Renogy Eclipse panels?

[HumbleBeginnings]

Dan'l - I thought about a cross pattern, but I decided that was the worst option. If I get shade across the front OR back OR left OR right, all the scenarios would compromise both branches of my parallel circuit.

John - Well dang... that's a really good idea so now I'm going to have to figure out a way to install my wiring so that it's agile. (Once I finally buy my components.

 

[John61CT]

Note the ideal for handling shading is a 1:1 ratio between SC and panels.

More expensive and less efficient with little low-voltage panels, so here just a FYI sidenote.

 

[HumbleBeginnings]

John, I didn't quite follow that. Can you dumb it down for me?

 

[John61CT]

OK, get a larger, higher voltage panel more suitable for taking advantage of MPPT's potentially greater efficiency.

e.g. SunPower SPR-X21-345

and match 1:1 with quality MPOT controllers, robust and fully adjustable.

e.g. Victron, lower amp units are very cheap (under $100), but for the above panel we'll need to go to higher capacity ones

Revevant panel specs:
Nominal power 345W
Open-Circuit Voltage (Voc) 68V
Rated Current (Impp) 6A

So Victron MPPT 100/30 will match up well.

If you have room for three panels, you buy three controllers

This 1:1 ratio means if one gets some shading, the others are completely unaffected.

Don't let anyone tell you that some special panels are somehow magically resistant to shading issues. Diodes can be incorporated, but these can cause other issues and be inefficient, and poly vs mono, serial vs parallel can also make a bit of a difference.

But in general, if multiple panels are sharing a single panel, even a small amount of shading, even from a leaf or bird poop, can drastically reduce the actual charging current as measured at the battery bank.

Going the other way, if you wanted to get the much less expensive MPPT 75/15 unit, then you would look for a similar high-voltage panel, but that's rated for 240W or a bit under.

 

[jimindenver]

John

I have not dealt with a Victron yet that I did not feel there was a issue with the MPPT program. Getting the dongle seems to help some but they back off the charge rate at 13-13.1v. In one case a Morningstar controller set the battery specs made all the difference in the world.

What has your experience been with your Victron and what system are you running it on?

 

[John61CT]

I haven't seen any installs with those issues, several dozen working great, mostly on boats.

I was just giving an example about setting up 1:1, not reco for OP, I wouldn't bother using them at low voltages, say under 35 VoC rated.

Yes Morningstar are great, along with Midnight, Outback, Blue Sky.

Favorite so far has been Bogart with Trimetric, but that's PWM and pricey.

 

[jimindenver]

Right but what of your system?

 

[HumbleBeginnings]

Hey Jim,

I'm looking at 4 Renogy 100W panels, which have a stated 20Voc. So if I'm understanding this right:

Series/parallel would give me 40Voc, 10A
All 4 in series would give me 80Voc, 5A

Have I got that right? And would one be better than the other? I contacted Renogy and they said they don't recommend one over the other. But I do want to make sure I get the most out of the 40A/100V mppt controller.

Thanks!

 

[blars]

If all your panels are lighted identically, and your MPPT controller can handle the VOC voltage with enough safety margin (20% or more), series is best. If you will have partial shading, parallel is best.

 

[tx2sturgis]

If you put all four panels in series, and you get blockage of even one small section on one panel, say from some leaves or a plastic bag up there, the whole array drops output. Or if one panel fails. Not likely, but it can happen. 

If it were me, I'd go series/parallel, because then you have redundancy. The total power derived might be a tad bit less this way, with a Victron, if Jim's assessment is correct, and I trust his observations.

However you would gain some confidence in a steady supply of power even if one leg of the array is underperforming.

But that's just me.

 

[Cammalu]

Don't let anyone tell you that some special panels are somehow magically resistant to shading issues. Diodes can be incorporated, but these can cause other issues and be inefficient, and poly vs mono, serial vs parallel can also make a bit of a difference.

But in general, if multiple panels are sharing a single panel, even a small amount of shading, even from a leaf or bird poop, can drastically reduce the actual charging current as measured at the battery bank.

Again, more bad info. What may seem like "magic" to you is just technology advancing. Lighting a match was once considered magic also.

My renology eclipse panels are not affected by a tiny leaf. In fact (because I sent someone up to the roof to verify) even a whole man size hand on a panel only draws the solar input down a small amount.

You are well aware of this and have seen the photos of this but keep spouting inaccuracies. You were kicked out of another forum for continuously spreading bad information and being argumentative to everyone.

You don't own any Renogy eclipse panels and to bad mouth them when you have zero experience with them is disingenuous at best.

 

[HumbleBeginnings]

If you put all four panels in series, and you get blockage of even one small section on one panel, say from some leaves or a plastic bag up there, the whole array drops output. Or if one panel fails. Not likely, but it can happen. 

If it were me, I'd go series/parallel, because then you have redundancy. The total power derived might be a tad bit less this way, with a Victron, if Jim's assessment is correct, and I trust his observations.

However you would gain some confidence in a steady supply of power even if one leg of the array is underperforming.

But that's just me.

This was my thinking as well. I just wasn't sure if I would be missing out on performance by not using the absolute highest voltage possible. I will of course try to minimize shading, but I'm not going to reposition my van three times a day, so I assume shading will happen at some point. 

The front two panels will be forward of the fan and towards the center of the van, away from the cross bar ends. It's the rears I expect to get shading on, since they will be crowded into a tight space with less than an inch on either side. So when the sun isn't high I assume I'll get some shade. Once I have my panels in hand I'll decide how I'm going to mount them. I've got an idea with aluminum angle on how I may make some tilting mounts, but it's only in my head at this point. We'll see if that becomes reality or not!

I do appreciate everybody's help and input.

 

[John61CT]

I've never said anything bad against any particular panel.

And I've never seen evidence that any particular type is specifically resistant to reduced output from partial shading.

Make sure when testing you measure **actual output amps** going into a discharged battery. Voltage output should of course remain constant.

You will see a significant reduction from even a small shadow, much higher proportionately than the percentage area shaded.

Designing with diodes can help, but at a cost. And nothing to do with any "new advances" in cell technology.

 

[Cammalu]

I've never said anything bad against any particular panel.

And I've never seen evidence that any particular type is particularly resistant to reduced output from partial shading.

Make sure when testing you measure **actual output amps** going into a discharged battery. Voltage output should of course remain constant.

You will see a significant reduction from even a small shadow, much higher proportionately than the percentage area shaded.

There is no significant reduction from a tiny leaf. You have seen evidence that I posted before and have chosen to keep posting misinformation about this and many other things.

If you don't know something that you have had practical experience in and not just read about on some other forum why post it?

 

[HumbleBeginnings]

I think you two should share a camp for a month. Run a series of solar tests and experiments. Share a campfire and a beverage. Become lifelong friends.

 

[John61CT]

You have seen evidence that I posted before

I have not seen that, or if I did don't recall, I do have memory issues. Feel free to repost it.

I'm not sure why you're taking this so personally, I'm just trying to provide accurate information and have no axe to grind.

And if there are cheaper ways than 1:1 design to avoid these shading issues I'd be very happy to learn about them, but will need credible sources, not from people selling stuff.

 

[Cammalu]

Selling stuff? Who is selling? I bought mine from Renogy like everyone else and am not affiliated in any way.


Sent from my iPhone using Tapatalk

 

[John61CT]

I did not say you were.

Just as I never said anything bad about those (or any other) panels.

 

[HumbleBeginnings]

I may have missed it, what was the advantage of multiple controllers? Is it just cheaper per controller, controller redundancy?

 

[GotSmart]

I have not seen that,  or if I did don't recall, I do have memory issues.

And if there are cheaper ways than 1:1 design to avoid these shading issues I'd be very happy to learn about them,  but will need credible sources, not from people selling stuff.

Many times you have been asked direct questions. All that happens is you ignore them. I have training and  experience. People track me down for my help. 

Do you have any credentials or experience?  

If not, please stop giving bad advice about things you know nothing about. If you do have knowledge, please go back to school. It is incomplete.