Solar Racking Guide · 2019-01-08 · Guide to learn the basics of solar. Get the Guide » Solar...
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How To Build a Solid Foundation For Your Solar System SOLAR RACKING GUIDE
Transcript of Solar Racking Guide · 2019-01-08 · Guide to learn the basics of solar. Get the Guide » Solar...
How To Build a Solid Foundation
For Your Solar System
SOLAR RACKING GUIDE
Common mount options available on the market, including roof, ground, pole and tracker mounts
What direction to face your panels to get the most production from them year-round
Pricing and recommendations for the best racking brands on the market
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IntroductionThanks for reading our Solar Racking Guide! Every solar system needs a solid foundation. We wrote this guide to outline the different types of solar mounts so that you can decide which works best for your system.
This guide will teach you:
Contents
1 Introduction2 What is Solar Racking?3 The 2 Most Common Types of Mounts4 How to Choose Your Mount 4 Budget 5 Sun Exposure /
Obstructions 6 Alignment 8 Cleaning & Maintenance 9 Space Concerns 10 Permitting11 Types of Roof Mounts 11 Pitched Roof Mount 12 Tilt Legs 13 Ballasted14 Types of Ground Mounts 14 Standard 14 Pole Mounts 15 Trackers16 How Much Does It Cost? 16 Roof Mount Costs 17 Ground Mount Costs 17 Pole / Tracker Costs18 Best Racking Brands 19 Roof: IronRidge 20 Tilt Legs: QuickMount /
Sunmodo 20 Ballasted: Dynoraxx 21 Ground: IronRidge SGA 22 Pole: General
Specialties / MT Solar 22 Trackers: Zomeworks /
Wattsun23 Continue Your Research
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What is Solar Racking?
Every system is built on a strong foundation.
A solar racking system (or solar mount) is the foundation that holds your solar array in place.
Mounts are used to attach solar panels to the roof, ground, or other surface on your property. With proper installation, a sturdy mount secures your panels in harsh weather and protects your investment.
To start, we'll look at the two most common options that most residential customers choose: roof mounts and ground mounts.
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The Two Most Common Types of Mounts
Roof Mounts
As you might expect, roof mounts make use of your existing roof space to mount your panels.
Modern homes will have a rooftop that is strong enough to support the weight of your system. It’s not necessary to install any extra structural support, as modern homes are designed to handle a small amount of extra weight.
As a result, roof mounts tend to be less expensive, because the installation requires less materials and labor.
Ground Mounts
Ground mounts provide the framework for you to install your solar system anywhere on your property. A ground mount is a standalone structure that acts as the foundation for your panels.
Ground mounts are more flexible and easier to access for cleaning and maintenance, but they cost a bit more to install because you are building a brand new structure to support the weight of your system.
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What to Consider When Choosing Your Mount
Both roof and ground mounts have distinct advantages and disadvantages based on the constraints of your project. As you decide which works best for you, take these factors into account:
Budget
If cost is your primary concern, a roof mount is the way to go.
When you install your panels on your roof, the weight of the system is supported by the pre-existing structure of the building. The load-bearing walls and trusses are strong enough to support the weight of your solar array.
As a result, you spend less on materials to lock the system in place - and less on labor to complete the installation.
Ground mounts are significantly more expensive, because you need to build a frame to support your system. In addition to higher material costs, you may need to dig holes and pour concrete to hold the frame in place. The electrical hookups are usually more involved as well, since you will run the wiring underground.
These costs can quickly add up. Make sure you save your receipts throughout this process. The money you spend on tools and installation costs counts toward the 30% Federal Tax Credit.
See page 16 of this guide for a more detailed pricing breakdown.
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Sun Exposure / ObstructionsThis shouldn’t come as a shock, but it’s worth pointing out: solar panels only work properly when they’re exposed to sunlight.
Be careful not to place your panels in an area that is shaded by trees, your house, or other obstructions.
If your roof is covered with heavy shade, it doesn’t make sense to build a roof mount and hinder the output of your system. You can build a ground mount in an area that is fully exposed to sunlight, so that your system performs to its expected capacity.
Be aware that shadows will move throughout the year. Obstructions will cast longer shadows in the winter, as the angle of the sun in the sky changes. Whichever racking system you choose, make sure it’s set up in a place that gets as much sunlight as possible year-round.
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AlignmentSolar panels work best when they face directly into the sun. The closer to perpendicular they are, the more electricity they will generate.
There are two factors in play here: azimuth and angle.
In the simplest possible terms, the azimuth is the horizontal orientation of your panels. The angle is the vertical orientation (or tilt) of the panels.
Finding the ideal azimuth: We recommend facing your panels toward the equator. If you’re in the U.S., that means your array should face true solar south. Anyone south of the equator should face the array directly north.
East and west facing arrays also work, but at a slightly lower efficiency. You can’t exactly change the orientation of your house, so in many cases this will be the only option available.
It does not make sense to position panels toward the North in the Northern Hemisphere, as there is not enough direct sunlight to produce a substantial amount of power. Same with South-facing panels in the Southern Hemisphere.
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Finding the ideal angle: We recommend tilting your panels to an angle that is within 10° of your latitude. For example, Los Angeles has a latitude of 34° N. A system built in L.A. should be tilted to an angle for 24° to 44°. With grid-tied systems, it makes sense to use a lower angle where summertime production is more valuable.
If your goal is to “set it and forget it,” these guidelines will give you the best output year-round.
With a roof mount, you’re locked into whatever direction your roof faces, so you may get stuck with a sub-optimal orientation. Ground mounts can be freely installed at the ideal tilt angle.
You might guess that ground mounts save money by making the system more efficient, right?
But that’s not really true. It might have been true 5-10 years ago, but panel prices have dropped dramatically since then. It’s much cheaper to add a few extra panels than commit to a ground mount install.
Think of it this way: you could spend several thousand dollars in materials and labor to get the perfect orientation with a ground mount system. Or, you could spend $600 on a few extra panels to account for efficiency loss.
It’s almost always smarter to build a little extra capacity into your roof mount system, assuming you have the space to hold a few more panels.
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Cleaning & MaintenanceOccasionally, you’ll need to access your array for routine cleaning and maintenance. Ground mounts make it much easier to reach your system. If you install the array on your roof, you’ll need to break out a ladder and climb up there anytime you work on your system.
Ground mounts are much easier to maintain because the work is done at ground level, and the back of the array is easily accessible.
How often should you expect to perform maintenance? Well, part replacements are fairly rare. The standard warranty for panels is 25 years, and you should expect to replace your inverter once or twice in that time frame.
This will be easier with a string inverter like the SMA Sunny Boy, which is a central unit that is easy to replace. If your system runs on micro-inverters (one small inverter connected to each panel), a roof installation will make it harder to maintain, since each part would need to be replaced separately.
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This setup is still manageable if you build your system all at once, and replace all the inverters at once. But one common approach to building a solar system to start with what you can afford, then expand the system gradually over time.
You might start with a few panels to handle some of your usage, then add to it over time as budget allows, until your array covers 100% of your energy use.
If you plan to build your system gradually over time, a ground mount will be much easier to work with each time you make an expansion.
Roof systems can be expanded, too, assuming you have the space. But you’ll need to break out the ladder and scaffolding whenever you plan to add on.
The last thing to consider is your local climate. If you live in an area with heavy snow, it will pile up on your system during winter. Snow buildup can obstruct the solar panels and limit the amount of energy they generate.
Fortunately, pole mounts are built to make snow removal easy. We recommend pole mounts for heavy snow regions. Their steep angle is designed to keep the panels clear: the weight of the snow causes it to slide right off the panels before too much accumulates.
In more moderate regions, a standard roof mount works just fine.
We go deeper into specific mount types starting on page 12 of this guide.
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Space ConcernsSometimes, you just run out of space.
Your roof isn’t always large enough to hold the array you would need to cover 100% of your energy production. Chimneys, vents and other obstructions can render large portions of your roof space unusable.
You might opt for a ground mount simply because there’s not enough room to build a system on your roof.
This goes both ways. If you live in the suburbs, chances are space is limited and you don’t want solar panels taking up half your yard. A roof mount could be the only viable option.
Better to install the system on the roof and save your backyard space for something else, like a pellet grill, a swimming pool or a playset for your kids.
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Permitting
In some jurisdictions, ground mount racking may be subject to a stricter permitting process.
That’s because a standalone rack may be considered a “new structure” by the office that distributes building permits.
Standards vary by location, but if you want to build ground mount system, you’ll need to do your research to make sure you obtain the proper clearance. That will add time to the process and introduce new challenges. You may need to:
• Submit a design plan• Consider soil type and property line setback requirements• Pay additional permitting fees
Building a roof mount system removes these obstacles. Since your roof is a pre-existing structure, you often don’t need any additional permits to get started.
The exception here is older homes, which may require engineering and structural improvements to bring them up to code, so they can support the weight of your solar array.
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Types of Roof Mounts
Pitched Roof Mounts
The most common residential roof type is a pitched (or sloped) roof. Pitched roofs set panels at a natural angle, pointing them toward the sun. The angle of your roof rarely provides the perfect alignment, but usually it’s good enough to get the job done provided the roof is facing south, east or west.
Standard roof mounts require you to make penetrations in your roof. They use clamps and flashings to lock the racking system in place. Companies have developed kits that are tailored for use with shingle, tile, metal and slate rooftops. For ease of installation and a leak-free install, be sure to find a mount that is compatible with your roofing material.
Tilt Legs For Flat Roofs
If your rooftop is flat, you can use tilt legs to face panels so that they are more perpendicular to the sun. Tilt legs simply lift the panels up to a fixed angle, so that they face directly into the sunlight.
Whereas most residential rooftops are sloped, flat roofs (or low slope roofs) are more common in a commercial setting.
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Ballasted
Most roof-mounted racking techniques require you make penetrations in your roof to clamp the mount in place. Drilling holes in your rooftop can cause leaks and make insulation less effective.
If you don’t feel comfortable putting holes in your roof, you can go with a ballasted mount. Ballasted mounts rest on a base that isn’t drilled into your roof. This type of mount relies on the weight of the array and concrete blocks to hold the system in place.
Ballasted systems only work on low slope roofs that are engineered to handle a significant amount of extra weight. Some buildings aren’t engineered for the extra weight of a ballasted racking system.
We used a ballasted system to mount the panels that power the Wholesale Solar office.
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Types of Ground Mounts
Standard Ground Mounts
A standard ground mount uses a simple metal frame to support the weight of the rest of the system.
The best way to secure a ground mount in place is to set the structure in a cement slab. If you choose to perform a DIY installation, you’ll likely need to rent equipment to dig footings and pour cement.
(Don’t forget: save the receipts for any equipment rentals. Those costs also apply to your federal tax credit!)
Standard ground mounts are normally installed at a fixed angle and position, though there are adjustable options for certain applications.
Pole Mounts
With pole mounts, you can mount your panels on the top of a sturdy pole. The pole ensures your panels stay off the ground out of harm’s way, but are easy to adjust and reach for snow removal.
The pole must be anchored in the ground by digging a hole and filling it with concrete. The hole for a pole mount will be fairly large (for example, 4’ or deeper into the ground for a post that is 8’ above ground level).
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Each system has specific requirements depending on things like the mount size and height, soil type, and local wind & snow loads. So make sure to follow all manufacturer instructions.
Most pole mounts come with a tilt adjustment feature. As the seasons change, the sun will change position in the sky. You can maximize the output of your array by adjusting the pole mount to face directly into the sun. If you’re diligent and do this once a season, you can gain a bit of extra output over the course of the year.
Pole mounts are great in snowy climates, because the steep tilt angle naturally sheds snow. If enough snow builds up, gravity takes over and it slides right off the panels.
Trackers
Trackers are a type of pole mount. Whereas fixed pole mounts must be manually adjusted, trackers automatically follow the path of the sun in the sky year-round.
Trackers offer the most potential to maximize your array’s output, without the need to manually adjust the tilt angle. The tracking technology ensures the panels stay perpendicular to the sun, no matter where it is in the sky.
There are single-axis trackers (which tracks East-West movement only), and dual-axis trackers, which offer full control of the orientation of your system.
There is one key downside to trackers: the moving parts make the system more expensive and complex. This can lead to mechanical failure and require extra maintenance over the life of the system. For that reason, they’re also more expensive than a standard fixed mount, both up front and from a maintenance perspective.
Trackers are mostly a thing of the past for residential systems. It makes more sense to add a few extra panels to meet your target output, which is a much cheaper (and more reliable) solution than getting a mount with fancy tracking technology.
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How Much Does Racking Cost?
Roof Mount Costs
For a lot of people trying to decide between roof mount and ground mount racking, price is the only factor that matters.
So let’s talk numbers.
Hardware for a roof mount system can cost anywhere from $40-80 per panel, not including installation. Shingle and metal roofs tend to be cheaper compared to tile roofs and flat commercial roof tops, especially when you start to add installation costs.
There are a lot of factors that can affect cost. First, there are different rails depending on local wind and snow load requirements. This will also dictate how many flashings, clamps, or tile hooks you need to buy.
This assumes that your roof is up to code and can support the weight of your system. Older roofs with damage or poor construction may need to be replaced.
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Ground Mount Costs
Replacing your roof is an expensive and time consuming process. We bring it up here because people often don’t anticipate they might need to replace their roof as a prerequisite for their solar project.
Many people who run into this problem skip the roof replacement and go for a ground mount instead.
Hardware for a ground mounted system is going to be more expensive, especially after adding in the cost of pipe and concrete to build the substructure. The rails, clamps and other racking parts will be similar to roof mount, with some extra components to attach to a substructure.
For ground mount systems, expect to pay $60-100 per panel for the base system, plus extra for steel pipe and concrete. The cost of pipe and concrete can potentially double the cost of a fixed ground mount, bringing the total to $120-$200 per panel.
Cost of Pole Mounts & Trackers
Adjustable ground racking (pole mounts and trackers) will cost a few hundred dollars per panel for hardware, with $100+ per panel in costs for concrete and pipe. Pole mounts are significantly more expensive, but adjustability and ground clearance are sometimes required for installations where there is a lot of snow.
The cost of ground mount racking can vary depending on local requirements from your building department. Areas with more wind and snow will require larger footings, and in some cases thicker pipe and upgraded mounts.
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The Best Racking Brands on the Market
By now, you should have enough information to decide which racking setup works best for your project. The last section of this guide focuses on specific brand and product recommendations.
Most of our packages include IronRidge racking for roof and ground mount. Several companies supply quality flashings and clamps that work with IronRidge roof mount racks, including Quick Mount PV and S-5!.
Pole mounts are available from General Specialties and Montana Solar. Sunmodo and Dynoraxx provide commercial racking solutions. We trust all of these brands and regularly recommend them in our default packages and standard system builds.
Let's go over the products we recommend for each specific racking configuration.
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IronRidge Racking Options
• XR10: a lightweightsolution for mild climates
• XR100: the standard optionfor most applications
• XR1000: A heavy-dutymount that can withstandextreme conditions
Roof Mounts: IronRidge
IronRidge is a leading PV racking manufacturer making quality roof-mount racking. Their solutions are available in three sizes: XR10, XR100 and XR1000.
The XR100 is our standard roof-mount racking solution. This will work for almost all systems, unless you need a reinforced foundation to hold up in heavy weather.
In high wind and snow areas, we recommend an upgrade to the XR1000, which is built to hold up in extreme conditions.
The XR10 is a viable lightweight solution for areas with no snow and very little wind loading. We commonly recommend it for installations in Arizona and Southern California, where the weather is warm and mild.
Most folks use the IronRidge XR100. It only makes sense to upgrade to the heavy-duty XR1000 if you live in hurricane regions or heavy snow zones.
You also need flashings to attach the base of the mount and provide weatherproofing and protection for your roof. Your roofing material will dictate which flashing you use:
• Shingle: The IronRidge Flashfoot 2 is our default choice. Quick Mount has niceflashings for shingle roofs as well.
• Metal roofs: S-5! clamps for metal roof tops. They have a wealth of options tochoose from, depending on your roof profile.
• Tile: Quick Mount tile hooks and flashings.• Slate: Quick Mount flashings.• Shake (wooden): Quick Mount flashings.
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Tilt Legs: QuickMount/SunModoWe recommend the IronRidge XR100 or XR1000 (same as a standard roof mount) with the addition of tilt legs. We commonly pair these with the Quick Mount QBase low slope flashings, which are code compliant for flat or low-slope roofs.
Another option is the SunModo EZ Sunbeam commercial racking system. It can be built on top of the roof, above air conditioners and other obstructions, which helps to maximize the usable build space on your rooftop.
Ballasted: DynoRaxxThe concept of a ballasted mount is to build your system without drilling into your roof, which is especially useful if you don’t own the property (for example, a commercial installation in a rented office building).
We like the Dynoraxx ballasted racking system. The trays are fiberglass, which are lightweight and won’t damage your roof.
The Dynoraxx ballasted mount is lightweight and easy to install. The fiberglass trays don’t expand and contract under the heat of the sun, which means it won’t warp and damage your roof.
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Ground Mounts: IronRidge SGA
The IronRidge SGA ground mount uses XR1000 rail, which is the same equipment used for heavy-duty roof mounts.
But for ground mounts, the rails need to be set on a substructure of 2” or 3” steel pipe. Since this would be incredibly expensive to ship, we strongly recommend sourcing the steel pipe from a local building supply store or well drilling company.
This is the most affordable and easy to install ground mount system. We recommend a fixed ground mount, unless you live in extreme climates or have unique space concerns that would necessitate a tracker.
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Pole Mounts: General Specialties / MT Solar
Our preferred pole mount comes from General Specialties. They make high quality, adjustable pole mounts which are manufactured in the USA and built to order.
Montana Solar (MT Solar) pole mounts are another great option. They designed their pole mount with ease of use in mind. They are easier to install and adjust than any other pole mount on the market.
Trackers: Zomeworks / Wattsun
As we mentioned above, trackers are the least cost-effective mounting option available, and we almost never recommend them for residential installations.
Trackers used to be popular when panels were 5-10 times their current price. It made a lot more sense to squeeze every bit of output you could from the panels.
Today, you’d be better off using a fixed ground mount or pole mount and adding a few more panels to cover the extra output.
But if you have your heart set on a tracker, Zomeworks and Wattsun make high quality trackers (at a premium, of course).
For commercial applications, single-axis trackers are a great way to save space and maximize efficiency for large utility-scale installations. But they don't make much sense for residential systems.
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More Resources
Getting Started With Solar We all start out in the dark. Download our Getting Stated Guide to learn the basics of solar.Get the Guide »
Solar Permitting Guide Permitting is the most time-consuming part of the process. Get a head start with our Solar Permitting Guide.Get the Guide »
Solar Cost CalculatorEstimate how much it would cost to go solar based on your location, personal energy usage patterns, and other factors.Get an Estimate »
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