✅How much power is lost with solar panel placed INSIDE cars windshield?

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Well-known member
Jul 7, 2012
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I am charging my Ecoflow Delta 1300 “solar generator” with two 100 W panels mounted on the top of my Toyota Sienna minivan. I would like to add more solar so I was thinking about buying a 100 watt (or more) FOLDING solar panel.


1) How much power will I lose if I place the folding panel on my car‘s dashboard against the INSIDE of my windshield? Let’s say in ideal conditions I’m getting 65 watts from the 100 watt folding panel when it’s outside, then how many watts would the same panel produce on the same day placed at the same angle when it is INSIDE my front windsheild?

2) I would still have the two 100 watt panels charging the Ecoflow while using the folding panel. Ideally I would use a short MC4 “Y” adapter that is always plugged into the Ecoflow solar generator so the fixed panels on the roof are always connected and would enable me to quickly connect and disconnect the folding panels. Does that kind of MC4 connector exist? Is that how you would do this?

#1 about 50%............STERNWAKE ....a geeky former member wrote about his test of this............

#2 will the panels "play" nice together......what are the outputs ?.....mixing panels on one CC is a problem...the Ecoflow has a built-in MPPT CC
Panels will utilize any light available to produce SOME electricity. If the windows are tinted, it drops of course. High temperature, it drops. The angle of the light affects output. Even outside panels produce fluctuating voltage depending on all these factors.

At work, I park inside a garage, and at my spot, there is an LED lamp directly above my 100 Watt solar panel, on the van roof. The controller shows 6 Volts coming in to the battery from the panel. In an enclosed garage.

So yes, the panel will take in any available light, but don't expect much.
It will certainly will not produce as much as the outside panels in direct sunlight.
magentawave said:
What do you mean by “outputs”?
When light comes in the panel,
electricity comes out.
Output is the measured amount of electricity that comes out.
It can be bigger or smaller amount.
Thank you but I was trying to understand what abnorm was asking about outputs.
With the 200 watts of panels on the roof plus charging the Delta with my cars 12 volt port (when I figure that out!), it might be worth getting a folding panel after all. Those extra watts while parked and pointing south and away from my vehicle could make the difference between staying off grid longer vs scrambling to find a place to charge the Delta with AC. Plus, I could lay the folding panels outside for maximum wattage when I can.

Now I need to find a folding panel that’s a maximum of 26” x 54” and then figure out how to connect it to my Delta. Hopefully I can find a short a “Y” MC4 adapter.
Wow, generating power from LED lighting.. this is quite a shocking event (pun intended).  I am going to have to look into this more myself.  I mean if parking under the correct lighting can generate MORE electricity that is going to change everything!  Urban van life would be greatly enhanced if we can find street lighting that generates power to supplement our daytime power generation so battery needs would be decreased some..
I charged my luci lights successfully on my dash. The panel on the dash does have reduced output, as mentioned above.

Last RTR at the Van show & tell, there were several rigs with side mounted solar. Like the angled panels, you would want to track your solar input for max charging.
Wonder about vertical on side of van?
I would use these portable panels outside when I’m near the van to supplement the 200 watts mounted on top but I also wanted to use them inside the windshield when I’m not around so they will be locked.