G'day everyone,

I ordered one of these Sunmaxx solar blankets (see below) to boost the power going into a couple of 110AH batteries. Currently only have the one 170Watt roof mounted panel. Anyway the panel arrived a couple of days ago and I had a go at hooking it up to the van, utilising the the second solar input on the BMPRO35. Without the 300Watt panel connected the input solar amps showed 6.2. After connecting the 300Watt panel it showed 9.4 Amps. When I removed the 170Watt panel connection, the amps dropped to 2.8 Amps. So basically, this 300watt blanket is providing less than half of the 170watt panel.

So out with the multi-meter and I get the following:

170Watt Panel: 21.2 Volts @ 6.2 Amps  which I guess means I'm getting around 131 Watts (which I guess is reasonable)

300Watt Panel: 20.4 Volts @ 2.9 Amps which would be around 59 Watts.

So I'm a little disappointed with what I'm seeing. I'm currently in email conversation with Sunmaxx to see what they say.

Just wondering if anyone has had any experience with Sunmaxx and whether its been good or bad?

Regards Paul.

https://sunmaxx.com.au/collections/solar-blanket/products/300w-solar-blanket-kit-t

There is a basic dimensional error of packed size in relation to open size on their website so I wouldn't have bought it from that point alone.

Since you have it have you calculated the actual surface area & multiplied that by let's say 0.15 (150 watts per square metre).

Just worked out the surface area.... its 1.716 square meters. So if we multiply by 150 watts we get 257, which is reasonable (its not 300, but its better than 59).

Is it absolutely square to the sun, elevated so it stays cool, is it perfect weather, not a single tiny section anywhere that has a shadow?

Well it was pretty close to being directly at the sun. It would have been more directed at the sun than the 170watt panel on the van roof would have been.

Well I managed to get a refund for this blanket and Sunmaxx let me keep the faulty one. They have removed these blankets from sale. So since I had the blanket I thought i'd just do some more testing on in (i.e. cutting slits in the material between each panel to expose the connecting wires). It is basically just 8 panels connected in parallel. I was hoping that there was just a loose connection that was disconnecting a few of the panels, but my measurements were as follows:

Cell # Volts Amps Watts
1       20.8   0.27   5.616
2       0        0         0
3       20.56 0.38   7.8128
4       20.1   0.31   6.231
5       19.8   0.49   9.702
6       19.96 0.4     7.984
7       19.95 0.33   6.5835
8       19.93 0.27   5.3811

Total 20.05 2.45   49.1225


For this to be a 300Watt blanket I would expect to be seeing around 1.8 - 1.9 Amps @ 20.05V for each cell.

Must give Sunmaxx credit that they were quick to respond and try to help and did not mess around with a refund.

From the web site ...

max power voltage = 17.4V

max power current = 16.66A

The max power is then 290W.

The surface area (not allowing for borders) is 2130mm x 675mm = 1.438 sq m

At 160W per sq m, that's an output of 230W.

The panel would have to have an efficiency of 20% to produce 290W from 1.44 sq m.

Here is their 250W panel:

https://sunmaxx.com.au/products/250w-solar-blanket-kit-t2

1270mm x 720mm = 0.914 sq m

That corresponds to an output of 273W / sq m, which implies an efficiency of 27%.

Clearly that's bogus.

Personally, I would avoid this supplier.

Another one ...

https://sunmaxx.com.au/products/sunmaxx-100w-fixed-solar-panel

max wattage = 100W

max power current = 5.11A

max power voltage = 16.5V

Therefore the max power wattage is 5.11A x 16.5V = 84.3W

Area = 640mm x 680mm = 0.435 sq m

Efficiency = 84.3 / 0.435 = 193W / sq m = 19%

This panel is claimed to produce 200W from 1350mm x 540mm:

https://sunmaxx.com.au/products/200w-folding-solar-panel-kit-t

That's an efficiency of 27.4%.

pghollis wrote:

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Cell # Volts Amps Watts
1       20.8   0.27   5.616
2       0        0         0
3       20.56 0.38   7.8128
4       20.1   0.31   6.231
5       19.8   0.49   9.702
6       19.96 0.4     7.984
7       19.95 0.33   6.5835
8       19.93 0.27   5.3811

Total 20.05 2.45   49.1225

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 These panels are all over the place from terrible to abysmal, & on top of it 1 doesn't work. Even the best panel x 8 would only be 77 watts.

Since you got a refund quickly. I would let them know what you found. It may help them with their supplier.

If you have a bit more space or have a space that a solar panel has to fit in why don't you knock up your own portable unit. It's not difficult & you get exactly why you want.

That's what I did & it works brilliantly.

https://thegreynomads.activeboard.com/t65231112/custom-6x20-watts-solar-setup-with-mppt/

The blanket you tested is almost identical to the Maxpro brand marketed by Outbax and through Catch. I bought a so-called 250watt blanket. On testing it was more like 120watt at best. Returned it and got a refund.

orid wrote:

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I purchase a 200 watt blanket from Bcf. Good quality .Puts out 11 amps through my dc to dc charger . In case this helps

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Hi orid 

Thanks for the info ! Just a comment and not to be critical. That 11A is well short of 200W !   

11A x 14V (to be generous) is only 154W. 

My suggestion is to just get some real panels and make up something that works as it should and for much less cost. 

Jaahn 

I don't get it why people willingly accept that solar panels under perform, but with other products they scream blue murder if it not up to scratch.

If anything, one is in the middle of nowhere, you have calculated your requirements & a solid margin, & one burdens oneself with crap solar panels.

Do it right once!

orid wrote:

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The make wasXTM. $359 Regards Orid

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If you mean this $360 panel, there is virtually no product info. I wouldn't have bought it without further clarification.

https://www.bcf.com.au/p/xtm-200w-folding-solar-blanket/578269.html

Can you tell us the dimensions of each panel?