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.

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.

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.

Federal Incentives

Federal Tax Credit

The Federal Government offers a tax credit for purchasers of solar energy systems. The credit is up to $2,000 and most people can use the full amount.

Residential Energy Conservation Subsidy Exclusion

You don’t have to pay income tax on a utility rebate or credit for a solar energy system.

State & Utility Incentives

Most states offer some sort of incentive for solar systems and, in many cases, they can pay for a substantial portion of the overall cost of the purchase.

Sales Tax Exemption

Many states exempt solar energy systems from sales tax.

Net Metering

While not actually an incentive, net metering legislation is in place in many states and is an important part of the solar value proposition. Net metering allows utility customers with solar systems to feed power back to the grid when their system is producing more power than they are using at the time. Power pumped back into the grid offsets the power you draw from the grid (like at night) and you only get billed for your net usage.

• An average U.S. household uses 830 kiloWatt-hours (kWh) of electricity per month.
• On average, producing 1,000 kWh of electricity with solar power reduces emissions by nearly 8 pounds of sulfur dioxide, 5 pounds of nitrogen oxides, and more than 1,400 pounds of carbon dioxide.
• During its projected 28 years of clean energy production, a rooftop solar energy system will avoid conventional electrical plant emissions of more than half a ton of sulfur dioxide, one-third a ton of nitrogen oxides, and 100 tons of carbon dioxide.

Source: NREL Report No. NREL/FS-520-24619

Reducing Toxic Pollutants

The electricity used in your home today comes from a variety of sources, but mostly from fossil fuels that produce a host of toxic emissions. Non-renewable electricity generation results in emissions of a variety of pollutants and toxins into the atmosphere:

• Carbon dioxide (CO₂), the leading greenhouse gas
• Nitrogen oxide (NO_x), which causes smog
• Sulphur dioxide (SO_x), which causes acid rain
• Particulates that can cause asthma and other diseases

Conserving Fossil Fuels

As more individuals, corporations, and public entities adopt alternative energy sources like solar, we conserve fossil fuels and other natural resources that are quickly diminishing. With ever increasing individual electricity consumption and a rapidly expanding world economy the demand for energy is increasing at an alarming rate. This makes conserving our resources more important than ever.

For more information, check out Other Solar and Environmental Resources.

Learn about other ways to be more energy efficient with our Top 5 Ways to Save Energy Around the Home.

For anyone that feels strongly about the environment and preservation of our natural resources, solar energy is a great value even if it costs a bit more than utility power. Still, cost is an important issue for anyone considering a solar energy system. The cost of solar relative to utility power depends on where you live, how much electricity you use and how much you pay for electricity. In some parts of the country, solar can provide tremendous savings, in other areas utility power is much less expensive.

To understand the real cost of solar, all of the financial pieces have to be pulled together to get an accurate financial assessment and that’s how Renewzle can help. Renewzle can identify all of the incentives and credits available in your area and combine that with information about your electric use, your utility’s rates, electricity usage patterns in your area, tax rates and a host of other information to provide you with a comprehensive financial analysis.

Sample Monthly Costs

The table below shows monthly costs with and without solar for a typical homeowner.

1. Solar Modules

   Solar modules are usually mounted on your roof, but can also be installed on the grounds of your property or on an adjacent structure such as a garage. The panels are comprised of photovoltaic cells that convert sunlight into DC power.

2. Inverter

   The power generated from the modules is sent to an inverter which converts the DC power into AC power; “standard” household electricity identical to what you receive from the utility grid.

3. Electrical Panel

   AC power from the inverter travels to your electrical service panel or breaker box. The system is connected to your service panel through a circuit breaker and is then distributed to any electrical loads in your home.

4. Utility Meter

   Whenever your solar system provides more power than you are currently using in your home, the excess power will flow into the grid through your electric meter. This will cause your meter to run backwards earning you a credit with the utility company.

5. Utility Grid

   You remain connected to the utility grid so power is always available when you need it, even at night and during the day when your demand exceeds your solar production.

The solar panels on the roof heat the water (and they seem positioned to shade the air conditioner, another energy-saver). An article in Kiplinger.com summarizes “sunshine economics”:

“A few big variables dictate whether a home PV system makes economic sense. But in rough terms, here’s how the numbers break down in states with the best incentives: The average solar-power system is 4 kilowatts. (Think of kilowatts as the size of the system. The power it generates depends on size, efficiency and sunlight.) Figure the price, including installation, is $10,000 per kilowatt, so the total comes to $40,000. Through various rebates, credits and tax breaks, some states pay half that cost. The federal government will also chip in 30% of the cost, up to $2,000. Taken together, those subsidies drop the total to $18,000. Manufacturers say that solar panels will last 25 to 30 years, and they guarantee them for 20 years. Assuming a 20-year life span, that averages out to a cost of $75 per month.” –Solar Finally Pays Off, Bob Frick, Sr. Editor, Kiplinger online

Even better: The economics above are for Solar PV, which generates electricity; the economics for solar thermal, which heats water and air, are even more favorable in even more states. Can we now stop grumbling about “payback” and move on to building the solar industry?

There are a lot of cool gadgets out there, but there’s a fine line between what’s cool and what’s useful. This is a green list of gadgets that are useful, but boast the extra-cool factor of using renewable energy. No batteries required!

10. The Ship has Landed

The lightship is a solar-powered LED mounted on suction cups. Result: a portable, hands-free, solar light. It’s even weather proof and weighs a slim 8oz. For under $15, this is the best 8 hours of clean light I can think of, and I might just get one for my car/camping trips/travels.

9. High-tech pool toy?

If you simply must have hot water anywhere, at any time, try a portable solar water heater. Could it double as a heated water bed? A pool toy? Bring some towels if you decide to try. This gadget is designed to bring cheap, easy hot water to people and places without access to indoor plumbing or electricity. It rolls up small enough to fit in a backpack, and it’s supposed to be affordable enough for people or communities in developing nations.

8. The Fridge without Power

A little ingenuity paired with the laws of thermodynamics have made Mohammed Bah Abba a famous man. His invention is simple: place a pot into a slightly larger one. Pad the space between them with wet sand, and cover with a damp cloth. As the water evaporates, it will draw heat out of the containers and cool whatever’s inside. The system has already proved itself in northern Nigeria, a hot and arid region. Food lasts for days or weeks longer compared to the only alternative: room temperature. Here in the land of plastic coolers, I can think of a few common uses: Camping trips could be easier without the weight of heavy packs of ice and the danger of freezing more fragile foods. Egg-cicle anyone? Even if you don’t intend to leave the comforts of modern civilization, consider these for cooling food or drinks at your next BBQ, or even for a DIY kid’s science project.

7. Speaking of BBQ…

We’re putting heat in the kitchen with solar cookers. The benefit here is that some designs are lightweight with easy-to get materials, like foil and pizza boxes. They also offer a neat alternative for your next BBQ (and yes, they can get hot enough to cook meat) if, for example, you live in an area with frequent fire-bans. Since there are no flames involved, it’s much safer and there’s definitely something fascinating about watching the sun roast your food.

6. Crank your Gadgets:

How about a MP3 player that you can crank? You’ll never run out of juice if you can charge your gadget by hand. Trevor Baylis, the inventor of the hand-crank radio, brings you an MP3 with plenty of whistles and bells. If a wind-up MP3 isn’t your cup of tea, how about a kinetic cell phone or phone charger? You might hesitate to buy anything that requires physical exertion on your part, but what happens when there’s no socket in which to stick your regular charger? Be the cool kid who can charge himself. Also, consider emergency applications. The MP3 comes with a flashlight, and the cell phone charger could keep you connected when you most need to call for help.

5. Personal Wind Turbine

We’re not talking about the huge wind-farm fodder; we’re talking about something you can strap to your house. Now I admit, gadgets tend to be smaller and more… gadgety. After much deliberation, I figured omitting wind power would be like forgetting Unix in a “Top-5″ for PC operating systems. Plus, they look really cool. For a mere $500 you could own this turbine, which is designed for charging batteries (the batteries would power a cabin or house). The Japanese turbine (shown above) hasn’t quite hit the American market yet, but it’d be my wind-power-of-choice. Airplane propellers are so last-year.

4. Sunlit Gadgets

Solar powered lighting aside, what about self-sufficient gadgets? Nowadays there’s a wide variety to choose from. There’s Msi’s solar’powered MP3 player, which you can also plug in when the sun won’t shine. How about a Bluetooth headset? You too could strut with all the style of a pocket-protector, smug in the knowledge that yours works indoors and out. Other self-sufficient gadgets include a mosquito repeller, tire gage, and all-in-one survival kit. However, some of the extreme deals associated with these makes me wonder if they’re worth the low price…

3. The Nerdies Lights Around

Let’s play with fiber optics. You could have natural sunlight (sans UV and infrared) for your home or office, and it could come from fiber optic cables (pictured above). Among the gadget you don’t get to see (assuming it’s wired through your walls), it’s got to be the coolest. You even get a futuristic collector dish on your roof.

2. Lightcap 200

This is a solar-powered cap for your water bottle. So why power your Nalgene? It turns your translucent water bottle into a solar-powered lantern. Every backpacker knows that every ounce counts, so now you can combine two heavy but necessary items into one. There is also the cool factor: pick you color with your favorite shade of kool-aid.

1. Solar Battery Recharger… even your laptop

It was bound to be on the list. There are a range of solar-powered rechargers. Some come with battery packs (for when the sun don’t shine) or bells and whistles. Voltaic Systems and Burton’s Solar Roll claim the prize of recharging a standard laptop. As you might expect, prices range from $20 to “owch”. But if you carry a purse, tote your gadget horde, backpack, geocache, or travel through regions with less-than-reliable electricity, any one of these could be invaluable. Plus, they all come with a magnificent cool factor.

(images courtesy of Sunlight Direct Products, EcoGeek.com, and Solarjo)

The National Renewable Energy Laboratory in the United States has announced that a new device developed by its scientists can convert 40.8 percent of light that hits it into electricity. This bests the previous record of 40.7 percent set by a different organization.

According to NREL spokesman George Douglas, the new device is both thinner and lighter than the previous model, which used a germanium wafer.

This solar cell, however, uses gallium indium phosphide and gallium indium arsenide to split light into 3 parts, each of which are then absorbed by the cell’s 3 layers.

The lab says that the new solar cell is an excellent candidate for concentrated photovoltaic arrays as well as space satellites.

While I haven’t seen anything mentioned about possible pricing, I can only assume that this technology will be unaffordable for most businesses and individuals for a long time to come.

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