bifacial panel production from the backside

[moonlight23]

These ZnShine 540W bifacial panels produces an astonishing 540w output for the size. Initially I assumed that this included the backside and ideal conditions, like properly mounting it a couple feet off the ground and snow or white surface. But from looking at the datasheet, it looks like this number is the FRONT face only. Factoring in the backside, it can be boosted up to 675w! Am I missing something or is this just marketing?

I have limited roof area, so I'm considering buying these panels for the front side only, even if it costs a little more than mono panels. Otherwise, can someone recommend another brand or panel that has high output for the size?

 

[Danke]

Do you have a flat roof?

 

[sunshine_eggo]

At 2.6m^2, it's not astonishing. It's typical for a modern efficient panel. Any panel with an efficiency of 20-21% will have the same performance/m^2 with the exception of the frame area.

Bifacial can see a 30% boost, but this is only in highly reflective environments (water or snow) with panels at a steep tilt. Bifacial mounted flat to a roof surface will need no benefit from the back side.

 

[moonlight23]

Ok, you're absolutely correct. I calculated the square inches per watt, and it's not that amazing. I didn't realize the size of these were so large.

 

[MrThisIsME]

I just finished putting 4 Q-Cells 480 watt bifacial panels on a white RV roof. Anyone that has been on an RV roof can attest that is about as white can get. So far (seat of the pants) not impressed. Might be some benefit in the morning and evening when the roof is not in shade.

I do see the same as you, bifacial panels are still rated/advertised in their mono state, with the bifical state as secondary.

 

[sunshine_eggo]

I just finished putting 4 Q-Cells 480 watt bifacial panels on a white RV roof. Anyone that has been on an RV roof can attest that is about as white can get. So far (seat of the pants) not impressed. Might be some benefit in the morning and evening when the roof is not in shade.

Huh? If your panels are flat mounted to an RV roof, it doesn't matter if it's a mirror. There's no light getting under there. No way Bifacial will benefit. Heat also wipes out any performance. Summer temps drive cell temperatures way above STC, and they suffer. You should be looking at the NOCT rating when in full summer sun.

Bifacial are amazing for northern climates with steep tilts, reflective ground and cold temps. Don't expect much/any benefit in other applications.

 

[MrThisIsME]

Huh? If your panels are flat mounted to an RV roof, it doesn't matter if it's a mirror. There's no light getting under there. No way Bifacial will benefit. Heat also wipes out any performance. Summer temps drive cell temperatures way above STC, and they suffer. You should be looking at the NOCT rating when in full summer sun.

Bifacial are amazing for northern climates with steep tilts, reflective ground and cold temps. Don't expect much/any benefit in other applications.

Sorry, I failed to mention they are tilting with linear actuators up to 47 degrees.

 

[cs1234]

Bifacial are amazing for northern climates with steep tilts, reflective ground and cold temps. Don't expect much/any benefit in other applications.

Nice to have something for everybody.

 

[sunshine_eggo]

Sorry, I failed to mention they are tilting with linear actuators up to 47 degrees.

That helps. ambient over 77°F? If so, cell temps are likely 45-50°C and the back of the panel is already radiating heat from the front side to give much benefit from reflected light/heat.

 

[HRTKD]

Sorry, I failed to mention they are tilting with linear actuators up to 47 degrees.

The last I check the spec on mounting of bifacial panels is that they need to be 1 meter above the reflective surface, regardless of the tilt.

There are some bifacial panels that are transparent. I read about this in passing, I have no further familiarity with them. I didn't comment earlier because I thought the panels you're looking might be that type.

My opinion: On an RV, bifacial is a waste of money and effort.

 

[MrThisIsME]

The last I check the spec on mounting of bifacial panels is that they need to be 1 meter above the reflective surface, regardless of the tilt.

Think I read the same thing and it would make sense. Although (seat of the pants and no scientific data), I do think the reflection from the side (morning and afternoon) has a slight increase.

My opinion: On an RV, bifacial is a waste of money and effort.

I would tend to agree. I went with the bifacial as it was the only ~480W panel I could source locally. Another factor to make them less attractive to RVers is the added weight. Crucial in an RV setting.

 

[HRTKD]

I would tend to agree. I went with the bifacial as it was the only ~480W panel I could source locally. Another factor to make them less attractive to RVers is the added weight. Crucial in an RV setting.

Weight is definitely an issue. If things get any worse in my RV trailer, I'm going to have to upgrade the axles from 5200 lbs to 6k or 7k. Or, just get a different trailer.

 

[MrThisIsME]

Weight is definitely an issue. If things get any worse in my RV trailer, I'm going to have to upgrade the axles from 5200 lbs to 6k or 7k. Or, just get a different trailer.

Unfortunately upgrading the axles technically gives you more capacity, not legally.

They say 80% of the RVs out there are overweight even more so when the tanks are full. Time will tell when the government (unfortunately) steps in and mandates more real world specifications.

 

[SunIsFree]

Is there any benefit with bifacials on a car port (close to a white wall)? (I mean when the panels are the roof)

 

[ArtDeco]

Is there any benefit with bifacials on a car port (close to a white wall)? (I mean when the panels are the roof)

Considering this double sided panels over reflective gravel patio or parking space that can be empty at peak sun hours.

 

[ArtDeco]

I should say will probably will be empty during peak sun hours. But probably no benefit if people or cars are under there. What do they use for big commercial parking lots?

 

[HRTKD]

I should say will probably will be empty during peak sun hours. But probably no benefit if people or cars are under there. What do they use for big commercial parking lots?

I would bet that they aren't using bifacial panels on a parking lot. When it's empty and the parking lot is asphalt, it won't do any good.

 

[SunIsFree]

They are being used like that, but I haven't found any article with actual numbers.