system and components voltages

Re: system and components voltages

For an off grid/battery based power system... Selecting battery voltage can be critical for long term sanity and keep short term copper wiring costs/complexity reasonable.

Basically for small/lower power systems (call it less than 1,200 watt, 100 amp @ 12 vdc loads, DC charging less than ~80 amps), a 12 volt system can work fine.

For 1,200-2,400 watt load system, and those with larger battery banks, 24 volts is not a bad place to go.

For >>2,400 Watt systems and large battery banks, then 48 volts is usually the better choice.

For the PV Array--You need to "match" Solar array Vmp voltage (Vmp-array) to the batter bank voltage... A 12 volt bank needs around Vmp~17.5 to 18.6 volts for optimum operation with a PWM charge controller (2x that for 24 volt, 4x that for 48 volt systems).

If you get the more expensive MPPT type charge controller--The minimum voltage is as above--But, depending on charge controller, you can typically go upwards of Vmp-array~100 VDC just fine (typical rule of thumb is Vmp-array should be around 2x battery bank charging voltage for "optimum" MPPT controller operation).

In the end--Start at the beginning. What are your loads (Watts peak, Watt*Hours per day usage, any "native DC voltage" devices?)....

As a start--lets talk specifics for your system/needs. It makes it less confusing/frustrating talking about all the possibilities/variations under the sun.

-Bill