Discussion in 'Photovoltaics' started by sunnybouy60, Jan 16, 2006.

1. sunnybouy60Guest

vs. 24 or 48v setups?

2. Steve SpenceGuest

The higher the voltage, the smaller the wiring for a given wattage.
typically large installations use 48vdc, medium use 24vdc, and small
ones use 12vdc.

3. Anthony MatonakGuest

I'm no expert but my understanding is that higher voltages mean
less loss of power in long runs of wires, higher capacity battery
banks using smaller cells and inverters using slightly less
expensive parts.

That is to say, if you run 1000 feet of wire and pump 12V through
it then you'll lose more power than if it were 48V. If you need
a total storage capacity of 1000 watt-hours then you could do it
with (1000Wh/12V) 83 Amp-hours of batteries but at 48V it would
only require (1000Wh/48V) 20 Amp-hours. So, if you wanted to do
either of these with 20 Amp-hour batteries the first (12V) would
require 4 in parallel and the second (48V) would require 4 in
series. Series works better. Also, some inverters use essentially
the same parts for 12V and 48V but the 48V version will put out
4 times the power.

Unfortunately, there are a heck of a lot more 12V appliances and
lights than 48V (or even 24V) versions. If you want to run things
without using an inverter then 12V has this advantage.

Anthony

4. Richard P.Guest

Well, as some of the others have mentioned, the line loss is lower on the
higher voltages. But I also believe there is increased inverter and battery
charger efficiency with the higher voltage input.

5. George GhioGuest

12 Volt - to 1000 Wh
24 Volt - 1000 to 2000 Wh
48 Volt - 2000 and up

These figures can overlap by as much a 100%

12V 1000W = 83A
6-2v Cells @ X Ah

24V 1000W = 42A
12-2V Cells @ 1/2 X Ah

48V 1000W = 21A
24-2V cells @ 1/4 X Ah

12V lots of consumer goodies, lights, appliances to choose from

24V less consumer goodies, lights, appliances to choose from

48V not many consumer goodies, lights, appliances to choose from

It comes down to what you want to do. If you want to run an average
house as you would in the city, as in 10+ kWh a day with all the
consumer goodies you can lay your hands on, 48V is the way to go.

If you prefer the minimal lifestyle and only need 1 to 2 kWh a day you
can do it with 12V.

24V fits in between as you may choose.

6. sunnybouy60Guest

If you are using a 48v inverter the appliances that you can run aren't
affected right? It's still being changed to 120vac. Also do higher voltages
perform better than 12v in extreme warm weather? ie. Southern Arizona.

7. Blue CatGuest

Yes, but the effect is from the resistance of the conductors, which
increases with rising temperatures. Using a higher voltage decreases power
losses from conductor resistance.