Solar panel realities experiment.

[AussieMick]

Just to show a true reality what to expect from a solar panel/ blanket.

I have put out 2 solar blankets in the direct summer sun .
One is 200w and the other is 150w, so combined 350w feeding into a redarc mppt controller.

Temperature is around 30c , we can see by the screenshot I am not generating 350w.

I can generate more solar input on a sunny day but the temperature cooler as once the panels heat up efficiently drops.

The reason I have done this little experiment is to show you rarely get the wattage output stated for your panels even in nice sunny conditions. So if calculating the size of panel/s to run your electrical system in your van it pays to upsize the panel/s

Screenshot shows 350w of panels generating 18.52 amps and 251watts.in pretty good conditions but perhaps a bit too warm.

 

[Grim Reaper]

Yeah, solar panels do suffer from the sun (ironic really)
I forsee water cooled solar panels being the norm for warm climates.

DualSun SPRING

DualSun designs and manufactures the world’s first certified hybrid solar panel (PVT): the SPRING 2-in-1 panel.

dualsun.com

Enhancing the performance of photovoltaic panels by water cooling

The objective of the research is to minimize the amount of water and electrical energy needed for cooling of the solar panels, especially in hot arid …

www.sciencedirect.com

 

[Dellmassive]

nice test . . .

also consider that you battery bank is showing 98% Full.

if you battery bank was 100% full you would show 0watts.

to show solar power on the Victron meter, the power has to go somewhere - like into charging the battery.

if the battery is full or nearly full then no power will flow or shown on the APP.

i get a lot of questions about this . .

Like - "I've just added 160w of solar to my dc-dc system and its not working" the reason is always the battery is already full from the dc-dc charging.


i always suggest people drop the battery bank down to below 80% and repeat the test.

 

[Dellmassive]

also consider that Solar PV panels are "rated" at there official "Test" conditions.


like this example:

its rated at:

100W
VOC - 22.5v
ISC - 6.18A

Standard Test conditions:

Irradiance=1000watts per meter squared

temp - 25 DegC

 

[Dellmassive]

can you post a few pics of your solar blankets and t he spec sticker?

 

[JOG]

As ever, great to have real world examples! Thanks @AussieMick

 

[AussieMick]

Hey Delmassive,
i had run my leisure battery which is a lifepo4 150ah down to about 90% and then hooked up the 2 solar blankets in parallel. It took the 18.52amps right up till full from 90%.
The screenshot was the last 5 to 10 minutes or so but being lithium it took the full charge right up till 100% then current dropped off to zero.
As you know they dont do the bulk, absorption, float profile.
The conditions were direct sun almost overhead but it was a hottish day so panels absorbed heat which probably dropped their efficiency by a bit.
Total input current is not to bad but wanted to point out the difference between rated wattage and actual performance wattage so others could calculate demand better if buying panels.
Redarc 150w blanket and Hardcore 200w blanket but details not printed on panel.

 

[Dellmassive]

i love the REDARC kit . . . i have a couple of BCDC chargers.

unfortunately only some of the kit is available in the UK.

I've seen the Solar blankets online, but not available in the UK.

You get get the LENSUN versions though.

 

[AussieMick]

Redarc gear comes from where I live in Adelaide, South Australia, so its handy for support but quite expensive. Excellent after sales back up but must admit my cheaper panels seem to work just as well.
They replaced my blanket last year 6 months out of warranty as it stopped outputting which I thought was pretty good of them.
I really rate their bcdc controllers as they work in extreme conditions and dont hear of many problems. BCDC dual controllers are fantastic, one unit does solar and altenator with a lithium profile.

 

[slocumjoseph]

Thanks @AussieMick and @Dellmassive. Noted with interest. I’ve just finished installing the Renogy 50a charger and controller in preparation for the solar power I plan to put on the poptop next month. I’ll use the Photonic Universe semi flex reverse junction box 200w panel as it’s more discreet. The fixing should be relatively simple as the roof is a flat surface, not ridged as the the original van roof. However I was concerned about heat generation, even in England and planned on using Correx directly on to the poptop surface as an air gap then Sikkaflexing the solar panel directly to that. If that’s successful and hasn’t burnt itself out I’d like to add another one when I’ve got the readdies. Perhaps then, even in the UK I can stay stealthy and off grid almost indefinitely.

 

[Dellmassive]

Thanks @AussieMick and @Dellmassive. Noted with interest. I’ve just finished installing the Renogy 50a charger and controller in preparation for the solar power I plan to put on the poptop next month. I’ll use the Photonic Universe semi flex reverse junction box 200w panel as it’s more discreet. The fixing should be relatively simple as the roof is a flat surface, not ridged as the the original van roof. However I was concerned about heat generation, even in England and planned on using Correx directly on to the poptop surface as an air gap then Sikkaflexing the solar panel directly to that. If that’s successful and hasn’t burnt itself out I’d like to add another one when I’ve got the readdies. Perhaps then, even in the UK I can stay stealthy and off grid almost indefinitely.

im not sure about that Correx idea though. - I've not seen that done before. (corex can be brittle when cold and can be torn easily)

you might be better just putting Vinyl wrap on the pop top and sticking down to that.?

 

[slocumjoseph]

I thought because it's used by sign writers and estate agents it would be weatherproof and tough enough to do the job but I'll do a bit more research before I commit Lee. Watch this space.

 

[Dellmassive]

more on T6 roof mounting here:

Solar Panel: Cutting Hole in Roof !!!

im going fit a solar panel I’ve made sure all cables and connections are under the panel. As I hate to see them. Until it arrives I don’t know how high the connections make the panel sit off the roof ! It’s a HiLow roof. Inside is unfinished. I’ve got to drill cable holes anyway. So...

www.t6forum.com

.

 

[Raul a/3]

On the other scale, here is the benefits of cooler temp, in full sun. Two panasonic HIT 295w into victron 100/50 smart. Location, south England mid July.

 

[djgriff]

Hey guys just testing my new panel with Victron 100/30 mppt . The panel is 360w but only generating 19w!? Any suggestions , or is this normal, cheers

 

[CAB]

Hey guys just testing my new panel with Victron 100/30 mppt . The panel is 360w but only generating 19w!? Any suggestions , or is this normal, cheers

View attachment 170972

View attachment 170973

Battery is full?

It's in Float?

 

[Jim Rey]

The crossbars are going across the panel. This will reduce output I think. Try taking the crossbars off

 

[djgriff]

Yep the battery looks to be 100% and in float mode, I guess what concerned me is the solar panel output of 20w when it should be a lot more considering it’s 360w and it’s blue sky sunny unless I am understanding it wrong and the 20w is what it is only using to keep in float mode? Cheers

The crossbars are going across the panel. This will reduce output I think. Try taking the crossbars off

Aah didn’t realise this would be an issue

 

[Pete C]

If the battery is full, your panels will not generate much power.
Try turning on some electrics in the van to draw current from the leisure battery, and see what happens.

You will also only get the full power if the sun is fully out, no shadows, and the panels are directly facing the sun.

Pete

 

[Dellmassive]

As above.

Battery is in full.

In float.

So nowhere for any power to go.

Turn everything on.... Run the battery down to 50% then re test.