Solar question. Two panels same 24v , Series/parallel math

[lawrosa]

OK. So I have these panels. 280 watt LG,s I currently use one with an ecoworth 20 amp mppt. Max volts is 50 volts for controller hence one panel..

I can get 17 amps or so out of it normally...

This is panel specs..

Max Power Voltage (Vmp): 31.5 Volts
Max Power Current (Impp): 8.97 Amps
Open Circuit Voltage (Voc): 38.9 Volts
Short Circuit Current (Isc): 9.56 Amps

So I want to carry another panel and upgrade the mppt. I would assume I should get a 40 amp..

I was looking at the cheap tracers, or the renogy rover..

Since this is my first solar set up I have nothing to compare it too.. so here are some questions I have..

1. Does the one panel above specs dictate that 17 amps is about the most I can get from just the one? I figure IMPP at 9 amps im kind of doubling it because of the higher voltage panels and I only need 14.8 for bulk... I dont quite understand it somewhat.

( Side note: When I was 5300 ft in NC I was blasting out 19 plus amps at 5pm...lol. Panel showed 240 watts.



You see how late in the day it was... ( Balsam Mountain NC)



2. With that said if I get normally 16 amps then if I use 2 panels and get a new controller (40amp) then I should be looking at 32 amps or so.. Does this sound correct?

3. Here is the kicker and I probably will not know until I try.. I this I need to understand ..

If I have two identical panels as specs show above, Would I get more amps putting the two panels in series . Putting in series would get me closer to the max 100v the controllers could handle.

Or, Put two in parallel? Will that net me max amps since this method doubles the amps.

4. The other trouble is both controllers I believe have a max of 520 watts. ( Ill have 560 watts)

This large panels are portable. I am not interested in more then two panels...

Eventually I have a plan for flex panels on the roof with a separate charge controller. But that will be another time.

[lawrosa]

Oh the 150v thing... good catch... I didnt really notice that... Probably why it has a huge heat sink... I thought it was the newer version of the A series... OK..

[BFL13]

Stay in parallel and save money by using the A. The BN can do 150Voc while the A does 100. Only matters if you go high in series.

A couple of "24s" in series is ok with the A but not three. I run three "12s" (23Voc each) in series with the A no problem, but prefer parallel anyway for any shading issues. Same amps no shading. More amps if part shaded when in parallel.

The 50 more Voc costs a bunch more--you can buy fatter wire for the array to controller if needed in parallel for less than that.

You have to know what is "good enough" for your scenario and not pay for more than that. Nobody else can know what you think is good enough 🙂

[lawrosa]

OK I got the green light from the admiral to get my MPPT..

I have one question...

Should I get the Tracer A series?? 169$ with everything..

http://www.epsolarpv.com/en/index.php/Product/index/id/653/am_id/134

https://www.amazon.com/EPEVER-Controller-Display-Battery-Charging/dp/B077HHYYHT/ref=sr_1_10?ie=UTF8&...

Or whats the difference in the BN series... I see 219$ for everything?

http://www.epsolarpv.com/en/index.php/Product/index/id/571/am_id/134

https://www.amazon.com/EPEVER-Controller-Regulator-Battery-Charging/dp/B077HQPV1Y/ref=sr_1_10?ie=UTF...


Im trying to read through the spec but am not sure why they carry two same units that do the same thing... maybe I am missing something IDK...

[BFL13]

lawrosa wrote:
Whats disturbing with the EP units is the reboot issues and the trouble to find max powerpoint...

Also over heat issues..

Ill have to test my eco, but I would say the eco has been flawless in this are..

Im going to hold off on an EP and look elsewhere... Ill need to re read this thread as I know someone mentioned the Renogy rover flaws...

https://www.youtube.com/watch?v=dFuZywwpfaU

I have the same Eco-W 20 amper and the Tracer 2210A and have run both off my 255w panel (taking turns depending on what I am doing with my 12v panels) with no such issues for two summers now. They get the same results for daily AH haul.

The place I got the Tracer 20 amper said their tests showed the 30 amper was a bit better than the 20 in some respect, I forget what, but ISTR it was the tracking speed.

The thing is, as an RVer you won't notice any of that. You do not have lab equipment and recorders. You are just camping and getting some sunshine to recharge the batts somewhat. For that, almost any controller will do.

IMO ignore all scientific "purist" talk about tracking speed or whatever, and see it in the context of your own typical camping day with solar. Mostly make sure you have the voltages that match the charging specs of your batteries.

In my case, the 12v AGMs and the Wet batts I have all call for 14.8 Vabs and a 13.7 Float (at 77F) so the fixed Tracer is just right set at Wet even for my AGMs, and the Eco-W is adjustable to that (except Vabs time is nil, so if you want any, you need to set Float at its highest of 14.5, and then drop that to 13.x later if it is not dark yet.)

With the ability to adjust the Tracer's charging profile you can't go wrong for any battery specs.

There are no doubt other controllers that are just as good or better, but there is no sense getting "features" for more money that won't do you any good in real life. Of course people do that all the time, being people. Got to have a 4x4 to go to the grocery store and back. 🙂

[lawrosa]

Whats disturbing with the EP units is the reboot issues and the trouble to find max powerpoint...

Also over heat issues..

Ill have to test my eco, but I would say the eco has been flawless in this are..

Im going to hold off on an EP and look elsewhere... Ill need to re read this thread as I know someone mentioned the Renogy rover flaws...

https://www.youtube.com/watch?v=dFuZywwpfaU

[lawrosa]

MEXICOWANDERER wrote:
Site Q & A

Ask how a warranty proceaa would work

I think its from amazon...Y solar who sells it is in china.. Comes with two year warranty... But since fulfilled by amazon I would assume you go through them...

Reviews are so so but it depends on what you read... Getting hot is an issue it seems and its slow to track... Something with the power point and reboot issues...

Im not sure how to compare that to the eco I have... My eco gets hot too, but no issues.. Im not sure how to compare my eco to its tracking ability..

[MEXICOWANDERER]

Site Q & A

Ask how a warranty proceaa would work

[red31]

some CC seem to have decent set pts and short abs time, that is what I adjust

momma said there would be days like this

after a few days like that longer abs time is in order for me.

[pianotuna]

Make sure the charging voltages can be adjusted.

[lawrosa]

Is this a crazy deal??? Fufilled by amazon. 40 amp, MT50 and temp probe...

Should I be wary?

https://www.amazon.com/EPEVER-Controller-Display-Battery-Charging/dp/B077HHYYHT/ref=sr_1_6?ie=UTF8&q...

[MrWizard]

its not so much positive ground, as "positive common", and the controller uses the negative side to control the charging

the positive is NOT grounded in the sense of being connected to the frame or to earth ground

it is a mistake in any literature or instructions to refer to it as 'ground' instead of common

[lawrosa]

well anyway guys thanks for all the replies... Im going to mull this all over in my head and definitely do something soon... By spring hopefully... Still need to get the 6 volt batts, but before the batts I need to get proper solar system installed...

I have learned much here..

[lawrosa]

Id have to use something like this to get the panels up on the roof eventually...

https://www.ebay.com/itm/solar-panel-mounting-rack-7-ft-rails-for-2-full-size-panels-up-to-320W-x-2-...


I would have to try to catch the feet on the rails at each roof stringer instead of just screwing into the sheathing..

Im afarid of what doing 75 MPH down the highway will do... LOL.. It would seem I can slightly angle the rails up toward the back some so the wind will not get under them...

The whole front of my RV is open realestate...



As far as series goes its easier and I dont need these..I can just plug + to - and then just have the +/- of each panel to worry about...






I wanted to use the output of the controller for a light in my pass through... I guess as long as its only mounted to wood in passthrough and no frame connection I should be good..

I was just going to hook up a two wire puck light... I was worried about that positive ground thing...

[CA_Traveler]

Neither is "cheaper" if you have to change the controller. What could be easier than disconnecting a MC4 connector and adding a serial panel? Parallel could involve more connectors or running wires to the combiner box or heavier wire.

Of course a lot depends upon your starting point.