Solar Energy Facts

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Solar Photovoltaic Systems Cost

What is "PV"?

PV is short for photovoltaic. One of the primary methods of capturing the sun's energy is through the use of photovoltaic cells or panels. PV technology utilizes the photoelectric effect and turns photons from the sun's light into electricity. This was first described by the French physicist Edmund Becquerel in 1839. Combining these photovoltaic panels with an inverter and conditioner makes up a photovoltaic system. Solar PV systems can range in size from very large systems all the way down to a small PV portable system that is used for camping. The cost of a solar photovoltaic system will vary according to the size of the system.

The photoelectric effect occurs when Ultraviolet (UV) light, composed of photons, strikes a negatively charged metal plate. This causes electrons to be knocked loose from the negatively charged plate. These free electrons are then attracted to the other plate by electrostatic forces. When this happens, it results in electrical current. This electron flow is in the form of direct current (DC). If the electrical energy is used for an alternating current (AC) circuit, an inverter is used to convert it from DC.

How do I determine what size of a solar powered system I need?

The primary goal when installing a solar photovoltaic power system is to supply a large portion of your electrical energy. By doing this, you will be charged for the extra energy you use at the lower tier rates. If you are wanting to eliminate your electric bill, gather your electric bills for the past twelve months. At an average, a 1-KW solar photovoltaic system will generate about 2,000 KW-hours in a year. Divide your total KW usage over the last 12 months by 2,000. This should give you a good rule of thumb number to go with. If your total electric usage is 10,000 for the year, you would need a 5-KW system to eliminate a majority of your electrical bill. Here is a way to eliminate 75% of your electric bill in the next few weeks!

Will installing solar panels affect the value of my house?

According to a study provided by ICF Consulting, photovoltaic solar systems can add $20 of home value for every $1 of yearly energy cost savings. If you are seeing a savings of $250 per month, that equates to a $3,000 annual savings. By using the ICF formula, it should increase the value of your home by close to $60,000. The size of your photovoltaic system will determine how much value you gain by installing a solar PV system.

Will installing a solar PV power system increase my home insurance?

Unless you do the installation yourself, all work should be done by a licensed professional that meets all city, county, and state guidelines. The equipment that is installed should also carry UL certifications. Make sure this is the case before proceeding with any company or individual. When installed properly, there should be no additional risk to your home. Therefore your home insurance shouldn’t be impacted at all. If any leaks occur or any other damage, the warranty you receive from the installing company should cover those damages. Verify the warranty that is offered with your installation prior to signing any agreement.

How does weather affect my solar photovoltaic electric system?

All professional solar PV electric systems are designed to withstand weather conditions of all kinds. Modern solar panels hold up well against lightning, extreme temperatures, and even wind storms typically up to 80 miles per hour. These conditions will however temporarily reduce the system’s energy production. Although the solar panels are very strong and durable, severe hail storms could cause some damage, as with any structure. If you live in an area that has severe thunder storms, you will want to make sure your insurance policy also covers your solar photovoltaic system.

What's the effect of rain and fog on PV solar production?

In fog, or cloudy weather, most systems will still produce up to 20% to 30% of a normal amount in most photovoltaic systems. A steady rain will cut back considerably on production but does have a side benefit of cleaning the panels.

Will snow covering the panels reduce electrical production?

Immediately following a snowstorm when the panels are covered, the system production will be minimal. Fortunately, solar systems are placed where sunshine is the greatest. Therefore the snow will melt quicker and restore production as it melts. Also with the tilted mounting of the panels and the slick surface, the snow will also slide off fairly easily.

How does a solar electric PV system store electricity so I can use it after the sun goes down?

The most common solar energy system is what is known as a "Grid-Tie Only" system. There are no batteries to store energy. Excess electricity production goes back into the local utility grid. In the process, your meter spins backwards. You will receive credit for any power that you "sell" to the utility company. This is what happens with Net Metering. One drawback with this system is if there is a black out, you will lose power from your photovoltaic system even if the sun is shining. The reason is, your inverters sync off of the AC power coming into your home from the grid. With no power coming in, the system has to shut down.

What maintenance is required on my PV panels?

Since there are no movable parts on photovoltaic modules, there is virtually no maintenance needed. The only real routine maintenance that is needed for your photovoltaic system is keeping the solar panels clean. In many areas, the normal rainfall will keep the solar panels washed off. In areas where it doesn’t rain much and there is a significant amount of dust, it will require you to hose off the panels every 30 to 90 days. Solar production is reduced if dust or any other debris builds up on the panels. Some have actually set up a sprinkling system that washes the panels off without having to get on the roof to do so.

How long do PV modules last?

It is estimated based on tests over a period of decades that single and polycrystalline modules degrade at a fairly steady rate of 0.25%-0.5% per year. Based on that information, PV modules should last a long, long time. Most solar manufacturers offer a warranty of between 20 and 25 years, but the panels are expected to last at least twice that long. The warranty states that the product will still produce 80% of its original power output after the 20th year. With an average of six to eight hours of active sunlight per day should provide up to 40 or 50 years of normal production. Photovoltaic panels and systems don't need to be updated either.

Is it possible to install a grid-tied PV system now and later put in a battery-backed system?

Both off-grid and grid-tied systems use the same solar panels. If you want to add batteries to a grid-tied system, you will need to replace the current inverter with a special hybrid device. Although this is possible, it could be fairly costly. It is best to design a battery back-up system in the first place if you want to store your own back-up power with your solar photovoltaic system, and not rely on the grid.

What kind of warranty do PV systems have?

Most solar PV panels have a 25-year manufacturer's warranty, while inverters normally have a 10-year warranty. The performance efficiency for solar panels is at least 80% of the original output after 20 to 25 years. Batteries that are used on a non-grid system should last between 7 and 10 years. The warranty time varies on different batteries depending on the manufacturer.  The actual installation is normally guaranteed for approximately 5 years.

Does my PV solar system produce electricity on a cloudy day?

Solar PV systems will produce electricity even with some cloudy conditions. There is a certain amount of UV light even with clouds or fog. The solar production will be diminished considerably, the cloudier it is. You may easily lose 60-80% of production.

Is there a way to know if my system is producing what it is supposed to?

Yes, you can monitor your solar production. Some companies offer a web-based tool to monitor the system in real time. Other companies offer a remote monitor that is mounted in a convenient place to monitor the output power. Many of these monitors provide current output production, daily output readings and even monthly readings. After monitoring your system for a couple of months or so, you will be able to determine if it is producing close to normal. If you suspect a drop off, contact the installation company and they will normally recheck your photovoltaic system for you.

Is there a way to keep power flowing during an electrical blackout?

The only way to achieve this is to have a battery-backed solar system. A grid solar system will only be powered when the grid is live. This is one of the disadvantages of solar PV systems.

What happens to my solar system when I need to re-roof?

In most situations, the PV panels can be easily removed and reinstalled. It is normally a good idea to have your roof in good condition prior to installing solar panels. If there is a chance of needing to replace within the next ten years, it is probably a good idea to have the roof replaced prior to installing your PV system. 

What is net-metering?

Net-metering measures the difference between the electricity you buy from your utility company and the electricity that is produced through your solar energy system. Any production of electrical power in excess is fed back into the grid. As it passes into the grid, it causes your existing meter to count backwards. Your electric meter keeps track of the “net” difference of the electrical energy you provide and the amount you draw from the utility grid.

Why is net-metering important?

Net metering allows you to track all energy you produce in excess of your current usage. If you didn’t have a meter to monitor the difference, you would need to install a battery storage system. There will be days when your system produces more than you use and other days where you use much more than you produce. If your photovoltaic system is designed properly, your usage should average out.

If I move, can I take my solar electric system with me?

You can take a solar electric system with you if you move. The real question is "SHOULD I take my system with me?" It is usually better to leave the system on the original house since it increases the resale value of your home. Also, you may qualify for tax incentives if you install a new system on a new home.

What do solar photovoltaic systems cost?

The price of a photovoltaic system can vary drastically from one system to another. According to the California Solar Statistics records, which are updated every Wednesday, the average cost of an installed solar system less than 10 Kilowatts (KW) in size is $7.57 per watt. For systems larger than 10 KW, the average cost is $6.71. For a system having 5,000 watts, the cost would be approximately $37,850. This is before any government incentives, which can amount to as much as 50% of the cost. A system of this size will supply enough electrical power to for about 70% of what is needed for a typical home that has 1,200 square feet. This will place the usage of this home in the lower tier, which costs much less per kilowatt hour (KWH). A system that would supply 100% of the electrical power for this size home would run closer to $54,000 before incentives. If, for instance, you get a 50% rebate/tax incentive, the larger system would cost approximately $27,000 out of pocket. If you were to purchase a photovoltaic solar system kit, and install it yourself, you can get a 5 KW system for as little as $13,000. Some incentives may apply here as well. Unless you are an electrician, or have a good friend who is one, you would still have to pay for the electrical hook-up. Also, check to see if electrical wiring is included. This can add several hundred dollars to the cost. By doing the system yourself, it is possible to save a substantial amount.

As you can see, the solar photovoltaic systems cost can be controlled by the consumer to a great extent. If you happen to be a handyman, that can save you even more on your solar system.