Alexandra/Clyde

Infinite Energy was commissioned to design and install a solar and battery system in 2021 for our client, Peter.

The brief was complex, with the solution to deliver benefits on a number of levels.

Often working from home and in an area experiencing regular power outages, Peter required a system that would deliver back up power to critical loads to allow him to continue to work in the event of a network disruption.

Critical loads were nominated in consultation with the client – then wired via a secondary main switch, which becomes active in the event of a network outage.

The Sungrow SH5K-30 inverter is designed to isolate from the network during an outage (to prevent any solar generation flowing back into the network) and allows the inverter to continue to operate without contact with the grid. This ensures any generation from our solar array is still captured – and the battery continues to operate storing and delivering energy to these critical loads.

Within the first two weeks from commissioning the system, Peter experienced a day long scheduled power outage (network upgrades) and the system operated automatically and seamlessly to deliver continuity of energy during this time.

At the time of installation, Peter was also planning to have a large swimming pool & spa installed – powered by an efficient electric heatpump.

As such, the brief needed to account for this additional loading and deliver enough energy through summer and shoulder seasons to provide a really cost effective way to maintain the swimming pool temperature at a relatively constant 28°C.

Solar power is an ideal solution when coupled with these large summer time electrical loads, as our peak generation periods overlap these peak consumption periods and place very little demand on network power.

With a background in accounting, Peter was also very keen to know that his investment would generate a sound return and made good financial sense.

Peter’s cost of distributed grid supplied energy is $0.33 per kWh (unit), so for every unit of energy he can generate and self consume, he’ll save $0.33

The system designed and installed was modelled using advanced solar power design software, referencing specific product efficiencies, installation parameters such as orientation, pitch and shading – and references up to 25 years of NIWA weather data from the local weather station.

This bespoke design scenario showed an anticipated year one generation of 14,778kWh, which if all energy was self consumed would generate a saving of $4876.74.

What we have seen through the detailed system monitoring is a July-June annualised generation figure of 14,478kWh (98% of estimate).

Given the pool was installed later in the year, exported energy was higher than anticipated – and pool heating settings need to be further refined in the coming summer to increase self consumption during the day.

At the end of the first full year following installation, Peter has generated an 8.8% return on his initial investment – and with refinements to time of use, we’ll see exported energy reduce significantly in the next 12 months. A pending change of electricity retailer will also see the tariff paid for exported energy jump from $0.08 per kWh to $0.16 per kWh, providing a greater return on energy generated, but not consumed or stored in batteries.

What is the outlook for year two?

We expect to be able to increase self consumption to circa 70% and increase returns on exported energy by 50% over the current tariff. The combined result of these minor tweaks would see savings shoot up over $3,800 in year two, with a simple return on investment for year two over 12%.

As energy prices continue to rise, these returns will only improve in the future.

The future is bright…

Peter’s investment in solar power & lithium ion batteries means he has a guaranteed energy supply for at least the next 25 years (Hyundai solar cells have a full 25 year warranty) and is now protected from rising energy costs, as well as having resilience for future power outages on the network. 

No moving parts means very little maintenance, so Peter can now sit back and benefit from the long term savings. 

Based on the generation modelling, we’d expect the system to have repaid the entire investment within 8 years… and following this, the savings for the life of the system after all capital outlay is recovered should total a whopping $50,000+