Blue Sky 3024il

[azrving]

I added 520 watts of solar and a Bogart 30 amp system to my rig. It works well but a new problem has happened. It's now common for people to ask how we can have all these lights going and a big tv and it's even more noticeable when the panels are tilted up. It seems to be a guy BS session magnet. So after meeting several new people we have become traveling friends with some of them. 🙂

One friend has Blue Sky 3024il system with 470 watts and 3 12v AGM batteries. As we sat around chewing the fat and comparing charge times etc, this guy said he never sees amperage above the teens. I jokingly told him I thought you MPPT guys had all the amps.

From there I gave him my beginner solar explanation of pwm vs mppt. He then said his panels all connected to a common bar just like mine. I said I dont think they can because it's mppt and they normally run those in series. At that point we went on the roof and sure enough it appears that they are all paralleled.

I looked at the specifications in his manual and it says PV input voltage: 57 vdc maximum.

He has 3 panels:
Kyocera 140
voc 22.1
vpmax 17.9
isc 8.68
ipmax 7.9

UL Solar: 140
voc 22.6
vmp 18.3
isc 8.21
imp 7.66

No name: 190
voc 21.45
vmp 17.4
isc 11.95
imp 10.92

I went the pwm route so my emphasis has been on playing with my Bogart system and learning it. I thought the idea behind mppt was to series the panels, reduce wire costs, etc. So I guess my main question is which voltage numbers are used. ocv of 66.06 OR vmp of 53.6? Second question is can these different panels be series? Will all 3 voltages drop to the lowest one of 21.5? Doesn't seem like it would matter as long as they are under max of 57 vdc.

He spent big money on everything and said he wanted the best when he bought the controller and inverter. Who ever installed the 3 agm batteries and inverter and solar controller did a beautiful job. All the cables are massive and well crimped.

He originally had a very cheap controller with one panel. It appears that as the next two panels were added they just kept paralleling them???? The last panel was added by a dealer in Yuma.

Any other suggestions are also appreciated. Thanks.

[azrving]

CA Traveler wrote:
The Solar Blvd Black Friday sale starts tomorrow (Thrs) at 9 PM.

However many panels are used the controller has to be able to handle them if they exceed the specs for a given temperature range. I haven't dug into the Blue Sky limitations.

540 watt 45.5 volts

I think if I recomended a controller to him it would be a morning star ts45 its inexpensive and probably good.

[CA_Traveler]

The Solar Blvd Black Friday sale starts tomorrow (Thrs) at 9 PM.

However many panels are used the controller has to be able to handle them if they exceed the specs for a given temperature range. I haven't dug into the Blue Sky limitations.

[azrving]

Can traveler
You mentioned 150 watt panels. Do you mean run 450 or 600? BS says 540?

[azrving]

Can traveler
I did mention to him that in order to test his agms we would have to remove all the cables and let them rest and check voltage. I have a load tester too. I said we could let him run the rig on one battery as the other 2 stabilize then let the 3rd one stabilize and test. He said it would be easier to just get rid of them and get new ones. 🙂

[azrving]

Salvo wrote:
See where you're at. Run the test I outlined!

rjxj wrote:


He realizes now that the system should have started with matched panels but too late now. Any ideas are appreciated.

I will. I'll reread this stuff again and we plan on playing with his system more. Im leaning toward just telling him to buy a common 100 watt panel with a close voltage number. I know its over panel by 30 watts but doubt that will kill it. Not as bad as our buddy who is running 685 on his go power

[Salvo]

Minor correction. Solar elevation = 54 deg.

sine (54 deg) * 750W = 607W

CA Traveler wrote:
Sal,

Thanks for the explanation. The sine of the sun elevation is a close match for my 3/3/15 noonish Phoenix measurement at 50 degrees.

sine 50*750W = 574W and the controller output was 600W.

[azrving]

CA Traveler wrote:
Oh and check out controllers with the features he wants AND remote voltage sense AND remote temperature sense. He might as well get it done right.

If he can find a good battery shop (certainly not in Q) a good load test might be helpful.

Lol. I thought about telling him to get Bogart stuff but he'd choke. I know I have 50 more watts than he does but his blue sky doesn't create any miracles. Its OK but sort of a rip when you consider he paid over $650 for a 30 amp set up and I paid $350. I can put back 72 ah while he's putting back 45 or 50.
I'm not sure why but I'm in float 3 hours or more before he is. He may just not need 5 hours of absorb.
He may still be facing the black screen static issue with the blue sky too.
I did buy my cynergy's at solar blvd. Four 130's for $620. Shipped too. Thanks to smkettner recommendation

[Salvo]

See where you're at. Run the test I outlined!

rjxj wrote:


He realizes now that the system should have started with matched panels but too late now. Any ideas are appreciated.

[CA_Traveler]

Sal,

Thanks for the explanation. The sine of the sun elevation is a close match for my 3/3/15 noonish Phoenix measurement at 50 degrees.

sine 50*750W = 574W and the controller output was 600W.

[Salvo]

I took this data a few years ago. Panel flat, vs. tracking, vs. calculated sine(alt). The sine(alt) is a little offset, but matches fairly well with the flat panel current.



I just looked up the sun's max altitude that day. It was 45 degrees.

sine(45 degrees) = 0.707

That's about what my plot says.

pnichols wrote:

Salvo wrote:
sine 35 degrees = 0.57

7.4A * 0.57 = 4.2 A (btw, I just posted a current plot with same 4.2A measured with my new A/D.)

Sal .... I'm curious. Why the straight cosine multiplication for derating of solar energy versis panel angle????

Does the collection rate of the Sun's energy degrade directly/linearly with angle? I'd be a bit surprised if it was that simple ... but maybe it is. :h

[CA_Traveler]

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[Salvo]

If his panels are flat then 15.2A is all he'll get. Probably less due to mismatch of Vmp. Q has similar solar elevation as SB.

CA Traveler wrote:


Given that then this "I = 4.2A * 470/130 = 15.2A" doesn't necessarily line up with generally consistent good sun in Q which is the location of this thread and could imply about 50% efficiency with Sal's tilted panel.

[pnichols]

Salvo wrote:
sine 35 degrees = 0.57

7.4A * 0.57 = 4.2 A (btw, I just posted a current plot with same 4.2A measured with my new A/D.)

Sal .... I'm curious. Why the straight cosine multiplication for derating of solar energy versis panel angle????

Does the collection rate of the Sun's energy degrade directly/linearly with angle? I'd be a bit surprised if it was that simple ... but maybe it is. :h

[Salvo]

Yes, I got Vmp = 7.4.

However, the panel is flat. The sun max altitude in Santa Barbara today is 35 degrees.

sine 35 degrees = 0.57

7.4A * 0.57 = 4.2 A (btw, I just posted a current plot with same 4.2A measured with my new A/D.)

That's max current this time of year. If I were out camping in Qrartzsite right now, I would be tilting to get more output.

CA Traveler wrote:

Salvo wrote:
My 130W mppt solar outputs about 4.2A now at noon when battery is at 14.0V.

Why did you use 4.2A vs Imp+ ? Isn't your Imp about 7.4A?