RE: Letter to the Editor regarding the transition of NES CEO
Jason Carney - TSEA Executive Director
Presently, NES management is conducting a confidential search to replace its current leader with help from its board members. Management has found several interested candidates internally and externally. The finalists will be made public and be interviewed by the NES’ board members ultimately leading to a selection.
It has been nearly 18 years since the Nashville Electric Service (NES) has chosen a new President & CEO. None of management or the power board personnel were in their current roles 18 years ago. It would take the current CEO, Mr. Decosta Jenkins, to describe what NES and the electric power board were looking for at that time. What we do know is that climate change was of growing concern in 2004. Russia and Canada would ratify the Kyoto Protocol that same year, bringing the treaty into effect in 2005. Even so, the United States was more gripped by the Iraq War than it was the ominous and existential threat of climate change. In hindsight, it is clear that the NES of 2004 missed an opportunity to address climate change and sustainability when the challenges were less daunting. Today, NES has the opportunity to choose its next leader with climate change a prevalent part of the local, state, and national conversation. NES’ next leader should be someone that understands the conversation and feels the responsibility to help lead Nashville into a future consistent with the city’s desire to reduce greenhouse gas emissions by 80% from 2014 levels by 2050.
Flying into Nashville with its rapidly developing landscape, the unlimited potential of rooftops is startling, Rooftop solar can be a powerful tool to help accomplish our goals, but right now, rooftop solar is being discouraged through unprecedented fees (and the removal of net metering). There is an application fee of $375 and a monthly fee based on the program you choose; Behind the Meter (BTM) or Dipersed Power Program (DPP). The fees are unfair, discriminatory, and unnecessary. These new solar fees are either $9/month ($2700 in 25 years) or $29/month ($8700 in $25 years). Even without the fees, NES benefits from every new rooftop solar system. Solar homeowners provide NES with their excess solar electricity generation either for free (BTM) or at wholesale price (DPP) and NES profits when it resells it at retail price. Thus, solar customers are not a drain on NES revenues. While customers who install solar lower their electric bills, they still pay the service fee and fuel cost riders on their bill. Would NES be justified in imposing extra fees on customers who install high efficiency appliances to lower their electric bills?
The fees are punitive to solar customers, especially middle income customers, because the monthly fee eats up the first 2-3 panels in production every month. These customers are making a significant investment with a good heart, but their system may only be 3-4kilowatts(kW) or about 8-10 panels. The monthly fee could eat up to almost 40% of what they would have saved. 4kW may only account for 25% of their electric bill. That means their investment would only take about 10% off their bill.
Also, NES could use savings from their 20yr contract with TVA to help offset or eliminate any fees.
Because NES is under contract to buy all its power from the Tennessee Valley Authority (TVA), TVA has an oversized role with regard to how Nashville will reach its climate goals. Because NES is Nashville’s liaison between the city and TVA, the next CEO will have a significant opportunity to be our advocate for more renewables and energy efficiency. We hope the new CEO will invite Nashvillians to reduce our green-house gas emissions and be a vocal advocate for more solar, especially rooftop.
Videos from Energy Electives
How to Save Money with Solar Appliances
Dr. Joe Schiller - TSEA Board Member
Many who have sought to install a home solar system have been frustrated by the high upfront cost despite the dramatic price decreases of solar photovoltaic (PV) panels over the last several years. This is because the size and complexity of a solar energy system designed to power an entire home is still too expensive for many consumers on a limited budget.
A solar system that powers an entire house has several components. All solar electric systems harvest the energy of the sun using PV panels. However, PV panels produce direct current (DC) electricity, but most household appliances are designed to use alternating current (AC) electricity, so a device called an inverter is needed to convert the DC to AC power. Thus, the simplest solar system that produces AC power consists of a PV array and an inverter. That does not seem so complicated; however, connecting this two-component system to the utility electric supply, i.e., “the grid,” adds additional expense and complexity. There are required fees, permits and inspections which in turn require certified experts.
This minimalist solar system has an important drawback. It only produces power when the sun is shining. If you want to use some of the solar energy you collected during the daytime at night you will have to add batteries. If you add batteries, you will have to add a charge controller, so the batteries are not damaged by overcharging. Now we are up to a four-component system as well as all the fees, permitting and inspection requirements of the two-component system. All these components and requirements add complexity and expense that discourages many prospective solar owners. Is there any way to simplify either of these systems and avoid some of the permitting and inspection requirements? The answer is yes—sort of.
Rather than installing a “whole-house” solar system and all the complexity and cost this entails, a homeowner could instead choose to power individual appliances that can run directly on the DC current produced by PV panels. This simplest possible system would only run when the sun shines, but this would be sufficient to greatly lower costs while providing abundant utility. Air conditioning, hot water heating, and water pumping are three examples of needs that can be mostly or entirely met with daytime solar. These needs are also the largest portion of a typical household electric bill. Additionally, many of the appliances described here can supplement daytime solar operation with grid power when the sun is not shining enabling these tasks to be performed 24/7. Further, some of these appliances can also utilize DC power stored in batteries to further reduce the consumption of grid power. I will provide an overview of appliances I know about that have these capabilities; however, I make no claim to describing every available option. My goal is simply to provide examples of real products currently available that illustrate the range of currently available options.
I am not referring to solar phone chargers, yard lighting, and other small devices, though there are many of those. My focus here is major appliances representing the major electric loads, and therefore, the major electricity costs of typical homes. An increasing variety of major household appliances such as air conditioners, heat pumps, refrigerators, and freezers, well and pool pumps, and water heaters are now manufactured to operate on DC power. Many appliances could be designed to run on DC instead of AC, but it is most cost effective to power those appliances with DC that use a lot of energy, especially those that run a lot in the daytime or can be programmed to do so. An added benefit of these solar powered DC appliances is their ability to function when grid power is lost.
Recent technological advances have resulted in the development of DC versions of these appliances that can run directly on the power produced by a modest PV array. Additionally, because these appliances and PV array are isolated from the house’s grid supply there are no fees, mandated permits, or inspections because these are only required to ensure the PV array does not back feed power into the grid. Excepting water pumps, most of these appliances involve highly efficient heat pumps, so it is instructive to review how this heat pump technology has opened all these new opportunities to economically tap solar energy.
A heat pump does not convert the chemical energy of fuel into heat in the way a gas or oil burning furnace or electric resistance appliance heats a house or water. Instead, it moves energy into or out of the house in the case of heating or cooling a house, respectively. The efficiency difference arises because it takes less energy to move heat than to generate heat. A 100% efficient gas furnace or water heater could transfer all the energy released by the burning of the fuel into the heating of the house or water. However, current highly efficient heat pumps can move 3-4 times the amount of energy in the fuel, i.e., electricity, into the house or water heater. This means 1/3 to ¼ as much energy is used to provide the same heating/cooling of a combusted fuel or electric resistance element. In the case of heat pumps for heating and cooling a house these heat pumps include their ability to reverse the direction they pump heat. Other key technological advancements of these appliances include highly efficient continuously variable pumps, fans, and compressors, and built-in inverters that power their extremely efficient “inverted” compressor motors. All these refinements have led to a revolution in the efficiency of these appliances.
Less than a decade ago a heat pump air conditioner with a Seasonal Energy Efficiency Rating (SEER) of 15 was considered highly efficient. Contemporary models incorporating the listed advancements have SEER values pushing 30 or more! This allows modest PV arrays to provide enough energy for them to function well. Effectively boosting their SEER rating to extremely high values if you consider only purchased electricity in its calculation. Another feature that can boost their efficiency much further is the fact that when moving heat from the interior of a house it can be channeled to make hot water instead of simply dumped to the outside. Or conversely, when moving heat into a water heater, it can be removed from the house, assisting in its cooling.
Before describing the various heat pump appliances, I will describe the water pumping appliances that operate on DC. DC water pumps have been around for years and are in no way novel. In addition to pool pumps, efficient DC water pumps are used for well pumping, water circulation in hydronic heating systems, and in solar hot water systems. However, many homeowners with pools are not aware of the large savings these appliances offer. We have a Lorentz solar pool pump, but many manufacturers make these. The same is true for well pumps. An Amazon or Google search will quickly yield many options. We have operated our pool pump for several years now with absolutely no problems. These pumps run directly on sunshine and will not run without sunshine. Some of these pumps, including ours, have the option to run from batteries. Ours simply requires a slight adjustment to the power connection and changing dip switch settings. Remember, batteries will also require a charge controller. Thus, complexity again begins to creep back in. In the case of well pumps an elevated reservoir tank may serve as a sort of water battery because it is filled by solar energy during the days and has sufficient capacity to meet nighttime water needs and during cloudy periods.
Now, onto heat pumps. I know of one manufacturer of heat pumps, and one of pool pumps that can run directly off a PV array without connection to household AC power or batteries (See Figure 1). HotSpot Energy in Chesapeake VA manufactures the ACDC12C model (https://www.hotspotenergy.com/solar-air-conditioner/ ). If you want to operate these appliances during cloudy periods or at night you have the option to purchase similar systems that can run on batteries or, alternatively, connect to household AC as described below.
Figure 1. Schematic of HotSpot Energy’s solar heat pump that runs entirely from a PV array. Note this model also can be powered with household AC electricity.
HotSpot Energy’s DC4812VRF solar heat pump (https://www.hotspotenergy.com/DC-air-conditioner/) runs from batteries charged by a PV array (See Figure 2). I own two of these and have operated them for a few years now. One required warranty replacement and that replacement unit needed a new circuit board after a couple years. In both cases customer support was exemplary. YMGI Group manufactures similar heat pumps, its Solar All DC 86 Series (YMGI Symphony SOLAR All DC 86 Series | YMGI Group) (See Figure 3) are available in more sizes and configurations than HotSpot Solar’s heat pump, but I have no experience with them.
Figure 2. Schematic of Hot Spot Energy’s DC48VRF heat pump that runs from batteries charged by a PV array.
Figure 3. YMGI Groups DC solar 86 series single zone heat pump that runs on batteries charged by a PV array. Note this model also has the option to be powered with AC as well.
The second alternative to avoid some of this creeping complexity is AC appliances that can run on household AC electricity but are also engineered to run directly on the DC power from a PV array when it is available. They have an asymmetric inverter built into them that converts the DC power from the PV array into the AC power that runs that the appliance. However, unlike most grid connected inverters, the inverter in these appliances is unable to feed power back into the house or its grid connection, thus, isolating the system from the power grid. This eliminates the need for permitting and inspection requirements for grid connection. This maintains simplicity by limiting the system to the appliance and its PV array. The HotSpot Energy ACDC12C model does not have to be connected to household AC power as described previously; however, if connected to AC power it can run all the time (Note the optional AC connection in figure 1). Another manufacturer of heat pumps that run directly from a PV array with AC connection is YMGI Group’s Solar Assisted 56 series (YMGI's Solar Assisted DC Inverter Single-Zone Wall-Mounted Mini-split models | YMGI Group) (See Figure 4, but note also that the Series 86 model in Figure 3 can also be powered by AC). I have no direct experience with their products, but they offer a wider range of heat pump sizes than Hot Spot Energy.
Figure 4. YMGI Group Series 56 solar assisted heat pump that prioritizes solar power but use AC household power to compensate for any solar deficit.
While HotSpot Energy does not currently offer the range of heat pump sizes and configurations offered by YMGI Group, they do offer some other very intriguing solar appliances. They offer a solar air conditioner, the ACWH18-35GW/BMVE, with a desuperator that generates up to 100 gallons of domestic hot water a day (https://www.hotspotenergy.com/air-conditioner-water-heaters/ ) (See Figure 5). This appliance requires household AC power and cannot run directly from a PV array or battery as the other models described, but it illustrates how a heat pump cooling the house can also provide most of its domestic hot water. HotSpot Energy also manufactures heat recovery valves that can be retrofitted to any refrigerator or heat pump air conditioner to capture waste heat for domestic hot water or pool heating (https://www.hotspotenergy.com/heat-recovery-valves/ ) including the previously described models that run directly from a PV array or batteries.
Figure 5. HotSpot Energy’s 1.5-ton heat pump that delivers up to 100 gallons of hot water a day in cooling mode.
Highly efficient heat pump water heaters are increasingly common. However, I have only identified one manufacturer that makes a solar assisted model that is islanded from the grid similarly to the solar assisted heat pumps described in Figures 1, 3, and 4 above. The Sunbandit (https://sunbandit.us/ , no figure available) can be illustrated by substituting a hot water tank for the HVAC components in figures 1,2, and 4. Like them, it prioritizes the use of solar energy from a PV array and uses household current to make up any deficit. More solar heat pump water heaters may be on the verge of commercialization. I know the Florida Solar Energy Center has made exciting progress on research versions of such systems (Colon and Parker 2018, https://www.homeenergy.org/show/article/nav/hotwater/id/2267 ).
There is a solar powered Chiller manufactured by Chiltrix (https://www.chiltrix.com/documents/Chiller-with-solar.pdf ). The Chiltrix 34 is a multi-purpose solar heat pump powered chiller that can deliver heated or cooled water for domestic hot water and/or home air conditioning and heating. I have no schematic diagram for this appliance. It operates similar to the HVAC heat pumps in Figure 4 but uses water as the heat transfer medium that is exchanged between the outdoor unit and up to 5 indoor fan coil units or floor hydronic loops. Thus, it is an extremely versatile appliance. The model 34 can also run from AC power and/or batteries for 24/7 reliability. Another manufacturer of a highly efficient air to water heat pump chiller—Multiaqua (MHRC-AE (multiaqua.com)) makes a 5-ton capacity chiller with similar features to the Chiltrix 34.
Interestingly, the integrated asymmetric inverters in the HVAC and water heaters described above that allow both PV arrays and AC household current to directly power the appliance while islanding the appliance from grid power have not been incorporated into refrigerator/freezers. Most solar refrigerators or freezers run in 12- or 24-volt DC and are quite small. These target the camping, tiny house, and off-grid house market. Sundanzer (SunDanzer | Household - 12/24V DC Refrigerator and Freezer) is a manufacturer of 12-48V DC refrigerator/freezers up to 16 cubic feet that are highly efficient but require battery backup. There are a few other manufactures of similar products. It is probably only a matter of time before refrigerator freezers incorporating asymmetric inverters appear on the market. Because refrigeration, along with HVAC and water heating represent the vast majority of electricity consumption in typical homes, this would allow 75-85% of a homes electricity consumption to be powered from modestly sized PV arrays while assuring 24/7 operation with grid back-up power.
The appliances I have described here are not a comprehensive listing, nor am I endorsing any appliance brand over another because I do not have first-hand experience with all of them.However, I cannot overemphasize the great potential these appliances hold for extending the use of solar energy and reducing our carbon footprint all while saving consumers a lot of money.One of the most important implications of these solar powered appliances is their ability to greatly reduce the up-front cost barriers enabling consumers with modest budgets to access the power of the sun to improve their finances!Indeed, utilizing existing utility company policies such as on-bill financing of weatherization and energy efficient appliances, even low-income households can benefit from the power of the sun because such programs eliminate up-front costs and immediately reduce monthly utility bills.I will describe those strategies in my next article.
Ten Facts To Know About Solar Energy
1. Solar power is the most abundant energy source on Earth.
Every hour, more solar energy hits the earth than all of humanity needs for an entire year. Solar panels harness this clean energy source by using photovoltaic cells.
2. You can use solar power to run your entire home.
It's a cheaper, safer, and green solution to running air conditioners, hot water heaters, appliances, etc.
3. Solar power has a long history.
The potential to harness solar power was first discovered in 1839 (a year after the first coal fired power plant was built) by Alexandre Edmond Becquererl. He found how to create an electrical current in a conductor that was hit by the sun rays, in other words, the photovoltaic effect. The creation of modern silicon photovoltaic cells was completed in 1954 at Bell Labs. Since then, the efficiency has increased more than four times, while the price has decreased significantly.
4. Solar is the world's most popular form of new electricity power generation.
Due to decreased cost and increased efficiency, solar has quickly become the preferred new electricity generator. More than 73 gigawatts of new solar power installed in 2016.
5. Solar power produces no pollution.
Apart from the pollution given off during manufacturing, solar power is one of the cleanest, most sustainable, and most renewable resources in the world. However, not all panels are created equal. SunPower panels are the only solar panels to have achieved a Cradle to Cradle certification, meaning the panels are manufactured in the most sustainable and ethical way possible.
6. Solar power improves world health.
The burning of fossil fuels creates toxic pollution, which has an impact on global health. Pollution affects as many people HIV or malaria, and has serious consequences on children, older adults, and all living plants and animals. Solar power reduces the amount of fossil fuels used, meaning less pollution is going into the air, and into our lungs.
7. Solar panels can increase your home value.
Initial studies have shown solar panels can increase your home value by an average of $20,000, a higher payback percentage than a kitchen remodel.
8. Solar can help lower electric bills.
Depending on where you live, you may be able to take advantage of net metering (your system is hooked up to the electric grid and you sell back excess energy you produce.) If you decide to finance, there is a possibility your monthly loan payment will be less than your electric bill. Solar can help you save money from day one!
9. Solar systems come with a warranty.
Most solar systems come with a warranty. Warranties often protect the quality of the system, repairs or replacements for defective panels, and power production.
10. You don't have to buy solar panels outright.
There are multiple ways to afford solar, and you don't have to pay cash to reap the benefits. Low interest loans are available to solar system owners, as well as other financing options. There are also incentives offered to go solar that help lower the cost.
Go to this website to find a cost estimate of powering your home with solar energy:
https://www.solar-estimate.org/
Online Courses from Solar Energy International
Find them here:
https://www.solarenergy.org/online/
Online Courses from U.S. Solar Institute
Find them here:
https://ussolarinstitute.com/online-solar-training/
Online Courses from Solar Living Institute
Find them here: