Draft 7 11-26-19
The Arizona Solar Center is often asked the question “How do I find out if solar energy is the right choice for me now?” It seems like a simple question, but the answer really depends on the situation.
There are many ways to use solar energy on both personal and commercial levels. Some of the exciting possibilities for solar electric (photovoltaic or PV) power use are:
- Highway, street, and sign lighting
- Pool and home accent lighting (especially with the new high efficiency LED lights)
- Signaling for railroad crossings
- Gate openers
- Power for forest or park lookout stations
- Telemetry packages, instrumentation, weather, earthquake detectors and recorders
- Power for control of valves in pipelines
- Gas detection systems in refineries
- Cathodic protection to prevent corrosion in pipelines, wells, bridges, etc.
- Lighting in rural areas (restrooms in parks as an example)
- Security for industrial buildings
- Power for refrigerators, lights and communications in remote medical centers.
- Power for water pumps - commercial, domestic and livestock water, or swimming pools
- RV power while parked
- Attic ventilation
- Security systems
- Remote and on-grid home power systems
If the previously mentioned uses of lighting, communication, refrigeration, water pumping, etc. are combined into a single power system, renewable energy can be used to provide power for the basic needs of entire villages, encampments, and recreational areas which may be too far from power lines to ever have grid-supplied electricity.
Over the last decade it has become routine to have home solar electric systems that are connected directly to the local utility and operate without batteries. These are called grid-tied systems, and are the focus of most residential and commercial activity. In Arizona there are utility rebates (actually incentives to install, with the resulting environmental credits being assigned to the utilities) that offset a substantial portion of the costs of installing grid-tied PV systems. In some cases this can include domestic hot water systems. Refer to other parts of the Arizona Solar Center website for more information. There is also information here about tax credits and rebates.
To begin answering the question “How do I find out if solar energy is the right choice for me now?” please review the following Frequently Asked Questions. After understanding this basic information, please see our "Path to PV" below, which follows a typical but fictitious family on their journey of learning and finally making the decision to go solar.
Frequently Asked Questions- Is solar energy the right choice for me now?
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Why should I be interested in solar?
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What alternatives should be considered?
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What are my solar objectives?
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Do I have a good site for PV?
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Is solar for me? Some points to consider:
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How much mounting space do I need? A small PV system can use as little as 50 square feet. A larger system, to meet the needs of a typical household, would use between 300 to 600 square feet. As a rule of thumb, 100 square feet of PV area produces 1 kilowatt of electricity. |
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What can I do as a homeowner?
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Are there any incentives and rebates available in Arizona? In Arizona there are no longer any utility based incentives on solar systems. But there are Arizona and Federal tax credits and/or rebates that may apply to your situation. Renewable Energy Incentives |
The following is specific to photovoltaic power systems
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Why should I consider buying a PV system? A PV system reduces or eliminates the amount of electricity you purchase from your utility or electric service provider. A PV system can be an excellent investment, save you money on your electricity bill and act as a hedge against future price increases. The electricity generated by your PV system is clean, renewable and reliable. You help your community by reducing the load on the utility grid. You can provide additional electricity for the grid when you generate more than you use during the day, when electricity demand is highest. |
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How do I relate system size to energy produced? You can match the size of your system to your electricity needs and budget. The average household in Arizona uses over 10,000 kilowatt-hours (kWh) per year. If your usage is typical of the average household, a system in the 5 to 8 kilowatt (kW) range would be adequate to meet most of your electricity needs. It is usually not advisable to displace your entire utility bill, since efficiency improvements and conservation could cause you to produce more energy than you use. Currently, utilities do not pay competitive rates for generation above annual usage. see Effect of PV Array Orientation - Phoenix AZ. and Considerations in sizing a PV system in Arizona |
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What do I need to know about connecting my PV system to the grid? You will need to enter into an Interconnection Agreement with your utility. This agreement addresses the terms and conditions under which your system will be safely connected to the grid. The agreement also specifies the metering arrangements for any surplus electricity your system generates on the electric grid. Excess electricity might be generated during the day when your system produces more electricity than you need. Your meter would simply run backwards to record the amount of electricity 'sold' to your utility. If you select a rate plan with Peak and Off-Peak periods, the utility will most likely account for the net metering by rate period. This is very utility specific, see the article Arizona Electric Utility Information. Older PV systems may have qualified for net metering where in any excess production is banked with the utility for later use. |
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How can I estimate the best size system for my home or business? To estimate the best system size for your home or business, please review our article on Considerations in sizing a PV system in Arizona. There are ‘Solar calculators’ on the web. APS and SRP have links to calculators that will give ballpark cost and performance estimates. Use these with some common sense as they may not consider rate period and demand charge effects on the resulting savings. There is also the NREL document: http://www.nrel.gov/docs/fy04osti/35297.pdf If you want your PV system to meet half of your electricity needs, then you should size it to meet half of your annual electrical usage. Alternatively you can offset only a small portion of your electricity bill with a single PV panel. First of all, do not install a system that produces more energy on an annual basis than you expect to use because the present utility tariffs generally have a low credit for the excess. If in doubt, start small and ask the installer to plan for expansion in the future (i.e. install a larger inverter and conduits at little extra cost). However, check on your utility policy on this as any system size changes may cause loss of any favorable grandfathering of buy-back rates. |
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What does a typical PV grid-tied system look like?
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How much does a PV system cost? Although many factors affect the cost, an average PV system costs from $2.50 to $4.50 a watt, including installation. This is about $10,000 to $18,000 for a 4 kW system. |
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Am I eligible for a rebate? At present (2019) there are no incentive rebates. There are tax credits that may apply to your situation, see our article on Renewable Energy Incentives. |
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Are there any financing programs available? The best way to finance a PV system for your home is through a mortgage loan, which includes a primary or secondary mortgage or home equity loan secured by your property. If mortgage financing is not available, look for other sources such as conventional bank loans. In August of 2008, APS announced a financing program for its customers who desired to finance systems installed under their incentive plans. A variety of “leasing” programs are becoming more common in the industry. The buyer is cautioned to do an in-depth financial analysis or consult a qualified party to determine the best approach for his or her system. |
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How do I find a PV retailer?
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How do I know if I am being offered quality equipment? Inverters and charge controllers should be listed to UL1741.
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How does it work with my electric utility? How does the billing work? What if I sell the home? APS (see also Summary of Residential Rate Plans for APS Customers See our article on Arizona Electric Utility Information for more specific information on utility policies. Generally, the utility installs a bi-directional kilowatt-hour (KWh) revenue meter that measures power flow in both directions. The resulting bill will usually show how much energy you have used and how much you fed back to the utility. Any balance in your account should be listed for future use. The utility usually requires the PV system installer to install a socket for a second KWh meter that measures the output of the inverter as well as a lockable disconnect switch in case the utility needs to work on the utility line nearby. |
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How do I operate the system?
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What will it look like? Will it affect anything? Most systems can be installed so that the owners are proud of their investment. <possible link> Modern inverters must meet radio frequency non-interference specifications and as such should not interfere with radio and TV. |
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Can I monitor the system with my computer? The smart meters used now by APS and SRP (and perhaps other Arizona utilities) gather detailed data on the output of the installed PV system and make this information available to their customers. For example see this article on APS- Understanding your APS Connected Photovoltaic System |
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How long will it last? What is the warranty?
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Do I have a suitable roof or ground area? Effect of shade on PV systems <possible link> Roof requirements are discussed in the Solar ABCs guide to expedited permitting What kind of roof can be used? PV mounting systems are compatible with all roof types including tile, shingle, metal and flat. |
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What about HOA Approval (when necessary)?
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What about Building Permits?
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How to decide on a company?
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How to proceed? See “A Path to PV,” below which follows a fictitious family through the process. |
A Path to PV
One day, Sunny and Sam Brightly were driving about town when they saw a home with a large number of solar modules on the roof. It looked pretty expensive.
Later while watching tv, they saw an advertisement on a new financing plan being offered to help make the installation of solar systems more affordable. They remarked about it, but took no action at the time.
The following week their oldest child came home from school and told them how they had just learned about using sunshine to make electricity. He asked his parents, "Why don't we do something to use solar energy?" The parents said "Let's see what we can find out on the Internet." They searched "Solar Energy" and "Arizona." A top hit was the Arizona Solar Center, so they looked at it. There was a lot of information and various descriptions of programs, including a list of other organizations.
Since they had seen news about utility incentives and there were links from their utility’s webpage to solar programs, they followed a link to their utility's solar section and reviewed the basic steps.
Using their utility, the Arizona Solar Center, and other sources as references they decided to ask three different companies to make presentations and estimate the cost and performance of potential PV systems that would best fit their home.
The interactions with the prospective suppliers varied. Some asked if they already knew the size of the system they would be interested in, but the family wasn’t sure. Others asked about their local utility company, the kind of roof they had, or their typical summer electric bill. One supplier requested that they ask their utility for a summary of their usage history (easy to get). The Brightly family had questions of their own such as “What will your system cost us after tax credits and how much will we save on our electric bill?”
All three suppliers visited the home, took measurements of the roof area, inspected the electrical service and decided on the best place for the inverters. Each approach was different; one supplier presented three basic standard kits with about a two to one range in costs and no specific options. Good looking literature, but only annual performance data.
Another supplier arrived with a copy of an aerial photo of the house (obtained from the www.maricopa.gov/assessor web site) with an initial layout of an array of specific PV modules that seemed to fit well. There was a detailed quote for the illustrated layout and an offer that the size could be easily varied and a new quote printed out.
The third supplier came out, made measurements, asked some questions, answered many questions and later sent an estimate. A typical form used by suppliers to gather site data is included here as a reference. <link to be made>
All three suppliers were either Arizona licensed contractors or used a related contracting company for the installation. All asked about any Home Owner Association (HOA) restrictions, which the Brightly’s did have. All explained the legal situation in Arizona and took photos for future reference.
It was determined that the home had a south-facing main roof area with asphalt shingles at a four to twelve tilt (about 24 degrees), and with no shadows on the roof from other homes or trees. The south side was the back of the house and the electrical service was on the east side of the house with 200-amp service and available space in the circuit breaker panel for a 2-pole breaker. Because of their HOA, the Brightly family also had the requirement of applying for permission from the Architectural Review Committee to install the system.
They were now faced with evaluating three differing bids, some with size options. All suppliers offered different brands of PV modules, different inverters, and different mounting kits. This was all very confusing. The family asked for some customer references and even looked at one system that was nearby. They checked the contractor names on the Arizona Registrar of Contractors website (www.azroc.gov/) and all were in good standing with residential electric (R11 or CR11) electric licenses.
The Brightly’s used several methods to compare and rank the possible suppliers:
Calculated the cost per installed watt for each quotation. This resulted in figures running from $2.30to $4.00 per peak watt (the maximum rated output) prior to any rebates. Small systems had the higher cost per watt.
For comparison the Brightly's calculated the estimated annual kilowatt-hours per PV array installed. This resulted in figures running from 1,680-1,825 kWh. The supplier with the higher figure could not give a good reference for the value, while the others stated that their calculated estimate closely matched the measured performance over a few years by a local utility in Phoenix.
They then calculated the cost per estimated annual kilowatt-hour for each quotation. This resulted in figures running from $1.60 to $2.25 per annual kilowatt-hour.
They eliminated the supplier who could not justify the high estimated annual output calculation. The decision between the other two suppliers was more subjective and they decided on the supplier who best answered their questions.
They asked the successful supplier back to settle on a specific system size and layout on their home. They asked the supplier if he could help with the HOA application and the supplier agreed and marked up a photo of the home to show the proposed changes.
With the signing of a contract and an initial payment, the supplier prepared the basic utility reservation for an incentive payment. Both parties signed the reservation and it was sent in to the utility. The utility generally acts on the reservation and sends the homeowner an Interconnection Application with their requirements identified.
The Brightly family contacted their HOA and picked up an HOA application. After asking the supplier for a few details, the application was filled out and submitted along with the requested fee. The application was approved and the Brightly’s were on their way to a clean and renewable source of energy.
Although your experience may not be exactly like the Brightly’s, there are certain steps that your contractor can do to facilitate the process. In addition to ordering the materials and scheduling the installation, the supplier usually has two related tasks:
- Prepare a set of drawings detailing the system installation for submittal to the local city for a building permit. The drawings and the application, along with the fee were submitted. The city building inspector required specifications of the PV modules, inverter, safety disconnect and mounting details. This was simple compared to some jurisdictions and earlier practices when photovoltaic systems were new technology. Depending on system size and the experience of the building inspector with PV systems, the permit process can range from simple to complex. As an example, the Solar ABCs-developed standardized permit application intended to be adopted by cities and counties is linked here for reference < http://www.solarabcs.org/about/publications/reports/expedited-permit/forms/index.html>. Most counties and larger Arizona cities have blank permit applications available online, but the forms do not detail all of the submittal requirements. Experienced PV installers have expertise in this area. The permits require identification of the licensed installer and are usually applied for by the system supplier. The building permit generally requires about a 2% fee; it is recommended to call first and get an estimate. Fees are based on the contract price. The permit is generally required to be posted on the building where inspectors can easily find it.
- The supplier submits the required drawings and information on the utility’s Interconnection Application form for approval of the PV system. Documents are generally signed by both the homeowner and the supplier. Requirements vary by utility, so refer to the website of the utility serving the home.
After both the permit and the Interconnection Application are approved, the system can be installed.
Installation generally requires 2-3 days depending on crew and system size.
After the system is installed, both the HOA and Building Inspector are notified of completion and the system is inspected. The Building Inspector will inspect the installation (but cannot operate the system due to the utility policy detailed in the Interconnect Agreement) and if all is good, will issue a ‘Green Tag’ and close the permit. The installer must correct any problems that arise.
The utility is then notified of the passed building permit inspection (they may want a faxed copy of the inspection tag) and will schedule the utility inspection. If all is in order (the utility is particularly interested in the grounding, cable sizes, required labels of parts, usually detailed in their Interconnect Agreement), the utility will turn on the inverter, observe proper operation, make a disconnection test, and then leave the system operating. Again, if there are any problems the installer is responsible for correcting them.
After the inspection, the utility generally requires an Installation Certification Form (name varies) along with copies of invoices and a statement of payments showing that the homeowners have paid for their portion of the system. Some utilities offer assignment of incentives to the installer. The utility generally mails the incentive payment check within a few weeks.
This might seem like the end of the path, but it is not. With the system now operating, the supplier should schedule a training visit with the homeowner and train the homeowner on system operation.
The homeowner is due a copy of all user manuals (a system manual is often prepared that contains copies of all documentation). Arizona law (see http://www.azsolarcenter.com/economics/guidelines1.html) requires that the homeowner be furnished a written statement of certification and a statement of performance. This must include what general performance the purchaser can expect from the system under typical conditions in addition to a statement of warranty.
There is really no end of the path, but just like the Brightly’s, yours can begin here. Your system should operate for over 25 years with minimal attention and continue to provide benefits that the whole family can share.
A quote from a Scientific American article sums it up:
“But the upside is that homeowners with photovoltaic panels on their rooftops can rest assured that as long as the sun shines, they will have power to spare without generating emissions of carbon dioxide and other noxious pollutants.”