# need help on wiring kc 120 panels wrongs amps

Hello, was looking for a little help
I have 2 Kyocera 120 watt panels ( I have one set of 4 wired in series = output in full sun 78 volt at 26.5 amps on my meter)=6.6 amps each
anyway I took 2 from another 4 panel set and wired parallel for 12 volt out put.(19 volt on meter no load). unload I am getting 19 volts out but only 4 amps
I thought the volts would stay the same but the amps should double at least 8 amps, I checked each panel is putting out about 4 amps each. but when hook parallel I am only seeing 4 amps.. so I checked my other set to see if maybe I had a bad panel.. they do the same, but if I hook them in series I get double voltage and double amps ! what am I doing wrong ?
I am hooked up to the outside post on each ( outside of diode) just like the wire diagram shows I checked voltage on inside of diode and it is like 10 volt not 19 like on outside) also on this same set in a series on 2 panels i am seeing about 10 amps at 19 to 20 volts

Re: need help on wiring kc 120 panels wrongs amps

You have something mixed up in your measuring of amps and volts.
Also, I don't understand some of your statements, sorry.

You state: "I have 2 Kyocera 120 watt panels ( I have one set of 4 wired in series)"

My Question: how many 120 watt panels do you have?

You state: "one set of 4 wired in series = output in full sun 78 volt at 26.5 amps on my meter)=6.6 amps each"

My Statement: If each panel outputs 6.6 amps and they are wired in series, there is no way you will get more than about 6.6 amps (dead short may give a wee bit more, perhaps another amp). Wired in series, you may well get 78 volts, but NOT 26.5 amps. If however, you wire them in parallel, you could get 26.4 amps but only around 19 volts, NEVER 78 volts. You can't have it both ways.

So, if you're not just pulling our leg, re check your measurements and then get back to us.
Cheers
Wayne
Re: need help on wiring kc 120 panels wrongs amps

yes you are right.. that is what I was thinking and no I am not pulling your leg.. here is what is going on
I have a 4 panel set of 4- 120 panels on a rack, wired in a series. and yes I know that in a series you double you volts not your amps. I also had another rack of 4 panels that I put 2 of them on my RV and re wired in parallel .. being I should have a 12 volt system 19 volt in full sun no load... and should have double my amp out put to around 8-12 amps or so
if both put out 4 amps each then 8 is what I should have gotten I tested each one by it self and got 4 amps in the sun light I had and no load. hooked to geather and still had 4 amps going in and out of my charge controller to my RV batt.
so I do not under stand why this is going on. so I test my other rack of 4 and the other 2 panels on the split rack to see if maybe I had a bad panel some where. but the other two did the same, when I hooked them in series I got 10 amps on a meter no load and 39 volts... when I hooked them  parallel I got 4 amps again but 19 volts... so I tested my 4 panel rack that is wired in series I got 78 volts no load and 26.6 amps on my meter with no load. I even put a had held grinder on it and it spun it like I had plugged it into the wall. so I know there putting out. I though maybe I had them hooked up wrong in the J box on the back of the panel. it has diodes and 2 sides on the lugs. I hooked them up like the wire diagram showed. but since I am new to solar maybe I doing something wrong.
and just so you know I do know a little about 110volt wiring and 12 volt ..I do know about this....but I am not testing them right maybe ?
Re: need help on wiring kc 120 panels wrongs amps

email me at [email protected] and i will send pics of my set up
thanks

how do you post pics
one more thing... when I was setting up my charge controller today on my one RV battery about 50% full.. I used a 14 gauge wire from the charge controller to the battery and it was enough juice to make the wire get hot...not real hot but pretty hot.so I know it was putting out .. maybe I will run the battery down a bit and the link my meter in between the battery and the charge controller to see if I get a diffent amp reading.
Re: need help on wiring kc 120 panels wrongs amps

Still a little confusing to read... But, basically, a solar PV panel is the same as a battery... Hook several cells + to -, that is a series connection and the output voltage will be, roughly, just n x Vpanel (4 panels * 19 volts = 76 VDC). The maximum current will be just the current of one panel.

If you connect + to + and - to -, then that is parallel... The voltage will be that of one panel, but the current will be "N" panels * rated current (6 amps * 4 panels = 24 amps).

Depending on the charge controller you are using, a simple charge controller should simple take the panel current and pass it, unchanged in value, to the batteries (assuming that the batteries are in need of charging and can take full current).

If you have a more expensive MPPT type charge controller (like an Outback MX 60), it can behave like a transformer and convert, say 24 vdc at 5 amps to 12 vdc at 10 amps--so you have to know the voltage and current at both the input and output side of a MPPT type controller.

So, if you take two 19 volt 6 amp panels and connect them in series, the voltage will be 38 VDC and the current will be 6 amps.

If you take the two 19 volt 6 amp panels and connect them in parallel, the voltage will be 19 VDC and the current will be 12 amps.

The above reading assume the panels are in full sun and you have a load that you can adjust for the maximum power point of 19 VDC and 12 amps. This is something a MPPT type controller does automatically--it adjusts the input current and voltage to find the maximum power point of the panels and, using an internal switch mode DC to DC power supply, to put out the 12 VDC and maximum available current to the battery (approximately 12 vdc and 19 amps in this example).

The simple way to test the panels is to check the open circuit voltage (see panel ratings) with a volt meter, then short the panel(s) with the voltmeter set to the appropreate amp scale (one panel, set meter to 10 amp scale), then short the panel with the meter... You should read, approximately 6-7 amps (depending on temperature, sun light, etc.). Putting several panels in parallel will probably exceed the maximum rating of your meter--so be careful.

Lastly, it is possible that you have every connected correctly and your RV's charge controller is simply limiting the current to 4 amps at that time--I don't know and can't tell from here though...

You talked about 14 awg wire getting pretty hot... The probably indicates that your are passing well in excess of 20 amps of current. That is not safe (can catch fire), and is also not very efficient--you are losing a lot of energy as waste heat... And if this is the wire going to the battery bank, you are probably not charging the batteries as well as you could be as there is significant voltage drop in the wire (so the charge controller thinks that the battery is more fully charged than it really is--and it will take longer to fully charge the battery bank).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: need help on wiring kc 120 panels wrongs amps

well, thanks for the help. i will explain a little more
the wire that got hot was just there for a few mins as a test wire. I replaced it with a 10 gauge wire.(maybe 12 but it looks like a 10)
also the charge controller i have is a cheap one. and the input voltage looks the same as the output. i think it just cuts off when battry is full.if i got the 14 /(it does not say so it could have been a 16 gauge)gauge wire hot then maybe i am putting out 19 volts at 15 or better amps.. I HOPE
i shorted the meter with the panel only. i will try shorting the meter as part of the curcuit to the battery. maybe it will read diffent
i also was thinking of it like a battery, as far as the volts adding up and amps that is why i was stumped.. but i have never set up a PV system before and thought maybe the lugs on the back of the panels were not hooked up right
ok here is what i think i have for wires.. the wire coming down from the Panels is 14 gauge i know this because i just bought it
the test wire was 16 .. i think... the replace ment wire was 10 or maybe 12 gauge
Re: need help on wiring kc 120 panels wrongs amps

i will try shorting the meter as part of the curcuit to the battery.

I am not sure how to read your statement here... But, the only safe method is to short the, otherwise disconnected, solar PV panel (one only) with your current meter... If you short any more than one panel (or a panel rated more than, typically 10 amps), you will damage/destroy your meter.

If you short a storage battery with your DC meter--you will cause massive sparks, current flows, melted wires, and possibly fire and/or explosions...

You may know exactly what you are doing with your meter--but I don't--so I want you to either be sure what you are doing, or get some help from someone who may have more experience.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: need help on wiring kc 120 panels wrongs amps

cool thanks, i do know what i am doing , BUT THANKS anyway... really thanks for looking out for others.
here is the deal the meter is fused at 10 amps
and by short i mean take one of the charge wires leaving the controller or leaving the panels and run the leg of the curcuit through the meter , so i can see the amp draw.

does that sound about right ? i have had some training with electricty and a few years working around it and with it, but i could still make a mistake that is why i am here on this board looking for help.
so once again thanks and please keep up the help
Re: need help on wiring kc 120 panels wrongs amps

Now that I got that warning out of the way...

If you have a simple charge controller (which for smaller systems is probably better than the expensive MPPT type controllers), you have to understand a bit how they work... In simple terms, there is an internal switch that simply connects the solar panel directly to the battery(ies) when charging. So, during absorb/bulk charging (batteries need all current possible from solar panels), if you connect the panels incorrectly (say in series rather than parallel)--you will see unexplained results.

What you will see is with two 19 VDC / 6 amp panels in series connected to a 12 VDC bank is (current can be 10-20% less and still be OK in full sun):

While the batteries are charging (full current from panels), you will see ~12-13 VDC at the batteries and 6 amps (if the panels are in series. As the batteries begin to fill, you will start to see the batteries approaching 14 vdc and the current start to ramp down (it may be a smooth reading of, say 3 amps, or it may read 6 amps / 0 amps / 6 amps / 0 amps as the controller switches on and off (depends on controller brand and, sometimes, settings). On the solar panel side, you will see approximately battery voltage as the batteries charge (12-16 vdc), and as the controller starts to limit current, you will see the input voltage to the controller start to rise quickly to 19 or even 38 VDC... You do run the risk of damaging the controller if the input voltage from the series solar cells is too high (above controller maximum input voltage).

If you have two 19 VDC / 6 amp panels in parallel connected to a 12 VDC bank:

Basically, it will be similar to above, but instead of 6 amps, you should see around 12 amps ramping down as the batteries fill. And the maximum input controller voltage will only be 19 VDC max (in full sun, batteries charged, controller taking very little current).

The solar PV panels behave pretty much like batteries--the only major difference is that they are current limited and shorting them does not draw that much more current than the maximum rated power current... And, because of this, they can be connected to storage batteries and operate at less the solar PV panel's rated voltage just fine (you cannot do that with most chemical batteries--they will try to output more current until they overheat or damage themselves). Solar PV panels put out more slightly more voltage when cold... And Current/Voltage (I/V) curve is pretty flat... Constant current until rated voltage is met, then as the current is reduced, the voltage rises a bit more to V open-circuit.

Hope the above helps you diagnose the problem a bit better.

-Bill

PS: Chad, you would be connecting the current meter correctly... Of course, you will want to stay under 10 amps and with multiple parallel panels in full sun, you probably will exceed it.
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: need help on wiring kc 120 panels wrongs amps

thanks for the help. 2 things i need to do today.
1) check with another meter , mine maybe be fubar. i long time ago i did short out on amp setting and blew the fuse
so maybe its not right anyway.
2) i will run the battery down to see if it is sucking more current from the PV. it could be that it was not that low and did not draw more that 4 amps yesturday ?
my father inlaw lent me his amp meter but it looks like to me it only does A/C amps so i dont think it will work ether.
it is cool here right now. in south west AZ , 51 deg in morning and maybe 75-83 during day time, but lots of sun
I am pretty sure that i wired the system correct. it is just when i hooked a meter up i did not see what i thought i would.
i mean when hooking a meter to a panel, with nothing else hooked to the panel, should you not see full current draw through the meter ? provided the meter is not damaged
Re: need help on wiring kc 120 panels wrongs amps

ok , now i am really confused. so i go out and test with my meter and get like 3.8 amp out on the PV today, ok well maybe battery is full. ( i even diconnect one leg and ran the meter as part of the loop to the battery)
so i goto the other 2 panels i have in that set and tested them in the sun(not full sun but mostly) its still 8am
i am getting 21 volts and 3.something amps through the meter, no load.
ok, well maybe my meter is bad right. so i checked a know source. i have a laptop transformer that say's it output is 19 volts and 2.6 amps
so i checked it yep 19 volts and 2.9 amps is what i got so it looks like my meter is working.
so lets say maybe i have week panels. ok then if each one is putting out 3 amps each i should still get 6 amps at the end ? i do not understand why i am not... could this be a diode thing ??? I lost  if i have a bad diode or diodes if i took them out what would happen ? i mean i know there there so you dont back feed at night , but if my controller shuts off at night because no PV right.
also anyone had a bad panel before and how did it act ? just trying to figure out if i got ripped off
Re: need help on wiring kc 120 panels wrongs amps

I am guessing you have this panel:

Module: Kyocera KC120-1
Max Power Voltage - Vmp 16.9 Vdc
Open Circuit Voltage - Voc 21.5 Vdc
Voltage Temp Coeff - Vtoc -0.0824 V/°C
STC Rating - Pmp 120 Wstcdc
Max Power Current - Imp 7.1 Adc
PTC Rating 105.7 Wptc

PDF spec. sheet for Kyocera KC120-1:

http://www.kyocerasolar.com/pdf/specsheets/kc120_1.pdf

So, assuming the meter is OK, and the panel(s) is OK, you should see a maximum open circuit voltage of 21.5 VDC (at 77F) and in excess of 7.1 amps (per above link, 7.45 amps is A max short-circuit) if shorted with a DVM/Amp meter rated for a minimum of 10 amperes DC. If neither of these is correct (outside of +/- 20%), then either your panel or meter is having problems.

If you look at the I/V curves on page two of the PDF, you will see that the open circuit voltage is the same in almost any sunlight conditions, and the short circuit current is directly proportional to the strength of sunlight hitting the panel (1,000 W/m2 is considered full summer sun, clear day). Probably close to your Arizona sun on a nice day.

To test the panels under a more accurate load condition... You can connect one panel at a time, through your amp meter, directly to a storage (or car) battery (without any charge controllers). The battery will hold the panel near 13-14 VDC, and you will be able to accurately measure the panel's current under operating conditions. Do not leave the panels connected for a long time (hours) without a charge controller or you may overcharge your test battery (a few minutes at a time is not going to hurt anything if you use a car sized battery, or larger, as a test load for your panels).

If the panel produces near 7 amps when connected to the battery without the charge controller--then it is possible that your charge controller has issues (broken, setup wrong or too small, too small of wire gauge between the controller and the batteries, bad cable, bad connections, etc.)...

Regarding your newest post--8am sun and 3 amps (per panel) is probably fine. To get full current, the sun will have to be withing about 10 degrees of high noon (and the panel must be pointed to within 10 degrees of the sun).

Assuming that all is good with the panels, yes, placing two in parallel should simply add the currents together (just like two flashlight batteries connected in parallel). And, you are correct, most controllers would shut the panels down in the dark anyways.

If you have a bad diode, then the panels will start accepting current from a battery (self discharging during night). Generally a diode will either fail shorted or open. I don't think that this is your issue here.

Other than connecting the panels in series instead of parallel--I cannot think of any reason that the currents are not adding correctly.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: need help on wiring kc 120 panels wrongs amps

thanks for the help, i argee . maybe i do not have the panels facing the sun with in 10 deg ,etc ,etc
but what gets me is why the amps are not adding up, if my out put is 3 amps then 2 of them them should be 6.
the PDF you sent do you have one that shows how and were to hook wires to in side J-box, i dont see how i could have gotten this wrong but who knows
when a panels goes bad what happens ? amps go down or volts or both ?
Re: need help on wiring kc 120 panels wrongs amps

Depends on what fails... If a panel reads the correct open circuit voltage and the correct short circuit current (clean panels, in full 9-3pm or ideally local noon, pointed directly at sun, or withing 10 degrees), then you are 95% sure that everything is OK...

It is possible that you have a marginal connection somewhere in the panel--lightly flexing the leads/connections and rapping the solar panel with your knuckles while monitoring the current may show an intermittent connection.

You can have an high resistance connection (corrosion or other problem) and V open-circuit is fine (a modern DVM draws very little current and it would take a very high resistance at a broken joint for the meter readings to drop). Amp short-circuit on the other hand requires everything to be making pretty good connections--it is possible that you could have a few Ohms of resistance (deteriorating connection in the panel) that a short circuit test would not catch--but it is not too likely.

Testing by placing the panel, + current meter, on a 12 volt storage battery in full sun (pointed at sun) would then tell you that 99.9% everything is OK with the panel. IMHO

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: need help on wiring kc 120 panels wrongs amps

ok, got a hold of a friend that is bring over a another meter of his, so i can rule out my meter being the problem.
also last night i tried to fire up the microwave in the RV on my 1kw inverter (2kw peak) and it would only run for a few sec before kicking out the inverter on low voltage, but today so far i ran it for 2 mins with no problem, so the panels , i would think are putting out more than 3 amps now i did draw the battery does to around25-50% per the leds on the charge controller on the PV sytem, i will how long it takes to top back of at 3 amps i would think a few(4) hours min...but if it is puttin gout 6-15 amps about 1-2 hours maybe ?
p.s. i ran a 12 volt fan off of the other 2 panels i have. spun it hard, but when i hooked up togeather to double amps it did not spin any faster that i could tell
Re: need help on wiring kc 120 panels wrongs amps

ok RV battery charged from 11.6 volts up to 14 in about 1 hour
still waiting on meter
Re: need help on wiring kc 120 panels wrongs amps

ok, got it now.
friend came over with another meter and we got 7 amps per panel on his
so it looks like it was my meter.
also tested other four panel set i was see 26 amp and 78 volts
he got 5 amps and 74 volts
so once again it was my meter because we did not move any wires and hooked up to same spots i was hooking up to with meter