When starting your journey into researching home solar power systems, you are probably feeling (more than a bit) overwhelmed. There is a lot of disjointed information out there, let alone all the info coming from the businesses that are competing for your buck. This can make for a tedious and painful process of combing through dozens of articles to get the info you need.
After lots of research, and to my surprise, solar power setups are pretty straightforward and are not as complicated as they appear to be.
I have written this painless guide to solar power to help you save some time and take some guesswork out of the solar equation!
By the end of this article you will have a good foundation for understanding the concept of solar, the different types of setups, all the primary components, how to maintain your system and factors to consider. Let’s get started!
Rural homes benefit greatly from off grid solar installations
First, a Little Bit of Science
I won’t dive into too much ancillary detail here but knowing some basics about how the whole “harnessing energy from the sun” thing works is quite interesting!
In a nutshell, solar electricity is generated when direct sunlight shines onto a naturally occurring semiconductor material (silicon) that is built into the solar panel. The sunlight is converted into a direct stream of energy through a chemical and physical phenomenon within the silicon, known as the photovoltaic effect.
The photon, or “particle of light” is ionized when it hits the silicon and strips the particle of its electrons. These electrons are then propelled into one direction that in turn creates the direct flow of energy.
An illustration of how a solar panel processes energy from light
The gathered electrons travel along the wiring that connects all the solar panels in a series that creates the current of electricity which forms the photovoltaic array. You can read more about the photovoltaic process here.
Now that wasn’t too bad, was it? Let’s move along!
The Different Setups of Home Solar Power Systems
There are three specific ways of how you can setup your solar power system: Grid-tied with no battery backup, grid-tied with battery backup, and off-grid. There are pros and cons to each setup; you will have to decide which is best for your situation.
1. Grid tied with no battery backup
In this common setup, the solar power system is directly tied into the electric utility grid. This allows for the home to use electricity from the grid if your system is not producing enough energy to cover household usage. On the reverse, if there is an overage of electricity made by your system, the overage can be sold back into the grid. This is the least expensive setup but offers no backup of power if the utility grid were to go down.
Let’s think about this for a moment. If you do choose to be tied into the grid, your solar system will go down along with it in any outages. The way that home solar power systems are wired means the energy goes into the grid first then into your system. Therefore, if the grid goes down, it renders your system useless. And with no battery backup, you will be in the same boat with everyone else – lighting candles.
The upside to a grid-tied system is that they are more affordable than their off-grid counterparts, mainly due to not having to install a backup battery bank – which is covered next.
2. Grid tied with battery backup
This option is the same as above with the addition of a backup battery bank; this is to provide additional hours of electricity if the grid goes down. When the energy production exceeds the demand, the extra power is stored in your battery backup system. Once the battery backup is full, the excess is then sold to the utility grid. These systems are more complex and therefore more expensive, along with less efficiency of the system due to the charging and discharging of the batteries.
However, having a contingency plan that is independent from the grid is a smart move, even if its only a temporary solution.
3. Off grid
The off-grid system operates completely independent of the utility grid and relies on the battery bank to store excess power. When the solar panels are having little to no production, the battery bank will release their stored power on demand. A backup generator is highly recommended for times when panels are not producing any energy and the battery bank gets depleted. The generator ensures that you will have power no matter what the situation, as long as you have a can of gas handy.
I have gone into more detail about the different solar power setups in my article: Off Grid Solar Power Systems VS On Grid – Explaining the Differences.
Home Solar Power Systems Components
The components of a solar power system are pretty standard across every residential setup. There are additional components that you can add to enhance the system, but we will go over the essentials that you will need for a basic and well rounded system.
Solar Panels –
The most notable component of your system are the solar panels themselves. The panel is comprised of silicon solar cells that are responsible for converting sunlight into electricity. The silicon cells come in different types of structures that changes the output, efficiency, and cost of the panel. There are three different ways the silicon can be structured in a solar panel, which greatly affects the efficiency of the output of power.
Monocrystalline – Also known as single crystalline silicon, this form of silicon is very high in quality and comes in a form of a bar. The bar is then sliced up to create square wafers with rounded corners that line the solar panel. The uniformity of color and size of these wafers denotes the quality of the silicon. These panels have the highest efficiency as they are comprised of the highest grade of silicon. However, they do come with a higher price tag.
Polycrystalline – also known as multi crystalline silicon, the production process is completely different than monocrystalline solar cell wafers. Instead of raw bars being sliced up, raw silicon is melted and poured into perfectly sized square molds. Since the production to make polycrystalline cells is simpler, it costs less and therefore is cheaper for the consumer to purchase. However, the solar cells are less efficient than their higher quality counterparts.
Monocrystalline solar cell vs polycrystalline solar cell used in solar panels
Thin Film – Also known as thin-film photovoltaic cells, this form of solar panel is highly flexible, and – you guessed it – very thin! Photovoltaic material is deposited onto a flexible substrate giving it the potential for many different applications. This type of solar panel is a great choice for land owners with lots of acreage to devote to a solar panel farm, but is not feasable for a residential installation as the energy output is too low.
You will quickly realize that you will have to make a choice between monocrystalline panels or polycrystalline panels. I have compared the two and have found that monocrystalline is the way to go.
With a little bit of research, it is easy to conclude that monocrystalline solar panels are the superior choice versus its inferior counterpart, the polycrystalline solar panel.
Monocrystalline Panels – the Superior Choice
Monocrystalline is more expensive, but not by much. After researching the price difference between panels I have found it to be quite nominal, despite many outdated articles claiming mono panels to be much more expensive. The price differences between solar panel kits are around 5%-15%. In many cases, single 100-watt panels are the same price, ranging between $90 to $120 per standalone panel in 2019.
Monocrystalline panels are much smaller than polycrystalline. Comparing a 100 watt panel made by the same company, their monocrystalline model is 22% smaller than their polycrystalline model. This means more energy for the space allotted to panels.
Mono panels are more efficient. According to the Photovoltaics Report by Fraunhofer Institute for Solar Energy Systems the lab record for monocrystalline silicon has an efficiency of 26.7% whereas polycrystalline silicon has an efficiency record of 22.3%. This is about a 17% difference in efficiency.
Although heat is not a huge concern for solar panels, mono panels do perform better in hotter temperatures and will result in a longer lifespan in comparison to its counterpart.
Monocrystalline silicone wafers have a sleek and uniform look as the wafer is cut from a solid ingot of silicon.
The silicon used to make mono wafers are sliced from whole ingots. These ingots are then rounded by cutting the edges off, which are then sliced into wafers. This cutoff excess of silicon creates much excess waste.
Mono panels are reported to last 25+ years at a reasonable efficiency.
Fused Array Combiner Box –
The solar panels are organized into a photovoltaic array to create a current. The current flows through the photovoltaic array through a series of connected cables known as strings. These cables run and terminate into an electrical box, known as the fused array combiner. This component is designed to protect the cables through fuses and also delivers Direct Current (D/C) energy to the inverter. The box combines all the strings and outputs and consolidates them into one string that goes directly into the charge controller.
The combiner box is not needed for all solar power installations; it is mainly used for larger projects with 4 or more strings. However, there are advantages to installing the combiner box on smaller installations. Bringing all of the strings to one centralized location makes for easier access, installation, maintenance, and disconnection. The combiner box also enhances the stability and reliability of the solar power system as the box protects the system from over-voltage instances which in turn protects the inverter.
If you are interested to know more about a fused array combiner box and all of its benefits, read my article about Solar Combiner Boxes.
Charge Controller –
The charge controller regulates the electric current delivered to the batteries of the system. It prevents the batteries from overcharging and overvoltage. The controller works by opening and closing the circuit as needed in order to charge the battery and prevent it from getting fried or from being undercharged.
The charge controller is placed between the combiner box (or the panels if no combiner box is used) and the battery bank.
There are two common types of charge controllers that use different methods to regulate the charge.
Pulse width modulated (PWM) – The PWM charge controller uses a pulse for constant voltage battery charging. Once the battery is full, the pulses become less frequent and shorter. This drop in voltage does lead to a loss of wattage, placing the PWM controller at a 75-80% efficiency.
Maximum power point tracking (MPPT) – The MPPT controller gives maximum efficiency to the system, through the means of regulating the charge at maximum operating point; this gives MPPT controllers a 94-99% efficiency rating.
The PWM controller can be used as a lower cost option for smaller systems and in moderate climates. MPPT controllers are required for higher power systems and more volatile climates.
Battery Bank –
The battery bank is an important component to becoming independent from the energy grid. A multi-battery system can deliver power to your home for days for when your panels underproduce energy and when temperatures are too cold or hot to produce irradiance.
There are three types of batteries to choose from for your battery bank: lead-acid, saltwater, or lithium-ion. Lead-acid batteries are less expensive, but lithium-ion batteries will last longer, are more efficient and have a better energy density. Saltwater batteries are very safe, but are inefficient and bulky.
Many things need to be considered when installing a battery bank. Battery banks are costly and depending on how much energy you use will depend on how large you want to design your battery bank. It is a good idea to work on cutting your energy usage before installing your bank by switching to energy efficient appliances, and better insulating your home.
Battery banks can also take up quite a bit of space. You will need to place your battery bank in a protected space with a moderate climate. Lead-acid batteries also require ventilation.
For off grid systems, a backup generator is necessary for days that your solar panels are not producing energy and your battery bank gets depleted.
The battery bank is usually the most expensive component in home solar power systems.
The inverter box is responsible for converting Direct Current (D/C) output into alternating current (A/C) for input into all major appliances. The inverter box is typically attached to the home next to the other electrical boxes for ease of access.
There are different types of inverters for different solar power situations:
String inverter – The most affordable and common option, string inverters (also known as centralized inverters) take the strings from the solar panels and connects into one centralized inverter. Although it is the cheapest option, with a central string inverter, your solar power system will only be as effective as its least productive panel. Therefore, if you have a panel that is partially shaded, the entire system will be reduced to that panel’s output.
Micro inverter – Micro-inverters are a relatively newer option; each solar panel has an assigned inverter directly mounted on the individual panel. This eliminates the efficacy problem that string inverters have and optimizes each panel individually for maximum power performance. You can also monitor the production of power from each separate panel.
Power optimizer – The power optimizer option is a mix of both string and micro-inverter technology. A power optimizer is located on each panel, just like the micro-inverter, but instead of inverting the electricity within itself, it routes it into a central inverter to finish the job. This system costs more than a string inverter, and less than a micro-inverter, and has the benefits of reducing the impact of partially shaded panels.
Backup Generator –
For off-grid systems, a backup generator is essential if your panels are not generating power and your battery backups have been depleted. The backup generator is linked directly into the inverter. You must consider the output of power from your generator, your GFI setup, and how to wire your generator into the inverter.
I have compiled a list of resources to help you configure your backup generator to your battery bank. Installing a backup generator not as straightforward as it seems, as it relies heavily on the specifications of the components within your system.
Keep in mind that in between most of the components, there should be sets of breaker panels and disconnects.
Considerations to make for Home Solar Power Systems
Shade does not eliminate, but reduces, the effectiveness of solar panels. The longer the panel is in the shade, the less output it creates over time. It also affects the cells within the panel that are not in the shade; those solar cells will work harder to output energy to overcompensate the cells which are in the shade. This can lead to overheating and burning out of individual cells. Consider removing the causes of shade if possible. If not, you can consider setting up your panels in your garden.
Shade on solar panels placed on a roof creates less output of electricity
Temperature does not directly affect the power received into the solar panel but does affect the amount of power that the panel will put out. Solar panels operate better at lower, more moderate temperatures than hotter ones, even with the same amount of sunlight; it is the light, not heat, that creates energy in solar panels. The cells in the panel loses the effectiveness of producing energy as the temperatures push the panel past its optimal operating range. A cool, yet bright, winter day will produce more energy than a hot summer day.
For North American dwellers, solar panels are optimal facing true south, not magnetic south. True south can be easily determined at noon; shadows from tall objects will run north to south. If you cannot orient your panels due south, you may need additional panels to compensate for less sun.
Do not neglect your dirty solar panels! Dirty solar panels can drastically reduce the efficiency of your solar power output in the range of 15-25%! Luckily, most solar panels do not require any special method or product to clean. However, you will want to double check with your manufacturer to see if it does have any special requirements for cleaning.
Spraying down your solar panels with your backyard hose could be enough to remove the dirt and debris without having to climb onto your roof. If you cannot manage to get them clean enough, a bucket of warm soapy water and a soft cloth will do the job.
Keep in mind that solar panels become extremely hot during the day, so cleaning should be performed in the evening after the solar panels have cooled off or in the morning before they have warmed up.
Also, be careful when clamoring onto your rooftop! You may want to consider hiring a professional.
Costs will vary greatly dependent upon how small or large your setup will be, the complexity of the setup, the quality of the components, and if you will be hiring an installer or installing yourself (grid-tied systems must be installed by a certified installer). Check out my comparison of DIY installation VS. Professional installation to help you decide if a DIY setup is right for you.
The national average price for a typical grid-tied solar power system for a single-family home in 2018 is around $22,000. Do keep in mind that the federal government is offering a 30% tax credit and most cities and states offer rebates on your solar power investment. You will also be possibly eliminating your electric bill in entirety and even selling energy back to the utility company.
Electromagnetic Pulse (EMP) or Coronal Mass Ejection (CME) Damage –
Many people choosing to go with solar are doing so out of concerns over our power grid failing. If our frail grid system did go down for long periods of time, it would throw us back into the dark ages. Our aging electrical grid infrastructure is in a state of disrepair and would cost trillions of dollars to upgrade according to our demands, as stated here.
A coronal Mass Ejection from the Sun could threaten our fragile electrical grid
Unfortunately, the chances of home solar power systems surviving an EMP or CME is low to nonexistent. The solar panels themselves do not have much for electronics built into them, however, the strings attached to the solar panels that connect to the more delicate electronic devices, namely the charge controller and inverter, will carry the EMP or CME blast down the strings and fry them. The only way to keep this from happening is to disconnect the panels from the electronics before such an occurrence which is highly unlikely. One way around this is to have a backup of the delicate electronic components and store them in a faraday cage.
Home solar power systems are becoming more efficient and affordable than ever before, making them attainable for most average single family home dwellers. As the grid antiquates, its not a bad idea to become energy independent and place less stress onto the grid. All in all, most systems will end up paying for themselves as the cost of grid energy becomes higher and higher.
Now that you have reached the end of my article, I hope you are feeling more enlightened about the basics of home solar power systems. I would love for you to share your thoughts with me in the comments below. I will be reading them!
– Regina C.