About those cheap "120 watt, 21 volt" flex panels.

[rickst29]

I just ordered another one ($94 shipped price on Ebay), and took some measurements on a cloudless day (April 1, too early in the year).

The Ebay specifications are V(oc) = 23.0V, I(sc) = 6.1A, V(mp) = 21.0V, I(mp) = 6.66A. Without taking my MPPT controller off the trailer and putting a load on it, I simply measured V(oc) and I(sc) at 1 PM, PST. The panel was flat on the ground, at a poor angle - and still has the protective film in place, pending installation on the TM. I got V(oc)=21.7V, I(sc) 5.2A.

If I apply a "SWAG factor" of presuming V(mp) Voltage to fall by 2.0 volts, but I(mp) current to rise by about 10%, I get a SWAG of 19.7 V(mp) with 5.7 Amps(mp). That SWAG is over 110 watts, with the protective film still attached. My temperatures were low, and I live at high altitude (those are favorable factors) - but I have no doubt that this panel would reach or exceed 120 Watts in standard test conditions. The white backing sheet is also pretty thick, compared to most flex panels. I like it, and they're super cheap!

https://www.ebay.com/itm/120W-A-Class-Semi-Flexible-Solar-Panel-120Watt-21V-Battery-Charger-For-RV-Boat/113874832993

[tentcamper]

Nice find. Last year I put a 160w flexible panel on the TM. It was about $185. You found a much better deal $/W. I think when I installed it flat on the roof I was getting about 8.x amps, or somewhere between 120-130 watts. This was up in ohio where the sun is a greater angle.

Thanks for sharing. I have been thinking about adding about 300 watts of panels to our MH.

Size; If the specs are correct they should be about 47" x 21". Is that correct.

[rickst29]

Nice find. Last year I put a 160w flexible panel on the TM. It was about $185. You found a much better deal $/W. I think when I installed it flat on the roof I was getting about 8.x amps, or somewhere between 120-130 watts. This was up in ohio where the sun is a greater angle.

Thanks for sharing. I have been thinking about adding about 300 watts of panels to out MH.

Size; If the specs are correct they should be about 47" x 21". Is that correct.
You also found a great price, Renogy wants $299 for theirs (regular price without a sale). On these little ones, specifications are also correct WRT size, roughly 46-1/2" long by 21" wide.

[tentcamper]

Ihad bought the ECO-Worthy Panel. SITE (https://www.eco-worthy.com/collections/flexible-solar-panel/products/160-watts-semi-flexible-solar-panel-for-rv-boat-battery-charging)

I had originally bought their portable 80W panel about 6 years ago. Held up well, so figured when I wanted to install a permanent one last year the quality would be okay.