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Is Solar Energy Reliable? — Several Factors to Consider

Solar power systems require a significant investment for the homeowner, so it is good to be cautious before going ahead.  Reliability is an important consideration with any large purchase—and solar is one of the most expensive additions to a home. But if it doesn’t produce power reliably, is the investment worth it?  

Is solar energy reliable?  Because the source of solar energy, the sun, is reliable, solar power’s reliability is based on the equipment that is used.   With the proper equipment, a person can rely on power during the day.  If a person wants to use that energy at night, requires being connected to the grid or purchasing expensive batteries.

Is Solar Energy Reliable? - Several Factors to Consider

Corporations don’t want to invest in unproven technology, so what does that say if solar installations for corporations is over 20 times as large as a decade ago.  The top 10 corporate solar users–Apple, Amazon, and Target are the top three–created enough electricity to power 1.4 million homes last year.  If these businesses are investing in solar, shouldn’t you?

Before making a final decision, you need to know about each of the key parts of a solar energy system and their reliability:

  • panels, which collect the sun’s energy
  • inverters, which convert the energy into a form our appliances can use
  • the grid, which guarantees power at night
  • batteries, which ensure the full reliability

We’re going to discuss the reliability of each of those. But let’s start with some background. What is solar power and how long have we used it?

Solar Power Has a Long Heritage?

Humans have used solar power for thousands of years.  We call what they used passive solar.  We still use some of the passive solar principles today.  For example, ancient cultures knew the importance of orientation. 

We place solar panels so that they face the south, and ancient cultures oriented their houses so living spaces would receive the most heat during cooler months.  How much heat a surface absorbs is another passive design. Since dark surfaces absorb the sun’s energy, solar panels are black.  Passive solar use was so common in ancient Greece the Greek playwright Aeschylus wrote

“Only primitives & barbarians lack knowledge of houses turned to face the Winter sun.”


Ancient cultures recognized that the source of solar power—the sun–was reliable.  The sun rose every morning, always from the same direction.  During the summer, they could count on it to be higher in the sky, and rooftops would provide some shade.  In the winter the sun was lower on the horizon, providing them heat they wouldn’t get if their houses faced north.   To them asking if solar power is reliable would have made no sense. 

“In 1447, Leonardo Da Vinci predicted there would be an industrial solar use–using solar power to heat water. ”

Passive solar won’t power our coffee makers, charge our phones, nor provide the energy needs of modern society. When we talk about solar power, we mean Active Solar.

How Does Active Solar Work?

Active Solar also uses the sun’s radiation, but the energy from the sun has to be transformed so that it can generate useable electricity.  Photovoltaic panels (PV) are comprised of solar cells that turn solar energy into an electric current we use for power.  A single cell doesn’t generate much energy, so they are strung together to produce adequate energy. 

For example, a typical panel might have 32 cells strung together into a series.  The energy the panels create can be used to run appliances, cool and heat our houses, or provide light.  The energy can also be stored in batteries to be used at a later date. 

These cells create energy through a process complicated enough that books have been written about it. A simple explanation is that the

  1. Cells are made up of two layers of silicon.
  2. One layer of silicon contains an added element that creates a negative charge.
  3. The element added to the second layer creates a positive charge
  4. The heat of the sun causes the movement of electrons that generate an electric current
  5. Metal strips help harness this current

This current cannot be used by appliances we plug into an electric current, so a solar system needs a power inverter.  The inverter takes the direct current (DC) that comes from the solar panels and turns it into the alternating current (AC) we use to power most of our electronic devices.

Not All Solar Devices Need an Inverter

Devices that can run on DC power do not require an inverter. Lights, batteries, even cell phones can be charged using small solar collectors. The size and design of the battery inside the device controls how long it will remain charged. 

The night lights homeowners install to light driveways and walkways don’t shine all night because they contain tiny batteries.  A cell phone fully charged by a solar collector will last as long as if it had been charged plugged into an outlet. 

If you live in an area where you winter storms or tropical weather could cause you to lose power, consider getting a small solar charger designed to charge up cell phones. I have a Ryno-Tuff Portable Solar Charger which I recommend all the time. You can find these on Amazon should this interest you.

Why Do Some Consider Solar Unreliable?

Since the reliability of the sun cannot be questioned, there must be other reasons why opponents of solar power claim it is not reliable.  The main ones seem to be

  • Inconsistent sun availability
  • Solar Panel Reliability
  • Inverters
  • Battery technology

Inconsistent Sun Availability?

A common myth is that solar panels don’t work on cloudy days.  That is simply not true.  An overcast day will reduce the amount of energy collected from the panels, but not stop it completed.  Estimates vary, but most experts agree that even when the sun is hidden behind clouds, panels will still collect at a minimum 25% of the energy they gather on a sunny day.    

If you live in a cloudy area, it will comfort you to know that areas such as Seattle, San Francisco, and New York are experiencing record solar installation.  This is because the cost of electricity is used in calculating the price of a system.  For example, if payments on the system are $200 monthly but the system will save the user $100 in monthly utilities, then the payment is essentially $100 a month.  This is how much the average solar installation will save annually, according to Energysage.

New York$1,091.25
Los Angeles$929.45
San Fransisco$916.12
Las Vegas$730.64

If you want to see an estimate of how much you can save with a solar power system, you can use an online tool developed NREL, a national solar lab connected to the U.S. Department of Energy.  It will provide information for a specific address and let you know how much you can save.  Make sure you know how much electricity costs if you want to get an estimate of savings.

New Jersey certainly isn’t mounting a strong challenge to become the new “Sunshine State,” and yet, it’s installed more solar than any other state in the U.S.


For more specific information, consult with your solar company.  The figures they provide you should match up with those from NREL. 

Are Solar Panels Reliable?

Solar panels have no moving parts, so it difficult to see how they could be unreliable.  However, sometimes it’s good to see if something that sounds logical is actually true.  To check the reliability of panels, the U.S. Department of Energy sponsored a study.  The study examined approximately 55,000 PV systems that had been installed from 2005 to 2015.  The researchers discovered that 5 out of 10,000 panels needed to be replaced.  The failure rate for the panels was 0.05% annually.

A comparison between panels of older panels built from 1980 to 2000 showed the older panels had a failure rate of 1 in 1000, which is still extremely small.  It also shows that panel manufacturing has further increased the reliability of them. Go here if you want to read the full report.

What Causes Solar Panels to Fail?

Two things can lead to solar panel failure:

  • Weather.  Locations with harsher weather conditions have higher failure rates.  Extreme hailstorms or hurricane-strength wind conditions can cause failure.  Panels in high temperatures or humidity areas have a slightly higher failure rate.

Manufacturing Defects.  As with most things, a defect can occur occasionally from a variable in the manufacturing process.  The industry standard for warranty coverage is 10 years although many manufacturers provide coverage for 25 years.

Solar panels are very much a reliable power source, which has led 2 million Americans to install solar panels on their homes.

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Reliability of Inverters and Other Equipment

Along with the solar panels themselves, some other equipment is needed. Let’s look at each of them and discuss their reliability.

  • Inverters.  Remember that the energy coming from the panels is direct current (D/C) but most of our appliances run on alternating current (A/C).  Inverters convert the D/C into A/C.  In the early days of solar power, enthusiasts built their systems and inverters required researching.  Today, inverters are typically part of a package.  Most have a 10-20-year lifespan with warranties starting at 5 years and going up to 15.
  • Racking and Mounting.  Panels are often mounted to a roof, although some folks opt for mounting them on a concrete pad for better performance.  This will also have to pass inspection, so reliability is not much of a concern.  If your installer does not inspect your roof before starting work, that’s a cause for concern.
  • Balance of Systems.  This is the control panel that connects the different electronic parts of the system.  Since this will be installed by a licensed electrician and inspected by city or county inspectors, there are no reliability issues with it.
  • Monitoring.  This equipment gives you information about your system’s performance.  It gives you information about energy production and usage, historical data, and more.  Many companies provide apps that allow you to check on your system when you are not there.  If the monitor malfunctions, the company that sold you the system will replace it. 

Bottom line—if you are planning to buy the solar system as a package, most of these will be under warranty. 

Are Batteries Reliable?

Power generated from solar panels is not always needed when it is generated.  Because of this, storage systems are needed, typically some sort of batteries.  Adding batteries to a system adds expense and other complications that create difficulty for many homeowners as well as businesses that are energy hogs. Let’s examine three questions:

  • How reliable are batteries used for solar systems?
  • What additional expenses are associated with batteries?

Battery Reliability

Batteries used for solar power use are as reliable as any rechargeable battery.  A battery used in solar energy production takes the energy it receives, houses it, and then delivers it as needed. Once empty, energy from the panels charges the battery, and it stores energy.  The same process is used with batteries for cordless tools. And batteries designed for solar power have the same problems.

Along with general advice about not letting a rechargeable battery drain completely, protect it from excessive heat or cold, and don’t overcharge them, solar batteries have additional requirements:

  • Limit battery connections.  Solar batteries are connected to “banks.” Connecting too many will create uneven charging.
  • Battery Rotation.  To lengthen the life of batteries in the banks, they should be rotated.  Batteries in the middle won’t receive full charges, so batteries in the middle need to moved to the outside of the bank.
  • Battery Gassing.  Solar batteries need to release excess gas build up. This will occur naturally once they achieve a certain voltage.  Ventilation is necessary so the gasses can escape.

These are maintenance, not reliability, issues. Homeowners typically avoid adding batteries to their systems because of cost.

Battery Expenses

The batteries needed to store the energy generated from a typical household installation make them prohibitive for most homeowners.  It’s difficult to make an estimate of the price for a system because power usage and the size of the system will affect how many batteries a homeowner will need.  But typical systems will be priced in a $5,000 to $7,000 range or approximately $400 per kilowatt-hour.

Here are examples from two of the leading solar battery manufacturers

This article is owned by and was first published on October 8, 2019

  • Tesla Powerwalls.  These batteries have made a media splash because of the Tesla name.  Unlike other battery systems, their sleek looks are an attempt to make solar more accessible.  In addition, they will automatically disconnect from the grid if there is a power outage. As batteries go, they are advanced. But the steep prices—approximately $6,500 per battery—will keep them out of reach of the average homeowner who is already going to spend an average of $8,000 to $10,000 for a system.  Even if you aren’t interested in buying one, they’re worth a look.  Follow this link to check out their futuristic looks.
  • LG Chem RESU.  LG has been involved in lithium battery production for over 20 years.  The company designed and manufactured batteries for a number of cars, including the Ford Focus, GM Bolt, and several Renault models.  Now the company has moved into solar batteries for the home, competing with the Powerwalls.  However, they are priced in the same range as the Tesla batteries.

These are not the only battery manufacturers.  Smaller manufacturers typically serve a regional area while Tesla and LG batteries are nationally sold.

Net metering

Most homeowners avoid batteries and use net metering.   This means the excess energy produced by the solar power systems is put into the power grid.  In most cases, homeowners or small businesses are “paid” for this power by having it count against their total bill. A solar array reduces an energy bill in two ways:  less energy and energy “sold” back to the utility. Net metering benefits the homeowner or small business until there is a power outage. In such an event, if the system is creating excess power, it stills feeds into the grid.  Utility workers at that point will have to work with wires that may or may not be live. That’s why most utilities require that the systems be wired so that if the grid loses power, the electricity the solar panels create will not be available to either the grid or the home.

The United States is the world’s fifth largest producer in solar power. Germany comes in first, followed by Spain, Italy, and then Japan


Final Thoughts

The sun is a reliable source of energy, solar panels are reliable, and battery technology for solar provides the reliability that is similar to other rechargeable batteries.  However, the high price of batteries and utility requirements for net metering means that you will have to use a generator during a power outage.

Tesla has found a solution for this where their Powerwalls immediately shut off power to the grid when it goes down. Perhaps this technology can be developed so it works in systems that don’t have batteries.

This article is owned by and was first published on October 8, 2019

More energy hits the earth from the sun in one hour than the whole world uses all year.

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This article is owned by and was first published on October 8, 2019

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