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Frequent Questions

You’ve got questions about solar power? We can answer them. You’ll find answers to the questions we’re asked most often below. If you don’t see an answer to your question here, just send us an email with your question and we’ll get back to you with an answer.

Performance and Durability

Will I have electricity during a utility power outage?

You will have electricity during a utility power outage if your solar power system includes batteries. Systems with battery storage have a transfer switch that automatically switches to battery power during a utility outage.

In either case (batteries or no batteries), your solar power system will be automatically isolated from your electric meter until the utility power is restored. This is done to prevent injury to utility technicians who might be working on nearby power lines or transformers.

Do solar panels stop producing electricity during cloudy weather?

No. This is probably the biggest misunderstanding about solar panels. Many people mistakenly believe that only direct sunlight striking the face of a solar panel produces electricity.

Actually, almost 40% of a solar panel’s annual electricity production is from diffuse sunlight. That is, sunlight bouncing around the sky; scattered by air molecules and reflected off of nearby ground, building structures and other objects. There’s plenty of this diffuse solar energy available even on a cloudy day.1

Which direction must solar panels face to perform best?

For solar panels installed north of the equator, facing the panels due south at a fixed tilt angle equal to the latitude will produce the highest annual electricity output. But flush mounting solar panels at a different angle, parallel with the roof surface, usually won’t change the annual energy production much. For the most common Florida roofs, any performance loss will usually be less than one percent.

The table below shows how solar panel performance changes with direction, as a percentage of the performance for solar panels facing due south. This table is for solar panels installed in Northeast Florida, about 30° north latitude, at a tilt angle of 22.6°, the same angle as the slope of a 5/12 pitch roof.

% South kWh100.097.095.488.586.276.478.272.3
% Loss vs. South0.03.04.611.513.823.621.827.7

As you can see from the table above, installing solar panels on an east- or west-facing roof slope still produces very good performance, even though, for much of the year, east- and west-facing roof slopes receive direct sunlight for only half of the daylight hours.2 The availability of diffuse solar energy explains the relatively small differences in the table above. Even a roof section that faces the worst performing direction, due north, will receive 72% of the energy of a due south roof.

Why do east-facing solar panels perform better than west-facing panels?

The difference is due to air temperature. Outdoor air temperatures are usually higher in the afternoon than in the morning. Heat reduces a solar PV cell’s efficiency, so solar power panels are a bit more efficient during the morning hours than during the afternoon hours.

Even though east-facing solar panels produce a bit more solar electricity than west-facing panels, it may be desirable to install solar panels on a west-facing roof to better match peak solar electricity production to peak utility electricity demand, which occurs in the afternoon on hot summer days.

How long do solar panels last?

Good quality solar panels should produce electricity for at least 40 to 50 years. Thousands of solar panels installed in the 1970s are still operating in the field today.

Exposure to the ultraviolet radiation in sunlight causes PV cells to lose a tiny amount of efficiency each year. This efficiency loss—which is called degradation—typically ranges from 0.2% to 0.7% (two-tenths to seven-tenths of one percent) per year. Better quality panels have lower degradation rates.

A solar panel with a yearly degradation rate of 0.5% will average about 94% of its first year electricity production over 25 years, and about 91% of its first year production over 40 years.

The standard solar panel performance warranty term is 25 years. The warranty usually states that performance losses will not exceed either 0.5% or 0.7% per year (the precise figure varies from manufacturer to manufacturer).

Our solar electricity production estimates are adjusted to account for ultraviolet degradation.

Buying Solar

How much do solar panels cost?

Your price will vary based upon how many solar panels are required to get your house to net zero energy consumption, how much usable roof area you have, the capacity of your electric service panel, and whether you add battery storage for emergency backup power.

Current 2020 installed prices are between $3,250 and $3,750 per kilowatt of system size for a home solar power system. Within this range, smaller systems tend to cost more per kilowatt than large systems; this is because some of the installation costs are the same regardless of system size.

For systems that include enough battery capacity to store excess solar power for overnight use, and to provide emergency backup power for critical loads, the price range is around $4,200 to $4,900 per kilowatt of system size.

The price ranges above include everything necessary to get your system operating: shipping and delivery of your system, installation labor, system design, permits, and any utility interconnection and HOA application fees. Solar energy systems are exempt from Florida sales tax.

Keep in mind that when you install solar, you receive a federal income tax credit equal to 26% of the system cost. Also, JEA customers can receive a rebate of up to $2,000 for battery purchases.

We have special zero down, low interest financing that allows you to install solar with no cash out of pocket. Best of all, most of your loan payment will be offset by electric bill savings. Once the loan is paid, you’ll enjoy decades of free electricity.

Why don’t you offer instant online solar price quotes?

The “instant” price quotes you can find online from some solar websites are loaded with disclaimers. It simply isn’t possible to produce an automated system design and price quote that accurately accounts for roof obstructions and shading, roof hips and valleys, existing house wiring and electric service panel capacity.

Also, it is not possible to determine how many solar panels are needed for your house to get to net zero electricity consumption without verifying your family’s unique electricity consumption patterns.

Every solar power system we install is custom sized, designed and installed. For us, satellite imagery of your roof is just a starting point.

Why would I go solar now if I plan to move in a couple of years?

Because it could help you sell your home faster.

Most people only consider electric bill savings when they think about going solar. But independent research shows that you are likely to sell your house much faster if it has solar,3 and that you can expect to recover 100% of your net cost for the system (“net cost” means net after subtracting the value of the tax credit).

Think of it this way: If your neighbor is selling a car that needs to fill up on a regular basis at a gas station, and you are selling a car that makes its own gas, which car do you think will sell faster?

When you look at it this way, the huge electric bill savings while you’re in your current house are just an added bonus.

Why not just wait until solar power systems get cheaper?

There are a few reasons why waiting to go solar is not a good idea:

The solar tax credit may end.  The 26% federal income tax credit is currently scheduled to decline and eventually phase out over the next few years. Whether it will be renewed is anybody’s guess. You don’t want to miss out on an incentive that reduces the cost of going solar by 26%.

Prices may increase.  Solar prices fell dramatically between 2008 and 2017. Most of this price drop was driven by mass production of solar panels, especially in China. However, U.S. solar manufacturers recently won a trade case against China, which resulted in the imposition of a new tariff on imported solar panels. Consequently, solar panel prices may increase in the near term, not fall.4

Electric utility rate increases.  The average annual percentage decline in solar panel prices over the next few years is not expected to be as great as the roughly 4% average annual increase in the retail cost of electricity from 1970 to 2015. In a recent National Renewable Energy Laboratory report, researchers estimated that through 2020, residential solar power system prices would fall by, on average, about 3.5% per year.5 So by waiting, you are missing out on valuable savings.

Why not just focus on energy efficiency measures for my home?

Minimum residential energy consumption in Florida, without curtailing comfort or lifestyle, for a family of three living in a house with a 14 SEER/8 HSPF heat pump air conditioning system and hybrid electric heat pump water heater, no swimming pool, no electric cars and no extravagant outdoor landscape lighting is about 7 kilowatt-hours per square foot of living area per year.6

To the extent that your household electricity consumption exceeds this 7 kilowatt-hour per square foot minimum, energy conservation efforts could make a difference. The major home energy efficiency measures for a Florida house—weatherstripping, more efficient air conditioning, smart thermostats, extra insulation, tinted windows, more efficient lights and appliances—all taken together will reduce annual electricity consumption for a Florida house by 2 to 5 kilowatt-hours per square foot per year.

But only older houses—more than 20–30 years old—can reach energy efficiency savings in the 3 to 5 kilowatt-hour per square foot per year range. Newer all-electric houses are relatively well insulated and should have at least a 13 SEER heat pump air conditioning system. Energy efficient light bulbs, appliances, and a hybrid electric heat pump water heater will get you combined total savings in the 1 to 2 kilowatt-hour per square foot per year range.

Energy efficiency makes a real difference, but you can’t save your way to net zero.

Only a solar power system can get rid of that minimum electricity consumption of 7 kilowatt-hours per square foot per year and get you to net zero annual power consumption.

Should I lease or buy my solar power system?

Buying a solar power system is a fantastic idea. Leasing solar is not. No matter what anyone tells you, leasing a solar power system is not just like leasing a car, for three reasons:

  • Solar lease payments increase every year.  One big benefit of going solar (with a purchase) is that you are protected against future utility rate increases. Consumer solar leases run for 20 years, with escalator clauses that increase the lease payments each year. The annual escalator is 2.99%. A lease payment that increases at 2.99% each year will be 75% higher in the 20th year than the first year. If you buy your system, the payment stays the same every year until the loan is repaid. Our most popular loan terms are 12 and 15 years. Not 20 years.
  • You don’t get the solar tax credit.  If you lease, you won’t get the 26% solar tax credit. The leasing company or their investors will. With a lease, your lease payment will typically be less than your electric bill savings for the first few years. Which seems great. But over time, the lease escalator causes you to give back the savings you got with the low lease payment in the first few years of the lease. The only way to get really big savings over time is to buy your system and keep the full value of the tax credit for yourself.
  • You could have trouble selling your house.  When you lease solar, the leasing company files a Form UCC-1 financing statement in the public records of your county. A UCC-1 filing does not create a security interest in your home, but mortgage lenders and title insurance underwriters usually treat it like a lien on your home anyway. This can throw a wrench into the closing. And you might need to pay off your 20-year solar lease early (which will be a lot more expensive with the lease escalator clause) if the buyer refuses to take over the payments. Or gets a credit turndown from the solar leasing company.

Our special solar loan program is unsecured, so it won’t impact the sale of your home. The same is true if you include solar in the mortgage loan for your house.

Remember, research shows that solar adds 100% of the net system cost (net after the tax credit) to your home’s value. If you buy your system and then sell your home before the loan is paid off, you can choose to either pay off the loan from the closing proceeds, or just pocket the cash from the increased resale value and keep making monthly payments on the unsecured loan.

Solar Investment Value

Is adding solar to my home a good investment?

Going solar is by far the best home improvement investment, per dollar spent, that you can make. Let us explain why.

  • Increased home value.  According to the largest independent research study to date, involving real estate appraisers, a U.S. government energy research lab and two universities, solar adds 100% of its net installed cost (i.e., net after the tax credit) to your home’s value.7
  • Faster resale.  Another study found that homes with rooftop solar power sold almost six months faster than similar homes in the same community without solar power.3 Imagine being able to save almost six months of mortgage loan interest.
  • Electric bill savings.  Just the two benefits above make solar an amazing investment. But can you think of any other home improvement that gives you the resale benefits above and also gets rid of 70% to 100% of your annual electric bills?9 A 9 kilowatt system, which will fit on most 2,000 square foot houses, will produce about $61,000 worth of electricity over 25 years, and about $129,000 worth over 40 years.10
  • Tax-free return.  You pay your bills with after-tax dollars, so electric bill savings are worth the amount of money you would need to earn to pay those bills. For example, if you pay an average of 25% of your gross income in federal income taxes, the $61,000 worth of 25 year electric bill savings discussed above would actually be worth $81,333 to you.11
  • Predictable return.  With most investments, earning a higher return on investment means accepting greater risk. But solar electricity production is highly predictable. Solar panels have no moving parts, solar panel performance is warranted by the manufacturer for 25 years, and thousands of solar panels installed in the 1970s have operated continuously for over 40 years.

My utility company says solar takes too long to pay for itself?

Your utility company is wrong.

Electric utility company payback estimates for rooftop solar power ignore the increase in home value from adding solar, the value of the solar tax credit, and electricity cost inflation.

See the answer to the “investment value” question above for information on increased home value and faster resale.

As for electricity cost inflation, utility company payback estimates for all home energy improvements—not just solar—pretend that the cost of electricity never increases. You know that’s just plain ridiculous. In fact, the cost of electricity has doubled every 19 years since 1970. According to the U.S. Energy Information Administration, electricity is over five times more expensive today than it was in 1970.12

And consider this curious fact:

Roughly two thirds of all solar power capacity in the United States is being installed in large solar farms owned by or operated exclusively for electric utility companies. Why are electric utility companies installing so much solar power if it doesn’t make economic sense?

The answer is that electric utility companies don’t have a problem with solar, as long as they own it.

Solar and Your Electric Utility Company

Do I need my utility company’s permission to install solar?

Yes. The utility company has a right to approve any equipment that is able to feed electricity to their power grid. Even if your system is sized to provide 100% of your annual electricity consumption, you want to stay connected to the utility company power grid so you will have power at all times, regardless of weather conditions.

What is net metering?

Net metering is an automated tracking program that allows you to receive billing credit for excess solar electricity you export to the utility company power grid. You can read more about net metering here.

Will I get a check at the end of the year from my utility company?

Probably not. Every utility company handles net metering credit differently, but any excess credit at the end of a calendar year is usually lost.

You should understand, though, that there is a perfectly good reason for this.

Most utility company interconnection agreements require that the solar power system be sized to provde not more than 100% of a customer’s actual electricity consumption for the most recent 12 months before the month the system is placed in service. So in principle, a system sized in accordance with this rule should not have any excess credit at the end of a full 12 months of solar electricity production.

Of course, exceptions do occur. Solar power systems on recently constructed houses may not have a 12 month history of actual electricity consumption. And available solar energy during some years can vary from the 30 year averages we use for system sizing by up to 9%. But generally speaking, a system properly sized for net zero household electricity consumption should not have any excess credit at the end of a full calendar year.

Is net metering credit on my electric bill taxable income?

No. Net metering credit is not taxable income. Net metering credit for solar electricity exported back to the utility power grid simply reduces your net purchases of electricity.

It is currently illegal under Florida law for any person or entity that is not a regulated utility to sell electricity to a third party. Consequently, utility net metering contracts in Florida are written so that bill credit for exported solar electricity is not characterized as a sale.

Why not just buy solar electricity from my utility company?

Because you will pay more for it.

JEA, the electric utility serving Jacksonville, gives its customers the opportunity to pay extra for electricity generated by one of JEA’s solar farms. Curiously, though, JEA executives admit there is no way to ensure that a customer receives electricity generated by a specific powerplant of any type. And the utility has not explained why anyone might choose to pay more than other customers for “solar” electricity.13

If you own a rooftop solar power system, you will have free electricity once your loan is paid off. And if you sell your home before the loan is paid, independent studies suggest that you will recover 100% of your net cost for the system.

On the other hand, if you buy solar electricity from a utlity company, you are going to be charged for the utility company’s overhead expenses, its profit, its tranmission losses (typically about 6% of power produced), and recovery of the costs for the solar powerplant and the land it sits on. And keep paying. And keep paying.

Why don’t electric utility companies like rooftop solar?

Investor owned electric utilities don’t like rooftop solar because it permanently reduces their customers’ total demand for electricity. Rooftop solar power system owners use a lot less utility electricity.

A regulated utility company’s allowed profit is a fixed percentage of its rate base, which is a somewhat confusing term that just means its actual and planned investment in assets during the period covered by each rate case filing. Investor owned utilities can only earn greater profits by building more electricity generation, transmission and distribution capacity. The allowed profit percentage is based on a utility’s assets.

Assets means a utility’s stuff: land and buildings, equipment, transmission lines, etc.

So here’s the problem with rooftop solar, from an investor owned utility’s perspective. When the utility files a rate case that seeks permission to build a new powerplant, the regulatory authorities look at electricity demand. If demand is falling, no new powerplant.

No new powerplant means no increase in profits.

Also, the electric utility industry sees rooftop solar as an existential threat. Industry analysts, consultants and executives have looked at other industries decimated by advances in technology: AT&T’s landline telephone and pay telephone businesses—once regulated monopolies—were wiped out by the revolution in wireless communications. The long distance passenger railroad travel business was decimated by low cost airline travel. Electric utilities fear that widespread adoption of rooftop solar could have a similar negative impact on their revenues and profits.14

So electric utilities are fighting hard to slow down rooftop solar growth.

Then why do electric utility companies promote energy efficiency?

Well, the truth is that the Florida Public Service Commission allowed the state’s investor owned electric utilities to kill most of their residential energy efficiency programs at the end of 2014.15

Generally speaking, any utility energy efficiency programs still offered by Florida’s investor owned utilities—like high efficiency air conditioning system rebates—are limited to those that can improve utility profitability by reducing peak demand. Increased fuel costs are passed through to customers via fuel charges, but peak demand often requires a company to spend more per kilowatt-hour to generate electricity with less efficient “peaking” generators.

As explained in the answer to the question above about why electric utility companies don’t like rooftop solar, a regulated utility company’s allowed profit is a fixed percentage of its rate base, which is the actual and planned investment in assets during the period covered by each rate case filing. Regulated utilities are not allowed to recover higher than expected costs. And they are also not required to give back excess profit, so any difference between a regulated utility’s forecasted and actual profit during the regulatory lag between rate cases either helps or hurts the company’s shareholders.

Customer energy efficiency programs can create extra profit that exceeds a utility’s allowed rate of return.

That said, an investor owned utility can only earn greater profits in the long run by building more electricity generation, transmission and distribution capacity. Its allowed rate of return is based upon its assets, not on its revenues or efficiency.

Other Solar Technologies

Should I add solar water heating to my solar power system?

We currently recommend hybrid electric heat pump water heaters (HPWH) as a more cost effective choice to reduce water heating cost in all-electric homes.

Independent testing shows that a HPWH operating in a warm climate like Florida’s can save up to 70% of the energy used by a conventional electric resistance water heater.

A typical Northeast Florida household uses about 1,376 kilowatt-hours per person per year for water heating.16 A premium 320 watt solar panel on a south-facing roof in Northeast Florida will produce about 482 kilowatt-hours of net usable ac electricity a year. So for each person in a household, a HPWH is worth 1,376 kilowatt-hours × 70% ÷ 482 kilowatt-hours = 2 solar panels. Or put another way, about 0.64 kilowatts of solar power system capacity.

Putting this in more practical terms, if we are trying to get a household with four occupants to net zero annual electric power consumption, by installing a HPWH we can reduce the size of the solar power system needed to get to net zero by 4 persons × 0.64 kilowatts = 2.56 kilowatts.

2.56 kilowatts of system size is eight 320 watt solar panels, which for most houses will make it considerably easier to find enough usable roof area to get the house to net zero annual energy consumption.

Should I use my south-facing roof area for solar pool heating?

No. While it is true that solar pool heating collectors are very efficient when wind speeds are below 3 mph and air temperatures are above 70°F or so, this idea does not make sense for two reasons:

First, swimming pool heating is a discretionary luxury. Home electricity is a necessity. And it’s a necessity that keeps getting more expensive over time.

Second, solar pool heating a screened Florida pool only extends the comfortable swimming season by about four months (from an unheated swimming season of May through September to a heated swimming season of March through November.17 But you need and use electricity every day of the year. So the greater solar energy collection from four months of solar pool heating is overwhelmed by the fact that solar power panels make electricity all year.18

Solar pool heating, ironically, doesn’t work very well during cold weather because cold air in contact with unglazed plastic solar pool heating collectors significantly reduces their performance.19

Are hybrid solar power/pool heating systems a good idea?

We don’t think so. This idea was introduced by the oldest manufacturer of plastic solar pool heating collectors after they started losing business to solar power systems. They were losing business because homeowners, quite wisely, were choosing to use the areas of ther roofs best suited for solar to install solar power panels instead of solar pool heating collectors.

So why not combine the two?

Well, actual field experience with solar power panels installed during the 1970s shows they should continue to produce electricity for 40 to 50 years or more. Actual field experience with solar pool heating collectors, which are made of plastic, shows they typically need to be replaced at around 20 years.

Also, as a practical matter, solar pool heating collectors are only going to add about one or two degrees to a pool’s water temperature if a big chunk of the sunlight that strikes the solar panels is either being converted to electricity, absorbed as heat, or reflected by the solar power cells.20

Another problem is that the increased mass of the hybrid solar power/pool heating panel assembly is probably going to cause the solar PV cells to operate hotter during the summer months, negating any performance improvement to the solar power cells from possibly operating cooler—and thus a bit more efficient—during the pool heating season.

Buy the solar pool heating manufacturer’s hybrid product if you want to help solve their business problem. But if you want the best value for your family, stick with solar power only. You’ll get twice the product lifespan and have less system complexity and maintenance.

Are hybrid solar power/hot water heating systems a good idea?

We don’t think so. Hybrid solar power/thermal systems either draw heated air through air channels underneath the solar power panels, or circulate a heat exchange fluid through tubes underneath solar power panels. The idea is that because solar power panels only capture and reflect about 25% of the solar energy striking the panels, the other 75% can be used to heat water. Also, solar power panels are more efficient at cooler temperatures, so an additional idea is that the solar thermal part of the system will keep the solar power panels cooler by removing heat.

This approach will provide useful heat but has practical limitations. For the thermal part of the system to deliver useful heat for water heating, the air or heat exchange fluid from the solar array must be warmer than the hot water storage. If it is, there isn’t going to be much cooling of the solar power panels. If it isn’t, there isn’t going to be any heat transfer to the hot water storage.

Hybrid solar power/hot water heating systems are a clever idea, but the increased system complexity and cost outweigh the negligible added energy savings. These systems are really just a marketing gimmick.

Solar Panel Cleaning

How important is it to keep my solar panels clean?

Very important. In 2009, Google studied the performance of a 1.6 megawatt solar power system installed at the company’s headquarters campus in Mountain View, California. Two solar panel arrays in the system were located downwind from an agricultural field that was tilled on a monthly basis. After professional cleaning, the solar electricity production of these two arrays doubled. A second cleaning eight months later resulted in a 36% performance increase.

Solar electricity production from the system’s other solar panel arrays, which were not exposed to the agricultural dust, increased by 12% after professional cleaning.

How often should I clean my solar panels?

Florida usually has enough rainfall to keep tilted solar panels clean. Even so, solar panels in Florida will still need cleaning at least once a year, especially in heavily treed areas (spring pollen), in beachfront areas (airborne salt), and in areas adjacent to new consruction (dust).

As a general rule, don’t clean your solar panels unless you can see visible pollen, leaves, bird droppings, dirt, or oily residue on the panels. Once a year is probably often enough. If your neighborhood does have lots of oak trees, it’s probably best to schedule an annual cleaning after the spring pollen season.

How do I clean my solar panels?

Cleaning solar panels on a roof involves risks of injury and electric shock. You should strongly consider using a professional cleaning service with experience cleaning solar panels. If you do, make sure you ask for evidence of both liability and workers compensation insurance coverage.

If cleaning the panels yourself, follow these rules:

  • Wear rubber gloves and rubber soled shoes.
  • Do not stand, sit or walk on solar panels.
  • Do not touch installed solar panels, racks, or power cables with any part of your body.
  • Never pressure wash solar panels.
  • Use only water to clean solar panels. Softened or distilled water is best, as mineral deposits from hard water can reduce solar cell performance.
  • Do not use soaps, detergents, or abrasive cleaners.
  • Use only a brush with soft bristles to clean the panels. Any scratches can reduce performance.
  • Use a soft rubber squeegee to remove excess water from the panels after cleaning.
  • Water-fed, telescoping poles for cleaning solar panels can be purchased online. For many single story homes, these poles make it possible to clean a solar panel array without climbing on the roof.
  • It is best to clean solar panels in the early morning or late afternoon. Cloudy or overcast days are also good. Cleaning solar panels first thing in the morning, when dirt and grime are softened by overnight moisture, will often produce the best results.
  • When using a ladder or scaffold, move the ladder or scaffold often enough so you can clean the panels without stretching to reach them.

Get My Free Solar Power Quote


  1. Many solar company websites use the example of a person getting sunburned at the beach on a cloudy day to illustrate how solar panels produce electricity in cloudy weather, but this example is not precisely accurate. Current solar photovoltaic cell technology converts only visible sunlight into electricity. Visible sunlight experiences very significant reflection when striking the water vapor in clouds. So most of the sunlight captured by a solar panel on a very cloudy, overcast day is diffuse sunlight. Sunburn is caused by UVA ultraviolet radiation, which passes through clouds with very little reflection or refraction (bending) because of its higher energy frequency and shorter wavelengths.
  2. A west-facing roof slope will receive direct morning sunlight—and an east-facing roof slope will receive direct afternoon sunlight—whenever the angle of the sun above the horizon is greater than the angle of the roof slope.
  3. Farhar, B.C. and Coburn, T.C. (2006). “A New Market Paradigm for Zero-Energy Homes: The Comparative San Diego Case Study,” National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401-3393. Volume 1 of 2, December 2006.
  4. Solar panels are typically about one third of the installed direct cost of a solar power system in the United States, so a 30% tariff on imported solar panels would be expected to drive prices up by about 10%.
  5. Feldman, et. al. (2015). Photovoltaic System Pricing Trends: Historical, Recent, and Near-Term Projections. 2015 Edition. National Renewable Energy Laboratory, U.S. Department of Energy. NREL/PR-6A20-64898. Golden, CO. August 25, 2015. p.30. Projected per watt price declines include hardware, soft cost reductions (e.g., marketing, administrative and labor), and effective price reductions from improvements in solar photovoltaic cell conversion efficiency.
  6. A 20 SEER heat pump air conditioning system can save as much as 1.5 kilowatt-hours per square foot per year more than a 14 SEER system, but the additional system cost and reports of lower reliability for very high SEER heat pump compressors may not make the investment worthwhile. Also, because a higher SEER air conditioning system is an “invisible” home improvement, it isn’t likely to increase resale value or help your house sell faster.
  7. Hoen, Ben and Wiser, Ryan, Principal Authors (2015). “Selling Into The Sun: Price Premium Analysis of a Multi-State Dataset of Solar Homes,” Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 90R4000, Berkeley, CA 94720. January 23, 2015. Prepared for the Office of Energy Efficiency and Renewable Energy (Solar Energy Technologies Office), U.S. Department of Energy.
  8. Farhar, B.C. and Coburn, T.C. (2006). “A New Market Paradigm for Zero-Energy Homes: The Comparative San Diego Case Study,” National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401-3393. Volume 1 of 2, December 2006.
  9. Even if you offset 100% of your annual electricity consumption with solar, your utility company may charge you a nominal fee for remaining connected to the utility power grid.
  10. Based on a premium (19%+ STC efficiency) south-facing 9 KW solar panel array flush mounted on a 5/12 pitch roof in Jacksonville, Florida, producing 13,507 kilowatt-hours of solar electricity during the first year worth $0.12 per kilowatt-hour. Solar electricity production is reduced by 0.7% each year. Electric rates are increased at 3.835% each year, the historical average yearly inflation rate for U.S. residential electricity costs from 1970 to 2017. Actual savings could be higher or lower depending upon a variety of factors including roof orientation, efficiency of specific solar panel model used, deviations from long-term average weather patterns, and the actual rate of chage in future electric rates.
  11. $61,000 ÷ (1 − 25%) = $81,333.
  12. U.S. residential electricity costs increased at an average rate of 3.835% per year during the 47 years from 1970 to 2017. See “Average Retail Prices of Electricity,” Annual Energy Review, U.S. Energy Information Administration. July 2016.
  13. See “JEA to offer solar power to customers — at a cost,” WJXT TV, Jacksonville, Florida. Story by Jim Piggott, Reporter, April 18, 2016. Accessed February 21, 2018.
  14. In March 2014, the Barclays Bank credit strategy team downgraded the entire electric utility sector of the U.S. high-grade corporate bond market to underweight, citing long-term challenges to electric utilities from solar energy. Here is an excerpt from their report announcing the downgrade:
    Based on our analysis, the cost of solar + storage for residential consumers of electricity is already competitive with the price of utility grid power in Hawaii. Of the other major markets, California could follow in 2017, New York and Arizona in 2018, and many other states soon after … In the 100+ year history of the electric utility industry, there has never before been a truly cost-competitive substitute available for grid power. We believe that solar + storage could reconfigure the organization and regulation of the electric power business over the coming decade. We see near-term risks to credit from regulators and utilities falling behind the solar + storage adoption curve and long-term risks from a comprehensive re-imagining of the role utilities play in providing electric power.
  15. Order No. PSC-14-0696-FOF-EU, Florida Public Service Commission, filed December 16, 2014.
  16. Household hot water consumption usually averages about 20 gallons per person per day. Average groundwater temperature for North Florida is 71°F and electric resistance heating element efficiency is 90%. We assume a water heater thermostat setting of 130°F and 15% added energy to offset standby heat loss from the hot water storage tank. Active households with heavy laundry use, more automatic dishwasher loads, and/or frequent long showers for hair shampooing can average as much as 25 to 28 gallons per person per day. A 130°F minimum water heater thermostat setting is strongly recommended to prevent legionella bacteria formation in the water heater tank. An anti-scald valve should be installed on the the water heater hot water line to the house.
  17. A March through November solar swimming season assumes a solar pool collector sun-facing surface area equal to at least 85% of the swimming pool surface area, on a south-facing sloped roof.
  18. Note that this argument is not true for solar hot water heating, which—like solar power—is used all year.
  19. A solar pool heating system is essentially useless in 60°F and colder air temperatures with just a 5 mph wind blowing across the surface of the collectors. The opposite is true for solar power panels, which actually perform better in cold air temperatures.
  20. Unglazed plastic solar pool heating collectors only add about three to five degrees of temperature to a swimming pool’s temperature on a sunny spring day, assuming a solar pool collector sun-facing surface area equal to at least 85% of the swimming pool surface area, on a south-facing sloped roof. This heat is lost to evaporation at night if the pool is not covered with a blanket. Alas, most pool owners find pool blankets unwieldy and give up on using them.