Latest reports indicate the solar photovoltaic industry will produce 5 GW of power in the U.S. and grow 30% in 2013. Little is written, however, about what impact solar storm and electromagnetic pulse (EMP) threats may have upon the survivability and continued market growth of the solar industry.
An EMP event elsewhere in the world that burns out all of the solar panels in the region could have serious impacts on future solar market growth.
Survival and performance of solar panels must become part of a solar rooftop optimization. This article emphasizes electromagnetic threats since they have the biggest impact and present the biggest challenge.
The electromagnetic threat problem
Power outage from hurricanes, tornadoes, tsunamis and earthquakes may range from five square miles to less than 1,000 square miles, for a day or so. The ground area of an electric grid blackout from a nuclear EMP burst may range from 100,000 square miles to one million square miles, or more. The outage from an EMP detonation may run into years, where the worst of more conventional outages is typically weeks.
Between these two threat classes are severe solar storms that may result in severe geomagnetic storms, causing loss of power of a year or more due to DC-like geomagnetic currents in unprotected large AC high-voltageÂ transformers.
Basic solar panel installations are resistant to the severe solar storm threat since solar storms are only a threat to equipment like the large transformers at central generating stations and substations.
Distributed power systems, such as grid-interconnected solar, could keep the local power grid partially operational during a severe solar storm as long as sufficient solar power is available to the grid. Solar storms would not harm the actual power lines, and it is very unlikely that distribution transformers – such as those on power poles – would be affected.
Thus, this article will focus on the nuclear EMP threat, against which properly designed shielded solar panel systems can be protected.
For protection against an EMP threat, generators are not practical. During any very long-term outage of the primary power grid there would be extreme difficulties in obtaining replacement fuel supplies. Also, unless the generator control circuitry were EMP protected, it would be burned out.
Preparing the solar rooftop
It may be cost effective for some building owners contemplating a solar rooftop installation to pay a relatively small extra expense as insurance to prepare the solar roof for a subsequent EMP protection update. This can be done on an average sized home by first placing bonded sheets of 1/64 inch (0.4Â mm) aluminum for roughly $2,000. This can later become a critical part of a shielded building and mounted solar panels.
If and when it is decided to EMP protect the building, the top side can have a welded screen-wire mesh cover the solar panels and and all their interconnected wiring. The wire mesh solar shield is bonded to the aluminum sheet around the entire outside periphery of the solar rooftop installation using one of a few techniques. This entirely encloses the solar panels and their interconnecting cables.
The above procedure will be changed in a few years as solar manufacturers build the wire mesh shield internally within the panels.
It makes a significant difference in price if the EMP protection is to be added to a new building rather than an existing building. For a new building, the shielded installation may cost 30-50% less.
Much of the problem with retrofitting an electromagnetic shield is completely covering the building with a shield that not only covers the top and sides but tries to cover the foundation footprint of the internal room walls. This is easily done in a new building where sheet metal can cover the entire foundation before walls are erected. The foundation sheet metal is then readily bonded to the shielded facade external walls.
Details are discussed in the 3rd edition of EMP Protect Family, Homes and Community, available at Amazon.
The windows are covered with a shielded wire mesh grid similar to the top of the shielded solar panels. The outside doors have a bonding finger stock around the entire periphery to ensure there is no electromagnetic shield leakage.
Compliance testing and certification
Open-air EMP test certification cannot be done using the industry-standard 50,000 V-per-meter pulse for a standard solar panel system since everything in the area would be burned out by the high level pulse.
Instead, take advantage of the fact that any pulse can be broken into a range of frequencies. SevenÂ discrete frequencies are chosen to test for a required 74 dB shielding effectiveness using readily available test instruments from the electromagnetic compatibility test community.
The test transmitter is a radio frequency (RF) sweeper or oscillator driving an RF amplifier, which then drives transmitting antennas. They are usually located in the bed of a pickup truck. The building receiver site has a receiving antenna driving a tracking receiver located next to the building being tested.
The test is repeated at the same seven test frequencies with the receive antenna inside of the building. The engineer can then determine the shielding effectiveness of the building. This can be repeated on all four sides of the building. If all frequencies at all sides indicate a shielding in excess of 74 dB, the building is in EMP protection compliance. If not, additional EMP protection in design and/or installation is needed. For larger protected buildings, the test transmitter may be located in a helicopter.
EMP protection can be carried out using widely-known methods to ensure that homes or entireÂ communities can be protected against an EMP event. A shed, home or a larger building can be EMP protected, along with protected solar power. The electromagnetically shielded solar rooftop installation allows occupants to enjoy a continued modern lifestyle after any electromagnetic event.
Don White is CEO of EMP Solutions and co-author of EMP Protect Family, Homes and Community. He is past president of the IEEE Electromagnetic Compatibility Society. He can be reached by email at firstname.lastname@example.org.
Jerry Emanuelson is co-author of EMP Protect Family, Homes and Community. He can be reached by email at email@example.com.