Solar Panel Half Cell Discussion

[CA_Traveler]

Half Cell or Half Panels are ramping up production and I wanted to know how they work and are they suitable for a RV. I'm not an expert but this is what I found. Lots of sites have the basic half cell marketing information, more power, better shade tolerance, higher cost, pros and cons, etc. I found the link below that has excellent information and comparison of full cell and half cell panels and is the basis for this post using 72 full cell and 144 half cell panels.

https://www.youtube.com/watch?v=AZ8VQ_zmf1M&t=34s
This link also contains excellent graphics on how full cell panels operate in the shade with bypass diodes.

Based on my understanding of the above link the Half Cell panels require a new MPPT controller that can detect 2 power points - The Global Power Point and the Local Power Point and is based on the 5A half cell amp rating and the higher voltage associated with twice the number of cells in the panel and the unique cell layout. Increased shade power is dependent on the type of shade and the panel orientation to the shade. Shade may also reduce the power available for series panels as shown at time 8:30 to 10:00 in the link. 10:15 strongly suggests that heavy uniform shading like a solar farm is needed for half cut cell performance improvement. ie All modules need to be similarly shaded in the lower half on any given row (series string).

My take is that half cell series panels (with the new MPPT controller) are more likely to be a disadvantage for the typical RV due to the unique shade and shade orientation required for more shade power vs the full cell panels. Plus no doubt the new MPPT with additional power point cost.

What's your take on the video?

[CA_Traveler]

Those panels are very efficient with low light. 92% @ 100 Wm2. Combined wiith the very efficient Victron MPPT contorller the output would be the same as a similar panel with full cut cells.

Half cut panels are designed to work to improve performance with a unique shadow pattern of larger grid arrays and a contoller that operates with both power points. But if starting over I'd look hard at the same panels and the Victron controllerl

[StirCrazy]

TechWriter wrote:

CA Traveler wrote:
My take is that half cell series panels (with the new MPPT controller) are more likely to be a disadvantage for the typical RV due to the unique shade and shade orientation required for more shade power vs the full cell panels.

This has not been my experience with half cells (aka half panels, half cuts, . . .).

I finished my 4th RV solar install about a year ago, and had several months to test them, both in shaded storage and on the road.

My three REC N-peak 2 365W 120 half-cut cell PV panels have been performing far better than any other panel and setup I've used, especially in the shade.

However, to be fair I think much of that improvement has to do with my Victron equipment, especially my Victron MPPT controller.

naw, it's not the Victron, it's the panels and the fact it's an MPPT controller. I get the same type of effect with my renogy and 325watt split cell panel when comparing it to my 5th wheel. I have a 480-watt PWM 12V panel setup on the 5th and the 325-watt split cell MPPT puts out more charge amps.

Steve

[pianotuna]

TechWriter,


Victron is first class. I'm glad to hear it is working well for you.

[TechWriter]

CA Traveler wrote:
My take is that half cell series panels (with the new MPPT controller) are more likely to be a disadvantage for the typical RV due to the unique shade and shade orientation required for more shade power vs the full cell panels.

This has not been my experience with half cells (aka half panels, half cuts, . . .).

I finished my 4th RV solar install about a year ago, and had several months to test them, both in shaded storage and on the road.

My three REC N-peak 2 365W 120 half-cut cell PV panels have been performing far better than any other panel and setup I've used, especially in the shade.

However, to be fair I think much of that improvement has to do with my Victron equipment, especially my Victron MPPT controller.

[pianotuna]

Hi CA Traveler,

My panels have diodes between each cell. Unfortunately they are no longer made. (Unisolar US-60) They also do not have any glass.

I chose series/parallel for an input voltage to a BlueSky MPPT controller of 33 volts.

There is one German company that does make panels with diodes between each cell. Unfortunately they never replied to my query about purchasing from them.

If I were starting out, I'd look carefully at these;

https://www.amazon.ca/Flexible-Panels-Efficiency-Charger-Accessori/dp/B0C8J69YBK/ref=asc_df_B0C8J69Y...

[StirCrazy]

CA Traveler wrote:
Did a search for solar controllers for half cell panels and came up empty. Anyone found one? ie A controller for 2 power point tracking capability which a MPPT does not have.

Regardless I still believe that these panels are only suited for the unique shade patterns available on a solar farm and not on a RV. But it's a learning process...

The only thing I have seen is dual channel mppt controllers, which allow you to have two different arrays with different azimuths run through one controller.

[CA_Traveler]

Did a search for solar controllers for half cell panels and came up empty. Anyone found one? ie A controller for 2 power point tracking capability which a MPPT does not have.

Regardless I still believe that these panels are only suited for the unique shade patterns available on a solar farm and not on a RV. But it's a learning process...

[CA_Traveler]

Series panels is likely a non starter (for RVs) for half cell panels because all series panels need to have the same amps to maximize power. All series strings in a series/parallel setup strings need to have the same voltage to maximize power. Of course there is a shadow pattern where this will happen but is this effective? Full cell parallel panel strings also have to have the same voltage on each series string to maximize power.

ie For series panels identical amps is a primary consideration and for parallel panels identical voltage is a primary consideration.

Updated

[CA_Traveler]

The video starting at 8:26 shows a panel with the lower half shaded and in series with other modules, hence this panel cannot be used since it can only produce 5A. So the bypass diodes kick in resulting in 3*0.6 voltage loss for that panel with the other panels producing 10A at their voltage. The video goes on to state that all of the panels must have the lower half shaded which results in 5A at 2X the voltage. In this case the full power for one panel is loss.

If the shading results in the one panel producing 10A at 1/3 or 2/3 of the voltage then the total power is equivalent to full cell panels. The video suggests that the half cell advantage only occurs when all lower panels are covered in shade and shows this with a large array of panels. Or perhaps a roof shadow from a neighbors house.

Prices and availability of half cell panels and Global MPPT controllers will improve but improved power for a RV environment seem questionable to me and there may even be less power than for full cell panels in which case best to use full cell panels. This is my take on this excellent video and I started this thread to learn more. In other words looking beyond the marketing hype for half cell panels how do they work in other common environments and are they better options for your environment?

As I drive around I see panels over parking lots and tops of building where tilted solar panels are more closely spaced for more panels and subject to the type of shadows that benefit the half cell technology.

[StirCrazy]

CA Traveler wrote:

My take is that the split cell panels and new MPPT controller will cost more and produce lower shade power for series panels for the RV environment. Parallel panel power will have no improvement vs the full cell environment.

ahh, I see, I missed it. The panels are nothing new, but it is the controller that is new. I was just trying to search, and I don't see any dual peek MPPT controllers for sale, so personally I am not going to worry about it until they are for sale.

What I do see though, is it shouldn't be too much more than the cost for a normal MPPT once all the other companies start doing it. If it isn't too much more (probably still be cheaper than a PWM Victron 😉 ) I defiantly will get one as it looks like it will help quite a bit in partial shading. I think this would be more of a fit for rv's with fixed panels than residential as normally when you set up a residential solar array it is in a clearing or on the roof with no obstructions. I guess int he case where the neighbor has lots of tall trees it would help also...

I missed the part about series parallel, that's a tricky one.. the video only takes about 1 panel but even in series I think it might help, my reason being if the normal one shuts down the bypass and only delivers 5 ish volts through for example then you are only adding 10 volts to the next panel in series so let's pick 28V as a full output and two in series that would give you 33v. but if you have this "new MPPT" then the first panel will give you let's say 18V (I'm making up the numbers so don't quote me) so that would give you 46V total. if I am thinking right, I'll have to do some more reading yet, but these should be great for campers who are in partial shade depending on the time of day.

[CA_Traveler]

The terminology may be confusing. From the video the new MPPT controller is referred to as "Global Maximum Tracking" MPPT. The "Local MPP" power point is the same as for the full cell power point and the "Global MPP" is associated with the half cell amps and 2x voltage for 2 cells.

[CA_Traveler]

Steve, I've seen similar results with MPPT, with leafy shade and panel voltage at 20V, ramping up in 10V increments to 90V due to the bypass diodes and serial panel connection. I've captured this data and posted it online in the past.

The video compares a given cell technology configured as a full cell or cut in half for 2 cells. My take is that half cell panels require a unique shade pattern (not likely for a RV IMHO) and a new MPPT controller that detects 2 power points unlike most current MPPT controllers that detect a single power point.

My take is that the split cell panels and new MPPT controller will cost more and produce lower shade power for series panels for the RV environment. Parallel panel power will have no improvement vs the full cell environment.

[StirCrazy]

CA Traveler wrote:
Half Cell or Half Panels are ramping up production and I wanted to know how they work and are they suitable for a RV. I'm not an expert but this is what I found. Lots of sites have the basic half cell marketing information, more power, better shade tolerance, higher cost, pros and cons, etc. I found the link below that has excellent information and comparison of full cell and half cell panels and is the basis for this post using 72 full cell and 144 half cell panels.

https://www.youtube.com/watch?v=AZ8VQ_zmf1M&t=34s
This link also contains excellent graphics on how full cell panels operate in the shade with bypass diodes.

Based on my understanding of the above link the Half Cell panels require a new MPPT controller that can detect 2 power points - The Global Power Point and the Local Power Point and is based on the 5A half cell amp rating and the higher voltage associated with twice the number of cells in the panel and the unique cell layout. Increased shade power is dependent on the type of shade and the panel orientation to the shade. Shade may also reduce the power available for series panels as shown at time 8:30 to 10:00 in the link. 10:15 strongly suggests that heavy uniform shading like a solar farm is needed for half cut cell performance improvement. ie All modules need to be similarly shaded in the lower half on any given row (series string).

My take is that half cell series panels (with the new MPPT controller) are more likely to be a disadvantage for the typical RV due to the unique shade and shade orientation required for more shade power vs the full cell panels. Plus no doubt the new MPPT with additional power point cost.

What's your take on the video?

This is nothing new, I have been using a 24V 325W 120 split cell (or half-cell depending on the company) panel for three years now on my camper. Yes, they are more efficient and do much better in low light and shade. to give you an example of the improvements in efficiency I got, my 5th wheel has a 12V 480W solar set up run off a PWM controller and the best ever see is 21 Amps of charging, where as my MPPT with the 325watt split cell set up routinely gives me 22 to 23 amps in the middle of the afternoon. I also get more charging power in the early morning and lait at night. in the 5th wheel it's not uncommon for me to have to wait till 8:30 to 9 am before charging registers, the camper with the split cell will be putting out 0.2 amps at 6am and you can watch it rise as it gets brighter out. shading I can't speak on with technical data as I don't measure the panels as I observe the shadows, but I take the camper to mostly partial shaded sites in the middle of the forest and I have never had an issue charging. I am also looking into replacing the panels on the 5th wheel with similar panels and a better controler to improve their performance.

Steve

[pianotuna]

Hi CA Traveler,

Nice find on the video.

The controller should lock onto what they are calling the Global MPP.

individual string on each panel would be better, but I've not seen any that are not for grid tied installations. (I've not looked for a couple of years).