It takes in power when charging the battery, the actual consumption depends on the UPS efficiency, the battery capacity, the backup load hooked on and the amount of load-shedding. Mine uses around 130 Watts when charging in hour-after-hour madness in summer. Air conditioners take more than 1.5 Kilo-Watts. 1 Wapda unit is consumed by a 1KW appliance in 1 hour.
Lets consider Wapda power to be 100%.. ie 100 units..
a ups will take wapda power in, and pass it out to the home appliances when wapda is on.. simple as that..almost 99% in out..at the same time, ups will take extra wapda power to run itself.. which is dependent on the transformer kit and other components of the ups..could be as low as 20W to as high as 300W just to run itself.
further more it will take extra power to charge the batteries.. this power consumption is based on 2 factors..
1 - how much batteries are discharged and need power to charge them fully.
2 - the PF of the ups , how efficiently it converts that power to DC.
Power conversions and losses:
At wapda level:
most of local / desi brands have a PF of 0.6 to 0.65. good brands like cyberpower vary between 0.6-0.75.. higher end models may go upto 0.8-0.85.. meaning for every 100 units of wapda consumed in charging, , between 60-85 units are converted in DC Amps.. this is where there is maximum loss of energy and high energy bill.. the PF... the bigger and more drained the battery, the more current needed, the more energy wasted in power conversion.
as for APC.. to be clear, every model has a different PF.. for the 1500SUI, its 0.65.. for the 3000VA and XL models, it is 0.7-0.8-0.9 for different models.. SMD have higher conversion Efficiency, but have other issues.. so a mid level compromise is best at anything near 0.8..
the sui1500 is the most economical and near ideal home use ups as it is 24V, the only option at 24V .
At battery level:
further power loss is incurred using the same pf when in loadshedding the ups consumes battery power and converts 100unit from battery to produce between 60-90 units AC (wapda power) for running things in loadsheding (depending again on the UPS efficiency)
and the cycle goes back to step 1 when wapda comes back.
Role of the UPS voltage (setup):
furthermore, the role of the system voltage is of as much importance.. a 12V ups is as bad at anything than anything most bad :P...24V are bit better at handling power as well as less power loss in wiring and longer distance between ups batteries and the AC input. also better conversion of power..
48V in our scenarios are best option.. have many many advantages including capacity to handle larger loads and torque, longer battery life over 2 years and longer back and very high efficiencies.. 96V would be ideal but the cost of the setup is just too high.. 72V systems are very rare.
just for comparison, dedicated Solar inverter such as Goodwe are capable of efficiencies of those 2 step power conversions at 95% and 99% (peak) .......
Phew ..........
