460 watt solar setup: wire sizes?

MEXICOWANDERER wrote:
It was all supposed to work out "that way" until XXXXXXXX HMO backcharged six hundred thousand dollars in hospital bills from City of Hope and I had to liquidate everything I owned and then some in order to not declare bankruptcy. So, a million a something later (that's a lot of income), I can say I do not have much and that yes, to me, money matters. So does safety. I harp on it on this forum. "The guy's an MEE and yet he keeps hammering about money". This incongruity needed to be explained once, here. And that is the end of that..

I understand.

O&S

Hi Almot,

My understanding is that the Tristar 60 is three modules @ 20 amps each. The 45 is two 22.5 amp modules

pianotuna wrote:
Hi Almot,

The Tristar 45 is less efficient than the Tristar 60, and would allow for any further expansion.

Tristar 60 leaves room for expansion, yes, approximately one more 250W panel.

As to the efficiency - their manual doesn't make any distinction btw model 45 and 60, and at Vmp = 66 and current 25A-45A the graph shows ~94% efficiency (Rogue has ~96%). Interesting finding - I wouldn't have noticed if you didn't touch the subject - thanks. It means that Rogue works better within 30A range, until 30A clipping exceeds 0.6A (after this point Rogue clipping kills more power than lower efficiency of Tristar).

It also shows significant drop in efficiency at Vmp = 98, i.e. 3*250 panels in series VS just 2*250, but this is to be expected.

My fool-proof way of getting expected AH or amps based on some measurements I made last year, is that 460w should get you 460/130 x 8.2 = 29amps pointed with PWM. If you believe the MPPT guys, add 10% = 3 plus the 29 = 32a

Just when or how long you get those max expected amps "depends" on your set-up, etc.

In cases where you are far enough north of 23N that flat is less than tilted, by "enough" then that could get you below 30 from that 32 I figured.

490w would be 490/130 x 8.2 = 31 with just PWM. Add 10% for MPPT= 34a.

The OP could go one more flat mounted panel and just touch the max on a Tristar 45.

Four would max out the 60. But max 3 in series due to Voc limit so 2 parallel 2 series would be pushing that #10 wire a bit harder. Safe but the losses would increase.

Hi Almot,

The Tristar 45 is less efficient than the Tristar 60, and would allow for any further expansion.

I hope we are still on the OP subject here. As I see it, at the moment there is no better choice for 460W than Tristar 45 (and the same for 490W).

I still think that 30A would suffice for a "fixed installation" as Don put it, i.e. non-tracking and with non-optimal tilt most of the time. To think about it, fixed all-year tilt North of 25 Latitude reduces the annualized output to 72% of the optimal. Fixed summer tilt - 75% of the optimal. Together with 96% post-controller power it means 460*0.75*0.96=331W. 30A clipping would never happen then. I would get the Rogue if it were available, but it is not.

Almot wrote:
And some more graphs etc in the Manual

Looks like Rogue can be set to enter float when charging amps drops to a preset level. This should work well to transition the charge cycle between heavy and light battery use. Still it could get fooled if loads are present but a timer can also be set. This might be better for AGM than just the voltage and time settings of Morningstar.

We have too much solar for sunny days but not enough for when days are mostly cloudy. It depends on your usual climate what you can count on for planning.

This summer here has been amazing for a long string of non-cloudy blue sky days, so batts are full by noon easy. No need for top charge /equalize sessions either like I figured on. SG shows true full and the Trimetric even goes "over" in AH by a few. I said before this was not possible. Hmmmm.

One thing to note is in these conditions, being in Float for the afternoon, every time you do use a high amp draw, even briefly, it kicks the solar controller into another two- hour absorption stage, so you can spend many hours a day at 14.5ish volts. Need to add some water to the bank of 6s every two weeks!

No doubt reality will set in soon and it will snow or something in August! :)

smkettner wrote:
I would have to know the flexibility of the Rogue charging profile before giving a solid recommendation.

Rogue specs

And some more graphs etc in the Manual

Though it doesn't say anywhere whether the 30A clipping generates much heat, or how high is too high, i.e. whether clipping may damage it at some point.

Mex - you can't do the controller bypass trick on 12V bank with 24V panels. Not to mention when they are in series.