why don't Solar controller mfg/sellers use honest ratings

[MrWizard]

example most 30amp controllers are listed at 390w of panels

and 40amp controllers at 500w of panels

but we don't charge batteries at 12.0v we charge at 14v or higher

14v*30 amps 420w output, going to need more than that input

40a*14v 560w output to batteries, controller must handle at 600w input

500w with 17.5 actual output 12v nominal panels only equals 28.57 amps into and thru Controller NOT 40 amps

so will these controllers really handle the rated amps ? which means a much larger array than the stated max

or are they just blowing smoke..uykw

30 amp ? 390/17.5v = 22.28 amps max from the array
so what is it really a 25amp controller ?

30amps charge at 14v =420watts out , 17.5 * 30 = 525 input
you need 525w panels to get 30amps out at 14.0v

this of course does not included mpppt panels although the same mfg/sellers are doing the same thing playing loose with the words

[MrWizard]

Okay temporarily forget I mentioned 14v
The point is 360~390w of panels on a PWM controller, (you keep ignoring I said PWM)
Can never produce 30 amps , a single 120~130w panel produces just over 7 amps , even if we round it up to 8 amps, 3*8=24 ...that is the max the panels will ever produce
How is it a 30 amp charge controller , if you are restricted to a max input of 24 amps (actually less) PWM does not convert like MPPT

That is the point either it can handle 30 amps thru put ..aka in from the panels drop the voltage to charge voltage and pass thru 30 (the rated amps) OR it can't , why the stated restricted limit if it can honestly carry the rated amps

I don't think I can make it any more clear than that
Others understand

[jrnymn7]

Same goes for the solar30 pwm. There is no fixed 14v charge voltage. You picked that number out of thin air. It has no basis in reality. I can say without any hesitation, charge voltage can, and will, range from ~13v to ~13.8v while bulk charging my 430Ah bank, at 45a, starting from a 70-75% soc. Sustaining only 2/3 of that current will not, and cannot raise Vbatt higher than that (unless the bank is not healthy).

If it's a standard rating you're looking for, then I would tend to agree it would be nice, but I don't think it's necessary. As stated earlier in this thread, it is up to the individual to educate them-self, and design their system accordingly. And this is why I ask questions about things like de-rating panels and such... so that I am aware of the possible things that can go wrong, and how to get around those problems, if and when they present themselves.

[jrnymn7]

When a 45a converter/charger drops from 14.6v bulk to 13.6v abs, and that 45a drops to 19a, does that mean it's deceitful to call it a 45a charger?

Likewise, if a 30a solar controller passes thru 30a at 13v, but only 27.85a at 14v, is it deceitful to call it a 30a controller?

You're right, I don't get it.

I just went thru some mppt solar notes, and Vbatt remained well under 14v for several hours, so I fail to see what a fixed 14v has to do with anything? During that particular charge, panel power stayed below it's rated output for the most part, (it was a partly cloudy day, in the mid 70's), however, even when panel power had maxed out their wattage, and amps to bank increased considerably, Vbatt still remained well below 14v, (13.4v as a matter of fact), while the bank was still heavily depleted.

My bank has no problem accepting 45a at less than 13.2v, at 70% soc. So it should go without saying, if ~13.1v is enough pressure to pump 45a into the 30% dod bank, then it would take even less pressure to pump in 30a.

That day, at 12:45pm, I saw 22.5a controller output at 13.4 Vbatt. That's 301.5w. Prorated to 390w, that's 29.1a. But if the two 140w panels can put out 7% over their rating, why couldn't three 130w panels? So prorated to 417w, that's 31.12a. And on a cooler day, mppt controller output would be even higher than that.

Now, let's imagine the bank was at 50% dod, is it not fair to say 417w divided by less than 13.4v = more than 31.2a ??? But the 130w panels are rated at only 7.57a Imp... so how can the controller put out more than 3x 7.57a? Because it's an mppt controller, and that's what mppt controllers do... except some clip the extra amps, while other get burned up.

So I fail to see how the Tracers 390w/30a rating is deceitful in any way. To say it will never see 30a at 390w goes against everything I've learned about battery acceptance, charge rates, kirchoff's law, etc., etc.

390w / 13 Vbatt = 30a... the numbers don't lie. And solar charges at a relatively low charge rate, (except for rather large systems), and therefore Vbatt remains lower than it would at a higher C-rate. And the lower the soc, the lower the Vbatt required to sustain those 30 amps. There is just no way around these simple truths.

[MrWizard]

one problem AKA "standard" is using system voltage
aka Nominal 12v panels, can be anything between 15~19v when working under load
with a VOC of 19~24v

and that doubles for 24v system panels using 72 cells

60 cell panels really are intended for grid tie systems and MPPT controllers to put power back into the grid

but I digress
you are correct, CONTROLLERS should be rated at the thruput amps at the acceptable max panel voltage
None of this******saying its a 30 amp 12v system controller with a 390w panel limit
thats not 30amp thats 23amps?

i wonder why the limit ?
so you can't hit the max amp rating ?
because its false adv and IT really is a 24amp controller ?

there is a "Solar30" from Renogy on Amazon
http://www.amazon.com/Renogy-Controller-Regulator-Battery-Charging/dp/B00BCTLIHC/ref=pd_sim_86_3?ie=...

Ideal for: 12V PV system: 24V for Max input 360W Solar Panel, 24V PV system :48V for Max input 720W Solar Panel

except for the color its identical to this one from windy nation

http://www.amazon.com/WindyNation-Regulator-Controller-Adjustable-Settings/dp/B00JMLPP12/ref=pd_sim_...
which says 390w panels

ideally my spare (when i find it) will be a true 40amp or larger controller

i have yet to go over 25amps with the new panels and the C40
but Solar conditions have been clear blue skys and hot weather
so by the time the sun is in position to give full radiance, the batteries are only taking in the "teens"
i got a 22.xx Pa reading about 10:AM, now reading about 12 amps
which will climb to about 16 amps in the next hour then taper from there
Sunday i will try for another full day test
will need to load up the batteries on Sat night, to bring down the SOC and up their acceptance level
the new panels have really helped my overall yield increase in this partial shade condition where the sun moves to the front of the RV in the afternoon

[MrWizard]

one problem AKA "standard" is using system voltage
aka Nominal 12v panels, can be anything between 15~19v when working under load
with a VOC of 19~24v

and that doubles for 24v system panels using 72 cells

60 cell panels really are intended for grid tie systems and MPPT controllers to put power back into the grid

but I digress
you are correct, panels should be rated at the thruput amps at the acceptable max panel voltage
None of this******saying its a 30 amp 12v system controller with a 390w panel limit
thats not 30amp thats 23amps?

i wonder why the limit ?
so you can't hit the max amp rating ?
because its false adv and IT really is a 24amp controller ?

there is a "Solar30" from Renogy on Amazon
http://www.amazon.com/Renogy-Controller-Regulator-Battery-Charging/dp/B00BCTLIHC/ref=pd_sim_86_3?ie=...

Ideal for: 12V PV system: 24V for Max input 360W Solar Panel, 24V PV system :48V for Max input 720W Solar Panel

except for the color its identical to this one from windy nation

http://www.amazon.com/WindyNation-Regulator-Controller-Adjustable-Settings/dp/B00JMLPP12/ref=pd_sim_...
which also says 390w panels

[MEXICOWANDERER]

Do we know of any source of 12-volt panels? Do they think ANY panel is going to be used at 12 volts DC?

This is as bad as the DC/DC boosters that advertise 600-watts but in fine print have a maximum input/output of 10-amperes. Why do you think they do not shout TEN AMPERES in the specifications headline?

Reminds me of my sarcastic remark about MAXIMUM SOLAR OUTPUT on Mercury.

These jokers have to learn to post specifications as obtainable using normal voltages or normal amperages. A billion watt controller is not much good if it has a 10-volt limit and a 300 watt panel is not much good if it is good for 12 volts. use terminology that CONSUMERS understand and work with.

[MrWizard]

Thank you...For the Bogart link

[Empty_Nest__Soo]

MrWizard wrote:
I see some understand...And some still don't get it..!

The point being is if you buy a PWM controller with a stated limit like 390 watts, and you abide by that limit, you will never have 30 amp charging, it's not possible when the panels sustained ability is only 22.xxx amps
When buying in the solar market, it's buyer beware, go in eyes wide open question everything you read from sellers

Grizzman do you have a link?

I'm still shopping for a controller to be my spare

Link to SC-2030 User's Manual pdf: http://www.bogartengineering.com/sites/default/files/docs/SC2030-2-15-15-UsersInstruc.pdf

See page 1 (suggests 4 X 135-watt panels @ 12 VDC) and Page 4 (Specs say input up to 60 amps, but will clip the extra's.)

I plan on getting one of these to play with my newly-installed Trimetric 2030 monitor,using about 400 watts of panels to start.

Also: See what HandyBob has to say: https://handybobsolar.wordpress.com/2015-the-trimetric-2030-perfect/

Wayne

[MrWizard]

I see some understand...And some still don't get it..!

The point being is if you buy a PWM controller with a stated limit like 390 watts, and you abide by that limit, you will never have 30 amp charging, it's not possible when the panels sustained ability is only 22.xxx amps
When buying in the solar market, it's buyer beware, go in eyes wide open question everything you read from sellers

Grizzman do you have a link?

I'm still shopping for a controller to be my spare

[NinerBikes]

MrWizard wrote:

Got it. However, to repeat, my PWM Solar30 only claims to be able to do 30 amps and has no panel wattage mentioned. It is up to you to not go over the 30 amps and the 48v Voc using whatever panel wattage you choose.

at least they seem to be making an honest statement and NOT putting a watt limit that keeps you from reaching the rating

this what we need to see more of
the input equals the output
or NO qualifier input that is lower than the stated output
is there a solar 40 ?

that prostar is nice..morningstar has quality controllers

I seem to recall seeing a time or two on Ebay or somewhere else, a Solar 60 model that was for sale, but my memory may be a little rusty.
Solar 60

Or split panels and wiring, do a little redundancy and parallel two solar 30's.

My take on it is that it will flow up to 30 amps, regardless of voltage, be it 28 or 30 for 24v system, or 17-19 for a 12V recharging system.

Watts are not mentioned, or I failed to acknowledge them. I guess it's a current limit, not so much a voltage limit, so they find watts a bit irrelevant or confusing.

Simple way that I see it, being a non EE type. Total up the lsc on your solar panels, and if the total is 80% or less of what the PWM Solar 30 or solar 60 charge controller is rated for, you should be fine under a worst case scenario. I would consider that a safe and adequate margin for design, at least for me. If the charge controller goes belly up, well, then, I've got some super duper good solar panels that were underrated... something highly unlikely to happen or come out of China these days. They'd sooner short you than give you more without charging you for it.

[MEXICOWANDERER]

Regardless...
Controllers -should- be rated in amperes -at the highest voltage normally seen. A 15-volt standard would be acceptable. 300 watts 20 amps @ 15 volts SUSTAINED at 45 C would be realistic.

It's like rating an alternator dumping into 12- volts rather than 13 volts.

Give the bozos leeway and they will exploit it. Like MARINE cranking amps on a battery rather than COLD cranking amps. Anyting to confound a simple comparison. If ANY formula offered serves to confuse then it is done out of ignornance or a lie of ommission.

Lumens and db are two other areas that are savaged in this regard.

[doughere]

KD4UPL wrote:
The rating of a charger isn't a guarantee that it will always put out that amount of current. It's the maximum rating the device should be run at. Typically you should only run an electrical circuit/device at 80% output if a continuous load and solar is defined by the NEC as a continuous load.
It's also not a guarantee that the unit will put out a given amperage regardless of voltage. A very depleted battery could very well be charging down around 12v or so. A 390w array would make 30A if that was the output voltage.
I don't see any deception, just simplification. They can't possibly state the amperage output for every possible voltage and wattage combination.
It's up to the thinking individual to take the ratings given, do some math, and come up with a proper design.

X2

Doug

[jrnymn7]

Again, The ONLY way voltage can rise very quickly to the setpoint, is at a very high charge rate. Last night, I converter charged my bank, beginning at 85% soc. Voltage started out at 13.08v, and rose from there.... that was at 45a. At 30a, it would take less voltage, over time, to maintain those lower amps. And at a lower starting soc, when charge acceptance is better, even less voltage.

390w / 13.08v = 29.8a

I have seen 18a out of 280w, using pwm, with fairly warm panels. 390 / 280 = 1.39 x 18a = 25a. A warmer panel would produce more amps, nearing the controllers limit. If one chooses to max out their pwm controller, that's their choice.

With mppt, those 390w could easily exceed the 30a limit, with cool panels. 390w plus say 5% = 409.5w / 13.1v = 31.26a. (I see 7% over power rating on fairly warm panels).

[grizzzman]

This is from chinasolarregulator.com "Solar30 30A Solar Charge Controller 12V 24V auto switch Lighting Controller
Pacakge Included:
1. 1pcs 30A solar Controller
2. 1pcs user manual
3. 1pcs temp senor

Ideal for
For 12V PV system: 24V for Max input,400W Solar Panel.
For 24V PV system :48V for Max input,800W Solar Panel"
This company claims to be the manufactuer.

One of the reasons i went with the bogart system is that it will handle 540 watts clips amps at 31 amps (you get a bonus amp) and can handle up to 60 amps (as long as air temp can be held below 120-130 F) seems to me an "honest" charge controller.

[MrWizard]

here is one example of what i'm saying

WindyNation P30L LCD PWM 30A Solar Panel Regulator Charge Controller 12V 24V 390W 780W + Digital Display +User Adjustable Settings for Off Grid Battery Charging

windy nation 30amp

here is another

Nominal System Voltage: 12V/24V Auto recognition
Max. PV Input Power: 400W (12V), 800W (24V)
Rated Charge Current: 30A
Max. Solar Input Voltage: 42V
Rated Load Current: 30A

Renogy 30amp controller

now this one EPsolar lists only charge amps
and does not apply a limiting panel wattage

EPsolar 30amp charge controller