Matakohe Limestone Island in the Whangarei Harbour has had many uses over the years, from a Maori pa site, to lime works, to a sheep farm. Now Matakohe Limestone Island is a predator-free scenic nature reserve with an on-site Ranger.
Kiwi are bred on the island to be repatriated to the mainland, and it is also home to tree weta, Grey Faced Petrel, skink, multiple species of gecko and many native trees and plants.
Over the years, many well-known Northland Companies have had parts to play in the timeline of the island, and Northpower’s involvement initially came about when we installed the first solar panels and battery system for the island ranger cottage in 1997.
In late 2020, Hubands and Northpower upgraded the solar panels and battery system to make it more practical for modern-day life on the island, and to make sure it would provide sustainable power into the future. With no power or sewer connection to the mainland, and it being very costly to create one, it is important that the inhabited island can run comfortably “off-the-grid”.
Initial assessments of power usage of the house and implement shed found that most of the power load used was actually during daylight hours, so Hubands designed a Low Voltage AC coupled system using the Selectronic Inverter/Charger in conjunction with a Fronius Inverter to give them the best self-consumption during the day from the solar panels. Excess energy generated by the solar panels during the day is fed into a Powerplus Premium lithium battery bank to use when the solar panels are not generating electricity. A Honda AutoStart petrol generator is used as a backup for when there is minimal sun for days on end and the batteries run low.
The solar and battery system runs automatically and requires minimal maintenance. The power required is supplied directly from the solar panels (through an inverter) in the first instance, from the batteries if the solar is not creating enough electricity, or through the generator as the last resort.
The battery inverter/charger is effectively the hub of the system and it controls the power flow, regulates charging, and controls the backup generator and reports of the usage status and data. The battery inverter/charger and the solar inverter/charger communicate and work together. When the batteries are fully charged, the solar inverter regulates the solar panel output to match the current energy loading requirements and avoid overcharging the batteries.
The backup generator automatically starts when the battery charge drops below a pre-set level, and will stop when the batteries reach a higher pre-set level of charge. Additionally, the generator can be started or stopped manually from the control panel. The generator runs a weekly 15-minute test.
The whole system can be monitored from the displays on site, or remotely through the internet. Reports can be generated by logging on to the system monitoring online, and historical data is available to see.
Since its installation, the new solar and battery system has proven to be incredibly reliable and has catered for the island’s ranger perfectly. They have barely had to use the backup generator at all. Hubands’ Matakohe Limestone Island Solar Project was announced runner up in the 2021 SEANZ Fronius Best Off Grid Implementation Awards due to its success.
Further Information
Want to learn more about our Limestone Island Solar Project? Check out the links below.