Installation

solar panel out in the field facing towards the sun

What Direction Should Solar Panels Face?

What Direction Should Solar Panels Face?

Leonardo

Written by qualified solar engineer Leonardo. Last updated:

If you live in the USA or any other country in the Northern Hemisphere, the best direction to face solar panels is south. Since most sunlight comes from the south, this will make your panels more productive. However, if the local power company charges higher prices in the afternoon, your panels should face west to maximize the dollar savings.

The electricity output of solar panels is directly related to how much sunlight they receive. Therefore, you should install them on the sunniest part of your rooftop. Also consider that solar panels are not productive when in shaded areas, and they represent a wasted investment. You can find out more about this by reading our article on solar panels in the shade.

If you are charged constant kilowatt-hour prices, your goal should be maximizing the electricity production of solar panels. However, if you are charged variable kWh prices throughout the day, solar panels should maximize production when the highest prices are being applied. This will increase the savings on your power bill.

Why Do Solar Panels Produce More Energy When Facing South?

To maximize the return on investment, the first step is knowing where to install the solar panels. Since the Earth is a sphere, sunlight reaches each geographic location with a different angle. If you track the sun’s position in the sky for an entire year in the USA, you will notice it is mostly towards the south. As a result, solar panels facing south produce the most electricity.

Consider reading about how a solar panel works before moving forward. Different results can be expected based on its orientation:

  • Since the sun rises in the east, solar panels facing in that direction are more productive in the morning.
  • On the other hand, west-facing panels are more productive in the afternoon, since the sun sets in that direction.
  • Installing panels that face north is not recommended, since it results in the lowest electricity output.

As you move farther to the north, the sun has a lower position in the sky and solar panels must be tilted more. In locations that are not far to the north, such as Florida or Texas, solar panels do not need a drastic tilt. However, if you must use them in Alaska, they must be tilted almost vertically to collect as much sunlight as possible. Qualified solar installers can determine the optimal tilt angle based on your geographic location. We can help you when it comes to choosing a solar installer.

A set of solar panels facing the direction of the sun

Make sure you get an inspection of your property to find the best areas for a solar energy system. Consider that the size of a panel does not affect the optimal orientation: the recommendations above apply for both 60-cell and 72-cell panels. You can read our article about the importance of the size of a solar panel for more information.

The efficiency of solar panels is not affected by their orientation either. The electricity output varies because the amount of incident sunlight also varies, but the conversion from sunlight to electricity is not affected. If you’d like to know more, take a look at what we’ve written about solar efficiency.

How Electricity Tariffs Affect the Optimal Solar Panel Orientation

Your panel can have different monetary values, so it’s important to know about the energy produced by a solar panel. If you are always charged the same kilowatt-hour price, your goal should be getting maximum production from solar panels.

However, many electric companies apply time-of-use (TOU) tariffs, which change throughout the day. The highest kWh prices are normally billed in the afternoon and evening, since that is when the grid faces maximum consumption. There are many factors that increase operating costs, and this leads to higher tariffs:

  • Electric companies must bring more power plants online to meet the peak in consumption, including the plants with high generation costs.
  • Since power lines and transformers are carrying a high current, they waste more energy as heat emissions.
  • Electrical faults are more likely when the grid is burdened, creating a higher risk of blackouts.

Many power companies apply higher electricity prices at times of peak demand to compensate for their higher operating cost. The high kilowatt-hour price also disincentives consumption in homes and businesses, helping unburden on the grid.

As previously mentioned, solar panels become more productive in the afternoon if they face west. If you are charged a TOU electricity tariff, you can take advantage of this. A solar power system facing south will produce more kilowatt-hours than an identical system facing west. However, if the kilowatt-hour price increases sharply in the afternoon, your dollar savings will most likely increase.

Solar Panel Orientation Tips for Roof and Ground Systems

When finding the optimal orientation for solar panels, a ground installation offers more flexibility than a roof installation.

With a rooftop solar system, you are limited to the orientations and slopes of your existing roof sections. If an optimal solar panel placement is not possible, you may need to purchase additional panels to increase generation. On the other hand, with a ground solar system, you can adjust the orientation and tilt angle of panels for maximum productivity.

A set of solar panels placed on a roof facing towards the sun

While ground solar systems offer more flexibility for positioning, they also have their limitations. In the first place, you must have a property with enough ground space for solar panels, while a rooftop installation does not need extra space. Also, since a ground solar system has a lower elevation, finding a spot without shadows can be more challenging. This applies especially with products such as decorative outdoor solar string lights which solar panel is installed on ground, easily exposed to shading. If you need more information on how all of this works, feel free to take a look at our article about solar installation.

Since each property is unique, the best recommendation is getting a professional inspection and a customized solar panel system design. Getting quotes from multiple solar companies is also recommended, since you can compare several options and find the best deal.

References

  1. Solar Panel Orientation – University of Calgary

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A large set of solar panels installed on the roof of a house

How Long Does It Take to Install Solar Panels?

How Long Does It Take to Install Solar Panels?

Aniket

Written by qualified solar engineer Aniket. Last updated:

Usually, it takes an average of 90 days to install solar panels on your house. This time is consumed by a mix of technical and mainly bureaucratic procedures, such as the permissions, the installation itself, inspections and approval. The climate crisis and climbing power costs have brought solar power into the limelight. On the other hand, there are guaranteed cost savings and even a rise in home value. It would be thus natural to decide in favor of installing solar panels.

Technically, getting the material at your house and installing it would be a matter of a few days. Unfortunately, there are other things involved and it cannot be that straightforward. This becomes essential solar panel installation information to have, and thus we lay out these procedures, steps and the respective durations required.

Finding the Right Company

The obvious first step is to choose a solar company. Choosing a reliable solar installation company is important, considering the fact that you are going to invest thousands of dollars for a product that has a thirty-year life. As far as the time required is in question, it can take anything from a day to a week and depends on when you finally feel confident with one of the installers.

Site Survey

A solar plant is not a general product. Every house or plot can have its own specific solar plant design. This is due to the fact that the areas and shapes of rooftops are seldom the same. The shadow cast by any trees, poles or nearby buildings also have to be taken into account. For a large roof, it is important to locate the best place to install the solar panels on it. Additionally, different locations in the country have different sunlight intensities, and the company might like to have a quick assessment of the available solar radiation in your location.

Two solar technicians checking the site before installing solar panels

All of this is done by a specialist that the solar company will send to your place. After measurements, shadow analysis, and probably even some noting of the appliances you run, the specialist will take the site survey data to his company’s design team. In some cases, if it is a really old house and the roof’s quality is drastically altered, you may need to have a roofing assessment for avoiding damage to your roof during installation.

The time between your enquiry and the visit of a site survey executive can range from one to two weeks. It can be much quicker than that, but it shouldn’t ideally cross this number.

Preparing the Optimum Design

The data collected about the roof type, orientation, shadow, etc. Is utilized by the design specialists to prepare the best possible design that suits your roof. This includes selecting the shadow-free areas that can have your solar panels facing the correct direction. There is also a systematic calculation based on your consumption of power that helps you in choose the sufficient number of solar panels.

This part of the journey towards going solar depends on how busy the chosen company’s team is. In any case, it should require 2-4 days and should not cross a week. At the end of this small wait, the company will contact you again with a technical-commercial proposal.

This proposal will include details on the required system size, information about the components, the proposed cost and possibly the time required to get it up and running. Once you accept the proposal and its terms, you enter a deal, after which comes your next step.

Permissions

Governing bodies believe they should be aware of how and where solar panels are being installed, and they even have an approval or disapproval mechanism for it. The permits are specific to solar photovoltaic. It can be related to construction or electrical systems. There can be some related to the homeowner’s association of your area.

If everything is perfect, there is no reason for your plant to be denied permission. Different states and even some different cities will have their specific guidelines about installing solar panels. This part may test your patience a bit because all you can do is wait.

The good news, however, is that most solar companies have people dedicated to tackling this part. They can prepare all the documents for you and kickstart the procedure. Overall, the permitting part can take anywhere between a week and a month, sometimes even more.

Installation

This is the part where you see the brand new packed solar panels entering your premises and getting mounted on your roof, ready to power up the devices in your house. The installation of solar panels requires setting up mounting structures, cables, inverters and of course, the panels themselves, along with other small components.

Solar technician fixing in solar panels with a drill

Depending on the number of panels required, the entire installation process should not take more than a week. There may be small variations based on how much the solar panels weigh and the size of the solar panels being installed, but it is usually negligible. In some cases, with very small systems and easy roofs, it can even be done in a day.

Inspections

The permissions obtained before the previous step are subject to certain conditions. For example, getting a permission to connect a 5kW plant to the grid and instead erecting a 10kW plant is a kind of foul play the governing bodies do not want. There are also other aspects of safety and quality.

Therefore, the installation step is hardly the final one, and is followed by inspection done by particular authorities. This again is a bureaucratic step and for most part, you cannot do much but wait. If you are lucky, this can be over within a week — but sometimes it can take up to a month.

Grid connection

Unless the panels you are getting installed are in some remote place without a grid, you would have them connected to the utility grid. This brings you flexibility of use by the net-metering policy, wherein you can send surplus power to the utility company and even get it from them when you need. This is useful particularly at nights, or high consumption days, or even low sunshine days.

The grid connection is, thankfully, the final step. Once completed, your solar panels are all ready to harness free energy and get your home running for nearly zero power costs and for a beautiful duration of 25-30 years.

Conclusion

To summarize everything, we would say that installing a solar plant that can take months. If you are fortunate, it would be just two or three. But if we think of the fact that the solar panels will serve you for a few decades to come, this wait is well worth it.

As far as the question goes of whether it is a good decision, there has never been a better time to install solar. The price of installing solar panels has dropped exponentially, the incentives are promising, and the home premiums show a healthy gain.

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multiple solar panels on a house

How Many Solar Panels Do You Need?

How Many Solar Panels Do You Need to Power Your Home?

Leonardo

Written by qualified solar engineer Leonardo. Last updated:

A home that consumes 1,000 kWh per month will normally need between 20 and 30 solar panels. The exact number changes depending on the specifications of the chosen panel model, as well as the sunshine available at the project site. Before purchasing a solar energy system for your home, an important step is finding out how many solar panels you need.

Solar Panel Calculator

Solar Calculator
1. How many kilowatt hours (kWh) do you use per month?
2. What percentage of this power do you want to offset with solar?
3. Which state is your house in?

Minimum PV System Size (in watts)
Recommended PV System Size (in watts)

Solar panels have been successful as a clean energy source thanks to their modular design. You can purchase just the right number of panels according to your home needs, instead of having to choose between predetermined system sizes. Solar energy can adapt to buildings of any scale, ranging from small homes to large industrial parks.

To size a solar system correctly, the best recommendation is getting in touch with a qualified solar contractor. He/she will also help you in knowing how much solar panels cost to install. A residential system has an average installed price of $3 per watt. Solar installers consider the following factors to calculate the number of panels needed:

  • Local sunshine: How much energy a solar panel produces depends on the sunlight received. If two homes in different locations need the same amount of energy, the home with the sunniest weather will need less panels.
  • Home size and energy usage: A larger home typically needs more panels to cover its consumption. However, usage habits and the efficiency of home appliances are also important. Two homes of the same size can have very different energy needs.
  • Panel specifications: The power rating of panels varies depending on the model and manufacturer, but most range from 250 watts to 330 watts. For any given energy production target, you need fewer panels if their individual wattage is higher. When roof size is limited, efficient panels with a high wattage can make the system more compact.

How Many Solar Panels do I Need – Solar System Size Comparison

System Size

Average Annual KWh Production

Estimated Number of Solar Panels Needed

4kW

5,000

10-12

5kW

6,250

13-15

6kW

7,500

15-18 

8kW

10,000

20-24

10kW

12,500

25-29

12kW

15,000

30-35

20kW 

25,000 

50-59

How to use a Calculator to Calculate how Many Solar Panels you Need

Our solar calculator can estimate the number of panels needed for your home. The tool works by taking your average monthly energy usage in kilowatt hours (kWh).

  • Calculators that use kilowatt hours are more accurate because they consider your exact energy needs
  • Those that ask for home area must assume the electricity consumption

Each electric company has a different power bill format, but they all display your electricity consumption for the billing period. The exact description will vary, but you should look for a term such as “kWh used” or “kWh consumed”.

Solar calculators also ask for your home location to determine how much sunshine is available. Based on those two values, they can estimate the system size in kilowatts. Some solar calculators assume a wattage for panels, while others ask you directly. Based on the total kilowatts and the rated watts per panel, the calculator can determine how many are needed.

woman calculating how much she saves by using solar panels on her house

It is important to understand the difference between kWh savings and dollar savings. kWh savings refer to the amount of energy that your panels produce. On the other hand, dollar savings are obtained when the solar electricity production is multiplied by the kWh price.

How Many Solar Panels do you Need for 1000 kWh per Month?

A family with several siblings can easily reach a monthly consumption of 1,000 kWh. In places with expensive electricity, this results in monthly electric bills of over $200. However, solar power is an effective solution to reduce energy expenses.

As explained above, the number of panels needed to reach 1,000 kWh per month changes depending on local sunshine and panel wattage. To simplify calculations, solar radiation is specified in peak sun-hours per day. Weather scientists calculate this value by measuring the total sunshine in a location and converting it to equivalent hours of peak sunshine.

  • Peak sun hours should not be confused with daylight hours
  • Since sunlight is moderate in the early morning and late afternoon, these hours do not count as complete peak sun hours
  • You may find a site that gets 12 hours of average daylight, and 6 peak sun hours per day

There are many online databases that provide peak sun hours based on site coordinates, including the Atmospheric Science Data Center from NASA. Once you know the peak sun hours, estimating the number of solar panels needed for 1,000 kWh is simple.

  • The first step is calculating the kilowatts needed. You must simply divide the average daily kWh by the peak sun hours
  • Assuming a 30-day month, an electricity generation of 1,000 kWh is equivalent to 33.33 kWh per day
  • If the site gets 6 peak sun hours per day, you need 5.56 kilowatts

Since no energy conversion system is perfect, you cannot assume the solar array will deliver its theoretical production. To compensate for this, you can increase the calculated wattage by 20%. In the example above, adding 20% yields a capacity of 6.67 kW or 6670 watts. The final step is dividing the total wattage by the individual panel watts.

  • If you use 250W panels, you need 27 of them
  • On the other hand, if they are 330W panels, only 21 are needed

Solar shingles are smaller than panels, and their wattage is lower as a result. However, you can use the same procedure to estimate how many are needed. For example, if the amount of power needed is 5,000 watts and each shingle is rated at 50W, you need 100.

How Many Solar Panels do you Need for a 2000 Sq. Ft. Home?

Estimating the number of panels based on home area is an indirect approach, since you must assume the kWh consumption. Some homes have more efficient appliances, and habits also influence electricity usage. However, average values can be calculated from official data:

  • The US Energy Information Administration estimated that the average home uses 867 kWh monthly
  • The US Census Bureau determined that single-family homes have an average area of 2467 square feet
  • When dividing these values, you obtain 0.35 kWh per square foot

Assuming 0.35 kWh for a 2,000 sq. ft. home, the estimated electricity consumption is 700 kWh. At this point, you can use the calculation procedure described in the previous section. Considering 6 peak sun hours per day and 300-watt panels, you need 16 to produce 700 kWh each month.

If you have limited roof space, the best recommendation is installing the most efficient solar panels available. This will maximize the watts installed per square foot, compensating the area limitation. Finding out how efficient solar panels are is simple: you must only divide their individual wattage and area. The panels with the most watts per square foot have the highest efficiency.

How Many Solar Panels do you Need for Common Household Items?

If you are considering solar energy for your home, you may also be asking how many panels are needed to power specific appliances. However, it is important to understand how solar generation works:

  • Solar systems deliver most of their energy production in the hours around noon
  • During the early morning and late in the afternoon, solar generation is much lower. This is because there is less sunlight reaching the panels
  • Households have the highest energy consumption in the evening and early morning

Since solar panels depend on sunlight, you cannot control their electricity production. Powering home appliances directly with panels is impractical and potentially dangerous, unless you use a solar battery to store energy. If you connect home appliances directly to the panels and inverter, a dark cloud passing over your home will shut off the power. At night, you would have to switch to the local power supply anyway.

house appliances next to a solar panel

The most practical solution is synchronizing solar systems with the local power supply, which lets them operate as a single power source. When solar generation cannot power your home appliances by itself, the rest of the energy comes from the grid. If your panels have surplus production, you can send it to grid to get a credit on the next electricity bill.

Sunlight is a variable input, and your electrical devices need 24/7 availability. For this reason, you cannot compare the wattage of panels directly with that of home appliances. Instead, you must balance the kWh produced with the kWh consumed. The following table estimates the number of solar panels needed for common appliances, assuming 300-watt panels and 5 peak sunlight hours per day.

Appliance

Usage

Monthly kWh

Panels Needed

20 LED bulbs

10 watts each

6 hours per day

36

1

12,000 BTU/h

Mini-split AC

SEER 16 efficiency

8 hours per day

180

5

Refrigerator

Always on

150

4

Water Heater, 5 kW

2 hours per day

300

8

This table considers the most power-hungry appliances found in homes. Most small appliances and electronic devices have a very low consumption, which does not even match the production of one panel.

How Many Hours of Daily Sunlight Does Your State Receive?

The sunlight available to produce electricity varies greatly throughout the United States. Southwest states like California and Arizona get the most sunshine, while northeast states like New York and Massachusetts get the least.

However, you should not discard solar power just because you live in a state that isn’t sunny. For example, New York only gets moderate sunshine, but it has very high electricity prices. Solar panels are worth it in this case, since they achieve high savings even with reduced production. Saving 750 kWh when you are charged 25 cents/kWh is better than saving 1,000 kWh at 12 cents.

After estimating how many panels are needed in your home, you can make better purchasing decisions. Keep in mind that you don’t have to pay the full system cost upfront. Many banks finance for solar panels, and you can pay off the loan with the electricity savings achieved. Leasing solar panels is also a viable option, where you pay a monthly price instead of purchasing the system. Your local solar installer may offer several purchasing options, adapting to your needs.

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group of men installing solar panels to a roof

Can Solar Panels Damage My Roof?

Can Solar Panels Damage My Roof?

Carlos

Written by qualified solar engineer Carlos. Last updated:

Solar panels will not damage your roof if the installation is performed properly by a certified NABCEP solar installer. However, improvised installations where the proper materials, technics, and calculations are not carefully considered could mean damage to the roof of any household – eventually leading to leakages or even a collapse of the structure.

As solar panel installations spread throughout the country, it is more likely to see homeowners asking themselves if installing solar panels will damage their roof. Having solar panels installed is expensive so you don’t need the issue of paying for roof repairs aswell further down the line, which is why it is wise to make sure your solar panels won’t cause any damage to your roof.

 Let’s see some of the mounting options available for solar panels and discuss this topic further.

Solar Panel Mounting Options

First, you must know that there mainly two types of mounting systems for solar panels: ground-mounting and roof-mounting.

Ground-mounting systems are installed on the ground, mainly in backyards of households or in wide land-farms. These types of systems have several advantages like easy maintenance, good cooling systems, and flexible designs. However, they also offer some disadvantages such as low installation times, high costs, and backyard use of land that could be used for recreation.

When visualizing the pros and cons of ground-mounting systems, you may want to opt for rooftop PV systems. These can offer you a set of advantages such as:

  • Fast installation times
  • Low installation costs
  • PV system is hard to reach for any unauthorized personnel
  • Can increase the value of the household
  • Protection for your roof
  • Better sun exposure

As you can see, one of the advantages of rooftop systems is that they protect your roof, so could it be possible that they also damage it? Let’s take a look at the installation procedure on rooftop systems.

Installation Procedures on Rooftop PV Systems

There are two main types of installation procedures on rooftops for PV systems.

The first and most common for commercial applications is the ballasted footing mount system. This applies for commercial buildings or even some households that have a flat roof. This is the most ideal combination between roof and ground-mounted systems, because the PV system is able to combine the advantages of ground-mounted systems with those of rooftop systems.

Basically, it consists of pre-cast concrete blocks or steel structures anchored to the roof that can be placed on any position and angle. Generally, these flat roofs are made of concrete, so the engineers can ensure that the roof withstands the weight of the solar panels and the ballasted mounting system. You can take a look at an innovative flat roof mounting system design here.

ballasted mounting system with concrete blocks for solar panel installation

Ballasted mounting system with concrete blocks (Source – Solar Panels Plus)

The second option, most common for residential US households is the sloped rooftop mounting. This option can be divided into several installation procedures:

Rail-Less Mounting Systems: This system does not use any rails to attach the modules to the sloped roof. Instead, it directly uses screws and bolts to attach the solar panels to the tiles. This type of system is less frequent now because it involves more penetrations to your roof, installation times are slow, and it can damage a tile by lifting it up with the force of the wind.

rail-less pv system for solar panel installation

Rail-less PV system (Source – Solar Power World)

Railed Mounting System: Attaches a set of rails to the rooftop by penetrating the roof and using screws and bolts. Each solar panel can be attached to the rails using a set of clamps.

Shared-Rail:  A variation of the railed mounting system. If the PV array needs several rows of modules, then these can be put together and use a single rail to act as the support of two rows. This system simply eliminates the use of one rail to optimize the installation.

Here you can take a look at a detailed explanation of a railed mounting system installation.

railed-pv system installed on the roof ready to install solar panels

Railed-PV system (Source – Quick Mount PV)

How Does my PV System Affect the Roof?

Installing solar panels on a roof may not see to carry much calculations and numbers, but in fact, there are a set of variables that must be measured if you want your PV system on your roof.

Solar panels can be very heavy. Weight variations can go from 15 kg to 30 kg depending on the panel size and power output. As you can imagine, if you have 10-15 modules on your roof, that is a considerable extra weight that your roof must be able to endure every day over 25 years.

That is why US regulations demand that a structural engineer checks your roof before the installation takes place. The structural engineer must take into account the age and current condition of the roof to make the installation. If the roof is very old, if there is a presence of termites, or if there are weaknesses in some spots, then the structural engineer will recommend that you make some upgrades to your roof.

These upgrades can be expensive depending on what it needs to be done, but it would be more expensive to install a new PV system on a roof that will eventually fall apart. Moreover, State regulations may require that you upgrade or check the conditions of your roof within a certain time period. If the roof needs to be replaced or improved in the next 10 years, then it is better to do it before installing the PV system.

Also, the structural engineer must take into account other things besides the distributed weight of the solar panels on the roof. He/she must also measure the impact of heavy snow, hail, and wind loads that will add additional weight that the roof must resist. State regulations will vary depending on the specific load design conditions according to weather conditions of the location. Seismic loads must also be taken into account in States like California.

Another important fact to take into account, especially if the roof has tiles, is to consider the uplift force of the wind with the solar panels attached to the roof. Uplift forces can reach up to 500 pounds per module on the roof, which could easily remove loose tiles. If you live in a state that often gets high speeds of windy weather, maybe consider solar shingles for your roof instead.

All of these considerations are important and cannot be easily addressed without an approved structural or civil engineer in place. PV sloped roof installations also need to make penetrations on the roof to attach the rails of the mounting system. It is essential that the PV installer uses a sealant to protect your roof against leakages in the future.

Despite all of these considerations for rooftop PV systems, we also mentioned that they can protect the roof. Hail, snow and other objects can damage your roof as well. However, by installing a PV system, you are assuring that the covered area of the roof will not be damaged by harsh weather conditions. Moreover, it has also been proven that solar panels reduce the heat inside the house because the roof does not directly receive the solar radiation, which improves the thermal conditions of the structure.

Basically, we must say that installing a PV system on the roof, does involve a technical process that, if not taken seriously, can definitely damage your roof. Therefore, it is very important that a certified structural engineer approves the installation.

Obtaining the approval of a certified structural engineer and making sure that the solar installer uses sealant during the installation is pretty much a guarantee that your roof won’t suffer any damage over the 25-year period of the PV system.

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men installing solar panels on a roof

Where to Install Solar Panels?

Where to Install Solar Panels

Carlos

Written by qualified solar engineer Carlos. Last updated:

Solar panels can be installed either on the roof or in the ground. When selecting the location to install solar panels, several things must be taken into account. We will address some technical considerations and details that you should pay attention to before choosing where to install your solar panels.

Orientation and Inclination

Solar technology is quite versatile. We can see examples across the whole industry with photovoltaic cells installed on products such as commercial solar flagpole lights.

However, no matter what kind of product you are dealing with in the industry, the solar technology must always consider orientation and inclination for maximum energy yields.

The Sun follows a specific path throughout the year, and according to the location, there is a specific angle (azimuth) that benefits solar power production. Generally, there are two main preferences when selecting the azimuth angle of the solar panels.

If the place is located in the Northern Hemisphere of the Earth, then the solar panels should face South. On the other hand, places located in the Southern Hemisphere of the planet must face North for maximum energy performance. For the US, your solar panels should face South. This applies no matter if it is referred to a large-scale solar power plant design or even if it is as simple as installing some outdoor solar security lights for your backyard, the principle is just the same.

If the roof where you have been thinking of installing the solar panels faces South, South-East or South West, then it’s a good spot for them. On the other hand, if the available space on the roof only faces North, then is better to find another spot.

The backyard is another possible place for solar panels through a ground mounted system. If the roof only faces North (N-E/ N-W), then possibly the backyard will face South. Consider the orientation as a critical factor for Direct Normal Irradiance values to reach the solar panels and maximize energy yields.

Inclination (or tilt angle) is also very important. Roof mounted systems have limited possibilities here, since the angle of the roof will also be the angle for the PV array.

The optimum tilt angle will vary according to the season, however, on a fixed PV system, we must choose a single angle that would maximize energy yields across the year. Choosing a tilt angle that is equal to the latitude of the location is a good approach for a solar design. Therefore, if your roof is not designed with an angle similar to the latitude of your business or household, you will have some annual energy losses associated with the tilt angle.

Ground mounted systems do not have that problem because they can be literally configured in any tilt position.

a house with multiple solar panels installed on the roof

The Best Angle for Solar Panels (Source – Clean Technica)

Available Space

Your solar installer will design the PV system taking into account several factors, one of them will be the available space for the solar panels.

Roof mounted systems have generally complicated scenarios that include limitations in the availability of space. If the space suitable for solar panels is limited or irregular (with interruptions along the way) then the PV design can lead to reductions in performance known as mismatch losses (associated with placing solar panels in different faces of the roof and azimuth angles).

Of course, there are methods to balance scenarios with such configurations, but they are generally more expensive (inverters with two MPPTs, two or more inverters, microinverters, or DC optimizers). In some occasions, if the amount of available space and the number of solar panels needed to back up a load (grid-tied with battery backup case) do not match, then it might be needed to reduce the load.

Ground-mounted systems can also find themselves limited in this case. It will depend on how big is your backyard and how big your load is. However, an advantage about the ground-mounted system is that you will not have to worry about mismatch losses because all solar panels will face the same direction.

Here, you must choose the option that offers better conditions.

solar panels installed on the grass outside of a house

Harvesting Clean Energy (Source – Yellow Lite)

Near-Shadings

One of the most constant and important factors to consider when installing a solar panel is the presence of shades that will reduce the energy yields of your PV system.

 PV systems cannot work efficiently with an object that constantly generates shades in the PV array, therefore the solar designer must take into account the presence of nearby trees, chimneys, antennas, or houses that could cause shade on your solar panels.

The only way to measure the losses attributed to near-shadings is through a solar design software that performs shading analysis of the PV system by developing a 3D model of the installation. Near-shading losses should not be above 10% annually (worst case scenario).

Since there are infinite possibilities of configurations on roofs or backyards it is hard to establish a winner on this topic, it will simply depend on your particular case.

a set of solar panels installed on the roof of a house

Impact of Shading on Solar Panels (Source – Sunkalp)

Rooftop Solar System or Ground PV System?

Each type of solar panel and system has its own advantages and disadvantages.

As you can see, regarding orientation and inclination, ground-mounted systems have a wider range of choice, therefore they are preferable from this point of view. However, regarding space and shadings, it is hard to say who would carry the advantage.

Other things must also be taken into account, like maintenance for example. It is a lot easier to clean your solar panels while they are on the ground than going up to the roof and finding a comfortable place to clean them. Cooling of solar panels is also important, and ground mounted systems have leverage on this topic as well because air flows more naturally if they are on the ground.

However, ground-mounted systems have disadvantages that are not easily visible. Ground-mounted systems tend to cost more than roof-mounted PV systems because the materials needed for the installation are more expensive. Ground-mounted systems need foundations, so excavations must be carried as well. All of this increases labor costs and installation times. Here is a useful post with more information regarding how much it costs to install solar panels.

Moreover, think about it. You hardly ever go and stay on your roof, but you may spend a lot of time in the backyard. The day you have a barbecue and there is missing space occupied by solar panels might be frustrating. This something that could end up bothering you in the long run.

As you can see, choosing the right place for the installation of your solar panels is harder than it looks. The best way to find the optimum solution in your case is to consult it with your solar installer. Ask him/her all the questions you have and try to find the balance between performance and lifestyle.

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