LG Bifacial pricing? And other questions....

wankel7 · November 2019

I'm looking at the LG 400w bifacial panels. They are supposedly the same panels. The only difference is the panel ending in AUS was made in the USA. Any guesses on why the US made panel is more expensive? The pricing is from platt.com.

LG400N2T-J5 $341
LG400N2T-J5.AUS $381

I'm getting one panel for my van and plan on being able to tilt it. I'm curious how rigid these large panels are. If you carefully lift one corner of the panel does it flex a lot?

My plan was to mount this length wise on two cross bars on my roof rack. It's a large van... Promaster.

BB. · November 2019

Panel pricing--Assuming the panels are otherwise identical (Vmp/Imp/Warranty)... Sometimes you find that local manufacturing is more expensive, but still available/sold for government related purchasing and/or local subsidies.

Purchasing the cheaper panels should be fine. Check that you don't have other issues (like availability/shipping costs/etc.) to your home/where you would be picking up the panels.

This large format solar panels are frequently very expensive to ship just a couple and can be more than the panel's retail price (repackaging, special shipping via truck or similar) because they are so large and fragile. In many cases, the shipping cost of a full pallet of panels is much cheaper than shipping for one panel.

-Bill

icarus · November 2019

What possible advantage is there to bi-facial panels installed on a van top? I suppose if you have a white van, and install them with significant air to get some reflected light below? Other than that does the added cost make any sense?

tony

Horsefly · November 2019

I know it's a bit off topic, but... I know nothing about these bifacial panels. I googled a bit, but still have a question. How are they rated? I understand STC ratings for normal panels, which is based on 1000 Watts per square meter irradiation. Since a bifacial panel has no advantage (I assume) unless the backside is illuminated as well, is there a standard expression of the rear illumination? Is there a separate STC for bifacial?

EDIT: Ok, I looked further down my Google results, and found this: https://pvpmc.sandia.gov/pv-research/bifacial-pv-project/bifacial-pv-characterization-and-rating-standards/

Sounds like Sandia labs (and the International Electrotechnical Commission) are actually still struggling with this question, or at least where when this page was posted.

Dave Angelini · November 2019

For commercial bifacial has been proven to make sense financially. Quite a few of my installer buds are doing large installs.
For offgrid it really is a labor of love. They are beautiful and if the price is right, why not?
A few more "normal" panels would easily outperform and since we design for winter offgrid it really is a nice thing to have.
You can't take it with you right?

bill von novak · November 2019

Horsefly said:

I know it's a bit off topic, but... I know nothing about these bifacial panels. I googled a bit, but still have a question. How are they rated? I understand STC ratings for normal panels, which is based on 1000 Watts per square meter irradiation. Since a bifacial panel has no advantage (I assume) unless the backside is illuminated as well, is there a standard expression of the rear illumination? Is there a separate STC for bifacial?

There's no standard because there's no standard height they are mounted at, or stanard surface they are mounted over. Most datasheets give performance at 5%-10%-15%-20% reflection, which is about as good as you are going to do. All datasheets give STC power for front illumination only.

Dave Angelini · November 2019

There are decent theoreticals that you can model. The other major unknown, that can be dealt with is the shading on the back-side from the rails, wiring, and module orientation. It is being done on a very large scale in the last 3 years. Good data for an investor from some very talented engineers.

wankel7 · November 2019

icarus said:

What possible advantage is there to bi-facial panels installed on a van top? I suppose if you have a white van, and install them with significant air to get some reflected light below? Other than that does the added cost make any sense?

tony

I presently have two 200 watt panels in series that I am less than impressed with and want to try something else. The panels I initially looked at to replace them was four 100w Renogy Eclipse panels that I would wire 4S. They are a little pricey at $167 but claim 22 percent efficiency. So, that puts me at almost $700.

Then I found the bifacial panel which would be around $600 shipped and weighs 15 lbs less. The panel will be about 6 inches above the white van roof and I will be able to tilt it....so I am hoping there will be some bifacial advantage there.

BB. · November 2019

Remember that panel efficiency does not affect your harvest (a 200 watt 17% and a 200 watt 22% panel harvest the same amount of energy from equal amounts of sunlight).

What it does do is make the panel size (x by y dimensions) smaller--So you can either have a smaller panel or fit more wattage in a confined space (good for RVs and such).

But many times, these are just marketing numbers... Many list "cell efficiency" not overall panel efficiency. Spaces between cells, frame, margins, etc.) are all "blank space" that do not collect any energy... So actual cell efficiency does not tell you as much as total panel efficiency.

Which only matters if you like the looks of the panels or want more harvest from a confined space.

-Bill

wankel7 · November 2019

BB. said:

Remember that panel efficiency does not affect your harvest (a 200 watt 17% and a 200 watt 22% panel harvest the same amount of energy from equal amounts of sunlight).

What it does do is make the panel size (x by y dimensions) smaller--So you can either have a smaller panel or fit more wattage in a confined space (good for RVs and such).

But many times, these are just marketing numbers... Many list "cell efficiency" not overall panel efficiency. Spaces between cells, frame, margins, etc.) are all "blank space" that do not collect any energy... So actual cell efficiency does not tell you as much as total panel efficiency.

Which only matters if you like the looks of the panels or want more harvest from a confined space.

-Bill

Back to solar 101 for me Bill. Thank you for pointing out what I was missing. Renogy doesn't seem to clearly publish module efficiency.... Only cell efficiency..... I'm guessing that is because they aren't proud of it....

BB. · November 2019

Cell efficiency is a big "marketing number" that is used to advertise their engineering prowess. And what that is the "number" you see in literature on solar cell development.

The efficiency of the whole panel is a lower value and not near as "sexy". (17% cell installed into a 12% panel when all the "blank space" is taken into account (i.e., 17% leading edge tech vs humdrum 12% panel--But both are true).

-Bill

Dave Angelini · November 2019

For an RV you really need max output per square foot. Just as important is how it will deal with vibration and shock. The third would be can you easily get warranty which may not be possible on an RV.

The big panel from Renogy would not be a good choice in my opinion. I sell 330w panasonic out of New York for my trackers because of all the reasons above for my clients trackers. A great choice on the used market is the old 330w Sunpower E20 series. Buy an extra for a spare.

LG Bifacial pricing? And other questions....

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