Comparison of cheap vs expensive solar

[Grandad]

I found this interesting. Ignore the PWM vs MPPT. I know the PWM is better for Lithium. This was all about LA.

https://www.youtube.com/watch?v=dZ_jrSAk-DU

Jim

[Vik351]

Have to show T1 this ...!!!


vik...

[T1 Terry]

What is really funny, not that pun but the fact I put up the same test results back on the old CMCA forum.That test involved a far wider array of solar conditions and side by side testing rather than one at a time, but not vian MPPT controller but rather direct panel output with nothing in between. The current was measured using a hall effect sensor so no resistance and each battery had its own volt meter.
The brains trust on that forum, a uni professor, an electrical engineer and a book writer, all said I must have done something wrong because my real life findings didn't match the computer modelling
The fact that the only solar panels made in Australia to suit Australian conditions, Tindo, use polycrystalline construction as apposed to mono crystalline, says their testing shows which works best in Australia.
The cool bit on the side these tests show up is the solar harvest the MPPT controller gets from each panel. The very best is 70 watts from a 100 watt panel, 70% into a lithium battery. We see better than 80% using PWM control no matter what type of panel is used, so much for the computer modelling of how great MPPT controllers are
The broken module semi flexible panels, clearly the grid in the back of the modules is still in tacked so the whole module can still generate. I've had a cheap semi flexible panel come unstuck except for one corner resulting in it folding over a flapping as the owner dragged the van for a few hundred kms, at speeds I wouldn't want to be towing any sort of trailer, but the panel still worked fine. I also just replaced two panels that blew off a roof and were collected off the road, they still both work fine, so abuse isn't the semi flexible panel killer. The killer is the heat causing the grid mesh under the modules to separate and the continuity is lost. I have yet to fine the fix for that, not all panels seem to suffer the problem and that is even more confusing. As far as cheap rigid panels v expensive rigid panels, you can buy quite a few cheaper panels for the cost of one high priced panel. The real difference is the way they are wired, get that wrong and the panel turns into a heater element and that kills cheap panels just as fast as expensive panels.

T1 Terry

[Vik351]

And a book writer... how subtle...

vik...

[Grandad]

Oh dear, my most humble apologies. That wasn't the correct link. As interesting as the wrong link turned out to be.

Take two!

This https://www.youtube.com/watch?v=3-sc4rlV93g is the right one. I think what happened is I watched one clip and when it ended, YouTube automatically loaded the next one and that's the one I copied the link to. Sorry. My bad.

At least this guy is an Aussie and what appealed to me was he was a complete amateur. And I loved his rig.

Jim

[BruceS]

Good morning Jim! How is the build coming along?
We need an update or 3!
You should have seen Ian's homemade 5th wheeler that was in Mannum the other day having LiFePO4's professionally fitted out. What a rig!!! I'll see if I can get Ian to post a few piccies? Ian?

[T1 Terry]

The first difference between the 2 panels tested, the iTech world panel is about 2 yrs out of date as far as technology compared to the SunYee panel. The panel area was the first hint, the fact the modules were the older style 3 piece with the obvious grid connection showing was the most obvious ..... but ..... the older panel suffers less from the heat effect that causes the panels to die a premature death. The grid connection through the modules sort of helps hold the whole thing together and these have a higher resistance to current flowing back into the modules when the controller goes into float mode and open circuit. Much more of a problem where multiple panels are connected in parallel but a definite problem if you attempt to join these panels in a series string to take advantage of the MPPT function of one of those type of controllers.
Something that did come out of this that the tester didn't expect, the cheap PWM controller actually outperformed the combo DC to DC charger and MPPT controller on the lower output panel. I expect if he had gone back and retested the Sunyee panel on the MPPT controller he would have found the output was less than he had seen the first time. All related to panel heat and sun position.
Something else that would have been interesting but for some reason he chose not to show it, which controller performed better with both panels connected? He showed he had the set up to do just that, but for some reason chose not to do the test or show the results .... might not have suited his view of how great the MPPT controller was

Having said all that, we have given up on semi flexible panels at the moment, just too many failures and I have narrowed it down to how the semi flexible panels are actually built, but I've already sort of explained my theories on that.
As far as cutting the MC4 connectors off, far better to knock the pins out of the plastic bit and buy new pins to attach to the extension cables. Then you can push the two connector pins fully home into each other and apply a bit of solder to keep them together, then slip the heat shrink over and the joint is sealed from the weather. If you ever need to remove the panel, especially if it's for a warranty claim, slice the heat shrink, heat the join and pull it apart, then push the pins back into the plastic holders. Looks much like the way it was supplied so they can't claim you have modified it and void the warranty.

T1 Terry

[Grandad]

Good morning Jim! How is the build coming along?
We need an update or 3!

G'day Bruce. I've been meaning to start a build thread but never seem to get around to it.
Not much happening over winter. (read: NOTHING has been happening over winter) Too bloody cold thank you very much.

I picked up the last piece of the aluminium sheet to finish the roof cladding off but have been waiting until my neighbour returns from his latest caravanning trip up north to give me a hand installing it. It's a big sheet to manhandle plus I want someone at each side to make sure its positioned correctly. So, in the meantime, I've been working inside on bathroom renos.

Right from the first week after I bought this van about 20 years ago there has been a VERY bad condensation problem on the roof. Originally it was just a sheet of alloy with 3mm ply underneath it. The condensation would run down front and back and wet everything. All of the rot that happened was a direct result of that. Windows and seams have never leaked.

To fix it, I've added 25mm of polystyrene between the alloy and plywood. Where I've installed the polystyrene from and back the problem no longer exists. But the centre section where its just plywood is now black from mould over winter. I've only recently noticed what had happened as I seldom go into the van unless I'm doing some work on it.

So, I've been reading up on killing mould.

Jim

[Grandad]

Thanks Terry. I was hoping you would comment on it.

I'm aware you've been advising against semi flexibles for a while now. I can tell you that threw a spanner in my plans.

As you can see from my avatar the roof has extreme curves front and back. So, at one stage I was climbing up on the roof with sheets of old ply cut to the size of a rigid panel to see how it would fit on the curve. Hmm Not terribly well as it turns out.

I've always anticipated an issue with solar on this roof because of the curves. Basically, only the front or back will cop any worthwhile sun at any given time except mid-day. To get around this, I had thought of a large roof rack on the ute or panelvan (Whichever I end up with) and load that sucker up with as many panels as I can fit. Picture a rack that runs bumper to bumper if need be. I may have to revisit that idea.

The end result was I would prefer a long, narrow panel going across the vans roof. There will be no centre hatch on the roof so there will be room for three.

Basically, I've put it in the too-hard basket as I wasn't really sure how much solar I was going to need as a minimum.
I really don't know what I'm going to do about solar now and I'm not really thinking that far ahead just yet.

I was interested in how the guy had Anderson plugs all through his rig. I thought that was clever.

Cheers
Jim

[BruceS]

mmm, mould! It always creates problems & in the long term I'm not sure there is a solution.
Many years ago had a house in Melbourne that had all wooden window frames & wooden sliding windows. (up & down type)
Being Melbourne they rotted out or simply jammed for 8 months of the year.
On our houseboat (1st one & 2nd one) we did have a problem with moisture running down the windows with gas heating but since we got reverse cycle A/C all fixed.
They remove moisture from the air.
In your case the moisture can't get thru the aluminium. It actually gets the moisture from inside the van and it condenses on the underside of the sheet.
Somehow you need to reduce the amount of moisture inside the van.
There are canisters of moisture absorbing crystals here in SA at Cheap As Chips that suck the moisture up.
I wonder if Kitty Litter will do the same?
Not sure there is an easy answer.
I'd hate to think the moisture on yours is now hidden behind the polystyrene?
We had styrene in the roof of the Civilian until I got fed up with the squeeking!!! Changed it to Pink Batts.