Rooftop Solar

As your electric cooperative, we are your source for energy and information. Interest in solar power to help residents and businesses save money while contributing to our efforts to generate more power with renewable energy is growing.

Before installing a system, rules established by the Hawai’i Public Utilities Commission require customers to submit an interconnection request application to KIUC for an engineering review.

This step is extremely important and ensures that the PV system can be safely and reliably tied into the utility grid and make sure you understand the rules of the interconnect agreement.

A PV system is a large, long-term financial investment and it’s important to understand your options and obligations before deciding.

Rooftop Solar FAQ's

Download an interconnection request application and read the rules governing interconnection in Tariff No. 2 – Distributed Generation – Interconnection Policies and Procedures.

If your system is going to be 10kW or less, which is the case with most residential systems, look for Tariff No. 2, Attachment 5. If your system is greater than 10kW, look for Tariff No. 2, Attachment 2. Applications are also available at our office.

The Hawai‘i Public Utilities Commission requires customers to submit an application to KIUC for an engineering review. This step is extremely important and ensures that the PV system can be safely and reliably tied into the utility grid. This step also allows us to tell you whether you will have to pay any interconnection costs. For example, the size of your system may require us to install a larger transformer. The engineering review will describe the interconnection costs, if any, and we can recommend ways to reduce your costs by changing the size of your proposed system.

For systems producing less than 10 kW, which are most residential systems, KIUC will acknowledge receipt of the application within five business days. KIUC will then evaluate the application and will notify you within 15 days of the receipt of the application whether additional information is needed or if the application is complete.

For systems larger than 10 kW, KIUC has 20 business days to acknowledge receipt of the application. KIUC then has 30 business days to review the application. If the application is approved, KIUC will send an interconnection agreement and the customer has 30 business days to sign and return the agreement. If the application is not approved, KIUC has 10 business days to schedule a meeting with the customer to discuss their options.

Schedule Q is the program by which KIUC pays you for the excess power you generate. The rate changes monthly and it reflects the amount KIUC would have had to pay to generate the power if we didn’t buy it from you. Because KIUC generates most of its electricity by burning oil, this so-called “avoided cost” calculation is tied to the price of oil. As more renewables come on line and KIUC burns less oil, the amount paid under Schedule Q is expected to drop.

There’s a limit to how much PV our system can take. On a sunny afternoon when all of the PV systems on the island are at their maximum output, there is often more power being generated than there is demand. So there may be times when our system won’t accept all of the solar power available. That’s known as curtailment (refer to Curtailment FAQ’s for more information on curtailment).

Curtailment FAQ's

KIUC frequently has more solar resources feeding into the grid than it has load during sunlight hours. When the amount of solar exceeds the demand for energy, KIUC must reduce the amount of solar energy feeding into the grid. This is called curtailment, and it potentially impacts KIUC’s Schedule Q customers who have installed an “oversized” system. Oversized systems generally produce significantly more electricity than is needed to meet the household’s average daytime energy demand. As part of their interconnection agreement, these customers were required to install a separate curtailment meter, and are therefore subject to curtailment. The below chart specifies the maximum size PV system, based on average monthly usage, in order for the system to be “right sized” and to avoid having to install a curtailment meter upon interconnection.

Right-Sizing Criteria

Average Monthly Usage in kWh	Maximum PV Size
0-500	2.5kW
500-800	2.75
800-900	3.00
900-1000	3.5
1000-1100	3.75
1100-1200	4.25
>1200	5.25

KIUC’s rights are consistent with its obligations, which in regards to interconnecting non-utility power generating resources, is the requirement that KIUC maintains a safe, stable, and reliable electric grid. This is important to ensure that all of KIUC’s members receive quality power service. To meet this obligation, KIUC has the right to place conditions on customer interconnections if a customer desires to interconnect with KIUC’s grid. KIUC’s curtailment policy was implemented in November 2015 and is part of each customer’s interconnection agreement if they applied for a new system, added to their existing system, or made a change to their system after that date. A curtailment meter was required only if PV size was above the calculated “right size” for their home at that point in time (see table above). A copy of the standard interconnection agreement is attached with the appropriate sections highlighted in yellow.

Our current interconnection agreement includes a condition requiring that the interconnecting customer grants KIUC the right to curtail a customer’s system (if it is larger than the specified “right size”) in exchange for KIUC granting the customer the right to interconnect with KIUC’s grid. The specific language in KIUC Schedule Q Modified Agreement, Exhibit 1 states, in relevant part, “Notwithstanding anything to the contrary, the Eligible Customer-Generator’s generating facility may be temporarily disconnected from KIUC’s system during periods of high solar penetration on KIUC’s system and as deemed appropriate by KIUC to ensure overall reliability of its system.”

The customer is required to install a curtailment device and accept the condition stated in their Schedule Q/Interconnection agreement in order to be given the approval to interconnect with KIUC’s grid.

As specified in the agreement, the member who wishes to oversize his/her system must install a separate meter specifically for the purpose of curtailment of the solar generating facility. If curtailment is necessary, KIUC will use a wireless meter to send a signal that will turn off the member’s rooftop system via the curtailment meter. KIUC will turn the system back on when the curtailment period is over.

It is necessary for KIUC to curtail solar resources when the energy generated by solar exceeds the demand for electricity on the grid. One trigger would be sunny, cold weather conditions, when solar is in abundance and load is generally lower than normal. However there are any number of circumstances where there is an imbalance of available load and renewable generation levels which can vary greatly.

Those decisions are made on any given day depending on a number of factors, the most important of which is maintaining a reliable and safe dispatch of power to the grid. Other factors include minimizing cost to members (i.e. curtailing the most expensive source of power versus the least expensive), maintaining adequate response capabilities based on the expected duration of the curtailment event, and insuring that enough “spinning reserve” is available to cover the single largest generator on line at any given time.

It is best to consult with your solar contractor on options available. Options could include splitting your system or adding a battery for energy storage.

We encourage members who have questions about their interconnection agreement and curtailment to contact us directly. They may also work with their solar contractor for any options that would minimize the impact of curtailment.

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Rooftop Solar

Rooftop Solar FAQ's

Curtailment FAQ's

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I’ve decided to put in a PV system. What is the first step?

Why do I need to submit an application?

How much does the application cost?

How long does the application process take?

What is Schedule Q?

Will KIUC always buy the extra energy my PV produces?

Do you have any suggestions on who I should select to install my PV?

If I have additional questions regarding the interconnection process, who do I call?

Why am I being curtailed?

What gives KIUC the right to curtail my system?

Where specifically does it state that KIUC can curtail my system?

How does KIUC carry out curtailment?

Why is curtailment necessary?

Does KIUC have options other than Schedule Q customers when it comes to curtailment?

How does KIUC decide which generation sources to curtail?

Does KIUC automatically curtail Schedule Q customers first?

What other options are available to me if I currently have a curtailment meter?

Schedule Q Modified Agreement

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Kauai Island Utility Cooperative providing reliable, renewable energy for Kauai.