Kyocera KC130TM 130W 12V Solar Panel w J-Box question

20 Posts
Nov 15, 2008 06:46 pm
Kyocera KC130TM 130W 12V Solar Panel w J-Box question

This is a 130w panel, but it says it's 7.39amps @ 12v....To me that seems like a 88.68w panel...


For it to be a 130w panel, it would have to be 10.83amps no?

 
Nov 16, 2008 07:27 am
Re: Kyocera KC130TM 130W 12V Solar Panel w J-Box question

The "12" is a nominal voltage.

Adjective: nominal  nóminul
Pertaining to a noun or to a word group that functions as a noun
"nominal phrase"
"Even though the battery voltages of his PV system could fluctuate between 10.5 to 14.7 volts, he has a 12 volt nominal system."

There is also the open circuit voltage. If you didvide 130 by 7.39 this would be 17.6, but is 7.39 the short circuit amperage or the nominal amperage? Then there is the power curve caracterisitics of a given PV module. Here is something that might help you to understand all of this.
http://photovoltaics.sandia.gov/docs/AMIntro.htm
http://photovoltaics.sandia.gov/docs/Database.htm
http://photovoltaics.sandia.gov/docs/ArraysModules.htm
http://photovoltaics.sandia.gov/docs/Standards.htm
You can "pull up" any particular PV modules entire specifacations, including power curves, at its manufactures web site. Here is something thats just plain cool to play with.
http://micro.magnet.fsu.edu/primer/java/solarcell/index.html
 
20 Posts
Nov 16, 2008 11:36 am
Re: Kyocera KC130TM 130W 12V Solar Panel w J-Box question

It says 7.39 is the MAX amperage... So that leads me to believe they can't put out more in any scenario....

So if my charge controller only accepts 13v max for my batteries, that leads me to believe I can never under any circumstances get 130w out of that panel using 12v batteries......

Is that correct?
 
Nov 16, 2008 02:16 pm
Re: Kyocera KC130TM 130W 12V Solar Panel w J-Box question

I would agree. The advertisement says max. amps. but consider this, when was the first time you saw an advertisement the didn't pan out to be the entire truth? Like that picture, of a roast beef sandwhich with the thinly sliced meat piled up 2" high, on the bill board menus over the cashiers, but then once you unwrapped yours to eat it, mouth all watering in anticipation, all you see is bun. You have to move the bun to see the roast beef.
Wheres the beef?!
I am not calling anybody a lier over here or nothing, just maybe their not telling the whole truth in advertising. You have to go to the manufactures specifcations PDF file, which they do provide a link to over there.
Those PV module ratings are at a STC or Standard Test Condition. The equivalent of 1000 watts per square meter of sunlight with a PV cell temperature of 25 degrees Celsius. There are very few, if any, places on Earth that receive the equivalent of 1000 watts of sunlight where a cell temperature of 25 degrees Celsius can be maintained for relatively long periods of time. There is however, calculations involved where the NEC or National Electrical Code and UL Underwriters Laboratories are concerned, in sizing the wire as well as charge controllers, means of disconnect, fuses, and breakers for PV source circuits. These calculations start with the Isc or short circut ratings at STC then this is multiplied by 125% to meet UL requirements and after that another 125% to meet NEC requirements, or it is acceptable to do this once by a factor 156% (125% X 125% = 156%). It has something to with "edge of cloud effect and snow reflectance."  So according to this the KC 130 is capable under very certain circumstance of producing 12.52 amps, but hey, I don't make these rules. So if you to argue about that with somebody go see them. I find hard to believe it could ever happen myself but those are the rules.

As for your charge controller "accepting" only 13 volts, if that is what its manufacture states is the high voltage input limit to the charge controller from a PV source, then no. You cant use any PV module with an open circuit voltage higher than 13 volts on that charge controller. That I find very hard to believe. Chances are your holding back on us. Your only giving us a few pepperonis, maybe some tomatoes sauce over here but we need the whole pizza to make a more informed decision. You know what I am saying? So what do you say? Eh? Give us break and let us know who manufactured that charge controller and what model it is? Then maybe we can help you to make a more informed choice.
 
20 Posts
Nov 16, 2008 03:35 pm
Re: Kyocera KC130TM 130W 12V Solar Panel w J-Box question

Hehe not holding back on purpose.... The 13v was my un-informed assumption, since fully charged batteries are at 13v.

The charge controller I'm using is a Sunforce 30 amp digital charge controller (the cheapy you get at Canadian Tire for $100).

I had the same issue with 15 watt panels I bought.  They say "12v, 1amp max".  So that lead me to believe they were 12 watt panels.

Anyway, after I set them up, sure enough, under perfect conditions here, I've never seen the panels go above 0.8 amps.

Charge controller says 0.8 amps comming in @ 13v... So that's 10.4w....

I'm okay if that is the reality.  I just wanted to know if I could expect 130w ever out of those panels or if they were designed to only provide 88-ish watts under perfect conditions.

I have some 80 watt panels from Sharp that I've yet to install that say they are 4.5 amps MAX .. So again, that leads me to believe I'll never see anything much about 54 watts coming out of them even under perfect conditions.

Bit of smoke and mirrors as you say, I think.  - Sure the panels themselves can generate their rated capacity at 17ish volts...but I've never heard of anyone with a 17 volt battery.
 
163 Posts
Nov 17, 2008 10:09 am
Re: Kyocera KC130TM 130W 12V Solar Panel w J-Box question

The charge controller I'm using is a Sunforce 30 amp digital charge controller (the cheapy you get at Canadian Tire for $100)......

Bit of smoke and mirrors as you say, I think.  - Sure the panels themselves can generate their rated capacity at 17ish volts...but I've never heard of anyone with a 17 volt battery.


Patrick,

The beauty of a Maximum Power Point Tracking (MPPT) Charge Controller is that it will allow the panels to operate at 17V (or whatever the voltage is for maximum power) and the controller does the step down to the charging voltage being applied to the batteries.

In California they conduct meticulous tests on panels before they approve them for use, so at this site you can hazard a guess as to what the exact output of your panels will be.
http://www.gosolarcalifornia.ca.gov/equipment/pvmodule.php

I have 3360 "rated" watts (28 x 120) of Evergreen PV panels and an Outback MX60 MPPT Charge Controller. In the hot summer months (most of the year) the output is around 2500 watts during peak sun, but in the winter months (Dec/Jan) the MX60 goes a bit haywire around solar noon when the power spikes beyond the 3200 watts that it is rated for.
 

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