question about poly and mono crystalline cells

[snake21]

hi friends,i was about to plan the construction of a solar panel of about 50watts.during my research,i found out that there are 2 types of cells,mono and multi crystalline.i did some further research work and found that the difference is that the cells of mono is made from 1 piece crystals whereas for multi,it is made from many cells.

before buying cells,i would like some advice.i have read somewhere that the life expectancy of mono is about 5 years and the cells give power more than multi whereas multi has a life expectancy of 25years and give less power compared to mono.is that true.

thanks

[DamonHD]

I know of no great difference between the lifetimes of mono- and poly- PV, at least of well-manufactured cells/panels.

Poly is cheaper per unit of power generated and takes a little more space to gather that power.

Rgds

Damon

[snake21]

hi friends,i have another question.what is the lifespan of a solar cell

thanks

[DamonHD]

If well looked after, 40 years, with some loss of performance...

Rgds

Damon

[snake21]

thx

[snake21]

hi friends,i have another question.i just bought some 50 solar cells that i will be hooking to my 12v,100amps battery but before making a panel,i would like to know according to your experience,the number of cells that i will need to put in one 12v panel.the specs of 1 cell is 0.5v,1.75amps

i was thinking to make a 15v panel to charge the 12v battery but i need to confirm before starting to assemble the panel

thanks

[Bruce S]

hi friends,i have another question.i just bought some 50 solar cells that i will be hooking to my 12v,100amps battery but before making a panel,i would like to know according to your experience,the number of cells that i will need to put in one 12v panel.the specs of 1 cell is 0.5v,1.75amps

i was thinking to make a 15v panel to charge the 12v battery but i need to confirm before starting to assemble the panel

thanks

The industry normally make them in 18Vdc sets. This allows for the panels to still output some power in less than ideal settings. So the number of panels for a single unit would be 36. You could use less, but then you run the risk of not having high enough voltage to get above the charging level of the battery(s).
This would leave you enough to build a 6V unit that would be almost enough to charge a 6V battery, or better for charging multiple AAs or something.
Hope this helps
Bruce S
 

[snake21]

thanks for your reply friends.
what if i make a 20v panel for charging a 12v battery,will that be ok or will it damage the battery

thanks

[Bruce S]

what if i make a 20v panel for charging a 12v battery,will that be ok or will it damage the battery

Well, that depends.
If you're going to connect it directly to a battery, and the battery is high enough in Amperage say 18Ahrs or more then it should not hurt it. The battery will hold the panel output down to its voltage.
In a perfect world you would be getting the full 1.75A directly into the battery, it would take more than 8 hrs to full charge a 18Ahr battery, so you run little risk of hurting either the panel or the battery.

IF you are looking to connect the panel to a controller or a MPPT then the voltage could be a concern. The HF panels normally run 21 - 23Vdc Open circuit and they don't hurt either unit. I have Ghurd's controller connected to my setup to keep my batteries charged, then dump the excess to another set of batteries,etc.

20V at 1.75A is ~33 watts. 33 watts at say 13.5Vdc (Acid based batteries) is ~2.4A . 2.4A could charge a acid based battery in about 7 1/2 hrs.
Still would not hurt the battery, UNLESS you left it charging like that every day.
The 18V setup would then leave you enough panels to build a smaller unit for AA charging or ...

Hope that helps;
Bruce S