Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

Tom Cleary

Hello,
I have a Kyocera 230 watt panel with a maximum voltage of 29 volts and a Bluesky Solar Boost 3024 i charge controller. A technician from Bogart Engineering (maker of the Trimetric 2025A) told me that the Bluesky Solar Boost 3024i can't handle all of the output of the Kyocera 230 watt panel. He said that Solar Boost 3024i cuts off the top 15 percent of the charge possible and that the extra electricity input will eventually degrade the Solar Boost 3024 i till the point where it won't work any longer, and that nothing can be done about it except to upgrade to a higher capacity model, he suggested the Bluesky 2512ix-hv. Can anyone please comment or offer a suggestion? I built my first offgrid solar charging system today using these components and am wondering if I should try another charge controller. Thanks very much for any help you can offer.
Tom

BB.

Re: Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

What is your battery bank voltage?

If the battery bank voltage is 12 volts, a single 230 Watt panel should be fine on the controller. Assuming these are the panel specifications:

Electrical Performance under Standard Test Conditions (*STC)

Maximum Power (Pmax)

230W (+5%/-3%)

Maximum Power Voltage (Vmpp)

29.8V

Maximum Power Current (Impp)

7.72A

Open Circuit Voltage (Voc)

36.9V

Short Circuit Current (Isc)

8.36A

Max System Voltage

600V

*STC: Irradiance 1000W/m², AM1.5 spectrum, cell temperature 25°C

Interestingly, there does appear to be a potential issue with the Bluesky controller and the Vmp/Voc of the solar array:

MPPT Current boost is less than expected

Nominal PV voltage has changed from 24V to 12V


If PV voltage is changed from 24V to 12V, battery and PV power must be removed momentarily to reboot unit and load initial 12V PV control values. Unit considers PV’s to 24V if PV voltage ever goes above 28V.

I am not sure--But the MPPT appears to be zoned somehow--It assumes a panel to be a 12 volt panel (Vmp~18 volts?) if the array voltage does not exceed 28 volts.

You may need to call Bluesky Engineering to see if there is an "issue" with using Vmp~30 volt panels on a hot day and the controller getting into a 12 volt panel mode (whatever that is).

I don't know how a Bluesky does the MPPT voltage set point (optimum voltage)--But it may be setting it too low for your array--especially on hot days (when Vmp/Voc tend to sag anyway).

If you can measure/log the Array Voltage and see what it is at in the middle of the day, and write down the Array Current and the Battery Voltage/Current (all at the same time)--Or do the measurements several times over the daylight hours (and note what mode the controller is in)--You might see the problem (if there is one).

If you are using a 24 volt battery bank, then we have a whole other issue where the single Vmp-Panel is not high enough to fully charge a 24 volt battery bank (and two Vmp~30 volt panels in series is too high of voltage for the Bluesky).

Just guessing here.

-Bill

Tom Cleary

Re: Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

Thanks much, I appreciate the detailed reply. The panel specs you listed are the same as listed on the back of my panel and are correct. My battery bank consists of two flooded 12 volt costco batteries of 120 am hours. The two batteries are wired in parallel. I will contact the Blue sky tech department to ask the question you mentioned, not sure I completely understand the question myself, but will read it a few more times when it is not past my bedtime. Thanks again. Best,
Tom

Cariboocoot

Re: Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

Some models of BlueSky controllers are not very good at handling down-conversion of Voltage. Their rated current handling is reduced if the input Voltage is above normal for the system Voltage (i.e. 18 Volts on a 12 Volt system is fine, 30 Volts causes a loss in maximum current capacity).

Personally I do not like their controllers at all because of these limitations. They offer very little advantage over a PWM type.

Tom Cleary

Re: Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

Thank you very much BB and Cariboocoot for your informative replies. Per earlier suggestion of BB I contacted BlueSky and received the following reply. The attachment may be found separately; I did not understand the attachment. I plan to drop the matter and hope for the best as it is too late to return the the model of Blue Sky controller I have anyway.

Tom,
Statements regarding the 3024 are incorrect. Either the SB3024iL or the lower cost SB2512iX-HV will run a 230W 60 cell module. Please see the attached.
Regards,
Richard A. Cullen

BB.

Re: Bluesky Solar Boost 3024 i charge controller inadequate to 230 watt panel question

I wonder if he knew you were charging a 12 volt battery bank (I think--Since you talked about getting a 12 volt controller instead)?

Anyway--He says it is fine, and their chart, as long as you are less than 400 watts (for the SB 3024iL) the higher voltage panel is OK at a lower current limit (which the controller will "enforce" with the higher voltage panel).

Apparently, some of the controller will support higher output current to the battery lower Vmp-array input voltages:

#4 Current limit and current rating are higher when charging a 12V battery from 36 cell nominal 12V PV modules. If PV VOC ever exceeds
30V (i.e., >12V nominal PV modules) current rating and current limit switch to the lower value until the unit reboots.

But note #4 appears to be model specific--So if you do not have the "iL" or "iX" (and a couple other models), #4 will not apply. And if your panel is under some maximum Imp limit--Then even if the controller falls back to a lower limit--The output current (or power) limit is still less than the panel you have attached to your controller.

In any case, the tech support guy (not from BlueSky) was talking about BlueSky reliability--Not specific functional issues (like note #4), frown what I can understand.

I have not read anything here that the BlueSky controllers were unreliable--Just less sophisticated MPPT designs (newer designs can harvest a more power).

-Bill