600W Solar - Getting 420W Max

The above 2 graphs show the advantages of series panels with 3x bypass diodes. In both low light and shadows they produce power where serial would not or produce less.

There is no definition or quantification of shade so one has to draw their own conclusions as to what's posted.

You have 600 watts of panel and get over 400 watts of performance..

I'd call that excelent, 300 is what I'd expect.

Here are 2 graphs starting with early morning solar production. Note: Check for the correct axis for values when looking at the graph plot.

Three Cynergy 250W Panels in Series

Vmp = 3x30.58 = 91.74V, Voc = 3x37.45 = 112.35, Imp = 8.18A


Casa Grande, AZ 3/5/15, Begin Civil Twilight 6:25 AM, Sunrise 6:50 AM
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Oceanside, CA, 12/26/14, Begin Civil Twilight 6:17 AM, Sunrise 6:45 AM, No picture but large heavy shade trees were several blocks away.
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Seems it was proven long ago that in some shaded conditions, paralleled panels will outdo series. And that make sense to me. But some always know better.
Me I couldn't care less, cuz when the sun ain't shinin, neither work very good.

CT_WANDERER wrote:
OP here, I am running with a Morningstar TS45 PWM controller.

You may see a improvement with a TS-MPPT-45 but it comes at a cost. The question is are your needs being met?

Don

It didn't matter if it was my single 230w poly or the three 250w poly in series, charging starts at first light.

I tested in series this year. 20-25a in heavy overcast at mid day was normal. Come to think of it, it was overcast by mid day most of the time.

Hi CA Traveler,

THANK YOU. I've been looking for this tidbit of information for six years. It explains why my system appears to punch above its weight.

Do you have measurements of what time of day charging begins? Ends?

CA Traveler wrote:
My 90V serial setup starts charging when the voltage is only 20V due to overcast weather.

OP here, I am running with a Morningstar TS45 PWM controller.

JiminDenver wrote:
You really need to understand how your needs work, your situation, location and even time of travel to get anything out of tweaking the design so. Start with what fits on the roof and you may find out the choice has been made for you.

Well said. I started by fitting the smaller 12V panels to my apparently limited space roof with scale drawings. But one factor kept making me question 12V panels - namely the cost/watt was much less for 24V panels. I then began to realize that there was no reason to mount the panels just a few inches above the roof. Eureka! The 24V panels then fit very well and no rig shadows and the cost with MPPT was very close to the 12V panels with PWM - so 24V panels and MPPT was a no brainier.

And there is a clear shoulder hour advantage with MPPT and serial panels with bypass diodes that you do not get with parallel panels. My 90V serial setup starts charging when the voltage is only 20V due to overcast weather. And bypass diodes allow partially shaded panels to produce more power any time there are partial shadows.

Hi,

At solar noon, if the batteries are "hungry" or if I place a large load on the system, I routinely get 17 amps from 256 watts of panels--that's about 224 watts.