Page 187 - Alternative Energy Systems in Building Design

ENERGY-EFFICIENCY AUDIT 163

must have UL certification and performance specifications that would allow program
administrators to evaluate its performance.
According to CEC certification criteria, all grid-connected PV systems must carry
a 10-year warranty and meet the following certification requirements:

■ All PV modules must be certified to UL Standard 1703.
■ All grid-connected solar watthour meters for systems under 10 kW must have an
accuracy of ±5 percent. Watthour meters on systems generating more than 10 kW
must have a measurement accuracy of ±2 percent.
■ All inverters must be certified to UL Standard 1741.

PV System Sizing Requirements

It should be noted that the primary objective of solar power cogeneration is to produce
a certain amount of electricity to offset a certain portion of the electrical demand load.
Therefore, power production of PV systems is set in a manner so as not to exceed the
actual energy consumption during the preceding 12 months. The formula applied for
establishing the maximum system capacity is

Maximum system power output (kW) = 12 months of previous energy
used (kWh)/(0.18 × 8760 h/year)

The factor 0.18 × 8760 = 1577 h/year can be translated into an average of 4.32 h/day
of solar power production, which essentially includes system performance and derating
indexes applied in CEC PV system energy-output calculations.
The maximum for PV systems under the present CSI incentive program is limited
to 1000 kW, or 1 MW. However, if the preceding calculation limits permit, customers
are allowed to install grid-connected systems of up to 5 MW, for which only 1 MW
will be considered for receiving the incentive.
For new construction, where the project has no history of previous energy con-
sumption, an applicant must substantiate system power-demand requirements by
engineering system demand-load calculations, which will include present and future
load-growth projections. All calculations must be substantiated by corresponding
equipment specifications, panel schedules, single-line diagrams, and building energy
simulation programs, such as eQUEST, EnergyPro, or DOE-2.

Energy-Efficiency Audit

Recent rules enacted in January of 2007 require that all existing residential and
commercial customers, when applying for CSI rebates, provide a certified energy-
efficiency audit for their existing building. The audit certification, along with the