How efficient is a SAPS, and what are parasitic loads?

Parasitic load is the energy the system consumes to run itself, cooling, inverter standby, communications, controls, before any of it reaches your load. It is the most commonly ignored specification in off-grid procurement and one of the most consequential, because on a small remote load it can be a large fraction of daily generation.

Vantara’s parasitic loads:

Component	Draw
HVAC	0.41 kWh
Inverters (2 units, approximately 60 W each)	0.12 kWh
Communications	0.007 kWh
Other	0.06 kWh

Inverter maximum efficiency is 96%; MPPT efficiency on the solar charge controllers is 99.90%.

When comparing systems, ask two questions that vendors rarely volunteer: what is the total daily parasitic consumption in kWh, and is the quoted usable storage before or after parasitic draw. A system with 10% higher nameplate storage and double the parasitic load can deliver less energy to your equipment. On a site where you are paying for every kWh of solar and storage, that difference compounds directly into capital cost.