What is the most efficient solar panel (watt per square inch) on the market?

[kllcbosmetris]

What is the most efficient solar panel (watt per square inch) on the market?

If you have a limited roof space (i.e. small van) and you'd like to maximize your solar power, what is the most efficient solar panel you can use? Meaning, the smallest space it takes on the roof with the maximum solar output? 

- Do you have a brand you recommend? 
- Is there a place where you can custom order size of the panels, to maximize your roof space?
- What do you think is the max I can put on my roof? [Dimensions are in the attachments] [For reference: Same roof carries 4 100w flex panels + fan]

Considerations:

- Thin-Flexible panels are nice but they are around 100w-150w per.
- Non-Flexible panels (300w+) are better use of a space but putting two of them together might be a too much or you might have "extras" hanging off your roof.

Thoughts?

 

[John61CT]

Sunpower cells.

They make panels too.

 

[kllcbosmetris]

Sunpower cells.

They make panels too.

Thank you. I've been researching and I found the attached lists: Solar Panel Efficiency by Manufacturer and Power Output of Solar by Manufacturer . [Though you can never trust these without knowing who published it]  It seems like Panasonic and Sunpower lead the efficiency list and the most you can get out of a panel is around ~350w (by Sunpower and LG). Now to find the smallest panels with 350w to see if we can fit 3 of them on a roof. I've seen YouTube videos of 1000w systems but most of them have a ton of roof space (i.e. RV) and use 100ws.

 

[John61CT]

Measure your length and width.

Find cheap panels with Sunpower cells that physically fit with a minimum of unused space, never mind the wattage, but only two or three different sizes would be best.

Ideal would be smallest number of high-voltage panels for simplicity.

Note going for 220+w @ 36+V (max 65) lets you get great cost efficiency and best shade handling using Victron's 75/15 MPPT controller at only $100 each.

These rated at 18+% efficiency, claim better off-peak production, use as basis for comparison

https://www.solar-electric.com/canadian-solar-cs6k-305ms-solar-panel.html

 

[jimindenver]

The rebranded Sunpower 435 watt on my truck is suppose to be 20% efficient. All I know is seeing 104 volts off a panel rated for 79 volts is a reason to give your controller some breathing room as far as Voc limits are concerned.

 

[John61CT]

Is that 79V, Voc or Vmp ?

 

[Jmel]

Wow this thread really got me thinking... I have enough room on the top of my van to replace my 100w panels with a couple of 300w panels...hrm...

 

[John61CT]

Usually a 300w panel takes up 3x the space.

Mix and matching NP, separate controllers.

 

[jimindenver]

Is that 79V, Voc or Vmp ?

79.9 Voc

 

[jimindenver]

A 300 watt panel is 39x77

 

[John61CT]

I've never heard of a panel actually producing voltage 30% over Voc rating.

How often? Circumstances?

Maybe something special about that model?

Or something faulty with your instance?

Have you tried contacting the vendor or mfg for an explanation?

 

[John61CT]

So that 300W panel takes up 10 sq in per watt produced. Other data points to compare?

 

[John61CT]

Note it is possible to order custom panels in whatever shape you like, a 60-cell unit can be 15x4 or 12x5 or even 30x2.

But it's only cost-effective by the pallet load.

Idea: for a given model van, create a design that maximizes the roof area usage without sticking out, but leaves a MaxxAir sized hole in the middle in just the right spot.

Would give a lot more power and actually save a fair bit of money if owners of that model van got together. The early pioneers get to make some profit off those that buy in later.

 

[jimindenver]

I've never heard of a panel actually producing voltage 30% over Voc rating.

How often? Circumstances?

Maybe something special about that model?

Or something faulty with your instance?

Have you tried contacting the vendor or mfg for an explanation?

Lots of things I haven't seen or heard of but that doesn't make them impossible.

I only saw it when we were switching the MC4 connectors to Anderson's and I checked the leads for polarity. We checked several times as we were hooking it up and even used two different multimeters. It ranged between 100 and 105 Voc for that hour or so.

Location was Gooseberry Mesa, Utah. I am not sure of the elevation but I know it wasn't sea level nor the 10,000 ft I am use to. There was also no cloud effect as it was a clear day. I have not looked into it farther because exceeding expectations isn't something I put a lot of effort into checking out. The person helping me out was a forum member 29chico. I guess I should have checked it in Leadville to see what it would do at 10,500 ft.

 

[kllcbosmetris]

Note it is possible to order custom panels in whatever shape you like, a 60-cell unit can be 15x4 or 12x5 or even 30x2.

But it's only cost-effective by the pallet load.

Idea: for a given model van, create a design that maximizes the roof area usage without sticking out, but leaves a MaxxAir sized hole in the middle in just the right spot.

Would give a lot more power and actually save a fair bit of money if owners of that model van got together. The early pioneers get to make some profit off those that buy in later.

From what I can find, the thin flexible ones come only in 100. Great stealth option but not optimal for perfect roof use. I also heard, on YouTube, that there is a new technology where you can put them on your windows like tint. Anyone heard anything about this? It would be a two birds one stone scenario.

 

[John61CT]

> Lots of things I haven't seen or heard of but that doesn't make them impossible.

Woah, I never said I doubted you!

Just trying to get a handle on it.

The usual rule of thumb is

"undersize the panel's Voc compared to the controller's rated max"

by 10%.

Here is a counter example of 30%.

 

[John61CT]

> From what I can find, the thin flexible ones come only in 100. Great stealth option but not optimal for perfect roof use.

Proper term is "semi flexible", more expensive, like over double. And don't last nearly as long, IMO requires perfect mounting (no flex, heat sinks) to get average three years.

But the custom option I'm talking about is available for those, more so than rigid framed ones.

> I also heard, on YouTube, that there is a new technology where you can put them on your windows like tint.

Futuristic vapourware, ignore.

Let anything new on the market actually be put to use by bleeding edge crowd for a few years before considering.

Tons of scammy PR junk info in the "green energy" topic space.

 

[ZacLee]

I've seen solar panels exceed their Voc (open circuit voltage) rating and generate more than rated wattage after rain storms clear the air. During one incident, it went high enough to damage a small (250 watt) grid tie inverter, but other equipment was not damaged.

 

[tx2sturgis]

Idea: for a given model van, create a design that maximizes the roof area usage without sticking out, but leaves a MaxxAir sized hole in the middle in just the right spot.

Or another related idea:

A flat, low profile, pancake type squirrel cage blower or two, under the panels, pulling air from the vehicle cabin, with vanes or channels to direct the exhausted air under the panels to assist in cooling the undersides.

Hmmmm....

 

[John61CT]

Nice concept, but don't think I'd DIY with a roof mounted fan myself