Page 154 - Solar Power in Building Design The Engineer's Complete Design Resource

124 SOLAR POWER GENERATION PROJECT IMPLEMENTATION

The project was constructed in two phases. The first phase was completed from 1988
to 1994, and the second phase began in 1999 and was completed in 2002. The present
net power output of the photovoltaic power system is rated at 3.6 kW ac. The solar
power generation consists of two systems; one is installed in the garden, and the other
in the kitchen above the counter, which also serves as a solar window for the adjacent
interior greenhouse. The kitchen solar power panels are building-integrated photo-
voltaic (BIPV) panes custom-manufactured by Atlantis Energy. They are built with
quadruple-pane tempered glass panels that sandwich Shell Solar Power Max cells by a
lamination process; dc-to-ac power conversion is achieved by the use of two stacked
Trace SW-4048 inverters and Outback MX-60 charge controllers.
The roof-mount solar BIPV panes are secured to the building structure at an angle
that matches the pitch of the rest of the roof, which is about 32 degrees up from the
horizon, in close proximity to the optimal angle matching the geographic latitude for
an equinox alignment that favors the winter sun angle.
The battery backup system has a 1600-A/h backup capacity. The batteries alternate
between a float status and net metering without the local utility—a rural electric
cooperative.
The total system, including all underground infrastructure and the battery storage
and monitoring equipment, but excluding the owner’s installation time, cost about
$80,000 or about $23/W, somewhat expensive compared to off-the-shelf type equip-
ment, but it is a totally unique solar integrated solution in harmony with the indoor
greenhouse environment.
Metering is dual-rate “time of use,” and the utility consumption averages
1400 kWh/month. Even with recent electricity rate increases, the average monthly bill
is $130/month. The owner also pays a $15 monthly fee to participate in the green power
program offered by the local utility. The owner estimates that the monthly saving result-
ing from use of the solar power system amounts to at least $200/month. The owner’s
average propane bill now ranges from $80/month in the summer to about $250/month
in the winter. Without the solar thermal system installation, his summer bill would
range from $150/month and his winter bill would be over $600/month, an average of
a 60 percent energy cost savings.
At present, the state of New Mexico does not have a cash rebate program, although
as of 2006, with federal and newly passed state incentives the owner will be able to
claim a 30 percent average tax credit from both federal and state governments.
Elsewhere in New Mexico, Public Service of New Mexico (PNM) has instituted
a 13 cent/kWh production credit feed-in tariff within its service in the Santa Fe and
Albuquerque areas.

Commercial Applications

The following plans are provided for illustrative purposes only. The actual design cri-
teria and calculations may vary depending on the geographic location of the project,
cost of labor, and materials, which can significantly vary from one project to another.
The following projects were collaborations among the identified organizations.