The following dissertation was the work of Jamie Johnson, the founder of Verde Sustainable Solutions, L3C. While the work discusses PHEV battery technology, which was predominant in 2009, there is a great translation into Electric Vehicles. It would be appropriate to rename the work, “Converting Solar Energy into the Batteries used in Electric Cars and the PHEV Battery”.
Meeting the Energy Demand of the Future:
Charging Plug-in Hybrids from Solar Panels – Are There
Efficiencies to be Gained?
Harris School of Public Policy
University of Chicago
Masters of Science of Environmental Science Policy Candidate 2009
Direction from: Professor James Sallee, Ph.D.
Solar Panels generating electricity and Plug-in Hybrid Vehicles for transportation are both possible ways to help the United States reduce our global warming gas emissions. However, currently they are both unable to compete economically with traditional, low cost methods. Through this paper, I demonstrate an additional advantage to owning both a solar panel and a plug-in hybrid vehicle. This is achieved through the efficiency gains for avoiding Alternating Current (AC) to Direct Current (DC) conversions, and equates to $229.95 each year for a plug-in hybrid vehicle designed to drive 60 miles on each battery charge. I also use various interest rates and energy price changes to find present values of the $229.95 over 20 years, with values that range from $2,057.13 to $8,213.64. These values, after paying for equipment to realize this potential, represent the money that would offset higher capital costs of purchasing both pieces of equipment.
Solar Panel’s Future
In 1979, President Jimmy Carter installed solar panels on the roof of the White House that harnessed solar power to heat water for parts of the White House. At the time, he warned, “a generation from now, this solar heater can either be a curiosity, a museum piece, an example of a road not taken, or it can be a small part of one of the greatest and most exciting adventures ever undertaken by the American people; harnessing the power of the sun to enrich our lives as we move away from our crippling dependence on foreign oil” (Jimmy Carter Library and Museum News Release, 2007).
Unfortunately, an argument can be made that the solar panel from the white house became a museum piece and solar power has yet to make any significant entrance into the energy market. When President Reagan removed the panels in 1986, it demonstrated the country’s short term memory regarding the energy crisis of the 1970′s. Again, we have entered a pivotal place in our history as a country and it is interesting to wonder if today’s push for wind, solar, and hybrids will become more museum pieces, or if they will make a longer lasting entrance into the marketplace.
Global warming is a serious threat to the planet as we know it. The planet has seen its carbon dioxide levels increase from 280 parts per million in the atmosphere in the 1800′s to over 380 parts per million today (Intergovernmental Panel on Climate Change, 2007). While global warming gases actually enable the planet to retain heat and allow life to thrive, this rapid increase of carbon dioxide from manmade activity over the last century has led to a planetary crisis.
Why does solar power offer hope in regards to mitigating global warming gas increases? For the last century, power has been provided at the most inexpensive option through carbon producing sources such as coal, gasoline, and methane. Specifically, electricity provided in the United States through (49%) coal, (20%) nuclear, (7%) hydroelectric, (2%) petroleum, and (20%) methane (Energy Information Administration, 2007).
Coal, petroleum, and methane together account for 61% of electricity generation in the United States, emitting carbon dioxide in the process and increasing atmospheric quantities of this global warming gas. Nuclear power provides a carbon free form of electricity, although it has its own environmental critics in the storage of spent nuclear waste. Hydroelectric power generation also has its own costs to the environment, disrupting species and flooding large areas of land behind the dam. Hydroelectric is also very near its capacity in the continental United States and will not be able to increase with current technology to offset other carbon producers (Chiras, 2006).
Wind and Solar Power both provide an opportunity for growth in the United States, perhaps as an opportunity to offset carbon producing electricity. While both struggle to compete economically, they still continue to grow with the help of government subsidies. Part of the goal of this paper is to look at ways to increase the value of solar panels, without having to increase public subsidies and the economic contribution of society to provide these alternative energies.
Solar has much growth potential in the future. The efficiency of panels continue to increase, and prices for panels continue to drop. The industry is a technological breakthrough away from competing with grid electricity sources, although there are other factors that may influence solar market share.
A cap and trade regulation, which is expected to pass through congress in the coming years, will lead to an increase in electricity prices across the board (Paltsev et al., 2007). It will also lead to a market that is favorable to solar panel electricity generation through permit sales. As each industry in the power generation is allotted permits to produce carbon, solar power producers will sell their share to the other industries for revenue as the emit zero carbon.
In this paper, I attempt to look at an additional market force that may increase the value of solar panels for owners of plug-in hybrid vehicles. As both solar panels and plug-in hybrid vehicles have large capital costs, increased efficiencies will allow payback to occur faster on these investments.
Plug-in hybrid vehicles are cars that offer a hope of reducing Americans from oil demand, along with increasing the quality of local air by providing transportation with zero emissions for the first several miles of a trip. These vehicles are plugged in to charge overnight, and when that charge is depleted, a combustion engine kicks in to operate a car in hybrid fashion. These cars may get 100 miles on the first gallon of gasoline, as they may potentially travel 60 miles on a full charge and then drive 40 miles per gallon in hybrid fashion (Simpson, 2007). While the first mass produced cars are projected for 2010, today there are aftermarket kits available that convert regular hybrids into plug-in hybrids. These kits are currently prohibitively expensive, and depend heavily on the cost and quality of batteries to be viable (Simpson, 2007).
While these cars offer hope, they are not inexpensive and they still consume power in the form of electricity. If every household in the United States switched to using plug-in hybrid vehicles, the power generation would have to increase dramatically. With no inexpensive alternatives to carbon producers, coal would be the most likely candidate to match the increase in demand. Fortunately, most plug-in hybrid demand can be designed to charge late at night when electricity demand is low. In fact, marginal costs for producing electricity at night is much lower than daytime production as plants that require long start-up times must continue running and producing electricity regardless of demand (Panzar et al., 1981).
It seems intuitive that solar panels will not be able to directly charge the majority of plug-in hybrid vehicles, given the fact that most vehicles will be used during the day and charged at night. The point of this analysis, however, is to prove that there are quantitative efficiencies to be gained by doing so and that this economic value may potentially exceed the cost of equipment that would allow direct charging of a car with a solar panel. In this paper, I show that $2,057.13 to $8,213.64 (depending on the size of the battery and interest rate) can be saved by charging your car directly with a solar panel, instead of owning a solar panel and selling excess electricity back to the grid as normally occurs in households today. This economic incentive to directly charge your car provides a long term economic benefit to doing so and will increase the payback from solar electricity.
Direct Current (DC) Solar Power
Solar Panels currently are a much promoted green energy that does not use fossil fuels to produce electricity. While solar panels do not economically compete with coal or nuclear energy, they do fill a niche of energy production off of the grid and do eventually recoup costs when subsidized. Currently, a panel costs approximately $9 per watt to install; it is estimated that it would need to drop to $4.50 per watt to be competitively priced with the grid electricity (Algoso et al., 2005).
The amount of sunlight varies throughout the country, with the best state for solar energy, Arizona, receiving six hours of peak sunshine average each day (Arizona Solar Center, 2009). Illinois averages 4.4 peak hours of sunlight per day throughout the year, with more than 6 hours per day in the summer and closer to 3 per day in the winter (National Renewable Energy Laboratory 2009). I will be assuming 5 hours of solar peak sunshine per day for calculations based on an average for the country.
The average household uses 30 kilowatt*hours (kWh) each day of electricity (Energy Information Administration, 2009), so the average home would need a 6 kW panel if there were 5 hours of peak sunshine available on average throughout the year. This panel would cost $54,000 when purchased and installed for $9 per watt. At $4.50 per watt, this panel would cost half, or $27,000, for a panel that would provide the average American family electricity each year.
According to the National Association of Home Builders (2009), the average size residential home was 2,330 square feet in 2004. With the average home, the roof is pitched and only half of the roof may be ideal for panels if half of the roof faces North. One kilowatt panels require sapproximately 100 square feet(Environmental California Research and Policy Center, 2009), enabling 11.5 kilowatts of panels on the roof of the average house.
At five peak hours of Sun, 57.5 kWh of electricity could be produced on the average day, exceeding the 30 kWh household average. In fact, this roof would have enough room to produce both the electricity usage of the average family, along with enough electricity left over to charge the 25 kWh battery of a 60 mile battery for a plug-in hybrid vehicle (Simpson, 2007).
Furthermore, a home with a flat roof would allow for use of the entire roof, and therefore, allow space for a 23 kilowatt panel on the roof. The panel would need to be built on a slope that would face south, allowing for maximum sun exposure. While flat roofs are more common to industrial or commercial buildings, a future that maximes solar power would influence design of residential buildings. The flat roof on the average sized household could provide space for 23.3 kilowatt panels, or 116 kWh each day. In summary, the average house has enough space to accommodate panels producing enough energy to power a plug-in hybrid car with at least a range of 60 miles.
DC Power vs. Grid Power
Solar Panels are also only reaching efficiency levels of 18% at competetive costs, although efficiencies have been much greater at high costs designs (Lewis, 2007). A breakthrough in the costs for current efficiencies, or a breakthrough in a greater efficiency at a similar cost would positively impact solar panel markets in a dramatic fashion. The future is very optimistic for this source of alternative energy, especially in high sun locations.
Solar panels produce power in Direct Current (DC). When used in situation that are off the grid, DC power can be used to power everything in a household. Appliances in these situations are specially made to run directly on DC power, or converted into AC power if the appliance is uanble to run directly on DC. However, since the majority of appliances use Alternating Current (AC) power, DC power from solar panel are typically converted to AC power. This can be done at the panel or at each appliance through an inverter. Typically, the efficiency of converting DC power to AC power is around 90% (Haeberline et al., 2001).
The grid of electricity in the United States utilizes AC power. Every outlet in a normal house uses AC power, and the majority of appliances utilize AC power by design. The exceptions include anything that utilizes a battery, electronics, and all car electricity needs. Battery operated devices include ipods, cell phones, computers, along with anything that uses electronic circuits. Plug-in hybrid vehicles will also be run on DC power.
Most conventional sources of power generation also produce electricity in the alternating current form. Coal, Nuclear, and Natural Gas all are used to produce steam that spins a turbine. As the turbine spins, electricity is produced as one magnet circulates past another. Wind mills and hydroelectric dams also produce alternating current.
In the normal house, where AC power comes out of the electrical outlets, power for DC appliances must have a converter that turns the AC energy into DC power. Typically, this is the square box on the cord of a cell phone or laptop charger. The efficiency of this converter is typically below 87%, the efficiency required to be an energy star rated converter (Energy Star Program, 2007).
Following is a situation that is typical for a house that has solar panels on its roof. The solar panel produces electricity during the day. A $54,000 panel purchased for the typical household will produce approximately 30 kWh each day on average, or approximately 912 kWh each month. This power is either used, stored in a battery (DC power), or excess power generated is sold back to the grid at a lower price than purchased instead of stored in a battery.
In order to be used by the majority of appliances in the house, and in order to be sold back to the grid instead of stored in a battery, the power must be converted to AC at an efficiency of 90%. This efficiency means that if the solar panel produces 30 kWh throughout the day, only 27 kWh will actually be available by use in the household or available to be sold back to the grid.
Electricity produced by solar power is especially attractive to energy experts and electricity suppliers, as the production aligns with peak demand. This electricity production is advantageous, as often peak demand is met with high marginal cost producers, such as natural gas plants. Natural gas plants emit carbon dioxide, along with being expensive to produce each kWh of electricity.
DC to AC to DC
DC appliances in a solar panel home, such as computers, cell phones, or electronics, must convert the 27 kWh from the example before into DC power at an efficiency of 87%. This will make the overall efficiency of this conversion at 78%, or 23.5 kWh of the original 30 kWh produced at the panel.
While it is possible in theory to convert some of the power from the solar panels into AC and leave some as DC, the house itself would have to have separate wiring and outlets, along with a sophisticated system that could determine demand of each type of electricity and would be prohibitively expensive (Ikki et al., 2007).
While it seems unrealistic to change your original power back and forth multiple times in a house that has solar panels, prior to plug-in hybrid vehicles, the overall amount of electricity that a household uses is predominantly AC. Therefore, the small amount of appliances that utilize DC power make the overall conversion loss rather low. If plug-in hybrid vehicles become prevalent in the United States, I contend it will be most beneficial in many situations to power these batteries directly with DC from the solar panel to avoid the inefficient conversions.
Energy Usage in the United States
The economy of the United States has been built around an infrastructure that provided inexpensive power for the past century to drive transportation, industrial, commercial and housing growth. Transportation uses only 29% of all energy in the form of joules or British Thermal Units (BTUs), residential uses 22%, industrial uses 32% and commercial using 18% (Energy Information Administration, 2009). While different forms of energy are used for each of these applications, breaking energy usage down to joules or BTUs can help them be related to overall energy usage.
We have a potential to change the power consumption of a household. A great amount of research and public interest has been centered around using less gasoline in cars, even though they only account for 29% of our energy use. Fuel cells have been heavily researched in the recent past, along with a recent resurgence of electric cars. The popularity of hybrid cars and their battery technology have allowed for the possibility of hybrids that can be plugged in overnight to top off the batteries. These cars promote the possibility of 100 miles on the first gallon of gasoline. However, there will be a larger cost of electricity in these households due to the electricity being used to charge the cars. In fact, if plug-in hybrid vehicles replace the 251 million cars in the United States (RITA, 2006), there would be a significant increase on the electricity demand.
Demand for Plug-in Hybrid Cars
It is important to examine this demand for plug-in hybrid cars, along with what is driving the demand for these cars. Multiple groups desire plug-in hybrids for different reasons, and each reason is important to accomplishing an entrance into the automobile market.
Some environmentalists desire a reduction in gasoline as the local air quality is sharply decreased with gasoline driven automobiles. With high rates of asthma in cities, urban areas will receive a great benefit from plug-in hybrids.
People concerned with the security of the United States dislike the fact that majority of our petroleum used is imported from the Middle East. Plug-in hybrid vehicles will use less gasoline and allow the United States to become energy independent.
Finally, environmentalists concerned about global warming gases released during driving desire a vehicle that drives further on a gallon of gasoline. Global warming has become increasingly urgent, as each carbon dioxide that we put in the atmosphere takes hundreds of years to mitigate (Intergovernmental Panel on Climate Change 2007).
These differnent groups makes a strong coalition and allow a future of plug-in hybrid vehicle, assuming the vehicle costs are not too high. However, it is imperative to look at supply and demand availability of electricity in order to understand if switching cars to electricity is actually better in regards to global warming gases. Switching all cars to electricity produced from coal would be arguably better for local air quality, although that depends on the number of new coal plants that would need to be built to meet supply.
Fortunately, as previously stated, demand for new electricity to charge cars would be done at night, when electricity demands are low. Lower marginal costs generation plants, such as nuclear and coal, would meet the majority of this demand, depending on the exact time and location that charging occurs. With smart technology within the house or from the grid, cars could wait until 12 am when electricity demand is at its lowest in order to start charging. Since nuclear power has the lowest marginal costs (Panzar 1981), I expect that nuclear will be utilized to meet the majority of this new demand for electricity at night, with the remaining supplemented by coal.
Nuclear power is by no means immune from criticism by environmentalists. However, it is better in regards to local air quality than coal or natural gas, and nuclear releases no global warming gases into the atmosphere even though it currently produces 20% of our nations electricity supply.
Plug-in hybrid cars use batteries to drive the initial miles. Once this electricity is exhausted from the battery, a combustion engine takes over. This electricity is stored in the form of DC power, and therefore must be converted from our AC supply into DC at an efficiency of approximately 87%.
Direct Connection – DC to DC
For a battery designed to drive 60 miles before switching to a combustion engine, the battery will be approximately 25 kWh at its maximum storage (Simpson, 2007). In order to fully charge a car from grid supplied electricity, it would take 27.8 kWh due to the conversion of AC to DC. Ultimately, $2.80 of electricity will be purchased based on the national average for electricity at $.10 per kWh. Only 25 kWh will actually reach the battery due to the conversion inefficiency and the remainder of the electricity will be lost as heat.
In the typical AC grid connected house with a solar panel, 78% of the electricity produced by the DC panel will reach the ultimate DC car battery. This is due to the fact that electricity is converted from DC into AC, then back to DC.
Imagine a scenario where a DC solar panels charge a plug-in hybrid car directly, instead of in the normal grid storage of the typical AC grid connected house. Electricity could be produced in DC and sent directly to the car battery. In this situation, 25 kWh could be produced per day and sent to the car battery. This would require approximately a 5 kilowatt solar panel, that could be exposed to at least 5 hours of sunlight each day throughout the year.
In a normal set up of solar panels, the plug-in hybrid car would be plugged into an AC outlet, and the electricity produced form the solar panel would have been converted from DC to AC to DC again. Electricity is net metered, so the electricity used throughout the house may come from the solar panel directly, or it may be purchased from the grid. When extra electricity is produced and not used by the house, it is distributed to the grid. The net metering means that all electricity given to the grid is subtracted from the overall purchased electricity, so the grid in fact acts as a storage battery for unused electricity produced by the solar panels at peak production.
The 25 kWh of electricity needed to charge the battery would have been converted at an inefficiency of 78%, meaning that only 19.5 kWh of solar electricity would actually reach the car battery.
For this purpose, the remaining 5.5 kWh of electricity would have to be purchased from the grid, although it would have to be 6.3 kWh to overcome the inefficiency of AC to DC. This would lead to an annual cost of $229.95, as shown in figure 1, assuming that 6.3 kWh would need to be purchased 365 days per year.
25 kWh * .78 efficiency = 19.5 kWh DC
25 kWh – 19.5 kWh = 5.5 kWh DC to fully charge battery
5.5 kWh DC / .87 efficiency = 6.3 kWh AC
6.3 kWh * 365 days * $0.10 per kWh = $229.95
Figure 1. Present Value of energy prices paid due to conversion inefficiencies over 20 years.
This $229.95 can be looked at in different ways. First, it is an added value to owning a solar panel if you already own a plug-in hybrid vehicle. This is extremely important as the energy produced by a solar panel is carbon free, so driving a plug-in hybrid vehicle that is fueled with green electricity adds a further utility to plug-in hybrid vehicle ownership.
Alternative forms of electricity need all of the additional economic benefits that can be found as they already have an extremely difficult time competing against traditional polluting electricity sources. Alternative energy in the form of solar panels require a large capital investment up front, and often are not repaid throughout the lifetime of owning a panel. However, by increasing the efficiency and the value of each kWh of purchased electricity, panels may be “repaid” sooner. This is the key to increasing the amount of solar panels in the United States.
Plug-in hybrid vehicles also share in their large capital costs. When electricity is available for cheaper, it also increases the payback time of owning a plug-in hybrid by making gasoline comparably more expensive.
Figure 1 demonstrates the present value of purchasing $229.95 each year for 20 years. For this discussion, I have used interest rates (r) of 0, 3% and 5%. I have also looked at growth rates for the price of energy (e) of 0 and 5%. Both of these rates are extremely unpredictable in the next 20 years. Historically, energy rates for the past 20 years have decreased on average each year, as supply has continued to outpace. However, there are currently no new large power plants being built in the United States and demand continues to increase. Cap and trade legislation will also increase the prices for electricity from the grid as long as it continues to be predominantly from carbon rich sources.
An annual electricity cost increase of 5% is possible, in my opinion, under the current political climate and assuming that there are no leaps of technology in the near future. An increase in nuclear power plants could also lead to an increase in supply, but there are no current plans for nuclear power plant expansion.
In Figure 1, an interest rate of 3% and an increase in electricity prices at 5% per year leads to a present value of $5,721.07 for the 20 years with a battery size for a 60 mile range battery. The 60 mile battery has the highest present value, at $8,213.64, under the scenario of an interest rate of zero and an increase in energy prices of 5%.
Any money that is spent in order to make the DC to DC direct conversion practical, if less than $5,721.44, will be beneficial to a solar panel owner that also owns a plug-in hybrid vehicle. For example, the owner could purchase a second battery set for the vehicle, in order to store power during the day while the car is out. This would also provide a second economic benefit, in that the original battery life would be doubled since it would be traded out every other day with the storage battery. It would also enable a plug-in hybrid to achieve much larger distances as they could fully charge both battery sets before leaving for a longer commute.
Another scenario is a household DC storage device that could store the energy during the day, and slowly discharge into the car battery at night. An added advantage of this set-up is that cell phones, computers, and other DC energy users could be plugged directly into this storage device, leading to further increased efficiencies.
There would be an advantage to automobile industries to allow batteries to be purchased separately and easily interchanged. For the solar panel example, it would allow the extra batteries to be charged during the day. For non solar-panel owners, it would allow filling stations to change out depleted batteries with charged batteries, instead of filling up with gasoline.
Another further advantage of this lies in the fact that battery technology may continue to improve. If so, leaving a universal battery port that is easily changed would allow a plug-in hybrid owner that purchases their battery in 2010 to upgrade to a better battery in 2012. If the 2012 battery is far improved, it will increase the payback of the car purchased in 2010.
40 Mile Range Battery – 15 kWh
To this point, all calculations have assumed a battery designed to drive the first 60 miles without using the combustion engine or gasoline. A smaller battery with a range of 40 miles is also possible in plug-in hybrids. These batteries store 15 kWh(Simpson, 2007), and would require $138.45 of purchased electricity to make up for the efficiency losses of converted the electricity from the solar panel into AC, then back to DC.
15 kWh * .78 efficiency = 11.7 kWh DC
15 kWh – 11.7 kWh = 3.3 kWh DC to fully charge battery
3.3 kWh DC / .87 efficiency = 3.8 kWh AC
3.8 kWh * 365 days * $0.10 per kWh = $138.45
Figure 2. Present Value of energy prices paid due to conversion inefficiencies over 20 years, including multiplier.
In these different interest and energy rates, there are various electricity savings that range from $2057.13 for a 40 mile range battery with 3% interest rates and zero energy costs increases to $8,213.64, for a 60 mile range battery when interest rates are zero and energy costs increase at 5% per year. This range represents that possible present value of electricity savings for varying interest rates from 0% to 3%, while energy prices may increase from 0% to 5%.
There are several assumptions in this calculation, which may impact the results depending on the driving habits of consumers of plug-in hybrid vehicles. The assumptions are listed below.
Full Battery Discharge, 365 Days a Year
Primarily, I assume that the consumers of these cars all drive the cars 365 days a year and completely discharge the battery each trip. This is not realistic for most consumers. According to the 2001 National Household Transportation Survey (2004), the average driver drove 13,785 miles per year, based on that an average driver in the United States drives 38 miles each day, seven days a week. It is fair to say that the average person drives more on a weekday due to work travel than a weekend, so those numbers are above 38 on the weekdays and below 38 on Saturdays and Sundays. However, that would vary per person across the board.
For these reasons, it would be appropriate to use a multiplier on the final numbers to get a realistic number. For the 60 mile range car, it would be appropriate to use a multiplier of 0.63 (38 miles driven/60 miles full charge) to account for weekend trips, along with days where the car would not be fully discharged. This would be a daily roundtrip commute of less than 60 miles and a person that does not stop or run errands after work. For the 40 mile range car batter, it would be more appropriate to use a multiplier closer to 0.95 (38 miles average/40 miles full charge).
Accounting for the multiplier leads to an interesting finding. The present value ranges are much closer between the 60 mile battery and the 40 mile battery for all ranges of interest rates and energy prices. This would lead the potential plug-in hybrid owner to make the same choice of battery size, regardless of whether they own a solar panel.
In my initial analysis for this project, I predicted that the 60 mile range battery would provide a much greater economic incentive than the 40 mile range battery. However, as the costs of the 60 mile battery are much higher, it would appear that there is not much added incentive for solar panel owners to purchase a 60 mile range car. This purchase decision would continue to be based on the individuals driving pattern. A person with a roundtrip of 40 miles or less would not benefit from owning a 60 mile ranged plug-in hybrid car. For this reason, I predict that the mass produced cars will have a lower range value to appeal to the average American, perhaps even lower than 40 miles.
Currently, there is a lot of research by automobile companies to pick the appropriately size battery for plug-in hybrid vehicles. As the range that the battery can provide increases, the cost and size of the battery increases. In a study by the National Renewable Energy Laboratory (Simpson, 2006), plug-in hybrid vehicles mass produced are expected to cost $28,000 for a 1.5 kWh battery, to $50,000 for a 26.4 kWh battery that would drive 60 miles. While this paper does not attempt to make the argument to purchase plug-in hybrid vehicles to save money, the mass production of vehicles should lead to a decrease in the cost of battery production. The economic viability of these cars in the future will depend on the reduction of battery prices.
These increased costs upfront lead to significant savings over the lifetime of the vehicle, depending on the cost of gasoline. While the electricity is not free, at $0.10 per kWH, it is much less expensive than gasoline. However, as demonstrated in the last assumption, the ideal battery size will most likely be smaller than 60 miles.
This research does not demonstrate the benefit of any particular size battery for a plug-in hybrid vehicle, nor the warrant of owning this type of vehicle or solar panel. This research demonstrates the benefits to direct connection if you already own both.
Increasing Electricity Prices
Another assumption is that energy prices for electricity will increase in the next 20 years. In the past 20 years, energy prices have in fact decreased as production capacity has outpaced demand. However, as demand continues to rise, capacity is currently at a threshold that will not dramatically increase without new plant production.
There are currently no plans for nuclear plant expansion. Coal plants are also in an unpredictable market for the future. When cap and trade regulation passes, as it is expected to do so, it will make a dramatic impact on the cost of operating a coal plant. For this reason, the market is very cautious in building new coal plants. Carbon sequestration is a potentially viable solution that would enable coal electricity to compete with nuclear and other non-carbon emitting sources. However, carbon sequestration is unpredictable as it has yet to be completed and the prices are currently extremely high.
DC to DC conversions
I have assumed through this work that the DC power produced by the panel will not need to be converted to a different voltage for the car battery. It is unclear to me at this time if the batteries would require a DC to DC conversion. However, once more information is available about the batteries in the plug-in hybrid vehicles that are mass produced, it would be possible to include those efficiencies in these calculations.
Solar at Work
If plug-in hybrid cars become a reality in the marketplace with a strong market share, there are great possibilities for solar panels at the workplace. Depending on the size of the batteries in the cars, there may be a market available for solar energy to be sold directly to cars in parking spaces. If the average battery sold is a 60 mile battery, then the average commuter at 38 miles rountrip would not benefit from midday charging. However, if the average battery sold was 20 miles to depletion, then there would be a great incentive for out of house charging.
There are many theoretical market niches here, but all of them depend on the proven ability for plug-in hybrids to enter the market. The viability of these solar panels charging your car away from home will depend heavily on petroleum prices. The higher the price of gas at the pump for the consumer, the higher price that they will be willing to pay away from home for electricity.
For example, in downtown Chicago where there are numerous cars parked while people are working, a niche could be found for a parking lot that has solar on its roof. This lot would be able to directly charge DC power to car batteries during the day while people are at work. There would be many ways of doing this in regards for the payment method. A credit card could be charged per kWh used during the day or this could be an added attraction to the parking garage and allow this particular garage to charge a premium for their spots.
With the conversion efficiencies demonstrated before, the payback at a large facility with a large amount of parked vehicles would be much faster. With economies of scale, a large commercial roof could hold an extremely large solar panel that could charge hundreds of cars during a day, often several cars in the same spot throughout the day.
This would also allow a market for smaller batteries in cars, which would significantly decrease up front costs of vehicles. For example, a commuter that travels 30 miles each way would only require a plug-in hybrid with a 30 mile battery, which would be much less expensive than a 60 mile battery, as previously discussed.
There is also a potential in the future for parking meters to incorporate mini solar panels on top of the meter in order to charge more money for the spot, or again charge per kWh in addition to the parking fee.
Suburban office complexes and shopping centers will have an additional incentive to provide solar panel charging stations for their employees and patrons. While they could simply provide AC power from the grid at $0.10 per kWh for these cars, they would have to purchase 100 kWh for every 90 kWh that enter their car battery due to the 90% efficiency of going from AC power to DC power. This would provide an additional economic incentive to install solar panels, along with the additional 87% efficiency that would be saved from converting DC power from the panel into AC power.
All of these business prospects would be a part of the green economy that is frequently discussed in politics and business. All of the jobs created would be local, as it would require a great deal of technical experience to install panels. While panels and other related supplies could be imported, the electricity would replace coal and methane produced electricity. The automobiles would also be using more electricity in this situation, which would replace petroleum purchased overseas.
Why Encourage Solar and Plug-in Hybrids?
If the market will eventually get to these places anyways, why push it sooner than it is ready? The simple answer is also a frightening one: there is currently no magic answer for the climate change dilemma. While we continue to get cleaner and more efficient as an economy, our population also continue to grow, with the problem getting bigger each day that passes. While Cap and Trade Legislation will create an economic incentive to encourage alternative energies, it is important to take as many small steps toward carbon dioxide reduction as possible.
Solar power alone is not the answer to the problem. With cheap coal producing electricity, it will take a long time before solar powered electricity makes a dent in our grid consumption. Solely promoting plug-in hybrid vehicles are also not the solution. Initially, their prices will be extremely high and will not penetrate the established combustion engine market for the next decade. Currently, both solar panels and plug-in hybrid vehicles qualify for huge government subsidies. If a direct DC to DC connection from panel to hybrid would save money, lower direct government subsidies could be applied and the money could be used in other manners to promote green technology.
However, all of these efforts, done in small amounts and in increasing quantities, could be the answer to the problem. Global warming is a real threat, and while it does not threaten our existence during this lifetime, the uncertainty of it warrants action today.
Algoso, D. Braun, M, Del Chiaro, B. “Bringing Solar to Scale”. Environment California Research and Policy Center. April 2005.
Arizona Solar Center. website. http://www.azsolarcenter.com/technology/tech-6.html. Retrieved May 12, 2009.
Bureau of Transportation Statistics. “Table 1-11: Number of U.S. Aircraft, Vehicles, Vessels, and Other Conveyances”. 2006. RITA. Research and Innovative Technology Administration. Bureau of Transportation Statistics.
Chiras, Daniel D. Environmental Science. Edition 7. Jones and Bartlet Publishers, 2006.
Energy Information Administration. Official Energy Statistics from the U.S. Governemnt. Annual Energy Review. 2007.
Energy Information Administration. Official Energy Statistics from the U.S. Government. Table 5. U.S. Average Monthly Bill by Sector, Census Division, and State 2007. Report released: January 2009.
Energy Star Program. “Energy Star Program Requirements for Single Voltage External AC-DC and AC-AC Power Supplies”. Eligibility Requrements, Version 2.0. 2007
Haeberline et al. “Evolution of Inverters for Grid connected PV-Systems from 1989 to 2000″. 17th European Photovoltaic Solar Energy Conference, Munich, Germany. October 22, 2001.
Environmental California Research and Policy Center. website. www.environmentcalifornia.org.
Retrieved May 20, 2009.
Ikki, Osamu and Matubara, Koji. “National Survey Report of PV Power Applications in Japan 2006″. May 25th, 2007.
Intergovernmental Panel on Climate Change. “AR4. Climate Change 2007″. November 2007.
Jimmy Carter Library and Museum News Release. “White House Solar Panel Goes on Display at Carter Library. 1979 Effort to Encourage Alternative Energy Sources Became “Road Not Taken”. March 27, 2007.
Lewis, N.S. “Toward Cost-Effective Solar Energy Use”. Science 315, 798-801. February 2007.
National Association of Home Builders web site. 2004 Statistics. www.nahb.org. Retrieved May 22, 2009.
National Renewable Energy Laboratory. web site. http://rredc.nrel.gov/solar/pubs/redbook/. Retrieved June 5, 2009.
National Household Transportation Survey. “Summary of Travel Trends, 2001″. National Household Transportation Survey. December 2004.
Paltsev, Sergey, Reilly, John M., Jacoby, Henry D., Gurgel, Angelo Cl, Metcalf, Gilbert E., Sokolov, Andrei P. and Holak, Jennifer F. “Assessment of U.S. Cap-and-Trade Proposals”. June 2007. NBER Working Paper Series, Vol. w13176.
Panzar, J. C., Willig, R. D. “Economies of Scope”. The American Economic Review. 1981. Vol 71. No 2.
Simpson, A. “Cost Benefit Analysis of Plug-in Hybrid Vehicle Technology”. National Renewable Energy Laboratory. 2006.