I am planning installing 4X140W panels(parallel)flat mounted going to 15A breakers(so they can be switched off if needed) to the charge. The panel have ISC of 7.50 each times 4 equal 30. The controller(Blue Sky 3000I) I want to use has ISC rate of 24A, however they say it will work up to 30A. So would my panels only reach this 30A on ideal conditions? Or will I be pushing the 30A limit a lot? If I could hit more than my 30a limit could I just shut off on breaker? And if I open one breaker to the solar panel from the controller would it case damage to the panel sitting in the sun and not being used? I plan on installing breaker on both sides of the controller Blue Sky seems to make it a point of having a way to shut down and turn on power to the controller? I am new with this and still trying to figure out how I want to install my system or if I need to make changes to my plan before I buys stuff. Thank for any information given.

CT_WANDERER wrote: The controller(Blue Sky 3000I) I want to use has ISC rate of 24A, however they say it will work up to 30A. So would my panels only reach this 30A on ideal conditions? Or will I be pushing the 30A limit a lot? If I could hit more than my 30a limit could I just shut off on breaker?According to my calcs, you'll be hitting it a lot. You need a bigger controller. Your plan is a lot of work, and, you're throwing away power. Are you going to be sitting around the rig watching your controller and throwing breakers?

If you only have a 24AMP solar controller that is all it will draw from the available 30AMP Capacity being produced by the solar panels. What is left over is being wasted if not used. This does not harm the solar panels at all if you do not use the available VOLTAGE being generated by the sun. It is just available for you to use when in high sun. This is why you have batteries connected. The available power being generated has to be stored in the batteries so it will be available to use after dark. No sense wasting the available power. Add more batteries to store it in... The switches and circuit breakers in the solar line is only really needed to protect the wiring in case of battery system overload or short circuits. Smaller wiring will not like to have 30AMPS DC being drawn from the solar panels. MrWIZARD had a short circuit mishap just a couple of days ago...Your system is looking almost like the my upcoming solar system using two each 120WATT panels on one end and hopefully a single 240WATT panel on the other end on top of my OFF-ROAD POPUP setup...Hoping big time to have 14.4VDC@30AMPs capacity coming from solar controller for 6-7 hours during the day to play with charging up my battery bank. Game plan for me is to cut back on my generator run time each day.Roy Ken

Are those Kyocera 140watt panels? They are excellent panels and can easily output more than their specsI have four of them (actually 2 - 135w and 2 - 140w) for 550 watts I see 40amps under good solar conditions Your controller might be a bit small - zero headroom Might want to consider a 45amp or 60amp controller in the future I agree 100% with installing Breakers/Switches/fuses (your choice) both before and after the controller

Mr Wiz said his Blue Sky 2000 (25 amp with 20 amp recommended max) clips any excess amps so it will not overheat and damage the controller.It is the US NEC that wants the 20% margin for controller amps rating with controllers that do not clip their amps. Regular PWM controllers just pass through whatever amps they get and overheat if that is too many amps for them for too long a time.So if your "expected amps" is 25 amps then NEC wants you to have a 30 amp controller for that 20% margin. Panels sometimes put out more than their rated amps, such as when they are cold or at high altitude, etc. The brief burst of high amps from edge of cloud effect doesn't matter AFAIK since that only lasts a few minutes at a time with those pretty white clouds going by the sun every so often.So what is your "expected amps" anyway? If the Isc of your 140 is only 7.5a I suspect it is a mono panel with corresponding higher Voc too, since a 140w poly's Isc would be near 8.8a. If yours is poly maybe that 7.5 is Imp? (Imp does not apply to PWM)But isn't the Blue Sky 3000 an MPPT controller? So now you have a complicated sort of "expected amps" depending on whatever watts you are getting and whatever the battery voltage is at the time, which is always changing.So let's say your four 140s are mono with Isc of 7.5a as stated, and your expected amps will be at least as good as what PWM would get.4 x 7.5s = 30. That's with panels aimed at high sun. Flat on roof will be less than that. It could be close with the sun overhead in summer in the south part of the USA mainland.Your MPPT controller should clip the amps as required so no need to fuss with input if the controller is mounted properly with good ventilation cooling.If I had four 140s I would make two pairs and get an eBay 20a PWM controller for each pair and parallel those two controllers on my battery bank. Save a bundle on controller costs and get approx the same amps.

It has been recommended to allow at least 20% of head room. Don't forget, current creates a lot of heat, so you need to oversize your controller considerably. I went with a 30 amper for my pair of 140w/8.15a Isc panels. I wouldn't go with anything less than a 50a controller with your panels, especially being in a cooler climate such as yours.And make sure you wire accordingly, to avoid excessive volt drop.

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CJW8
Explorer
Jan 22, 2015
My 3ea 135 watt Kyocera panels are fairly shade tolerant. I don't lose the whole panel in partial shade.

I have considered adding a 4th panel. My Rogue 3024 will handle it even though it would be about 35 amps maximum.

Yes I would lose some during occasional peak. BUT- I would make more under the following conditions:
1. Sunrise and sunset IE. shoulder areas. I would produce peak longer.
2. Cloudy days
3. Partial shade over one or more panels.
4. Low sun angle such as at Glamis in the winter.
All of these could be significant and I seldom hear them mentioned.
BFL13
Explorer II
Jan 22, 2015
Isc for 120w poly should be about 7.6 and for 130w its 8.2 (80w is 5.1) It is all in proportion, so 140w should be 140/130 x 8.2= 8.8

Some panel Iscs are lower than that per watt, which means of course that their panel voltages are higher. Price comparison between 12v PWM should be in dollars per amp, not dollars per watt, since it is the amps you are after not the watts.
NinerBikes
Explorer
Jan 22, 2015
BFL13 wrote:
Ok so 480w flat is lots of solar. My single 230w tracking does all our needs (big inverter, the works) and if flat instead of tracking that 230w would be like having 369w flat where and when we camp. 480w flat is 111w more than that, so you have tons of solar.

That means you don't have to extract every drop out of your solar to get by, there is lots of margin. Which means any "extra" you would hope to get by going MPPT is not needed. You already have lots of "extra" So whyinheck pay big bucks for enough MPPT to run those four panels? Crazy

You are like the guy who got an extra panel for his PWM instead of going MPPT because it was cheaper that way to get the extra.

So IMO the two eBay PWMs is still the way to go and you even get redundancy out of the deal.

This... get a pair of Ebay Solar 30's PWM's, one for each pair of panels, have the margin, and call it good.
CT_WANDERER
Explorer
Jan 22, 2015
MrWizard wrote:
do you mean BYpass diodes ?
AFAIK
only need one blocking diode in the output of the panel
unless there ares multiple sets of parallel cells,
which is highly unusual

if you mean Bypass diodes
go with the 8 diode panels
they will be more shade tolerant than the 2 diode panel

Yes, Thanks. It looks like they are talking Bypass diodes. Am I right on my estimated amp output? if I am using PWM converter. As I am seeing a big difference in the price for the two panels
MrWizard
Moderator
Jan 22, 2015
do you mean BYpass diodes ?
AFAIK
only need one blocking diode in the output of the panel
unless there ares multiple sets of parallel cells,
which is highly unusual

if you mean Bypass diodes
go with the 8 diode panels
they will be more shade tolerant than the 2 diode panel
time2roll
Nomad
Jan 22, 2015
Not going to matter much in parallel. Small shade on one cell will probably drop out the whole panel if the others are producing in full sun. Those are bypass not blocking diodes.
CT_WANDERER
Explorer
Jan 22, 2015
I am still adjusting my plans for my solar panel system. For now, I have settled on the Morningstar TS-45 PWM. Now looking over the Solar Cynergy 120W panel, I see that has ISC 7.5. so with 4 panels I would get a mathematical 30AMP. This panel has two blocking diodes.
During mu research I see that the Kyocera 140W panel has ISC 8.63 and I was going to us 3 so that would be 26.4 amps. This panel has 8 blocking diodes.
so what does this mean, with the Cynergy panel with two diodes I would lose more of the panel if it was shaded that you would on the on the Kyocera panel for the same around of shading? Am I understanding this right yet? Thanks Gary
pianotuna
Nomad III
Jan 05, 2015
Hi,

One switch between panels and controller is all that is needed.
ewarnerusa
Nomad
Jan 05, 2015
Another vote for just a single CB between panels and controller, that's what I did for my parallel 12V panels with PWM controller.

KJINTF
I have done quite a bit of tinkering with the MSVIEW application and my MS TS45 PWM controller. Mostly because I have a finicky inverter that doesn't like voltages above about 14.8V. Thanks for your help in getting that link set up, the key is a RS232 STRAIGHT THROUGH cable, not a null modem cable!
jrnymn7
Explorer
Jan 05, 2015
I would think with all four panels in parallel, only one breaker between array and controller would suffice. Wouldn't each panel's diode protect it from the other panels, in case of a short?

Then another breaker between controller and battery bank.

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