Photovoltaic (PV) systems convert sunlight directly into electricity. They work any time the sun is shining, but produce more electricity when intense sunlight strikes the PV modules directly. When sunlight interacts with semiconductor materials in the PV cells, electrons are freed and subsequently captured to create an electric current.

PV systems are made up of solar cells; multiple solar cells are connected to form a PV module. A PV system connected to the utility grid includes these components:

• One or more PV modules
• An inverter, which converts the system's direct current (DC) electricity into alternating current (AC) electricity
• Batteries for energy storage or backup power in case of a power interruption or outage (optional)

AC electricity is compatible with the utility grid and is used to power our lights, appliances, computers, and televisions. Appliances that run directly on DC power are available, but can be expensive.

Things to Consider Before You Buy a PV System

• PV systems produce power intermittently because they only work when the sun is shining.
• Photovoltaic systems connected to the grid get additional electricity automatically from the utility; non-grid or stand-alone PV systems require batteries to store energy for later use.
• PV power requires a high initial investment; you can lower the cost of your system by taking advantage of State of Hawaii and federal tax credits and incentives. Most people see their Payback within 5 years!

Is your home a good place for a PV system?

To make the best use of your PV system, the PV modules must have a clear "view" of the sun for most or all of the day—unobstructed by trees, roof gables, chimneys, buildings, and other features of your home and the surrounding landscape. Some potential sites for your PV system may be bright and sunny during certain times of the day, but shaded during other times. Such shading may substantially reduce the amount of electricity your system will produce.

The orientation of your PV system affects its performance. The best location for a PV system is typically a south-facing roof, but roofs that face east or west may also be acceptable. Flat roofs are ideal.

Solar modules can also be placed on the ground, either on a fixed mount or a tracking mount that follows the sun. Other options (often used in multifamily applications) include mounting structures that create covered parking or provide shade as window awnings.

PV systems work best in energy-efficient buildings. Adding insulation and energy-efficient lighting, appliances, and windows can reduce your home's overall electricity use.

Our experienced consultants can help determine whether your home is suitable for a PV system, contact us today.

How much space does a PV system require?

Some residential PV systems require as little as 50 square feet (for a small starter system) or as much as 1,000 square feet.

Some PV modules offer more efficiency per square foot than others and thus need less surface area to create a given amount of electric power, but they are typically more expensive. System sizing should be discussed with your PV provider.

What kind of roof do you have, and what is its condition?

An experienced solar installer will be able to mount a PV system on to any roofing material and eliminate the possibility of leaks. Composition shingles make for the easiest installations, slate shingles are the most difficult.

If your home will be in need of a new roof in the near future, you may want to replace it at the time of PV system installation in order to avoid future removal and reinstallation costs. In fact, PV panels can often be integrated into the roof itself; some modules are even designed to mimic roofing materials. These systems can offset the cost of roof replacement.

How big should your PV system be?

Consider what portion of your current electricity needs you would like your PV system to meet. Examine your electric bills over the past 12 months, and work with your PV provider to determine what size PV system you need to achieve that goal.

Other factors to consider:

• Some solar rebate programs are capped at a certain dollar amount; a solar electric system that matches this cap will maximize solar rebate benefits
• To qualify for the DER program in some service territories, your PV system must have a peak generating capacity

State of Hawaii and federal tax credits are available to help offset the cost of your PV system. To learn more, visit Tax Credits and Incentives.

DER Program

In October 2015, the Hawaii Utilities Commission (PUC) announced the Distributed Energy Resources (DER) program will replace the Net Energy Metering (NEM) program for new PV customers. The DER program includes a Grid Supply program, which allows rooftop PV customers to send extra energy to the grid in return for energy credits on their monthly electric bills, as well as a Self-Supply program, which allows rooftop PV customers with energy stroage, such as our Home Energy Storage Site (HESS), to capture excess solar power for their home and business.

Existing NEM customers and those who filed applications for the program before October 13, 2015 are unaffected by these changes. However, if these customers want to modify their PV systems they will be required to adopt the Grid Supply or Self-Supply program. The NEM+ program allows a NEM customer to add PV as a non-export system.

For more information on the DER program, see Your Guide to PUC's Energy Program Reform.