Stand-alone Power System (SPS)

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

A stand-alone power system, or SPS, is a power supply that does not connect to the grid. In most cases it is made up of solar panels, an inverter, a battery bank and sometimes a diesel or gas generator for the days the sun falls short.

Two meanings

Installers meet the term in two ways. The first is a customer’s own off-grid system on a farm, a remote home or a cabin. The second is a network program in which a distribution business replaces a long, costly power line to a few customers with an SPS that it owns and operates. The word means the same thing technically, but the commercial arrangements differ.

In practice

A customer-owned off-grid solar system can qualify as an SGU, so it can create STCs based on its rated panel output, its zone and the deeming period. The design and installation standards for off-grid are stricter than for grid-connected, and the CEC has separate accreditation for stand-alone systems. See solar designer.

Worked example

A 5 kW off-grid array in a zone 3 postcode, installed in 2026, is deemed at 5 x 1.382 x 5 = 34.6, so 34 STCs after rounding down. A battery on the same site is assessed separately under the battery rules if it meets the program criteria, which require VPP capability, so many off-grid batteries will not qualify.

Common confusion

Off-grid does not mean exempt from paperwork. The system still needs a compliance certificate, an installer with the right accreditation and evidence. Do not mistake SPS for a hybrid grid-connected system with a backup function. That is a different design and has a different approval path through the network. See DNSP.

See STC trading, battery STCs and the glossary.