Mono- or Multi-Crystalline? What say Ye?

MarkJ · 02-07-2009, 05:57

Right-o I'm sure this has been asked before but I want condensed, good knowledge from you smart-bums

Should I buy Mono-Crystalline or Multi-Crystalline solar pannels?

Thanks for your kind thoughts

Mark

GordMay · 02-07-2009, 06:13

I think you have to compare specific examples (products) of each technology.

Generally:

Single Crystal Silicon cells are more expensive, more efficient, and work better in hot weather & low light conditions.

Poly/Multi-Si cells are less expensive & less efficient.

Multicrystalline panels, while having lower efficiencies than single crystal panels, can nonetheless have the same wattage per square foot as some single crystal panels, because the cells can be rectangular, filling all of the available surface without the gaps left by round or octagonal cells.

mesquaukee · 02-07-2009, 09:40

Gord May sums it up.
One point which may be important should be added about multicrystalline panels. When a small shadow say from rigging occludes part of the panel the output is less affected than the single crystal panels.

MarkJ · 02-07-2009, 15:02

Thanks guys.

Mark

GordMay · 02-07-2009, 16:15

Quote:

Originally Posted by mesquaukee

Gord May sums it up.
One point which may be important should be added about multicrystalline panels. When a small shadow say from rigging occludes part of the panel the output is less affected than the single crystal panels.

Thanks. I hadn't heard that; thinking it was more a matter of individual cell connection strategies. Can you tell us (or direct us to) more?

mesquaukee · 03-07-2009, 05:21

It is from an article I read more than 10-15 years ago. It was either in Cruising World, Sail, Practical Sailor or ?????.
It has something to do with how all the little bits in the panel are hooked together in a multicrystalline panel. Sorry I couldn't be more helpfull.

GordMay · 03-07-2009, 05:54

Quote:

Originally Posted by mesquaukee

... It has something to do with how all the little bits in the panel are hooked together in a multicrystalline panel. Sorry I couldn't be more helpfull.

Quote:

Originally Posted by GordMay

Thanks. I hadn't heard that; thinking it was more a matter of individual cell connection strategies. Can you tell us (or direct us to) more?

Quote:

Originally Posted by mesquaukee

... One point which may be important should be added about multicrystalline panels. When a small shadow say from rigging occludes part of the panel the output is less affected than the single crystal panels.

Ah - thought so.

mesquaukee · 03-07-2009, 20:45

Okay it took a while. My brain is taking longer and longer accessing files.
Here it is why multicrystalline panels tolerate shadows from rigging better.
This is a simplified explanation.
Each cell in a panel produces 0.5 volts. To be able to overcome the resistance in connecting wire and create a potential difference to “force” current into a battery a series of 32-36 cells are strung together to give a 16-18 volt panel.
Single Crystal Panel
Shading one cell cause a greater voltage drop than 0.5 volts. The rest of the cells have to overcome the resistance in that “dead” cell. A further reduction in voltage. The voltage difference between the panel and the battery is what “drives” the charging process. The “3 volt” differential is now for;
- 1 shaded cell, 2 volt differential, 2/3 the charge rate.
-2 shaded cells, 1 volt differential, 1/3 the charge rate
-3 shaded cells, 0 volt differential, zero rate of charge
Multicrystalline Panel
There are numerous parallel series of cells. Anywhere from 10 to 50 or more parallel series of 32-36 cells. All the parallel series of 32-36 cells are interconnected. If the shadow of a rigging line crosses the panel the “dead” cells are bypassed by rerouting the current to the other cells in the parallel circuits. There is some loss in output.

02-07-2009, 05:57	#1
MarkJ Registered User Join Date: Dec 2007 Location: Asia - on Sea Life Boat: Beneteau 393 "Sea Life" Posts: 3,211 Images: 6	Mono- or Multi-Crystalline? What say Ye? Right-o I'm sure this has been asked before but I want condensed, good knowledge from you smart-bums Should I buy Mono-Crystalline or Multi-Crystalline solar pannels? Thanks for your kind thoughts Mark __________________ OurLifeAtSea.com

02-07-2009, 06:13	#2
GordMay CF Adviser Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 13,552 Images: 233	I think you have to compare specific examples (products) of each technology. Generally: Single Crystal Silicon cells are more expensive, more efficient, and work better in hot weather & low light conditions. Poly/Multi-Si cells are less expensive & less efficient. Multicrystalline panels, while having lower efficiencies than single crystal panels, can nonetheless have the same wattage per square foot as some single crystal panels, because the cells can be rectangular, filling all of the available surface without the gaps left by round or octagonal cells. __________________ Gord May ~~_/)_~~ (Gord & Maggie - s/v"Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?" Custom Search CF ➥ http://www.google.com/cse/home?cx=01...%3A2lb6ozabif0

02-07-2009, 15:02	#4
MarkJ Registered User Join Date: Dec 2007 Location: Asia - on Sea Life Boat: Beneteau 393 "Sea Life" Posts: 3,211 Images: 6	Thanks guys. Mark __________________ OurLifeAtSea.com

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02-07-2009, 09:40	#3
mesquaukee Registered User Join Date: Jun 2009 Location: Western Caribbean & ocassionaly inCanada Boat: Mesqua Ukee, Buccaneer 40 (Salar 40) Posts: 466	Gord May sums it up. One point which may be important should be added about multicrystalline panels. When a small shadow say from rigging occludes part of the panel the output is less affected than the single crystal panels.

03-07-2009, 05:21	#6
mesquaukee Registered User Join Date: Jun 2009 Location: Western Caribbean & ocassionaly inCanada Boat: Mesqua Ukee, Buccaneer 40 (Salar 40) Posts: 466	It is from an article I read more than 10-15 years ago. It was either in Cruising World, Sail, Practical Sailor or ?????. It has something to do with how all the little bits in the panel are hooked together in a multicrystalline panel. Sorry I couldn't be more helpfull.

03-07-2009, 20:45	#8
mesquaukee Registered User Join Date: Jun 2009 Location: Western Caribbean & ocassionaly inCanada Boat: Mesqua Ukee, Buccaneer 40 (Salar 40) Posts: 466	Okay it took a while. My brain is taking longer and longer accessing files. Here it is why multicrystalline panels tolerate shadows from rigging better. *This is a simplified explanation.* Each cell in a panel produces 0.5 volts. To be able to overcome the resistance in connecting wire and create a potential difference to “force” current into a battery a series of 32-36 cells are strung together to give a 16-18 volt panel. Single Crystal Panel Shading one cell cause a greater voltage drop than 0.5 volts. The rest of the cells have to overcome the resistance in that “dead” cell. A further reduction in voltage. The voltage difference between the panel and the battery is what “drives” the charging process. The “3 volt” differential is now for; - 1 shaded cell, 2 volt differential, 2/3 the charge rate. -2 shaded cells, 1 volt differential, 1/3 the charge rate -3 shaded cells, 0 volt differential, zero rate of charge Multicrystalline Panel There are numerous parallel series of cells. Anywhere from 10 to 50 or more parallel series of 32-36 cells. All the parallel series of 32-36 cells are interconnected. If the shadow of a rigging line crosses the panel the “dead” cells are bypassed by rerouting the current to the other cells in the parallel circuits. There is some loss in output.