Testing Gains From Bifacial Panels | Round 2

I think you’ll have to do a full day comparison to get the most accurate results. I have bifacial panels set up to run one of my campers and regular panels on another. The bifacial panels start charging earlier in the morning and continue later in the evening.

Several reasons for the low additional gains of the bifacial panels: 1. Your mounts provide shading 2. The ground under and behind the panels doesn‘t provide a high albedo 3. The most important reason is, your panels are already maxed out by the direct sunlight. They are in their steady state under the given conditions and can‘t generate much more because of the temperature they reach. They are 395 Wp which would mean about 1580 Wh of Energy in 2 hours IF they could sustain that for the whole time, which they can’t due to heating up. The maximum sustained power is usually around 90% of the peak power with moderate air temperature. That would give you about 1422 Wh in 2 hours which is pretty darn close to your results. Bifacial panels can not shine, when the front side can already max out their long term power cap.

Yes, please test them in overcast conditions!

For me the big advantage that bifacial panels is that they can be used in vertical east-west orientation. This is the gamechanges since they can now be used for fences in roads and in agriculture. Unfortunately the backside only has 60% the peak capacity of the front side. Hopefully it will eventually get to 100%. And that would mean that a bifacial panel in vertical east-west orientation will be able to produce close to 90% of what a monofacial panel with angled south orientation would have. Furthermore east-west orientation will definitely help with the duck curves we are seeing all over the world.

Bifacial is going to give you much more benefit if you test it for a full day. Of course, during the two hours when the sun is just burning down on that south side, you won't see much difference, but the sun moves around in a large arc, and will sometimes hit the back of the panels directly, especially if they are angled as steeply as you have them there. That's where the bifacial factor will come into play.

I see the same issue over and over again - the ground mounts that are not optimized for bifacial gain are used in majority of cases. The transverse bar is shadowing through the whole width of the panel greatly reduces the gain. Try to put a beam accross the panel on the front side to see the equivalent effect of shading. It is true that the backside light is much more diffuse, but still the mounts are waay suboptimal.

Ive never had a monofacial panel hit 100% of its rated output, ehile ive never had a bifacial not hit at least 10% over its max output rating. I also use them on the brightmount arrays 5 feet in the air

Love doing the DIY projects and especially the projects you've been doing. 👍👍

You need something to reflect light behind those panels like white rocks or reflective material to get actual gains

Scott, I have one of those power meters( actually several). I have found them to be terribly inaccurate in both low current and high current conditions. One of them doesn’t show any current until it exceeds 2 amps! Just suggest you test them and get a feel for their accuracy. Love your channel.

EG4 now has an extension kit for the Brightmount rack kit. It adds 5 inches to the length and is fairly inexpensive at about $12 US. I've used it to get my four 44.6" Bifacials mounted.

Good test, I was expecting more on this one. I read about a test with bifacials and height. They need a minimum height raised off the ground to hit that max gain. I believe it was like 6 feet so like a full commercial rack would do it. I built a similar temporary base for my Brightmounts but I used 4x6's. Also due to the location requirement I didn't connect the two halves together in the middle so each rack is a two panel rack.

I think you made a good, crucial point about the performance in all conditions(sunny, partial sunny, all clouds). What is the difference then? Also, I think a long term test, say a whole week, would be good and might yield better gains for the bi-facial panels. Also, as a few of us have said, a vertical East-West setup.

Diy, roof mount on a large pole barn, grid tied, but big enough to reach a zero power bill minus service fees and battery backup for atleast a few days. I've been interested in the qcell bifacial 480w panels and the (i think its called) eg4 pro system. Little fuzzy on the exact name of it but its the grey and black all in one system. Worst part of the setup is about a 200ft run from the roof of the pole barn to the house where the inverter and attery setup would be.

Can you test and compare the energy production by placing various materials beneath it to reflect sunlight onto its rear side? Materials such as white-painted sheet, aluminum-painted sheet, aluminum foil, mirror, etc.? It would be great if you could set up the panel at least 5 feet above the ground.

6:08 RuttRo - It’s ok, at least for now bifacial is the way to go on ground mount. The EG4 Bright mount is great, I have two of them. Kinda curious about the width issue. 45” would be better, they offer a 6” extension kit too.

have you ever tried using a light guide to direct the sunlight directly from the sun at the bottom of the panels? in such a way that both the sides of panel are LIT properly?

The white tape on top of the blue tape is still not enough. When the camera is behind the panels, you can still see right through that white and blue tape. I can clearly see the grid. Cover it with black tape. Fully block out any light coming through.

I only have the EcoFlow Bifacial panels. Did not really see much of a gain on sunny days. I mainly use them at the beach where the sun can reflect some from the sand. At most I got about 200 watts out of the panel. If any advantage to my bifacial panel is that on cloudy days it produced 22 more watts over my 160 watt panel. Don't know if it is because the bifacial is a 220 watt panel. Regardless it was enough to maintain my 12V fridge over 4 days in cloudy conditions running. I might have run out of battery power had I only used my 160 watt panel by the 3rd day.

I wonder how well a white background behind bifacial would work.