-_- 32cells 15.9 volts in the garbage ?

littleharbor2 · December 2018

The MPP voltage range is the voltage that the controller needs to see operate in maximum power point mode. In your case here +2 volts over battery voltage to 72 volts. The 100 Voc. limit is the max allowable voltage your controller will tolerate before damage can occur. The Vmp. is the working voltage your panels will be producing, which is the lower voltage rating of your panels. Of course the actual voltage your panels produce at any given time will likely be lower than the rated Vmp. because of their operating temperature in anything but a very cold environment.

KhellSk · December 2018

jonr said:

Don't add a blocking diode.

I havent decided if I stay parallel but straight onto the battery lik @BB. Suggested

Or go the series on mppt route like @mcgivor @Photowhit suggeted. I need to be sure i can respect the ratings of the tracer3210an.

But for that I need their answer on the difference between
Max. PV open circuit voltage
vs
MPP voltage range

Because i cant tell what im supposed to check for that. Right now I think maxPV Voc is; 19.8Voc x #panels in series //and MPP volt range may be; 15.9v x #panels in series.

I cant afford to assume and be wrong anymore. I just wasted 500$ on 210ah while having recently bought a 130ah thinking I was getting myself 420ah like an idiot. The 130ah is collecting dust right now

KhellSk · December 2018

@mcgivor

The Epever controller will work, however if the panels are all in series the VOC is a little too close to its rated maximum. The better arrangement would be two strings ( two panels in series ) combined in parallel, the output dose not change just the VOC and VMP will be reduced. This will not be a problem with a 12V nominal system.

VOC is the array, or module, voltage without load, this voltage will increase at lower temperatures. At -30°C 93.6V is close the maximum rated input of 100V, in the series / parrallel arrangement the VOC would be 46.8V so well within limits.

VMP is the voltage when module is at maximum power. With series modules the VMP voltage is additive

The MPPT controller will automatically find its maximum power point by tracking the constantly changing voltage, hense Maximum Power Point Tracking, MPPT.

Practically all the information needed is in the learning center, take the time to read especially what's relevant to your application if there are questions by all means ask, as a beginner this resource is invaluable https://www.solar-electric.com/learning-center
This link contains a glossary of terms used in solar discussion https://www.energy.gov/eere/solar/solar-energy-glossary

Yeah I knew all that. Its the term MPP voltage range that bugged me. Is the 15.9Vmp x #panel in series

jonr · December 2018

Go ahead and put your 130ah battery in parallel with your pair of 210ah batteries.

For panels, I would stay parallel and use your PWM controller. 15.9Vmp is enough for a 12V battery, even when warm or in lower light conditions (amps drop off but voltage stays almost the same). I don't think that direct connection (ie, no PWM controller) will gain you anything but trouble.

Carefully monitor your batteries to make sure they are getting fully charged.

KhellSk · December 2018

jonr said:

Go ahead and put your 130ah battery in parallel with your pair of 210ah batteries.

I dont wanna prematurly wear out the 2 new 6v because the 130 if 6months older ???

I would stay parallel and use a PWM controller. 15.9Vmp is plenty for a 12V battery, even in lower light conditions (amps drop off but voltage stays almost the same).

yeah thats what i lean toward doing. I ll just add blocking diodes to each panels. I am in the woods, trees and branch shadow half the panels through out the day, even more since the sun is lower now. I dunno how much more I would gain from going MPPT probably not much. That way I could keep my 1x 36cell 100w 17Vmp in parallel too.

jonr · December 2018

Batteries in parallel don't wear evenly (but much more evenly than most people think). But adding more parallel capacity will increase, not decrease the life of your new batteries.

mountainman · December 2018

@ jonr would you elaborate on how adding old to new batteries makes them last longer? A well known company that I purchased panels from just changed their 12 volt rv panels from 19 vmp 36 cells to 32@ 16 vmp. Not so good for summer parrelel on pwm. But 2 in series 64 cells. @32 volts on mppt may work better than 72@38. Less cc heat less volts to down covert slightly more efficient?

jonr · December 2018

Because the old batteries will take some load, reducing load on the new batteries. Less load on batteries results in less DOD and longer life.

Summer heat reduces panel watts, but then summer sun also has higher intensity, which increases watts. Remember, you can trade watts for volts (by operating a little above Vmp). So most 16 Vmp panels are fine for charging a 12V battery with PWM, even when quite hot (even 65C). Don't agree - run the numbers.

KhellSk · December 2018

jonr said:

Less load on batteries most 16 Vmp panels are fine for charging a 12V battery with PWM

Mine are struggling right now and I cant wait to figure out solution... i have no other power source. I cant wait to find out if its worth spending 200$ on a mppt or if just the blocking diode should be enough to show a big difference cause of my shading. I still waitinf on some answers from @mcgivor and @Photowhit before deciding.

mountainman · December 2018

Tracer 3215bn 150 voc 30 amp 400 watt $128

KhellSk · December 2018

mountainman said:

Tracer 3215bn 150 voc 30 amp 400 watt $128

I know but how much more am i gonna get. Maybe not that much.

KhellSk · December 2018

@BB. @littleharbor2 @mcgivor @Photowhit @jonr

It made it to 12.4 today before it gets all cloudy at 1pm.

I received the battery temp sensor late today and just installed it on the CC. I ll receive the diodes in a week and hopefully I ll figure out a way to install them nicely to block power from going into shaded panels. I will also raise the panels to 45° before the weekend. I ll take down few more spruces too.

I ll keep you updated.

Hope you guys enjoy your holidays and thanks again for all the help so far!

jonr · December 2018

You want to check the battery voltage after it has sat idle for 6 hours or so - not during the day. I'd also purchase a battery hydrometer.

BB. · December 2018

You really need to get the batteries to 14.4-14.8 volts (when charging, these are AGM batteries? these are not AGM...), and hold it for at least a few hours (24 hours scrolling to the manual, unless I am mixing up posters and their systems).

At this point, you should charge the batteries on an account battery charger and get them fully charged.

Trying to get the batteries back full with solar, when they are well discharged during cloudy winter weather and done dappled shade, it is just a losing game for now.

Bill

jonr · December 2018

+1 on what Bill said. I'd pull the batteries and take them somewhere to be fully charged, equalized and then tested. This week.

PV Solar is complicated. You might want to get a good book and study all of it.

KhellSk · December 2018

BB. said:

You really need to get the batteries to 14.4-14.8 volts (when charging, these are AGM batteries? these are not AGM...), and hold it for at least a few hours (24 hours scrolling to the manual, unless I am mixing up posters and their systems).

At this point, you should charge the batteries on an account battery charger and get them fully charged.

Trying to get the batteries back full with solar, when they are well discharged during cloudy winter weather and done dappled shade, it is just a losing game for now.

@jonr

When I left this morning at 9 voltage was reading 12.9. Pretty sure they went through the 2 hours over charge already

BB. · December 2018

9am insert charge? What current?

Bill

KhellSk · December 2018

BB. said:

9am insert charge? What current?

Bill

9am. Voltage with sun on panels. I dont own a meter capable of handling that many amps and the CC doesnt show it

BB. · December 2018

9am "solar" charge....

You need to get 14.8 volts during charging and hold it for a few hours (6-8 hours for deeply discharged batteries).

Or, at least 14.2 volts for 24 hours...

Bill

KhellSk · December 2018

@jonr @BB. @Photowhit @littleharbor2 @mcgivor

MERRY CHRISTMAS !!

i am removing my panels today to reposition them. I left 1x 100w 36cells and 1x 48w 32cells plugged as they r mounted together.

First , i was reading 14.7ish for a while and.now 13.9 slowly decreasing. (Battery was already full). And sun was angled pretty bad 40°

Secondly, i tested all 4 others 48w 32cellls and.... i dont know why, full sun on and facing it at 90°ish... I was reading 20.7 to 20.9 but 1.25ish amps.Thats half of what they were reading last summer (3ish amps. 18-19ish)

******update; voltage was stuck at 13v overnight. And today it went onto float mode reach 13.6. Now at night its at 13.1

¤¤¤¤¤¤¤¤¤Second update. Im still on just the 100w 36cell panels amd 1x 48w 32cell. I only used a bit of power yesterday to charge my cellphone leaving the battery at 12.6. TODAY IS Cloudy AND SNOWY AND volt meter is reading 13.1..... i really feel like those 32cells panels are just trash.. well wired in parallel.

Estragon · December 2018

Assuming you're in the northern hemisphere at a relatively high latitude... it's normal for cold panels to have a bit higher voltage. My strings run up to ~120v in winter, more like high 90s in summer. Current tends to be lower in winter even with good tilt, because at lower angles the sun has to go through more air, water vapour, etc.

KhellSk · December 2018

@BB. @Photowhit @littleharbor2 @mcgivor I just added blocking diodes to 4 of 32cells.

Condition outside arent great and its 4 out of 5 panels 32CELLS plus the 36cells. Almost noon with panels facing SSE.
The voltmeter is reading 13v. Never had that in condition like this.

So far @BB. Is the winner xD... even if im still using the charge controler

jonr · December 2018

Your #1 problem is clear - you live in a forest with no clear view of the sun. Ideally (for this poor case), you would have special panels with lots of bypass diodes (every few cells) and a MPPT controller with plenty of voltage margin to accept low voltages (caused by lots of bypassing). Would be interesting to try using diffuse reflection from the snow to increase output.

Lithium batteries would be better suited to the charging you are likely to do (no need for a full charge or absorb time).

Also consider skipping solar and charging batteries with a generator.

KhellSk · December 2018

@jonr

I know the probleme is the forest brother. Im trying to make it work with what i have as money is tight. The reason im asking you guys help is because im not sure how to proceed to optimize what I have. So far i got 3 suggestions;

@BB. Said parrallel blocking diode direct on battery ( no additional cost)

@Photowhit said 1x string in series with mppt controller (cost a mppt controller plus i would be losing 2 of the panels due to 1 being 36cells and the other would exceed the limit of the controller ) thing is, from what i read and what people say, seems like mppt controller are worst at handling shade than pwm.

I also though about buying 2x 300w panels but then thats gonna cost me those panels and I might be stuck with those 32cells.

##########

Estragon · December 2018

Ordinarily, using an mppt controller and wiring in series of (eg) 2/string would make sense to make use of marginal Vmp panels.

In this case though, putting them on a pwm controller (or no controller at all) as BB suggested for now may be the better option.

A couple of hours with a saw would likely help the most though.

mike95490 · December 2018

Removing trees is your fix. Anything else is a waste. And in summer, if that sun is not above the tree line, you get nothing too.

throwing diodes in your wires is not going to "make" power appear magically, they will steer power where you want it to go, but only the power that was generated at the panels. And every diode will waste power at heat, you will likey have to heat sink them too.
0.8V drop x ____ amps = ____ watts lost as heat in the diode.

KhellSk · December 2018

mike95490 said:

Removing trees is your fix. maple farm, not happrning. Anything else is a waste. not moving anytime soon, need power And in summer, if that sun is not above the tree line, you get nothing too. i didnt just install these. I runned them last summer and everything was fine.

throwing diodes in your wires is not going to "make" power appear magically, i know its a parallel aray with lots of shade, didnt want.my.power to get lost in shaded panel they will steer power where you want it to go, but only the power that was generated at the panels. i know And every diode will waste power at heat, you will likey have to heat sink them too.
.55v drop x _1.25_ amps = _.65___
summer .55 x 2.75 = 1.5w Not enough to care

My situation isnt an easy one you can solve by just dropping by and pointing the most obvious like captain insight in south park. I came to advance forum because i need advanced help. I bet you re the same mike as in solar-talk website.

BB. · December 2018

I think I asked you before... Any way you can put the solar array 100 to 300 feet away? With MPPT controllers and a medium sized MPPT controller, it can be done.

However, it would not be cheap (just the MPPT controller would probably be in the range of $400 to $600--Depending on Amp rating and voltage rating you need.

Higher Vmp-array + MPPT controller can keep the cable AWG much more reasonable (much smaller cable, less $$$ spent on copper).

But I understand that you probably cannot justify the costs for this version of solar charge controller...

Lets start with 12 volt @ 210 AH and you can find a place within 300 Feet. And a 13% rate of charge...

Size of solar array:

210 AH * 14.5 volts charging * 1/0.77 panel+controller losses * 0.13 rate of charge = 514 Watt array

If you get a 100 Vmp-array, that would be 3x Vmp=30 volt panels in series. Get some ~200-300 Watt panels (whatever is cheap in your area/find on Craig's List). Let's say 250 Watt panels @ 30 Vmp:

250 Watt / 30 Vmp = 8.33 Amps

Now, to send that Vmp-array=90 VDC @ 8.33 Amps 300 Feet with 3% or 1% voltage drop--Although I will use 5.5% drop here to keep wire gauge on the less expensive side (you will lose 5.5% of your energy on a clear/sunny/around noontime day):
https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=3.277&voltage=90&phase=dc&noofconductor=1&distance=300&distanceunit=feet&amperes=8.33&x=60&y=18

Voltage drop: 4.99
Voltage drop percentage: 5.55%
Voltage at the end: 85.01

That will work... The amount of current that charge controller would manage:

514 Watt array * 0.77 panel+controller deraging * 1/14.5 volts = 27 Amps typical maximum battery charging current

The Midnite Kid is a bit small for this system, but it should work OK ($325).

https://www.solar-electric.com/midnite-solar-kid-mppt-solar-charge-controller-black.html

You can do some array calculations and figure out the mix/match between array and charge controllers (Midnite brand):

http://www.midnitesolar.com/sizingTool_kid/index.php (Kid 30 amp)
http://www.midnitesolar.com/sizingTool/index.php (Classic ~80+ amp charge controllers)

There are higher voltage MPPT controllers, but they are eye wateringly expensive ($1,100+++$$$). You could even possibly go farther than 300 feet--But for smaller systems, again, the costs for high voltage MPPT controllers can be prohibitive unless it is the only way to make an installation possible..

-Bill

PS: Note that as thread get longer, people don't usually go back to the beginning and will miss the Maple Syrup farm/cannot cut production trees... But everyone here is trying to help.

Solar electric panels only work if in full sun.... Any shading just kills their output. And cutting trees or moving the array a large distance away is about the only way to get a "useful" amount of energy from a solar system.

mcgivor · December 2018

One of my arrays gets partial shading in the morning at this time of the year by banana and papaya plants that were planted last year, didn’t expect them to reach 6 meters high but being temporary plants they will soon be gone. What I have observed is when the sky is clear the shadows cover the lower portion of 3 of 6 panels in 3 series 2 parallel layout, the output from 1500W rated, is ~60W, as soon as the shadows leave the output rises to ~1200W.

During a day with thin cloud cover the output at the same time when shaded is ~500W probably due to refraction of light, there are no visible shadows. There are some who believe the use of mirrors can be used to reflect light onto shaded areas thus increasing output.
This is not something I've personally tried as my particular situation is both temporary and the array can still produce more than I need, but perhaps in your situation it may be worth looking into, or at least doing some research, and or, experimentation as mirrors are relatively inexpensive.

https://theconversation.com/can-mirrors-boost-solar-panel-output-and-help-overcome-trumps-tariffs-90663

mcgivor · December 2018

Continues from post #60
Did some experimenting with a 20W 12V module these were the results.

Battery voltage 12.52V not charged in a few months, module shaded 4 cells on one side, voltage remained the same current 0.0-0.1A, meter fluctuations? Mirror positioned at the base reflection covering the shadow, voltage after 5 minutes 13.56V climbing slowly , current 0.8-0.9A .Full sun after test voltage 14.15v climbing slowly current 1.2-1.3A

So it appears mirrors can increase the output of a partially shaded panel. This was just a quick experiment to satisfy my curiosity but thought I'd share my findings, sure it's not a perfect output but >50% over nothing is nother bad. Your results may differ but would be interesting to hear your results if you decide to experiment.

-_- 32cells 15.9 volts in the garbage ?

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