Sustainability Trust

The Sustainability Trust in Wellington is an organisation that provides energy services, education and community programmes. As such, they felt it important to add solar to their central city offices, just off Courtenay place.

Project Goals

They estimated that they would use 90% of the energy they created and would export power back to the grid on the days they were closed (Saturday/Sunday and Public holidays).

Project Design

They installed a 3.2kW Mitsubishi solar array onto their Eco Centre which is located on the bottom floor of a 6 story building. Even though they are located in the central city, they have perfect North facing frontage with minimal shading during the solar day.

The 12 Mitsubishi 270W panels were installed on a steel rack that is bolted above the main doors at a height of 4M. The panels are tilted at 45 degrees and pretty much face due North which is perfect for maximum generation throughout the year.

Solar power generated from the panels is fed into Enphase microinverters that are mounted on the back of each panel and then fed directly into a single phase on the building subpanel.

Project Outcome

Over the past month (winter) they have produced 180kWh (6kWh/day) with peak production of 2.65kW. Over the year they expect to produce over 4000kWh, when the sun hours get longer. The expected savings, based on the retail rate of 19c/kWh and export rate of 7c/kWh are around $700/year.

What is interesting to note is that their installation is generating at least 20% more than the other microinverter installs they have conducted over the past couple of years, on a kWh/kWp basis. They suspect that this is due to efficiency of the Mitsubishi panels and also the pitch of the array at 45 degrees.

They have also recently hooked up the system to Splash Monitoring.

Solar PV panels

12 X PV-MLE270HD

Solar Inverters

12 X EP-M250 Micro inverters

Energy Generation

3.2kW peak output


Sustainability Trust

Published: Thursday, 19 November 2015

Sustainability Trust