By Bob Johnston, President and CEO, Hawaii Pacific Solar

Hawaii has been at the forefront of solar photovoltaic installations for both residential and commercial applications for many years and continues to increase grid penetration in growing numbers. Economics, public policy and environmental issues are strong motivations for continued growth of renewable energy systems statewide.

This growth presents opportunities and challenges.

Systems that were installed 20 to 25 years ago are nearing their useful life and losing their efficiency. After seven to 10 years commercial facilities have used their investment tax credits, accelerated depreciation benefits and written off the value of their systems. The result is that many system operators are choosing to remove and replace their existing systems with the latest technology which provides more efficiency and meets current utility standards.

Another strong motivation to repower is the ability to take advantage again of state and federal tax benefits and accelerated depreciation thereby reducing the overall cost of installation.

The solar PV industry has made significant and consistent advances in technology and efficiency while Hawaiian Electric Companies have learned to manage the ever- increasing addition of distributive power. Solar modules are much more efficient, inverters meet the latest technical standards and advanced monitoring allows both the system operator and the utility to see and understand the system’s load profile in the most granular way.

There are some challenges to repowering systems, such as disposal of the old material. Currently there are no recycling facilities for used PV panels in Hawaii, but a couple of alternatives are available. Solar panels may still have some residual life and can be resold at a deep discount perhaps for off-grid uses. However, the primary method of disposal is shipping to accredited facilities on the mainland. Typically, this requires containerization and the cost of freight so it can be expensive.

As more and more systems age and need replacing disposal will become a major problem for Hawaii. Until a recycling facility is available the burden of disposal will continue to be a challenge and an expensive cost of repowering.

Another issue that may arise is the interconnection agreement with HECO. The original system was probably installed under a Net Energy Metering (NEM) agreement which allows excess power to be stored and then returned to the system owner when needed (typically at night). If the new system is the same size or smaller there is no need to amend or change the interconnection agreement. However, if the system is larger due to increases in usage then a new interconnection agreement may be necessary. Owners should avoid losing their original NEM. If they want or need to add system size, they can apply for a NEM+. For example, if the original NEM was for 75kW and the new system is 100kW, they can keep their original NEM and apply for the additional 25kW under the NEM+ program. It is best to have the solar contractor notify HECO of the change of equipment.