By Brad Smith

So, you want to know how to install solar panels? It is simpler than you might think but, given the high voltages and high wire act involved, it is not for the do-it-yourselfer.

We will focus on the most common type of solar installations, roof mounted grid-tie solar systems. While battery based solar systems that provide backup power are in use, they are more common in off-grid locations. Since most of us live in homes that receive electric service, grid-tie systems without batteries dominate because they are much more cost effective than battery based systems. Almost all residential systems are roof-mounted so we will also ignore ground-mounted applications.

The first step is designing the solar system and determining the equipment specifications. We want to get into the installation process, so we will also assume that the design work is done and the system is ready to be installed.

Part 1: Mounting the array (the solar panels)

Mounting the array on the roof begins at the attachment points. The number and location of the attachment points will have been specified as part of the design. They are normally in a rectangular grid pattern and spaced 4-6 feet apart. The exact locations depend on the type of modules and rack system being used, the roof type and construction as well as roof and wind load calculations.

On asphalt/composite shingle roofs, L-shaped brackets are sometimes lag-bolted (a lag bolt is a big screw with a bolt head) directly through the shingles into the roof joists and sealed with roofing compound. Most other roof types require stand-offs with flashings and flashed standoffs are also a more durable and weathertight (but more expensive) alternative for composite roofs.

A standoff is simply a bracket with a flat base that has bolt holes and a post that will stick up through the flashing and serve as a mounting point for the rest of the racking system. A flashing is a flat piece of aluminum with a domed center (usually with a flexible rubber grommet) and a hole in the middle. The standoff is bolted through the roof into the joists while the flashing slips over the top of the standoff and the top edge tucks under the shingles and is nailed to the roof. The end result is a reliable, water tight seal that will last for years. The technique is the same one used to seal vent pipes and you can probably look up at your roof and see an example or two.

Once the roof attachments are secured, the next step is to install the rack itself. There are a variety of rack systems manufactured by a number of companies and all have similar characteristics. They are usually made of aluminum and have vertical and horizontal pieces that attach to the standoffs and form a grid to which the solar modules are attached. Irrespective of the particular choice of attachments and rack systems, the array is always positioned 4-6 inches above the existing roof surface. Solar modules (commonly referred to as solar panels) generate less energy as they get hotter and allowing room for air circulation underneath the panels is important to maximize efficiency.

Once the rack is in place, it is time to attach the solar modules. Some installers will pre-build assemblies of 3-6 modules to reduce the amount of on-site assembly, but modules are most often installed one at a time right there on the roof. The exact method varies depending on the type of rack system, but most have some form of sliding bolt to allow easy positioning and access to the bolts from above the modules. Most modules also have quick connectors for the wiring and simply plug together without any tools.

Getting the wiring right is critical and should follow the design specifications exactly. The modules are attached together in series strings of 8-12 modules per string. The configuration of the strings is based on the specific requirements of the inverter and modules being used; it has to be right or the system will not work.

Part 2: Connecting the wiring

Once the modules are mounted and all of the wiring connections are made, the array installation is pretty much done. There will be a positive and negative wire for each string of solar modules and the next step is to make the wire run to the inverter(s). This is good old fashioned electrical work and requires running electrical conduit (galvanized pipe) from the inverter location to the array. The conduit may be mounted on the outside of the house or may be routed through the inside of the house and pop out through the roof at the edge of the array.

However the conduit is routed, it will end up at the edge of the array and connect to some sort of junction box or combiner box. There isn’t any magic in these boxes, they just provide a place to make wiring connections that are secure from the weather. Local and national building codes provide very detailed requirements for the exact type of equipment to be used and your installer and building inspector should pay close attention to make sure that the right equipment is used.

Part 3: Installing the control equipment

The basic control equipment for a solar power system is pretty simple: an inverter and disconnect switches. The inverter converts DC power produced by the solar array into AC power that exactly matches that currently used in your home. Inverters also have a lot of safety and power management features, but converting DC electricity to AC electricity is their primary role.

Disconnect switches are essentially big, giant versions of a light switch that can handle the high voltage and amperage of a solar system. They are used on both the DC side to control the power coming from the array and the AC side to control the power coming from the inverter. The main purpose of the switches is to provide on/off switches so the system can be repaired or turned off.

The control equipment can be installed indoors or outdoors and is usually located near your existing electrical service. Indoors is slightly preferable to promote longevity, but the main goal is to keep them cool. Inverters are essentially big transformers; they can get hot and become less efficient and less reliable as a result. Avoid mounting them in direct sunlight and small, enclosed spaces.

Connecting the solar system to your existing household electrical system is very straightforward. The output from the solar system is fed directly into the existing breaker panel using a standard circuit breaker. The existing circuit breakers all take power from your utility meter and send it to the outlets, lights and appliances in your home. However, circuit breakers don’t care which direction the power flows so they handle incoming power from the solar system in the same way. The electricity produced by the solar system flows into your breaker panel and is used in your home. If the system is producing more power than you are using, the excess flows back out into the utility grid…and your meter run backwards.

Editor’s Note: This article is meant to provide a general understanding of how solar panels are installed, not as a do-it-yourself guide. A lot of the critical details are not discussed. The process also involves working on a roof (dangerous in itself) and handling up to 500 volts of DC current, easily enough to be fatal. The bottom line is, please do not try this yourself.

Bradford Smith is a former solar installer and founding member of the Renewzle team.

By Brad Smith

There are quite a few checks and balances in the process to make sure you get quality work from your solar installer. While it pays to be diligent in your consideration and selection of a solar installer, the system specifications and workmanship will be subject to inspection and review by a number of additional parties.

Submit a Solar Rebate Application

The first step in most cases is submitting a rebate application. This is usually done through your utility company, but that process will often identify any gross errors in the system configuration such as an undersized inverter or unapproved equipment.

Building Permits and Inspections for Solar Installations

After securing a rebate reservation, the next step is getting a building permit. While the exact requirements are determined by the city or county building or planning department that serves your neighborhood, your installer will almost always be required to submit detailed plans and equipment specifications before receiving approval to start work. While you can’t rely entirely upon this inspection, it is their job to make sure that the planned installation meets or exceeds all code requirements and general standards of quality construction.

Once the installation is completed, the project will be inspected at least two more times before it ever gets switched on. The first inspection will be by the local building inspector. If at all possible (skip work if you have to), make sure you are present for the inspection and make sure the inspector does a good job on your behalf. If there is any part of the installation they don’t take a close look at, ask them to! The building inspector is a qualified inspector that should only sign off on your solar installation if they are confident that the work was completed satisfactorily. If they find anything that’s not up to snuff, they have the power to tell the contractor to correct it.

There will also be a second inspection by your utility company before they allow the system to be connected to the electric grid. This inspection is usually pretty limited and focuses only on the electrical performance, but it still represents an additional safeguard.

When your installer completes the project, they will contact the local building department to arrange for an inspection. Your local building inspector will come to your home and inspect your solar system prior to “signing off” on the permit. Never pay your installer in full before receiving sign off and if you are asked to do so, point out that it is illegal — a violation of contractor’s licensing laws!

What can go wrong?

With all the inspections that take place, the range of things that can go wrong is pretty limited. The most important point is that the roof attachment points are installed correctly. As long as good construction practices are followed, your solar system should be safe, secure and leak free for years and years to come. If you attend the inspection, make sure the inspector pays close attention to the roof attachments and everything should be fine. If your solar system is roof-mounted and the inspector doesn’t go up on the roof, you’re not getting your money’s worth from them.

Make sure the job is finished before your solar installer leaves…

Oftentimes it is necessary to cut some holes to run the electrical conduit and mount the inverters and switches. It is the installer’s responsibility to put everything back the way it was before they started. Make sure they patch and paint any holes in your drywall and caulk around any conduit penetrations and make sure they clean up after themselves! Before the installer calls the job complete, all the little details like patching, caulking and sweeping should be done. It’s easy to have sympathy for workers that have been hard at work on your home all day but don’t let them slide, they probably won’t be back and you’ll be the one sweeping up after them!

How about the money?

In California, contractors are not permitted to ask for a deposit greater than $1,000. You shouldn’t be asked to provide any additional payment before work commences and never, never, never deliver the final payment before you have signoff from the local building inspector and the utility interconnection process has been completed. Also, make sure they have submitted all of the rebate paperwork if that was part of your agreement.

How about the schedule?

One of the biggest challenges for an installer is scheduling. Often, there may be long lead times to receive the equipment for your solar system and sometimes those delays are beyond the installer’s control. Also, approvals from building and planning departments and scheduling of inspections is entirely up to your local building department. The lesson is that you should try to be patient with the installer, but you are also entitled to good information about the schedule. Make sure they keep you informed and put your foot down if there seem to be unreasonable delays that are within their control.

The most important thing you can ask of your installer is that they minimize the time on site. It shouldn’t take more than a few days (at most) to install your system and you don’t want the construction spread out over an extended time. Other than inspections, they should start and finish the job without a break (I mean days, not coffee breaks).

What else should I look for?

If you follow the tips listed here, you will probably find yourself very satisfied with your solar installer and your solar system.

Bradford Smith is a former solar installer and founding member of the Renewzle team.

By Brad Smith

As a rule, most people do not consider choosing a contractor, solar or otherwise, to be one of the more pleasant tasks they face. However, it is not as bad as it might seem and, with a little bit of good advice upfront, it can be much less daunting than you might think.

If you follow these tips, you will probably get a quality solar installation that will do what it’s supposed to do for many years to come.

What’s the difference between a solar system retailer and a solar installer?

Nothing! When it comes to a solar system for your home, there are few companies that only sell solar systems and even fewer that just do solar installations. In almost all cases, the company that sells your solar system will also do the installation. Since 70-80% of the total price is for the equipment itself, it is just as important that you choose a company with competitive prices as it is that you choose a company that does high quality installation work.

What do I look for in a solar installer?

Experience in both years and number of projects is often the best indicator. While it is not a bad idea to ask for customer references, the installer is obviously going to give you names of their satisfied customers. Other than finding out that they have some satisfied customers, you won’t learn much.

Get the contractor’s license number and look it up with the State’s contractor license board. If you can’t verify the contractor’s license information…run! The lack of a valid contractor’s license (classification C-10, C-46 or B) is a sure sign that you are in for trouble. The license check will also allow you to verify that they are properly bonded and insured. If they have any severe complaints, you may see them there. However, keep in mind that most minor complaints will not be disclosed due to some complicated disclosure laws.

Installing a solar system is relatively simple as construction projects go and the vast majority of licensed, experienced installers can and will do a good job for you.

Found a solar installer you’re happy with? Read about How to Manage Your Solar Installer During Your Solar Panel Installation.

Bradford Smith is a former solar installer and founding member of the Renewzle team.

A note from the editors: Installing solar panels is not for the inexperienced. It’s a serious and potentially dangerous process that involves both handling live power generators (how do you turn off a solar panel?) and climbing around on the roof of your house. We here at Renewzle recommend that you talk to a professional (and if you live in California, you can use our solar calculator and get matched with local installers!)

That said, for those of you who want to find cheap or free solar panels, you couldn’t find a better intro than Michelle Bennett’s below. Enjoy!

My cousin mentioned to me that her family wanted to install solar panels on their roof. She said it was a huge disappointment because it was far too expensive. It would take twenty years for them to regain the cost in energy savings, even with state solar initiatives! I decided to do some digging and came up with a handy solution to help reduce the cost:

Find used solar panels. Maybe you can get them for free. (more…)