6x12 cell Panels? ~37V Vmp?

Yeah they're out of stock on the ones I bought, too. The site shows yours in stock, so I guess they need to update their page.

jrnymn7 wrote:
Looks like you already bought one, but these appear to be an exact match:

2solar

Yep, that's where I bought my first two. From Flora at 2Solar. Nice place.

But they no longer carry them. Which is too bad as finding 32" wide high voltage (72 cell) panels is hard. I don't know of any right now.

Like a lot of local solar retailers, you really have to call them to find out what's available. They don't update their web site very often.

Looks like you already bought one, but these appear to be an exact match:

2solar

For anyone interested, I bought my two 12v 140w polys from 2solar in Markham... good prices... about $1.05/watt, I believe it was.

After further web surfing and several phone calls, I found another source for panels in Southern Ontario (Solar Trader Inc. in Burlington) and got a Canadian Solar 72 cell Mono 300W panel for Can$300.

Thanks to JimInDenver's experience and advice, I stuck to mono panels and 72 cells to match the original panels.

The CS6X-300M panel's Vmp is 36.5V, compared to Sunny Power's Vmp=36.7, and the Voc is 45.0 versus 44V.

Hopefully these #'s indicate the two panels are close enough electrically for the MPPT controller to do its optimization.

With a total of 700W, I'll now exceed the max 30A of my Rogue MPPT controller on bright sunny days with no shade. It won't harm the controller but the energy will be wasted (unless I go to a 24V battery bank).

But that doesn't matter at this point, as our daily energy usage is currently low enough that the existing 400W can fully recharge the batteries on bright sunny days. The problem is rainy, grey days and/or shady sites, especially in the shorter days of fall, winter and spring.

No solar energy will be wasted on grey days as the max 30A will never be exceeded. And the additional panel will be mounted in parallel far from the other two and so provide greater overall chance of one of the panels avoiding shade.

North Ontario Prov. Parks and Smoky Mountains N.P. here we come.

But first I have to get the new panel up on the roof. This thing is quite a bit bigger than the old panels: 39"x77" versus 32"x63".

By the way, Solar Trader Inc. seems to be a reasonable supplier and were very helpful. With the recent reductions in Ontario subsidies for solar tie-ins, a lot of their business has been with off-grid installations, so they stock batteries, inverters and so on as well. Only problem seems to be that they don't keep their web-site up-to-date. You really need to phone them to find out what's available.

JiminDenver wrote:
You don't just match up the ratings, you have to match up the characteristics too. Mono's and Poly's react differently to different light levels and that will confuse the controllers ability to track.

I have found this in my original panels, a 220w mono and 230w poly. They were never at the same no matter the light level. My 245w mono and 250w poly were close in bright light but vastly different when that light changed. So if you can't match them up, do dual systems.

That's why I suggest to cover the roof at the get go. I would have been happy to use my 230w Schott poly for it's low light abilities but they were discontinued years ago. Newer polys have a smaller foot print and that made it easier and cheaper to start fresh with three matching panels than finding two panels that matched up with the Schott.

It is far easier to add to a PWM system even though you lose a good chuck of power when the batteries voltage is low.

Good advice; I should have bought the 3rd 195W panel at the get-go.

But an issue with adding a separate PWM (or any) controller is the additional cabling and mess on the roof and down to the batteries. Yuk, more wires/cables/junctions I don't need. Was hoping to just pop open a couple of MC4 connectors and add a couple of Ys on the roof.

I have found a 72 cell mono with basically the same Vmp that should match the existing 72 cell mono panels well. But it's a much bigger, more expensive 320W panel that in combination with my other two 195W panels will surely be wasted on my 30A max Rogue, unless I switch to a 24V Battery bank with a DC/DC converter. :E

Yikes, this is getting out of hand. Time to put it all on the back burner for a bit while I mull it over some more.

You don't just match up the ratings, you have to match up the characteristics too. Mono's and Poly's react differently to different light levels and that will confuse the controllers ability to track.

I have found this in my original panels, a 220w mono and 230w poly. They were never at the same no matter the light level. My 245w mono and 250w poly were close in bright light but vastly different when that light changed. So if you can't match them up, do dual systems.

That's why I suggest to cover the roof at the get go. I would have been happy to use my 230w Schott poly for it's low light abilities but they were discontinued years ago. Newer polys have a smaller foot print and that made it easier and cheaper to start fresh with three matching panels than finding two panels that matched up with the Schott.

It is far easier to add to a PWM system even though you lose a good chuck of power when the batteries voltage is low.

smkettner wrote:


Or Google shop 72 cell solar panels

:S

Thanks.
First hit is 72 cell with 36.4Vmp. Probably close enough.
Now to find the closest/cheapest source.

EDIT: and a few hits down, there's a 320W mono panel with exactly the 36.7Vmp of my existing 72 cell panels. Looks like 72 cell panels are alive and well, just bigger!

If you could match Imp and run in series I think it would work well unless Voc puts you over the controller max.

Or Google shop 72 cell solar panels

Hi,

This website has locations in Miami and Phoenix AZ.

SunElec.com

Look for panels with a frame and in the approximate voltage you desire. They are close to $1 per rated watt at this site.

If all else fails, you can always just install a 12 volt nominal panel and a PWM controller that cost between $25 and $35 for a 20 amp rated model.

I made my mounts out of 2" angle aluminum from Home Depot. I drilled 3 holes for #10 screws into the roof and 5/16" hole for a 1/4-20 bolt into the panel.

I ran my wire down the refrigerator vent, to the controller, then to the battery. It is pretty simple to install.

I was looking up their website today, and saw this 145 watt panel for $229. You can wire two of these in series, then to the MPPT controller that you already have if you have enough amperage capacity left.

http://sunelec.com/solar-panels/12v-solar-panels/solarworld-145w-solar-panel.html Or run them with a PWM controller to your battery. You do not lose a significant amount of power by using a PWM controller.

Good luck!

Fred.