Magnum PT100 solar calculator

[cmduran]

I'm about to install 6 180w Grape Solar panels (VOC=24.06; VMP=19.67; ISC=9.77; IMP=9.16) to charge my 4 300ah batteries in series and parallel for 12v and 600amps. I've spent many hours in these forums perusing the voluminous threads on solar and still was unsure about some things. I finally sent an email to Magnum technical support and they (very quickly) replied and directed me to this calculator :


https://www.magnum-dimensions.com/re...rge-controller


One thing I was struggling with was the series/parallel question. I see quite a few folks have recommended parallel because of the shading issue, but I think I've figured out that shading is not an issue with newer panels which have a diode bypass.

According to the calculator my panels have to be wired in series, otherwise one or two or all three "Design Check" calculations will read "too low" and "too few panels in series." I tried entering 2 strings of 3 and 3 strings of 2, but nothing would work except all modules in series.

So it seems like all modules in series is the correct configuration until you reach the maximum voltage for the PT100. For my configuration that was 8 panels (192.5voc). Nine panels produced 216.5voc and the "too high" result.

Anyway, I just thought I'd share this info and the link to the calculator and see if anyone thinks I'm misinterpreting the calculator results or have other comments.

--mike

[cmduran]

I meant to mention that I also played around with the minimum number of panels. For my panels, that was five (120.3voc; 98.4vmp). Below that I got the "too low" result.

[jcussen]

https://baymarinesupply.com/solar-wi...0v-85a-tr.html
No low voltage restrictions. and a lot cheaper.

[C.Martin]

The PT-100 manual changed this past year. The minimum Vmp was increased. You will need at least 3 panels in series.

So you could do two parallel sets of three series panels. The PT-100 will throw an error code if you tried three parallel sets of two in series. It is not a serious fault...it just tells you the controller is unable to find the Maximum Power Point.

If you go six in series...good luck finding economically priced switching/breakers rated for the higher voltages...

I haven’t seen the calculator...and if you can’t achieve the Minimum Vmp with three panels...they must be having more problems with the controller...and have again increased the value.

You might be better off with a Victron. I am very happy with the SmartSolar MPPT150/100-TR.

I originally designed my system around the PT-100. But didn’t have room to mount it with the air space clearances they recommend. Went with Victron instead.

The built-in Bluetooth control is amazing. Make sure any Victron Controller you get has VE.Smart networking capability. This let’s the controller get voltage and battery temp from the Victron Smart Battery Sense, or the BMV-712 Battery monitor with additional temp sensor. Less of a concern with Lithium since you don’t compensate for temp. Adding Venus GX gives you remote management and monitoring.

In retrospect...I am so convinced that a Victron was a better choice that I wouldn’t recommend a PT-100 controller to anyone.

Having said that.llInstill think it is a good choice to add the ME-ARC advanced remote, and you can piggyback the ME-BMK-NS onto the Victron BMV-712 shunt. This gives you better control over charge and AGS functions.

[10 fan]

Connecting 6 in series gives you a VMP of 118v and a VOC of 144v.
This is in the range of 60v to 187v for the PT100. Allows you to run smaller wires from roof to the bay below. This is what I'm doing. 2 runs of 6 in series which puts me in the middle of the voltage range for the PT100.

[Itinerant1]

I'm running a 2s4p 160w panel setup and at times get a P04 code but my panels are 18v or 36v in series. You should be good with 2 in series then parallel the sets.

Make sure voltage is high enough so you don't a P04 code.
Power Limited (Internal Frequency) - the controller includes a variable frequency converter, the P04 power code will show if the output current is being dialed back to prevent the frequency from going too high or too low.
Note: The active charge status LED indicator will blink during this power status.
Info: The P04 power code can be triggered by sizing the PV array’s VOC too close to the battery voltage. If P04 is seen often, the array wiring may need to change to increase the PV voltage input.

If Magnum hasn't updated the manual, yet.
☆☆The "Lower Vmp level" in the manual is wrong. It should be 48-50V not 24 V (pg17, Table 2-1).

[10 fan]

I could be wrong but thought the manual said 60v. When I called they told me 60v min. to 187v max.

[cmduran]

Originally Posted by jcussen

https://baymarinesupply.com/solar-wi...0v-85a-tr.html
No low voltage restrictions. and a lot cheaper.

Thanks for the comment.
I've got a Magnum 3000w sine wave inverter and remote panel, so I thought it wouldn't be a bad idea to match that up with a Magnum controller. I see them out there for only $60-$100 bucks more than the Victron. I don't think I'll run into the low voltage problem with 6 panels in series and I don't think I'll ever go over 8 panels in the future.

[cmduran]

Originally Posted by 10 fan

I could be wrong but thought the manual said 60v. When I called they told me 60v min. to 187v max.

I sent another email to the tech dude. Maybe he can clear that up.

[cmduran]

Ok, so the tech dude got back with me (man, those guys are fast!) but his answer is open to interpretation:

With 4 series the voltage is high enough but 5 would be better to get voltage up to around 120vdc. I believe we are working on calculator not changing based on charge voltage.
Glenn Darby
Sr. Product Support Technical Specialist
Magnum Energy, a product brand of..."

I think that means that the minimum voltage that the calculator is using is low. But I guess it's close, since he say "four (96vdc) would be enough," but "5 (120vdc) would be better."

[Itinerant1]

Originally Posted by cmduran

Thanks for the comment.
I've got a Magnum 3000w sine wave inverter and remote panel, so I thought it wouldn't be a bad idea to match that up with a Magnum controller. I see them out there for only $60-$100 bucks more than the Victron. I don't think I'll run into the low voltage problem with 6 panels in series and I don't think I'll ever go over 8 panels in the future.

My system is all Magnum
Hybrid 3012, pt100, me-arc50 with lfp batteries. They've been playing well together. No bluetooth but with the remote in the middle of rig I don't think it's a big deal. Truth be told after the navalty of the system running day in and day out quietly in the background not much attention is paid to it.

[10 fan]

Found out today after racking my brain and 3 calls to Magnun tech support the on line calculator for the PT100 only uses 48volts. Said they are working on it. Even though you can switch from 12v, 24v, 48v, it only uses 48v to make the calculations. Thought I would pass it on.

[Itinerant1]

Originally Posted by 10 fan

Found out today after racking my brain and 3 calls to Magnun tech support the on line calculator for the PT100 only uses 48volts. Said they are working on it. Even though you can switch from 12v, 24v, 48v, it only uses 48v to make the calculations. Thought I would pass it on.

When using the 12v field.

I went to the calculator in the link and put my setup info I've been using for 3 years now in the required fields, the results seem to coincide with the readings I get from my PT100 at 12v.

The results below is with current 2s4p panel configuration. That will throw a PO4 code for a short bit which seems to be when the LFP batteries are near full anyways. It will max out near 80amp charging but as seen in the image below typically 70+ is usually the norm. Maybe with AGM/ lead batteries it makes a bigger issue.



Now when I run the numbers using a 4s4p panel setup it eliminates the "too low" vmp. Other than the voltage has change to keep it in mppv.



I did try a 3s3p configuration and it also still showed "too low" vmp.

[Itinerant1]

There was a typo in the above post which should have been 4s2p not 4s4p.

I forgot to add the power readings for some pass days to put it in perspective.