panels have Vmp too "far apart" to be efficient when all are in parallel. Depending on the MPPT charge controller, the higher Vmp voltage panels (Canadian Solar) may make the MPPT controlller pick the Vmp-array to be equal to the Canadian solar panels, the lower voltage REC panels will not provide very much (if any) current. Sort of like placing 24 volt batteries in parallel with 12 volt batteries (with blocking diodes). The "24 volt" batteries set the battery bus voltage at 24 volts--And the 12 volt batteries will not supply any power.

It is possible that the MPPT controller will "split the difference" and pick a Vmp-array voltage in between the Vmp-Canadian and Vmp-REC, but this is still a compromise and neither set of panels will produce full power. The ideal is that Vmp "match" within 10% (or less) Vmp-panel voltage. Yours are further apart in Vmp rating. And actual array performance will depend on the MPPT Controller's design (cannot tell from the controller specs what will happen with Vmp-array--Which is is "set" by the MPPT controller's programming).

This "panel matching" issue is a common problem with different brands/models of panels mixed together in one solar array.

You have a difficult match of panels, and a MPPT controller with a "lower" (not worse, just lower) max input voltage. If you are "stuck" with the panels you have--The best you can do--I would suggest getting a different brand/model of MPPT controller with a maximum Vpanel input voltage of ~140-150 volts minimum Vpanel input. And place one REC+Canadian panel in series facing West, and a second REC+Canadian panel set facing South. The panels have a closer match in Imp/Isc (less than 10% difference) and will be a good "match" together. This setup will work for any 12/24/48 volt battery bank (assuming MPPT controller you pick supports your bank voltage)

If you have a 12 volt battery bank, your other option is to get the 2nd MPPT controller and place two REC panels in parallel facing West, and two Canadian panels facing South (REC vs Canadian panel pairs facing south or west does not matter). That will give you optimum harvest at the cost of a 2nd controller.

If you have a 24 or 48 volt battery bank, these panels and your HQST controller are not a good match (24 volt battery bank and parallel panels--Vmp voltage is pretty low for REC panels, and will not work with 48 volt battery bank).

One of those "simple" questions that have a complicated "it depends" answer.

If you want to continue talking about your system--Go ahead and start a new Discussion/Thread. That way we don't confuse your specific system setup with the original posts.

Good luck!
-Bill

PS: I see that you have a new thread... Lets continue the Q&A over there...