IN THE WAKE OF THE JANUARY 1998 ICE STORM
The January 1998 ice storm in Northern New York, Quebec, Vermont, New Hampshire and Maine caused severe damage to electric power transmission and distribution lines. Several million customers were affected by lengthy power outages. Some outages lasted several weeks.
Several of the costliest consequences of the outage could have been avoided if only a fraction of the electrical power normally available from the utility power grid had been available to customers.
Reasonably sized PV systems (i.e., 1-2 kW for individual residences) would have supplied enough energy to power refrigerators, emergency lights, computer and communication equipment as well as [non-electric] heating systems.
This assertion is based on a site time specific monitoring of the solar
resource following the ice storm, using cloud cover data from geostationary
weather satellites. The viability of this methodology has been thoroughly
assessed and presented in numerous publications by the author [1,2,3,4]
PHOTOVOLTAIC AVAILABILITY AFTER THE ONSET OF THE STORM
The satellite image in figure 1 shows that there were large areas of cloudless conditions in the regions affected by the storm, in the days that followed its onset.
Figure 1: Satellite view of the Northeastern US on January 12, five days after the onset of the storm
Figure 2: Global irradiance near Plattsburh, New York
Regionally, the map presented in Figure 3 shows that the average hourly
output of a 1 kW-ac PV system in the area affected by the storm would have
been of the order of 120-160 Watt, that is 2.9-3.8 kWh per day. This regional
map is based on the analysis of 150 satellite images. The uncertainty in
the average PV output is of the order of ± 20%.
Figure 3: Average hourly output of a PV array throughout the northeastern United States for the 2-week period following the onset of the storm
Therefore, a typical 2 kW residential PV system with a 10 kWh emergency
battery storage (2 average days' output) would have been able to sustain
a 250-300 Watt continuous load. This is more than enough to sustain all
critical loads. Meeting these critical loads would have considerably lessened
the financial impact of the storm for the affected customers.
Photovoltaic is considered by many as an attractive, environmentally safe and renewable source of electrical power. The advent of net metering legislation and other existing or pending incentives (e.g., New York's 25% tax credit) are bringing residential PV systems closer to economic feasibility, particularly if the systems can be financed through mortgages.
The added benefit of user-side power output reliability, demonstrated through this case study (as well as other power outage case studies by the author and colleagues [5,6]), should further increase the economic attractiveness of PV to all concerned parties: end-users, the insurance industry, governments and utilities (power distributors). The concerned parties should work toward incorporating these benefits into tangible financial decision-making elements: e.g., subsidies, enhanced tax incentives, or enhanced net metering schemes such as have been pioneered in several European locations.
Acknowledgement: This study was made possible thanks to the ongoing support of NREL for the acquisition of satellite data archives (NREL contract XAH-515-222-01) and their analysis to investigate the impact of PV on regional and local electric loads (NREL contract XAD-817-671-01). Thanks to Marek Kmiecik for processing of satellite data.