PV Installation Guide
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2.8. Overall Project Coordination
Once the decision is made to install a PV system, several issues must then be addressed.
2.8.1. Utility Considerations
The electric utility company providing service to the residence plays a very important role in this process.
Interconnecting a PV system to the utility grid is not a trivial undertaking. Fortunately, PV has a welldeveloped
set of utility interconnection standards making the process fairly straightforward. However, utilities
are generally cautious since most have little experience interconnecting PV systems. The key point is to
involve the utility as early as possible in the installation. Most knowledgeable utilities have adopted IEEE
929-2000 Recommended Practice for Utility Interface of Photovoltaic (PV) Systems. If the utility is unfamiliar
with this document, make sure that they obtain a copy and thoroughly review it.. An inverter listed to UL 1741
(with the words "Utility-Interactive" printed on the listing mark) indicates that the unit is fully compliant with
IEEE 929-2000.
The other major utility-related consideration is metering requirements. In California, as in many other states,
there is legislation mandating utility companies to “net-meter” a certain amount of PV systems. Net metering
refers to a standard house utility meter that measures the flow of electricity in and out of the home2. California
law allows customers to carry-over excess energy from month-to-month with an annual true-up and payment of
the electrical bill for any net consumption over the whole year. The net metering law does not require the utility
to compensate the customer for excess electricity at the end of that 12-month period. For more information
about this and other consumer-related PV issues, download the document, Buying a Photovoltaic Solar Electric
System: A Consumers Guide, from the California Energy Commission’s website at
http://www.energy.ca.gov/reports/500-99-008.PDF or call 1-800-555-7794 (Renewable Energy Call Center) to
receive a copy by mail.
2.8.2. Acceptance of Systems (performance evaluation)
Typically, the installer verifies that the system has been installed according to the manufacturer’s
procedures. A checkout procedure should be developed, such as the one provided in section 4 of this guide,
to ensure an efficient and complete installation. Obtaining extremely accurate performance is difficult and
requires expensive test equipment. Fortunately, it is not necessary to define the performance with extreme
accuracy. A system can be checked with some common test equipment to verify proper installation and
performance. A key to keeping the system testing simple is to do the tests on cloudless days. Clouds can
cause fluctuations that confound evaluation of the results. The PV System Installation Checklist that
accompanies this guide has a detailed System Acceptance Test.
2.8.3. System Documentation
Up to this point, selection, installation, and performance of PV systems have been discussed. Of similar
importance are operation and ongoing maintenance of the equipment. As with other major systems in a
home, it is essential that the owner have complete documentation on the system. System documentation
should include an owner’s manual and copies of relevant drawings for whatever system maintenance might
be required in the future.
2.8.4. System Monitoring
The key component of the system providing feedback to the customer is the power and energy metering.
Without proper metering the customer will never know whether the system is operating properly or not. A
simple meter, registering the power output of the PV system and recording the energy delivered to the
house, can provide the owner with the satisfaction that they can monitor the performance of the system.
2 Yes, out! Even a 500-Watt PV system on a sunny day may generate more electricity than the home
consumes at any given time.
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June 2001 Page 13
Maximum power output of most properly installed PV systems occurs near midday on sunny days in the
spring and fall. If the owner fully understands this characteristic they will not be disappointed with
unavoidable low output in the middle of the winter. The meter is also a way of proving to the owner that the
equipment is properly installed. Often, the owner’s primary indication of whether they feel the system is
operating properly on not is their monthly electric bill. If the owner suddenly begins using more electricity,
they may not see much decrease in their bill and assume the PV system is under-performing. A meter can
help avoid disputes between the installer and the owner by showing that the system performs as advertised.
One of the attractive attributes of PV system is low maintenance. However, even electrical systems need to
be maintained from time to time. With proper metering, an informed owner can easily determine if their
system is operating properly or not. It is important that the owner have contact information for contractors
that can perform system maintenance in their area. Although many areas do not have full-time PV
contractors, it is always helpful to provide a list of two or three local contractors that offer PV maintenance
services. Along with the information on local contractors, the system warranty information should be provided
so that the customer clearly understands what is and is not covered by their warranty.
2.9. References
1999 National Electrical Code (NEC) Article 690 and Article 702.
Emerging Renewables Buy-Down Program Information: http://www.energy.ca.gov/greengrid
Buying a Photovoltaic Solar Electric System: A Consumers Guide:
http://www.energy.ca.gov/reports/500-99-008.PDF
Clean Power Estimator: http://www.energy.ca.gov/cleanpower/index.html
List of Certified PV Modules: http://www.energy.ca.gov/greengrid/certified_pv_modules.html
List of Certified Inverters: http://www.energy.ca.gov/greengrid/certified_inverters.html
California Energy Commission, 1516 9th Street, Sacramento, CA 95814-5512, 800-555-7794
(Renewable Energy Call Center)
UL Standard 1703, Standard for Flat-plate Photovoltaic Modules and Panels
UL Standard 1741, Inverters, Converters, and Controllers for Independent Power Systems
IEEE Standard 929-2000, Recommended Practice for Utility Interface of Photovoltaic (PV) Systems
IEEE Standard 1262-1995, Recommended Practice for Qualification of Photovoltaic (PV) Modules
Environmental benefits of PV systems can be found at the following USEPA website:
http://199.223.18.230/epa/rew/rew.nsf/solar/index.html