out what size charge controller for solar panels.??

[carl2591]

I was gifted a couple of 335 watt solar panels the produce 46.3V Voc, 37.9V Vmp, 8.8A Imp, 9.36A Isc.

I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system??

This is going on camper shell to provide extra power when needed or if RV parked in shady spot. I was going to mount this spare MPPT and take some wires out to a connector so i can plug in large panel to put power to mppt controller to help charge up 2-6 v batteries. (12V)

there will be several 12v panels of about 360 watts total which could be wire in series to make 24v system but do to shading issues my stay parallel. '

Not sure the best way to go on this system.

I have checked voltage and with full sun it at like 46 volts DC (not hooked up to any thing just the leads)

[pianotuna]

Hi,

You would be far better off with the Grape 40 amp PWM controller from Home Depot, as opposed to the Bogart. It is a best buy item.

I would use 4/10 which would allow 2 #10 wires for positive and 2 #10 wires for negative.

[carl2591]

look like i am talking to myself again.. LOL

the 20 amp mppt controller can handle two of the large panels being 24 volt. The mppt can handle 545 watts at 24 volts which is some 16 amps.

not sure what all the fuss was about now.

I have 2 - 50 ft sections of 10 awg solar cable on the way and will use some for roof wiring to combiner box and rest for extension card.

When looking at wire size chart with a 3% line loss according to ABYC-E-11 I see a 10 awg is good for the 35 ft I plan to use from large panel to mppt controller on AS for additional power when needed.

the controller will figure out what battery voltage and use higher panel voltage to provide more power to batteries when needed.

thanks for all the help and it seems there is a lot of confusion on this subject i see.

[carl2591]

Just to update a bit on controller I was going to use.

On the RV which currently has 360 watts of 12 v panels I was going to use the bogart SC2030, However i was not sure that was big enough and was thinking to go with moringstar 45 amp PWM.

That way if and when i add more panels I would not need to replace controller for a while.

Then in looking at bogarts website i see "how to hook up 2-SC-2030 to one TM-2030 RV". I was like YYYYEEEESSSS.. this is perfect and I feel the best way to make sure i have needed over head this will give me 60 amps to use.

I have the TM part now to get one SC and with the 20 amp MPPT to use for large panel I feel this is a good way to get this project off the ground with a solid plan.

the fun part is installing all this stuff in my space

anywho thank for all the info and help.. you guys are the best..

happy trails.

[carl2591]

true.. Plus most of the time the panels on AS will be doing the charging.

The panel on truck will only be used when there is too much shade or lots of overcast and the extra power will be needed..

My , our, plan is to stay in cool summer weather with little rain or cloud cover etc.. LOL

BFL13 wrote:
You can put the PWM and the MPPT on the same battery bank and they will add their amps if their set voltages are similar. It is the voltages that count, not whether they are in bulk at the same time. It is no different from any number of chargers on a bank at the same time. Keep their voltages nearly the same.

I don't know what the Bogart's voltages are. The Tracer will go to about 14.6 or 14.8 (you can adjust a little by picking AGM or Flooded)and then stay at that for 2 hours then drop to about 13.6.

So for most of the day they ought to be fairly close in voltage to mostly add their amps if the Bogart high set point is about 14.6 or so.

[BFL13]

You can put the PWM and the MPPT on the same battery bank and they will add their amps if their set voltages are similar. It is the voltages that count, not whether they are in bulk at the same time. It is no different from any number of chargers on a bank at the same time. Keep their voltages nearly the same.

I don't know what the Bogart's voltages are. The Tracer will go to about 14.6 or 14.8 (you can adjust a little by picking AGM or Flooded)and then stay at that for 2 hours then drop to about 13.6.

So for most of the day they ought to be fairly close in voltage to mostly add their amps if the Bogart high set point is about 14.6 or so.

[carl2591]

good info..

I do understand the 12v battery and 12 volt PMW. the difference between a tri start 45 amp and a bogart 2030 is only like 50 bucks. While i know Handy Bob raves about the bogart system want to make sure I am not tripping over a dime to get to a dollar. (in reading on bogarts site they say in the sc2030 manual it can handle 4 135w panels of 12v panels and I like the pairing of similar equipment so that might work after all. ) I will have the ability to tilt panels on AS as well.

in watching some you-tubers that full-time with solar systems installed by AM solar, one of the better installers, they still have issues when camped in shaded areas like the north west or pretty much anywhere on east coast. SO more is better in panels. (currently east coast based)

I agree with the 20 amp mppt controller i have as being usable. I do plan to have ability to tilt panel on pickup for winter low sun angles so that might be OK overall..

Doing a bit of reading it not uncommon to mix mppt and pwm on same battery bank.. one item of interest was to make sure the different points of charging rates were same. ie bulk 14.5, float 13.2 etc..(made up numbers) so one controller is not trying to do bulk and the other in float. I need to make sure I have enough control of the mppt controller to do that.

The MPPT controller is a Tracer 2210RN and appears to have set voltages depending on type of battery. I understand the tristar is very adjustable with remote meter and the 2030's have some adjustability as well.

getting there, thank for info.

BFL13 wrote:
The Bogart 30 amper can run 460w of panels aimed at a high sun for 29 amps plus it is able to clip the amps at 30 if you ever get more amps.

You do understand that the PWM controller must be on a 12v array with 12v batteries. (still not clear you got that) So it has to go with the 12s on the Airstream.

Meanwhile, you said in the OP you also have a 20 amp MPPT controller. A 335w panel should get around 21 or so amps aimed at a high sun, and all MPPTs limit themselves to their rated amps (or output watts, whatever,) --so no harm in using the 20 amp MPPT you already have with one of those 24v panels.

You won't be getting the full 21 or so amps very long during the day even if aimed, so you are just doing the recommended over -panelling with MPPT to get more AH haul when the sun is lower am and pm.

So you don't need to buy anything. You already have it, so just use it and enjoy! 🙂

[BFL13]

The Bogart 30 amper can run 460w of panels aimed at a high sun for 29 amps plus it is able to clip the amps at 30 if you ever get more amps.

You do understand that the PWM controller must be on a 12v array with 12v batteries. (still not clear you got that) So it has to go with the 12s on the Airstream.

Meanwhile, you said in the OP you also have a 20 amp MPPT controller. A 335w panel should get around 21 or so amps aimed at a high sun, and all MPPTs limit themselves to their rated amps (or output watts, whatever,) --so no harm in using the 20 amp MPPT you already have with one of those 24v panels.

You won't be getting the full 21 or so amps very long during the day even if aimed, so you are just doing the recommended over -panelling with MPPT to get more AH haul when the sun is lower am and pm.

So you don't need to buy anything. You already have it, so just use it and enjoy! 🙂

[pianotuna]

Carl2591,

480 amp-hours only requires 288 watts to charge--but you need to replace the energy used each day, too. That is why a proper energy audit is one good place to start the design of the system.

I would not buy the 45 amp Tristar. Better to jump right to the 60 amp. That has to do with controller overhead. The 45 amp has 2, the 60 has 3.

[carl2591]

SO I am back.. first off... Happy New Year to all... 🙂

currently NONE of this stuff is installed or hooked up.. I am trying to make sure I have enough head room for what i have with some space to upgrade the smaller (100 w) panels on top of AS. I can only use one of the large 335w panels so that is that.

I do have a bogart battery monitor with 500 amp shunt.. did not think the 30 amp bogart charge controller was enough but I guess if you look at the real world I might get 30 amp only for a short time of the day in a cool area. Plus I want to have something that is large than i might need in the future. so looking at 45 amp tristart PWM controller. with the remote control panel.

To address some points.. I am aware the bogart 30amp PWM controller will not work with a 46 volt 335W panel.. for that I am going with a 30 amp mppt.

for the 360 watts currently to be installed on AS, which may be increased over time to 460 or 560 I was going to use a 45 amp tri star PWM.. but in reading it seem i need to keep the different CC the same MPPT controllers vs one PWM , one MPPT.. not sure is that is correct might need to call morningstar to find out for sure.

I see one comment that say the 30 bogart pwm may be big enough for up to 500 watts which I might need to ask bogart about as well. if i add two panels it could be close to 560 watts.. not sure if that would be big enough.?? still might just go with 45 tristart to be sure.

Better safe than sorry..

While is seem like a 160 dollar 40 amp MPPT controller (EP Ever) might not be all that but in watching several youtube videos on them it appears for the money they represent a good value. One guy took the cover off and went through the components and was commenting the electronics used are not under sized or inferior quality for the unit. in fact some stuff was over sized.

The main wire he commented were extra large for what is generally 2 -20 amp units tied together. You might want to watch some of Adam Welch video
https://youtu.be/r3LrWeYYtnQ

thanks for the info..

looking to be upgrading from 2 6v wet cell, to 4 -6v agm in future so wanting to make sure i have enough watts to charge the system.

[Almot]

BFL13 wrote:
The OP said he was looking at the Bogart 30 amp PWM to run his 24v 335w panel

I didn't see it clearly stated. Could've been interpreted like this, yes, but then, there's been a bit of ambiguity and missing pieces of info in his posts. I'm out.

[Almot]

CA Traveler wrote:
... but a battery monitor is very valuable to determine battery state, charging/discharging etc.

The battery monitor was the first thing I installed.

... And he might already have Bogart monitor - there is no info from the OP on this, either. If this is so, then adding Bogart controller is what I would do (that is, if I were planning 12V parallel array).

The first thing that I installed, after researching my energy needs and solar harvest data in my area, was 2*250W flat solar and 30A Rogue MPPT with infinitely adjustable and well automated charging profile and very detailed display. Reads V/A in before and after controller, and gives me full report in the evening - whether the Abs was reached and if so - whether it was completed, and how long it stayed in Float afterwards.

The estimate was (given the needs and weather) that it will never drop below 70-75% after dark, and will go into Abs before noon 8 times out of 10 - and it worked. Up to this day I don't know whether I need a battery monitor, and what for 🙂

[BFL13]

The OP said he was looking at the Bogart 30 amp PWM to run his 24v 335w panel but that only works if his batteries are 24v. He needs MPPT for its buck converter to do 24-12, and he already has an MPPT 20 amper.

335 aimed at high sun should get at least 335/130 x 8.2 = 21 amps, but most of the day, lower sun or panel not aimed, amps will be under 20. Any MPPT can handle over amperage to some degree--not PWMs though at least not for long as they heat up and fry.

The 360 worth of 12s on the Airstream will be fairly flat? ( but is there a flat spot on an Airstream? ) Could be 23 amps aimed but under 20 flat. He could use his MPPT 20 amper on those (in parallel of course) but he must have MPPT to use the big panels with the 12v battery system however they are aimed.

A 30 amper for the single 335 would be ok even if aimed (as he might do as a portable) even the 20 won't fry. If using both panels, just price a single 60 MPPT vs two Tracer 30s (which can be in parallel on one battery bank)

However it is all just weird with no scenario for how much solar is needed.

[CA_Traveler]

Almot wrote:
Keep in mind that Bogart controller is an add-on. It won't work well unless you couple it with Bogart battery maintainer, and this one would cost more than the controller.

Yes but a battery monitor is very valuable to determine battery state, charging/discharging etc.

The battery monitor was the first thing I installed.

[Almot]

while i do have two panels i as planning on only using one of them and it sounds like that is all the MPPT can handle.


No. You might want to read the answers again. Your 20A MPPT won't handle even one of those two big panels. "Some" MPPT can handle much more than they are rated for (or claim so), but without any information about your MPPT it should be assumed that it can't.

seems like i need a 45 amp PWm

More like 25A PWM (for 360W of 12V panels). Panels have to be of the same wattage, or very close.

for the larger higher voltage 335 watt 40 volt panel I need an additional 30 or maybe a 40 amp mppt controller when when i use that panel.

Still want to do it the hard way, eh? 🙂 You don't mix PWM and MPPT, there is no need to, it complicates things. As said before, if you want more watts - get a few big 24V panels and one big MPPT.

I was looking at the bogart 2030 charge controller but it only go to 30 amps which would not be a problem now but woiuld be limiting in the future if i decided to add another panel or two.

Not really. For 360W array of 12V panels you need 25-30A controller. Bogart will do. Also, Bogart is one of those PWM that do allow higher wattage without going up in smoke. With a bigger 500W array it will still limit the output to 30A, yes, but you will rarely get 30A even with 500W. Keep in mind that Bogart controller is an add-on. It won't work well unless you couple it with Bogart battery maintainer, and this one would cost more than the controller.

the Mppt I am looking at is on amazon EPEVER 40A MPPT with remote and temp sensor cable.

I doubt that $150 will buy you a decent 40A MPPT. Though, EP Solar aka Tracer have been around for a while and cobbled up many models. With varying specs on the same model, depending (probably) on which factory printed it.

You don't really need MPPT with 12V array. Bogart will do fine for 400-500W, and will kind of forcefully make you aware of your battery charging state, which is something that you might find useful.
Alternatively, Grape Solar 40A PWM will suit your needs fine.

PS: BFL is right, for a pair of 6V batteries you don't need a lot of solar. Get 3*120W or 4*120W in parallel and $50 Grape Solar PWM, he's a good one.