15 FEB 2015
Hi All. My system has grown to 1KW in panels and looks like I need to upgrade my Kid to a Classic 150 (see sizing chart attachment). My Kid will make 30 amps. I like the Kid, but I am running it at max output. Had some issues last summer with it going into safe mode and dropping the current. Since then (and over this winter). I have added 4 more panels (10 total). They are wired series-series-parallel (two strings of five panels, 60v). It works well. The Kid senses the higher voltage and MPPT tracks optimal voltage. However when the sun is at full/peak...the Kid hits "overload".
According to the chart below, looks like the Classic 150 (not the Lite version) is the way to go.
Chris
Here is the Classic sizing chart...with my data entered for my system using 10 Renogy RNG-100D solar panels.
Don't forget that the KID is rated in Amps, but can do many voltage configurations. If switching your battery bank around is an option, then the KID can handle a lot more watts with the higher battery bank voltages:
Nominal 12v * 30A = 360W
Nominal 24v * 30A = 720W (not a bad spot for 1kw of panel)
Nominal 48v * 30A = 1440W
Not saying you would want to drive the KID at 100% all the time, but it is always good to know you have options other than a new charge controller.
It would be fun if the sizing chart included the KID as it is very capable for smaller arrays.
Yep - You are 100% correct. I do plan on switching the battery bank to 24v. My inverter will also need to be 24v. So...more $$$. I wish I would have started with a 24v system. The Kid is pretty nice...but, with 1KW in panels it runs pretty darn warm even this winter due to hitting "overcurrent" and the orange light blinking.
I might consider upgrading the inverter first and rewiring my battery bank. My inverter is not a pure sine wave, but has a lot balls at 3500 watts / 7000 watt surge. I have run over 1800 watts out of it...didn't even break a sweat.
What are your recommendations for a good 24v pure sine wave inverter? Looking for one around 2KW.
Thanks.
cGs
For a stand alone type, I have had good success with Samlex for both cost and performance. Before too long I am hoping we will be recommending MidNite inverters, though I don't know if they will be entering the stand-alone market...
There is Cotek too, they make some of the Samlex models AFAIK.
Quote from: Jacotenente on February 15, 2015, 08:14:04 AM
15 FEB 2015
Hi All. My system has grown ... They are wired series-series-parallel (two strings of five panels, 60v). It works well. The Kid senses the higher voltage and MPPT tracks optimal voltage. However when the sun is at full/peak...the Kid hits "overload". Chris
Hi Chris, guess that the 5 PVs in series = 60 V must be a TYPO. Looks more like 94.5 from the data entered in the CL Sizer.
Yes, this is a fairly high input voltage for a 12 V system. The Kid will produce about twice the output power when going to 24 V, and run cooler and more efficiently at a higher battery voltage, and probably spend no time current-limiting. So you should see more power yet.
FWIW, Vic
Can you rearrange the PV panels and do it with two Kids? Then you also have some redundancy in case of a problem with one.
Thanks. So, investing in a Classic 150 won't be a good match for my system with 10 panels running a 12v system? Right now I hit overload (30 amps) at 1030L in the winter in Oklahoma. Wouldn't a Classic with this array be a better fit? And according to the Classic sizing tool and the data I entered, the Classic would output more than that (69+ amps/918 watts). Or not? Would it hit OVR current like the Kid? What about overheating the Classic?
My Kid reads around 425 watts @ 30 amps. With a 24v system I am sure it put out more watts. However, isn't 30 amps, 30 amps despite the voltage?
I agree with running a 24v system...gonna have look into a 24v inverter.
Thanks.
2 Kids is an option that gives you a backup so to speak, as you will still have 1 CC, and is a bit cheaper (~1/2) than a Classic. The CL 150 is ~ 3 x the output no matter which V you use. Mind you if you get a CL150 you will still have a Kid as maintenance charger if the CL crashes.
Your choice.
Thanks Westbranch! I may have another use for the Kid once I get the Classic 150. More renewable energy tax write-offs for FY15. The best price I have found is around $610 from NAWS (Northern Arizona Wind and Solar). That is where I got my Kid.
Chris
Quote from: Jacotenente on February 15, 2015, 03:15:01 PM
... And according to the Classic sizing tool and the data I entered, the Classic would output more than that (69+ amps/918 watts). Or not? Would it hit OVR current like the Kid? What about overheating the Classic?
My Kid reads around 425 watts @ 30 amps. With a 24v system I am sure it put out more watts. However, isn't 30 amps, 30 amps despite the voltage?
I agree with running a 24v system...gonna have look into a 24v inverter.
Thanks.
Chris,
The Classic has a maximum output current on a 12 V system of about 94-ish Amps with your string voltage. This is absolute maximum, so yes, the Classic will output about three times the KID's max current.
And, yes, 30 Amps IS 30 Amps, but, as noted above, the output POWER capability of the KID on a 24 volt system is double the amount of power on a 12 volt system. And (also as noted above), PVs are rated at STC, where the cell temperatures are 25 degrees C, and we often do not quite get the STC irradiance from the sun -- 1000 watts per sq Meter of area.
In the real world, the sun heats the PVs, and the output voltage is reduced which reduces the power available, as does haze, humidity, grime on the PV glass, etc all reduce the PV output further. So your 1 KW STC (Standard Test Conditions) of PV can normally output between about 750 and 800 watts maximum under most conditions. This would fit nicely with what the KID can produce on a 24 volt battery system. And, the efficiency will be increased somewhat because the KID is not converting the 90ish string VMp down to the correct voltage to charge your 12 V battery.
Furthermore, when the KID Limits its output due to heating, the PV voltage rises above the nominal STC string Vmp of about 94.5 volts to something near 108 - 110 volts. This even higher voltage will contribute to more heating in the KID, which would further reduce the power output of the KID.
"Simply" going to a 24 volt system will mean that you should be able to often use all of the power that your PV array can produce. There may still be a bit of limiting due to high ambient temperatures (where the KID is located), etc, but this should be a small amount of power and only on occasion.
In addition your battery will go from SIX parallel batteries, to "just" three. Parallel batteries can often cause trouble, as one battery can ruin all of the rest if one cell shorts ... and getting the charge and discharge currents to share equally is nearly impossible. And, even if they start sharing well, batteries do age differently, and the sharing will change in time.
There are other negatives to having many parallel batteries, but you get the idea.
Ideally, one would have a single string of batteries, with sufficient AH Capacity to meet your needs ...
FWIW, my opinions, Have Fun, Vic
Excellent advice Vic...appreciate the information.