Page 288 - Solar Power in Building Design The Engineer's Complete Design Resource

PROJECT COST ANALYSIS 255

numerous charges such as commissioning, decommissioning, bulk purchase, and
other miscellaneous cost items that generally appear on electric bills (that vary sea-
sonally) but go unnoticed by consumers.
The most significant of the charges, which is in fact a penalty, is classified as
peak hour energy. This charge occurs when the consumer’s power demand exceeds
the established boundaries of energy consumption as stipulated in tariff agree-
ments. In order to maintain a stable power supply and cost for a unit of energy
(a kilowatt-hour), service distributors, such as Southern California Electric (SCE)
and other power-generating entities, generally negotiate a long-term agreement
whereby the providers guarantee distributors a set bulk of energy for a fixed sum.
Since energy providers have a limited power generation capacity, limits are set as
to the amount of power that is to be distributed for the duration of the contract. A
service provider such as SCE uses statistics and demographics of the territories
served to project power consumption demands, which then form the baseline for
the energy purchase agreement. When energy consumption exceeds the projected
demand, it becomes subject to much costlier tariffs, which are generally referred to
as the peak bulk energy rate.

Project Cost Analysis

As indicated in the preliminary solar power cogeneration study, the average installed
cost per watt of electric energy is approximately $9 as shown in Figure 9.6a to c.
The unit cost encompasses all turnkey cost components, such as engineering design
documentation, solar power components, PV support structures, electric hardware,
inverters, integration labor, and labor force training. Structures in that cost include
roof-mount support frames and simple carport canopies, only. Special architectural
monuments if required may necessitate some incremental cost adjustment. As per the
CEC, all solar power cogeneration program rebate applications applied for before
December of 2002 were subject to a 50 percent subsidy. At present, rebate allotments
are strictly dependent on the amount of funding available at the time of application and
are granted on a first come, first serve basis.

MAINTENANCE AND OPERATIONAL COSTS

As mentioned earlier, solar power systems have a near-zero maintenance require-
ment. This is due to solid-state technology, lamination techniques, and the total
absence of mechanical or moving parts. However to prevent marginal degradation in
output performance from dust accumulation, solar arrays require a biyearly rinsing
with a water hose.
Figure 9.6 is a detailed estimate, designed by the author, for a solar power project for
the Water and Life Museum located in Hemet, California. As discussed in Chapter 3 the
project consists of two museum campuses with a total of seven buildings, each con-
structed with roof-mount solar power PV systems.