Hawaii County Permit (it’s the law)

Hawaii County requires a building permit.

For residential PV system the additional requirements are
(a current version of this list is available at County building permit office):

•   Permit application with payment.
•   Electrical engineered stamped system schematic drawing (there is a detailed list of  requirements; the Electrical Engineer will know what he needs).
•   Plot plan showing module layout, inverter and disconnect locations.
•   PV Module spec sheet.
•   Inverter spec sheet.
•   AC/DC Disconnect spec sheet.

Collect all the information and the Electrical Contractor will file the permit.

Installation (at last)

Hawaii County and HELCO require a Licensed Electrical Contractor to do the work, I got bids from D R Electric and Powers Electric.

The rails and panels were installed by Gary Vant Riet. The electrical work was done by Powers Electric, tidy and timely so I was happy.

Keep out of the way, and let somebody else do the work for a change. The Electrical Contractor will arrange for the County permit inspection. The County inspection occurred one week later.

The new AC disconnect switch is on the right (with the warning label), and the new conduit (from the inverter) going up to the roof is on the left. The inverter and the disconnect switch are located back to back on the same wall.

In the event I need to replace my roof I would have to remove the panels, rails, and combiner box. Then reinstall the same components after replacing the roof.

HELCO Agreement (just when you thought..)

Next, HELCO requires a ‘Net Energy Metering Agreement’. Complete the first page and give the form to the Electrical Contractor. The Electrical Contractor will submit the Agreement and the county permit to HELCO . HELCO replaced the electricity meter with one that separately records electricity flow into, and out of, the grid; and informed me I could turn on the system. I am billed on the difference between these two, plus a connection charge.

HELCO has a minimum billing charge of $20, which includes the connection charge and “about 30kWh” of  electricity from HELCO.

The new electric meter cycles through four displays:

•   0) Display test
•   1) 50000 + net energy supplied by HELCO
•   2) Total energy from HELCO used by house (i.e. at night)
•   3) Total energy sent by house to HELCO  (i.e. during the day)

Note: The second display will be less than 50000 if on average the house  generates more electricity than it uses. The fourth display ‘Total energy sent by house to HELCO’ will show a number that is less that the ‘Total energy generated’ displayed by the inverter, because some of the generated energy is used immediately by the house and does not propagate through the meter to HELCO. In my case about 25% of the generated energy is immediately used by the house.
 
HELCO is only required by law to accept a certain fraction of its total generating capacity to be sourced from net metering. When that limit is reached HELCO is no longer required to accept Net Energy Metering Agreements. So the opportunity to use Net Metering will only be available on a limited basis, first come first served.  Currently the limit is, I believe, 0.5% of HELCO’s peak usage – I have no idea how many houses that would be. The PUC is authorized to increase that limit. A limit is necessary to allow HELCO the manage it’s business; but peak usage is around sunset and peak solar generation about 6 hours earlier and there are no energy storage system on the island – so IMHO the way the rules are written is totally frelled.

Sanity Check

Applying Norton’s Theorem and reading from the inverter
and the HELCO meter for the first 10 days:

Energy Used = Energy from HELCO + Energy from Solar— Energy to HELCO

                       =  56 + 83—61  kWh

                       = 78   kWh

                      = 7.8 kWh/day

Which is fairly typical energy usage for the period prior to the system installation (see the snippet from my old electricity bill on this page). So I conclude all the meters are about correct and the results are reasonable.

A ‘How To’ for Grid-Tie PV on the Big Island of Hawaii

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