The job
The library's original array was 400 panels rated at 250 W each, installed on a low-pitch roof and well past its best. We removed the lot, recycled the old panels, and rebuilt the system with 210 Trina 475 W panels on a 20-degree tilt frame so the array faces the sun properly for the first time.
A single 110 kW Sigenergy inverter replaced the old string inverters, which simplifies monitoring and gives the council one point of service. Total system size is 99.5 kW.
Installed cost was about $115,000. Based on the site's daytime consumption we estimate an annual benefit of around $52,750, which puts the simple payback at roughly two years and two months. After that, the site is saving in the order of $50,000 a year for the life of the system.
The job took two weeks on site from first panel off to switch-on.
