Maxray folding solar mat

markf · Senior Member

Maxray folding solar mat

Terryt · Veteran Member

Haven't used one but I am in the same boat as you in trying to find out about them. Haven't been able to locate a review about the mats. I did drill down a fair way in the "not so stellar" reviews you talked about and they seemed to mostly relate to panels that only had 28 segments and a 14v output. They were more suited to direct connection to batteries for auto gates and pumps than charging deep cycle batteries re a regulator

Terryt · Veteran Member

In case anyone is interested my 200w Maxray solar mat just turned up. Tested it with multimeter with mat flat on the ground. No cloud, hot day about 2pm so sun was close to overhead. Not connected to any load but gave reading of 20.9 v and about 7.5 amps. The only info that came with it suggested 21.6v and did not metion the amps it would produce. On the web site I think it said about 10amps. Certainly nothing earth shattering but it seems well made and folds up quite small. Will be a lot easier to pack than my folding panel

Whenarewethere · Guru

Have you tried spraying it with water to see if you get any more capacity out of it if it is cooler.

markf · Senior Member

Terryt wrote:
Certainly nothing earth shattering but it seems well made and folds up quite small. Will be a lot easier to pack than my folding panel

Thanks for that.

That's about what I was hoping to hear. I didn't expect earth shattering but I was hoping to hear that they seem well made and packs down smallish. I'll get to it and order a 250W unit and see how I go.

markf · Senior Member

Well my 250W mat arrived today. Spread it out flat on the grass in full slightly hazy and hot sun. 22.3V open circuit. Connected it to my Victron 100/20 and it is producing between 130W and 150W.

It seems pretty well made and as TerryT says it's a LOT lighter and smaller than my 100W folding panels. I'm in agreement with TerryT - not earth shattering but given the price I reckon pretty good value.

I would suggest ditching the supplied regulator - it can only supply around 110W - 120W to the battery whereas the Victron can give it 130W - 150W.

All in all I'm pretty pleased.

Whenarewethere · Guru

I find it a bit rich that you only get 60% of 250 watts. I get 124 watts from 120 watts without trying & am getting am getting 136 to 137 watts with water. The other day I briefly got 142 watts under perfect conditions.

Have you supported the panels on some sticks angled correctly. You could knock up a simple portable frame.

markf · Senior Member

Whenarewethere wrote:
I find it a bit rich that you only get 60% of 250 watts. I get 124 watts from 120 watts without trying & am getting am getting 136 to 137 watts with water. The other day I briefly got 142 watts under perfect conditions.
Have you supported the panels on some sticks angled correctly. You could knock up a simple portable frame.

Given that the mat was laying flat on the ground and it was hazy I'm well pleased. My 100W panels under the same circumstances were only producing around 50W or less. This is measuring power going into the battery via a Victron MPPT controller

On a less hazy day with the mat at a better angle I'd expect that the results would be a LOT better.

markf · Senior Member

Well today while it wasnt hazy or anything I set the mat up at a good angle with a few bits of wood and half a dozen tent pegs and viola max 252 watts at around 1.00pm. Flat on the ground at the same time produced around 210 - 220 watts. So they seem to be the goods.

Whenarewethere · Guru

Just goes to show what a couple of sticks can do! Now you will need to design a compact foldup support system to squeeze that last watt out of them.

It would be interesting to see if you can get a bit extra will cooling.

Ron-D · Guru

I carry a 160 watt portable panel if were on 240 caravan parks it just lays under the bed ,I dont find the panel a hassle to trans port ,the Folding Matt is a great idea but constantly haveing to find the right angle to the sun with it puts me off, something just laying flat on the ground cant be a good idea can it,haveing to find a place to put a blanket at the right angle to the sun all the time could be challenging...

Whenarewethere · Guru

Ron-D wrote:
something just laying flat on the ground cant be a good idea can it

It's asking for someone to step on it. Probably oneself!

You need a perimeter frame, with internal spring cord that would snap the frame into a square & folding legs on one side to angle it to the sun. Maybe Velcro to hold on the panel on the frame. Just a few thoughts!

markf · Senior Member

Yeah messing around propping it up and getting it the right angle will be a pain should I choose to do it.

With my 100W panels I needed to do it to keep up with our power usage. If we were getting clear and strong sunlight and not too hot temps the panels could just keep up.

If I can just lay the mat out and get 120 or 150W it puts us a bit ahead of the game and going for a few days with less than ideal sunlight is now doable without needing to run the car to get the battery up a bit.

kev071 · Member

Just looking at the same mat, have you had much chance to use it? Seems like a good option for limited space.

dorian · Guru

ISTM that the claimed specs are bogus.

From the eBay site ...

Our manufacturer uses only Grade A mono cells with a high efficiency of 23%.

The maximum area is 1.270 x 0.720 square metres - 0.914 sq m.

Let's allow a loss of 5% to borders, etc, so the actual area available for collection is 0.869 sq m.

When this panel is irradiated with 1000W per sq m, it should receive 869W of incident energy.

If it produces 250W of output, then its efficiency is 250 / 869 = 28.8%.

If the cells really do have an efficiency of 23%, as claimed, then the expected output should be 869 x 0.23 = 199.9W.

If, OTOH, the cells are typical consumer grade products, then their efficiency would be more like 16% - 17%.

At 17% efficiency , the panel's output would be 869 x 0.17 = 147.8W.

Therefore ISTM that the actual measured output is more in line with a 150W panel constructed from standard grade cells.

Edit:

It just dawned on me why Maxray's name was familiar:

https://thegreynomads.activeboard.com/t66202769/stay-away-from-outbax-camping-solar-panels/

-- Edited by dorian on Thursday 11th of June 2020 10:20:20 AM

Whenarewethere · Guru

Not to detract for the useful information above.

Make sure there is not the slightest shadow over any part of a panel otherwise you will pretty much have no amps out of the panel.

If you have an inline amp meter or DC clamp meter it makes it abundantly clean how easily an setup can be brought to its knees!

Whenarewethere · Guru

My 6 panels, 120w total, are producing a bit over the manufacturer's specifications, up to 135w under perfect conditions with water cooling, but often 127w square with the sun midday in summer in Sydney on a clear day.

But looking at it from a different perspective of watts per square metre. The actual cells only cover 72.7% on the panel. So the overall foot print in not overly efficient.

My needs were a panel had to fit a certain space when stored on the roof. When open on the ground I was not worried about the efficiency per square metre.

If you have panels fixed on the roof you will want good efficient per square metre of the actual panel, not the cell as is generally stated by the manufacturer.

_MG_1837 (2).jpg

Cells moved with Photoshop 72.7% of the overall area.

_MG_1837-73percent (1).jpg