====== What does nominal mean? ======

//Nominal// refers to a thing's name, rather than its actual status in the present moment.   The point of the term is to keep new folk from thinking that 12v literally means the system or device is running at 12.0 volts.  It's usually not. 


The most common uses of //nominal// for 'dwellers are:


===== nominal battery bank voltage =====
The most common battery bank voltage for 'dwellers is 12v, although some run 24v or specialized, exotic voltages like 48v.((the latter most often found when using automotive hybrid battery packs for house power))

Nominal 12v banks are rarely actually 12.0v.  Examples:

  * lead-acid banks can range from ~12.1v (full discharged) to something like 14.8v (absorption voltage).  When full/rested they are something like ~12.7v.
  * LiFePO4((aka //LFP//)) lithium banks((typically [[electrical:12v:parallel_serial|4S]])) range from ~12v discharged to ~14.6v when full.((this is why LFP is so well suited for drop-in lead acid replacement))
  * Non-LiFePO4 li-po((actually Li-Ion, typically 3S)) range from 9v discharged to 11.3v when rested.  Just after charging you may see ~12.3v.((not a good match for 12v systems, which is why this chemistry is relatively rare))  




===== nominal solar panel voltage =====

Similarly, "12v" solar panels are called that because they are used to charge/power 12v systems.  The voltages on these vary even more widely:

  * As low as battery voltage in the morning, ~12.1v((pwm))
  * they make max power (Pmax) at a particular voltage (Vmp) which is usually way above battery voltage, like ~18v. 
  * when unconnected (i.e. "open circuit"/Voc))((or in late Absorption with MPPT controllers)) voltages are very high, like 22v.

Nominal 20v (~30Vmp) panels are common on residences in the U.S.  Nominal 24v panels (~36Vmp) panels are more common in commercial installations.  Solar farms may use panels of much higher voltage.