Page 166 - Alternative Energy Systems in Building Design

142 SOLAR POWER SYSTEM PHYSICS AND TECHNOLOGIES

■ Labor wages (prevailing or nonprevailing) and site supervision (project management)
■ Engineering design, which includes electrical, architectural, and structural disciplines
■ Construction drawings and reproduction
■ Permit fees
■ Maintenance training manuals and instructor time
■ Maintenance, casualty insurance, and warranties
■ Spare parts and components
■ Testing and commissioning
■ Overhead and profit
■ Construction bond and liability insurance
■ Mobilization cost, site office, and utility expenses
■ Liquidated damages

Energy cost factor On completion of the preliminary engineering study and solar
power-generation potential, the designer must evaluate the present costs and project
the future costs of the electrical energy for the entire life span of the solar power system.
To determine the present value of the electrical energy cost for an existing building,
the designer must evaluate the actual electric bills for the past 2 years. It should be
noted that the general cost per kilowatthour of energy provided by service distributors
consists of numerous charges, such as commissioning, decommissioning, bulk purchase,
and other miscellaneous cost items that generally appear on electric bills (and vary
seasonally) but go unnoticed by consumers.
The most significant of these charges, which is in fact a penalty, is classified as peak-
hour energy. This charge occurs when the consumer’s power demand exceeds the estab-
lished boundaries of energy consumption as stipulated in tariff agreements. In order to
maintain a stable power supply and cost for a unit of energy (a kilowatthour), 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 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 statis-
tics and demographics of the territories served to project power-consumption demands,
which then form the baseline for the energy purchase agreement. When energy con-
sumption exceeds the projected demand, it becomes subject to a much costlier tariff,
which generally is 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 $8–$9, as shown in Fig. 3.72. The
unit cost encompasses all turnkey cost components, such as engineering design docu-
mentation, 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