Solar energy harnesses the energy of the sun to power your house. A 2017 report from the International Energy Agency says that solar energy has become the world's fastest growing source of power--marking the first time that solar energy’s growth has surpassed that of all other fuels.
Most people who want to install a solar panel system are motivated to do so because either saving the planet is important to them and/or because saving money on their utility bills is important to them. Either way, solar panel systems are tremendously beneficial.
This week you'll get a basic overview of solar power systems, including the pros and cons of the different types of solar panels, the average cost, and the amount of maintenance needed. We’ll also talk about leasing solar panels.
Before we get to the mini lesson, let’s go over a few Pro Terms:
On the grid, zero energy homes and off the grid.
ON THE GRID
On the grid systems use solar power (or some other sustainable energy system) and they’re also connected to the grid of the local utility company. An electrical grid is an network that delivers electricity to consumers. The grid consists of generating stations that produce electrical power, high voltage transmission lines that carry power from producers to demand centers, and distribution lines that connect to individual customers.
Staying on the grid with a solar panel system, allows power to get to your house at night, when it’s cloudy, or any other time the solar panel system may not keep up with the home's electricity demands.
On the grid systems benefit the homeowner and the utility company. When a home’s solar power system generates more electricity than it needs, the excess power is sent to the utility company’s grid and the home’s power meter actually rotates backward. Most utility companies credit the homeowner for the excess energy that is produced by the home’s solar energy system. Interestingly, though, most utility companies charge homeowners at a retail rate for the electricity they use, but the utility companies credit homeowners at a cheaper wholesale rate.
Staying connected to the grid also allows a home’s solar energy system to be used as a supplemental power source instead of the primary power source. That usually cuts down on the number of solar panels the house would need, so you can save on the up front cost of the system. Many on the grid systems reduce energy costs, as opposed to eliminating them.
To totally eliminate the home’s energy bills, consider either a zero energy home or an off the grid system.
ZERO ENERGY HOMES
Zero energy homes are air-tight, well-insulated, and extremely energy efficient homes that produce as much energy from as they use. Zero energy homes use solar panels, or other sustainable sources, to create energy. The energy created by a zero energy home provides the heating and cooling, electricity, and water heating for the home. The net payment to the utility company over the course of a year is zero. So zero energy homes can eliminate electric bills. To learn more about zero energy homes take a look at/listen to BYHYU 045 called “What exactly is a Zero Energy/Net Zero Home?”
OFF THE GRID
Off-the-grid solar power systems are totally independent of the utility company’s grid. Off the grid systems are most popular in areas where power from a utility company is limited--we’re talking more remote, rural areas of the country.
An off-the-grid solar power system relies only on available solar energy (or other sustainable energy source) to power the house. Usually, an off-the-grid system will utilize another form of energy, such as a diesel generator or an ion battery, as a backup source of power.
If you are considering an off the grid system, your home or home site should have a large area that gets uninterrupted sunlight for a large part of the day. When building a new, off the grid house, you’ll want to invest in highly energy efficient building materials. In fact, using highly efficient building materials is important if you plan on installing any type of solar power system. This includes excellent insulation, highly efficient windows, and an air tight building envelope. These energy efficient building materials will cut down on the overall amount of energy the house will need.
Okay, on to the mini lesson...
Solar panel systems go by several other names— solar energy systems, solar power systems, and solar photovoltaic or PV systems. PV panels are the most common type of solar technology. Photovoltaic is a word that comes from the words photon, meaning light particle and voltage, referring to electricity.
Here’s a quick, very simplified version of how solar panels work.
The sun releases photons, again they are tiny light particles that filled with energy. When the sun’s photons hit a solar panel, the panel converts the sun’s light energy to DC or direct current electricity. The direct current electricity flows to an inverter. The inverter converts the DC (direct current) to AC, or alternating current electricity. AC electricity can then be used to power our homes.
Now, let briefly cover inverters. Remember inverters convert DC electricity produced by the solar panels to usable AC electricity.
Conventional central, or string, inverters have been dominant in the solar industry for a very long time. Central inverters are connected all the panels in entire solar panel system.
Microinverters are fairly new on the market and are one of the biggest technology shifts in the industry.
Microinverters are connected to each individual solar panel, not to the entire solar power system, as central inverters are. This enables every solar panel to perform at maximum potential. When a central inverter is used, whenever there is a problem with one solar panel, maybe because of shade or dirt on the panel, that problem can drag down the performance of the entire solar panel system. With microinverters, which again are connected to individual panels, a problem with one solar panel will not decrease the efficiency of the entire system.
So why would anyone choose a central inverter over a microinverter? Because microinverters are more expensive than central inverters. Therefore you should consider the layout of your solar panels before automatically choosing microinverters.
If a solar panel system is facing multiple angles, meaning some panels are facing south, some east, and some west, then microinverters are the way to go. Or, if you have shading issues from trees, close by houses or a large chimney, again go for microinverters. In these situations, the solar panels will be producing different amounts of electricity at different times of the day, and microinverters will maximize the amount of energy collected. With the microinverters, one poorly performing solar panel won’t bring down the performance of the entire system.
With a conventional, central inverter, problems with shading, will cause your system to lose some energy production. That’s because the one poorly functioning solar panel negatively effects the entire solar panel system if you’re using a central inverter.
But, if your solar panels are all facing one direction, and you have minimal shading issues, then your best option is probably a conventional, central inverter. You’ll get about the same production as you would with microinverters, without paying the higher cost.
In summary choose microinverters if your solar panels are facing multiple directions or if they are affected by shade. Choose conventional central inverters if your solar panels are all facing the same direction and you have minimal shade issues.
Now, what about the efficiency of solar panels?
The efficiency of solar panels is basically how much energy output is able to come from the solar energy input. The efficiency of solar panels is less than what I had imagined, ranging from about 10-20%, depending on the panels you choose. When you are comparing solar panels, make sure you compare the panel’s efficiency. If 10-20% efficiency seems low to you like it seemed to me, consider that plants are only about 3% efficient at converting the sun's energy.
Ok, what about maintenance?
One of the great things about solar panels is they’re what you call “solid-state” technology, which means there are no moving parts that could malfunction or break. This makes solar panels very low maintenance.
And solar panel systems are also highly durable. PV panels are made of tempered glass and can withstand hail, snow, rain, and high winds. They can even extend the life of your roof by protecting it from daily wear and tear.
Some sources say solar panels almost never have to be cleaned, except for in very extreme cases. Other sources say that dirt, debris and bird droppings should be cleaned off the solar panels at least yearly. The dustier and dryer your climate is, the more often your panels will probably need to be cleaned.
Since rain will naturally cleanse the solar panels, the more rain you get in your area, the cleaner your panels will stay. Always follow the manufacturer’s recommendations for cleaning, but generally, solar panels can be cleaned by climbing a ladder and hosing the panels down with a garden hose. You can also leave that task to the professionals.
If you're considering a solar panel system for some or all of your home's electrical needs, part of the decision-making process will include choosing the right type of solar panel to invest in.
There are 3 main types of solar panels: monocrystalline, polycrystalline and thin film panels.
Monocrystalline panels originated in the 1950s. Many small solar cells, cut out of silicon, are combined to make up a monocrystalline panel.
Advantages of monocrystalline solar panels
1. Monocrystalline panels are generally constructed from high-quality silicon, giving them the highest performance rates in the industry, usually up to 21% efficiency.
2. They offer a high power yield per square foot, so you don’t need as much roof space as compared to other types of solar panels.
3. Most monocrystalline panels can produce electricity for 25 or more years. And most manufacturers offer a 25 year power production warranty. This warranty guarantees that their solar panels will continue to generate electricity at a certain capacity for the warranty’s duration.
4. Panels perform relatively well in low-light conditions.
Disadvantages of monocrystalline panels:
1. Monocrystalline panels are expensive.
2. The manufacturing process produces significant waste, so they are not the greenest choice.
3. The performance of monocrystalline panels decreases if temperatures get too low or too high. These panels work best in warm climates.
According to the U.S Department of Energy, polycrystalline silicon panels are leading the market share; they are the most popular panels right now. Polycrystalline panels, like monocrystalline panels, are made from silicon. But instead of cutting out small silicon solar cells (the smaller, individual roundish shapes) as with monocrystalline panels, manufacturers pour silicon into a large mold to form polycrystalline panels.
Advantages of polycrystalline panels:
1. The manufacturing process produces little waste.
2. Some argue they are the best value in solar PV technology, offering decent levels of efficiency, but sometimes costing only half as much as monocrystallin panels.
Disadvantages of polycrystalline panels:
1. Lower efficiency, typically between 13 and 16 percent.
2. The panels require more space to produce the same electrical output as monocrystalline panels.
THIN FILM PANELS
Thin film solar panels are portable and light weight. Thin film panels are made by depositing one or more thin layers of photovoltaic material, such as silicon, on a surface made of glass, plastic or metal. Thin film panels are the least popular solar technology, but they are a decent option for projects with lesser power requirements or projects that need lightweight, portable solar panels.
Advantage of thin film panels:
1. The panels are lightweight, they are generally immune to problems from shading or obstructions and low-light conditions generally don't hinder their performance.
Disadvantages of thin film panels:
1. Most thin film panels score low in terms of performance, with an average operating efficiency of about 9%. Remember, monocrystalline panels are up to 21% efficient and polycrystalline panels are up to 16% efficient.
2. Thin film panels generally require a lot of space. For large commercial buildings, they can make sense, but for most residential installations, where space is tighter, they usually won’t work.
3. The system can be expensive. Due to the number of panels required for a thin film system, associated costs are higher because you'll need to purchase more support elements, cables and so forth to accommodate the system.
4. Shorter Life span. In most cases, thin film panels don't last as long as other systems. They are more easily affected by weatherization. You typically won't find a manufacturer offering a long warranty .
In addition to solar panels, there are also solar roofing shingles that look similar to conventional asphalt shingles, but like solar panels, they can produce electrical power.
HOW BIG OF A SYSTEM DO YOU NEED AND HOW MUCH WILL IT COST?
Like electricity, solar energy is measured in kilowatt-hours. The most important factors affecting a solar panel system's effectiveness are orientation toward the sun and unobstructed access to sunlight. PV systems work best on a south-facing roof, and with sunlight that is not obstructed by trees or other shading..
A home energy audit will help you assess your home’s energy and solar panel needs. Make sure you get a solar site assessment as well. You don't want to pay for an expensive solar panel system to later discover your property doesn't really get enough sunlight to make it worthwhile.
One factor that may limit the size of the solar panel system you can get is the available surface area of your south-facing roof. A solar installation company can supply a precise calculation, but a general rule of thumb is:
-400 to 600 square feet of roof area is needed for a 4 kwh system
-1,000 to 1,500 square feet of roof area is needed for a 10 kwh system
The average home in the US uses 10,000 kwh per year.
Typical residential systems range from 3 kwh to 10 kwh in size.
As a general rule, a 3 kwh system will generate approximately 3,600 to 4,800 kwh per year.
A 5 kwh system will produce 6,000 to 8,000 kwh per year.
A 10 kwh system will produce 12,000 to 16,000 kwh per year.
And what about price? A 5-kwh system may run $35,000, but federal and state incentives can reduce that expense by more than half.
Here are some tips to keep in mind when consider a solar panel system.
1. Don’t go too big.
Many people think they should install the largest solar power system they can afford. But if your system produces way more power than your household needs, it may take many, many years to recoup your initial investment in an oversized system. That’s because, as I told you before, utility companies credit homeowners at cheaper wholesale rate, not retail rates. So get a system that’s appropriately sized for your house and needs.
2. Don’t wait too long to invest in your PV system.
Federal incentives and rebates for solar panels systems are slated to last through 2019. After that, we can’t be sure if they will continue. Those incentives are likely to decrease as solar becomes more popular. Plus, every year you delay your solar decision is another year that you miss out on the financial benefits your solar energy system could provide.
The current federal renewable energy tax credit is 30%. Some state and local governments offer similar programs, they will also likely be reduced over time.
Check out the following link for U.S. Department of Energy Database of Tax Incentives by state. http://www.dsireusa.org
3. To save money, have solar panels installed on the roof of your home.
Although panels can also be installed on the ground or on a solar canopy, Roof mounted systems are usually the most affordable. You’ll typically pay more for ground mounted systems.
Solar panels can be installed practically anywhere that receives direct sunshine for most of the day and is not shaded by trees or buildings. Remember, panels that face south will produce the most electricity, but your panels can also face east or west.
4. Talk to your insurance company.
Make sure your new solar power system will be covered under your homeowner's policy. If you lease your PV system, the company providing the lease may also have specific insurance requirements you need to fulfill.
That lead me into the last part of our mini lesson…
At the time of this podcast/post, about half of the states in the US have solar lease programs for those homeowners who want many of the benefits of a solar power system but not the upfront costs.
There are lease programs and PPA programs, which is short for power purchase agreement programs. These terms are often used interchangeably and they are very similar, but monthly payments are calculated a bit differently. Many, but not all, lease and PPA agreements require no downpayment.
With a solar lease or PPA, you do not own the solar panel system on your property and you don’t get the tax credits and other financial incentives. Those benefits belong to company that owns of the solar panels. But homeowners leasing solar panels do get the benefit of lower electricity bills.
Lease and PPA agreements generally last around 20 years and during the lease, the leasing company monitors and maintains the solar panels.
Most companies allow you to buy the solar panel system at any time during the lease term at the price defined in your contract or its fair market value, whichever is higher.
If you sell your house, you can transfer the remainder of your lease to the homebuyer or buy the system from your leasing company yourself and include the cost of the system in the sales price of your property.
When your lease agreement ends, you can either buy the system outright, have the leasing company remove the system, or leave the solar power system in place and renew the agreement.
Wow, that was a lot of information. We’ll do a couple of quiz questions in a second to review some of the important points, but If you feel overwhelmed by the information, you may want to listen/read through another time or two. I think that might help.
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Alright, ready for your quiz?
1. True or False. (This is not meant be tricky, by the way)
Solar panel systems produce power for our homes when the sun’s photons hit the solar panel and produce DC electricity, and when that DC electricity is converted to AC electricity which can be used to power our homes.
That is true. That is a very simplified explanation.
2. What type of solar panel is the most popular on the market?
C. Thin film
D. Foreign film
The answer is polycrystalline. Polycrystalline panels are leading the market share. They are a great value and produce little waste during the manufacturing process. But they are less efficient than monocrystalline panels and they take up more space.
Well, that’s all for me this week. I hope you learned as much as I did. Thank you for staying with me to the very end. Come back for the next edition of Build Your House Yourself University -- BYHYU.