24 volt or 12 volt?

[Smithson]

Hello.     I was wondering if there was a reason for most installations here using 12 volt and not 24 volt solar panels.  I searched the site and cannot come up with any 24 volt solar panel information.  Are the 12 volts systems better?

The 24 volt panels seem to be a better buy as you could seem to buy them for 67 cents a watt.  And it would make more sense if you were planning a 24 system.

http://www.solarblvd.com/Solar-Panels-&-Systems-24-Volt-Solar-Panels/c1_270/index.html

To admin:   If providing a link to another retailer is not allowed please remove it.   Thank you
  Smithson

[OperaHouse]

Having had a number of panels fail, I prefer 12V 100W to keep loses minimum.  In the past 12V was just more common.  As we head toward grid tie it will be 24V.  Economics are better with higher voltage and half the number of connectors is a factor.

[Bruce S]

NO worries about the link.
They are very well known and currently a good reputation.
Cheers
Bruce S

[Caleb]

Can you just put two 12V panels in series for 24V's?

[Mary B]

Yes you can series 2 for 24 volt, I series 4 to feed my MPPT controller with about 80 volts

[hydrosun]

One small advantage of 12 volt panels wirh mc4 connectors is it is easier to series connect several into a higher voltage array with less parallel strings for the same wattage. For instance I did two 3000 watt grid tie system with one series string and still keep the voltage under the limit of the inverter. With a mppt offgrid controller I can put 6 in series and keep under 150 volts (in a mild climate) and get 1200 watts without having to make parallel connections. Parallel connectios require either a special wye connector or more breakers in a special breaker box to connect each string. But if 24 volt or higher panels are much cheaper or the syatem is bigger it makes sense to go with the 24v panels.
Chris

[trbarto]

The higher the voltage, the less the amperage for the same the wattage system which means you can cut down on your wire diameter...So...rule of thumb, the higher the voltage, the more efficient the system. 

Also - weight to amp;hr rating for batteries is also important...2V are better than 6V are better than 12V by and large...go in series to achieve your voltage rating for batteries (again Volt to power (Ah))...

I also found the best grid tie inverters out there are for 24V or 48V inverters with the best of the best being the 48Vmin inverters.

I have a 3kW solar system with a supposed 2.8kW wind generator...the wind is totally aweful...I got taken for a ride - during a 48mph wind - it was only generating 7-9 amps at 53V...I've talked to the company - they say it melts at 2.8kW output and that is how pma's are rated...dunno...I wrote it off to being my fault for not requesting any wind/power curves.

The panels are 250W, 30V panels with 8.Xish amp rating and when its cold and sunny outside the arrary holds 3.3kW into the inverter (Outback Radian)...pretty impressive - and you'll need to consider this when sizing your wires (higher output)

[birdhouse]

So...rule of thumb, the higher the voltage, the more efficient the system. 

i don't fully agree with this.  there are certainly advantages to higher voltage systems, but i think a better way to state this would be: the higher the voltage creates a better use of copper.  (efficient use of spendy wire)  if the correct gauge of wire is used, both a 12v and 24 or even 48v system should have the same efficiency. 

don't get me wrong, i run a 24v system, and love it!  my system is not large enough to justify going to 48v though. 

Also - weight to amp;hr rating for batteries is also important...2V are better than 6V are better than 12V by and large...go in series to achieve your voltage rating for batteries (again Volt to power (Ah))...

this is not always true either.  some of the best battery manufacturers (rolls) offer true big boy deep cycle batts in 12v.  sure they also make 2v and 6v batts. 

just giving the new guy a bit of a hard time on the first day of the year...   

welcome aboard trbarto!

adam

[David HK]

Years ago someone on this web site wrote the following:-

The more volts you've got, the easier it is to play with the electricity!

David in HK