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Contains FAQs about general solar topics that don't fall into a more specific category.
Solar energy applications are many and varied ranging from planning, policy, solar architecture and building construction to different kinds of equipment and their applications, and technical engineering. The information ranges from conceptual to technical. The Arizona Solar Center website provides for these different aspects of "solar and renewables" and for a variety of connections to a multitude of resources. Please review the site for the aspects of solar you are interested in, and use the resources available to you on the site.
Yes! In Arizona, depending on your electric utility, there are incentives on solar systems. In addition there are Arizona and Federal tax credits and/or rebates that may apply to your situation.
This inquiry is best met by direct contact with the various non-profit organizations and for-profit businesses. The Arizona Solar Center's Resources Directory is a good place to start. 

[Answer content currently under review - 12/10/2016]

The so-called “cost-barrier” to PVs is overstated. Costs are not a barrier to large systems, remote systems, systems where competing costs are high (e.g. Japan), or when environmental costs are given any consideration at all.

  • Many in the solar community would (if predictably) say “What cost hurdle?”  And they have a point.  Japan has removed all incentives as of Jan. 06 and the orders are still very strong.  Of course, electricity prices are not subsidized as they are here, so they tend to be higher.

  • Solar is now cheaper than conventional electricity in most of the rest of the world.   Electricity, like oil, is subsidized in the US. Japan ’s retail electric rate is $0.25 / kWh (about 3 times Arizona ’s average rate)

  • Many recent studies have pegged the per kWh cost at below $0.10/kWh.  The recent spot market cost for PVNGS is over $0.10/kWh.  It is widely known that the estimated cost per kWh is thought to be 3-5 cents per kWh for large-scale systems in the 100 MW range.

  • Tucson Electric Power generates currently at 9.9 cents/kWh, albeit their system is adjacent to their existing coal-burning Springerville power plant, obviating the need for the usual infrastructural costs (transmission, land, etc.).  Their site might be a ideal site for additional large-scale centralized installations.

  • “The new federal energy bill also includes an important component for the current discussion. Beginning in 2006, residential solar systems are eligible for a 30% tax credit. [“Residential Solar and Fuel Cell Tax Credit,” Database for State Incentives for Renewable Energy, DSIRE data for AZ & US, accessed September 30, 2005]. This web site is an amazing collection of state and federal policies concerning renewable energy. The database is updated almost daily. ] The tax credit is allowable on the installation price less the state tax credit. So in this case, the allowable credit is $4,050 based on the $13,500 net after the state tax credit ($14,500– 1000 = $13,500 X .30 = $1,350).” Out of pocket expense is thus $9,400 for a five kW system (most people around here have been installing 3-8 kW).

Table 1: Net cost of a 5kW system

Retail Cost ($)


Az Tax Credit ($)

Federal Tax Credit

30% of $13500

Out of Pocket Expense ($)


- 1000

- 4,050


  • It should also be said that the use of PV is an economic choice right now for off-grid and remote locations, including many Indian reservations.   If one were to give any value at all to the environmental benefits of using solar, there would be no question that it was economic. The economic argument may well be the most compelling, as solar emits no greenhouse gases after manufacture and an infinitesimal amount when compared to coal.

  • Many solar dealers/installers are offering leased systems with little up-front cost.  These have become very popular starting in 2015.
  • Caution: Recent changes in electrical service rates for homeowners with PV systems by SRP (and applied for by APS, etc.) along with changes in net metering will impact the savings.  This is complicated, make sure that the dealer explains the situation.  See the topics under 'Economics' on the top menu of our main web page.

Yes. The solar energy device must meet the required criteria except for the warranty and professional licensing requirements. The value of your own labor is not allowable for tax credits, only out of pocket costs.

Some points to consider:
  • Do I own my own home, or can the improvement be moved?
  • Do I have a suitable area for a solar system?
  • Do I have the cash or financing for the system?

The Arizona Solar Center is not currently hiring.  However, we suggest you consult the GreenStart Job Board  on the American Solar Energy Society website ( ). They have jobs posted in the solar energy area.  Our own Internet site has many links to sources of information on renewable energy as well.

Internships are also possibly available from individual companies.  We suggest you contact them directly. And there are many internship programs you should be able to find on the Internet. Among them is the Environment and Energy Study Institute ( ) in Washington, D.C. Their telephone number is 202-628-1400. Their job and internship board can be found at .

In line with the simplicity and availability of the other materials we have used 1) black tempera paint (needs a very good adhering surface, cardboard or well sanded metal. 2) Barbecue black spray paint (This is formulated for use around food and is our preference) 2) Black latex paint (longer seasoning time.) Only the outside of pots and jars is painted; never the inside where there would be contact with food. Black is the traditional color, however, any dark color will work - red, green, blue, brown.....Whatever is available. The surface of metal or glass needs to be clean and scrubbed with sand to help the paint stick. Any of the paints need to be well dried in the sun to release the initial vapors, then baked in a solar cooker until all remaining vapors have been driven off.
  • Technically, this is true, but what they have told you is misleading; the slight reduction is overwhelmingly offset by the quality (consistency and abundance) of our resource here.
  • We in the Valley of the Sun get 70% more power from the same PV than they do in Germany (The world's biggest market).
  • In Flagstaff , we get 83% more power than Germany does, due to the elevation and less atmospheric absorption, with the lower temperature contributing a slight increase in efficiency.
  • They might be referring to the aging that the heat does to inverters (that change DC into AC), but it is not considered significant enough to deter solar deployment.
  • By the way, their claim is not true at all for solar thermal systems.
  • Obviously, the sun goes down, but the problem is not insurmountable for several reasons as several Arizona users have demonstrated.  Moreover, PVs will provide their electricity just about when we need it in our homes, off-setting some traditional generation without additional power plant construction.  Any time they are not producing enough to meet demand, the normal grid-tied system can take over.  If the solar arrays are large and constructed near an existing power plant (coal, hydro) they can firm up the solar.

  • Local solar firms have been putting in PV systems for the last 30 years with 5 sunless days of battery storage.  The batteries cost $2 per pound, last 6 or 7 years and are 100% recycled. This is less than a pound of food that only lasts one meal.

  • Products are now entering the market to allow smaller battery banks to operate with grid-connected PV systems and operate in a mode that reduces utility demand charges.  We hope to have news on this soon (2017).


  • Not a problem for grid-tied systems until we get into the hundreds or maybe 1000s of Megawatts.  One option is to site solar at existing generating facilities, like a gas-fired or coal-fired power plant.  If the solar backs off due to weather or storms, the fossil-fueled portion of the plant can ramp up to keep the power output steady. There are merchant gas plants considering this right now – and it’s not a bad deal considering wholesale gas plants are selling power to the grid at $100 / MWH ($0.10 / kWh).

  • Conservation - Invest in better air conditioners, insulated windows, etc.
  • Conduct a home energy audit.
  • Switch to efficient lighting such as compact fluorescent and LED bulbs.
  • Contribute to the value of the house (tax free equity increase)
  • Make a good return on investment
  • Lock in some of my energy costs in an inflating economy
  • Take advantage of incentives, rebates, and tax credits
  • Get it right the first time
  • Do the best for my family
  • Improve the environment

You may follow current news releases on our front page of the website under 'Featured', our 'News Feed', the blog section, and the Twitter section.

  • Many remote homes and ranches have worked without problems for 25 and 30 years.

  • City of Tucson’s 60 kW photovoltaic array at the new Pennington St. Garage (top deck has a 30+ space canopy that uses PV modules to shade the cars parked on this level)

  • Imperial National Wildlife Refuge near Martinez Lake, AZ.  Good example of a Refuge Manager taking control of his energy situation and prominently displaying solar for public viewing.

  • Arizona State University is highly covered by PV arrays of many types.  Worth a visit to see.. 

  • Major supermarkets are installing PV shaded canopies that provide both shade and power.  There is even PV shaded parking on a public street in Parker, Arizona.

  • The 280 MW Solana plant, a partnership between Abengoa Solar and APS, is located near Gila Bend. This concentrating solar power (CSP) facility will provide thermal storage adequate to produce electric power for several hours after the sun goes down.
  • Invite and encourage additional large-scale development of solar here (of several hundred megawatts).  Several large projects such as Solana (CSP) and Agua Caliente (PV) may be the models for others.

  • Establish ambitious goals.  The Western Governor’s Association has a target of 30,000 MW of renewable for the western states by the year 2015.  See  for details.

  • Increase the Renewable Portfolio Standard, a function of the Arizona Corporation Commission.

  • Get real teeth in a law mitigating CC&R restrictions on homeowners.  There is existing law that protects homeowners in Arizona, but CC&Rs tend to scare possible users

  • Get major developers to design homes for easy installation of PV systems.  They build some 90% of all new homes. Most designs make it more difficult to install solar than it need be.

  • Have the utilities pay a closer to a real price for on-peak PV power.

  • Establish tradable Green Credits (tags) in favor of PV that are valued closer to the equivalent pollution that they avoid.

ASP currently has over 1000 MW of combined company-operated and distributed residential and commercial PV capacity.

SRP in 2016 reported 117.5 MW of residential PV, 52.7 MW of commercial, 91.9 MW of investor owned utility scale PV, and 381 MW of SRP owned PV systems.

TEP owns three PV plants and operates two others which are rated at a combined capacity of over 16 MW (outdated). 

  • Install a Domestic Hot Water system (DHW)
  • Install a Grid tied PV system
  • Install a non-grid tied PV system (attic fan, yard lights, shed power)
  • Install a wind energy system (if the location is suitable)
  • Install skylights
  • Install pool heating
To understand you energy usage, get a summary from your utility. 
A smart grid is a segment of the electrical distribution grid that uses information and communications technology to gather data, such as information about the plentiful availability or short-term shortage of electricity from grid suppliers and the electricity demand-oriented behavior of consumers, and act on it in an automated fashion. As more homes and businesses become equipped with solar electric systems, and eventually with energy storage devices, smart grids will become more and more important in terms of balancing electricity supply and demand on a real-time basis. The main goals of smart grids are to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity.
Passive solar uses building and site elements and natural processes to accomplish a given task (comfort, water heating, air movement, etc.) with no, or minimal, mechanical and electrical equipment. Active solar technologies include PV and solar water heating systems and utilize mechanical and electrical equipment.
  • Technological strides are not necessary. PV is at least 35 times more efficient than biomass in converting solar energy to electricity today.  Improvements are being made as the industry expands at a very rapid rate.  We were growing at a compounded rate of about 35% per year until 2004 when we saw a ~50% growth rate for the next several years. In 2008, the worldwide PV market size nearly doubled, led by Germany and Japan, and it doubled again in 2010. In recent years, manufacturing and installations in China have been dominant factors. 

  • What we need is volume production - The industry has not and is not expecting "breakthroughs." The technology has been known for over twenty years.

  • That said, improvements do continue. Check out SunPower . They have the most efficient PV modules on the market and the aesthetics of their 300 Watt module are unmatched by any competitor.  They could dominate the US market in the next 2-4 years.

Please see the Arizona Solar Center Calendar (not presently implemented- will return soon)

You may review our recommended list of books and other resources.

To many, PVs lead the way because costs are dropping rapidly, supplies are increasing, emissions are non existent, there are few if any moving parts, the maintenance effort is small, transmission lines can be minimal or even absent. Passive solar design is even better; that is, design our buildings so that we don’t need as much electricity in the first place.
In Germany solar development owes much of its success to their so-called feed-in law.  Here’s a web site that concisely describes how it works: .

Here are the basics

  • The "Feed-in Law" in Germany permits customers to receive preferential tariffs for solar generated electricity depending on the nature and size of the installation. Under the new tariff structure introduced in 2004, the base level of compensation for ground-mounted systems can be up to 45.7 euro cents/kWh. PV installations on buildings receive higher rates of up to 57.4 euro cents/kWh.

  • The Feed-in Law fixes tariffs for approved renewable energy projects for a 20-year period from the plant commissioning and will apply incremental price cuts. Tariffs were initially set at 48.1 cents per kilowatt hour for solar energy, 8.6 cents per kWh for wind, from 9.6 to 8.2 cents per kWh for biomass, 8.4 to 6.7 cents per kWh for geothermal and 7.2 to 6.3 cents per kWh for hydropower, waste and sewage gas.

  • Some German states have subsidy programs for PV installations that can be used in combination with the national Feed-in Law.

In other words, the German government subsidizes solar power in order to help it get a firm footing.  They do the same, as it says above, for other renewables, but at a reduced rate. 

In Japan , the competing cost of conventional electricity is so much higher that it goes a long way to make solar an economically sensible choice.
  • I want to be more environmentally responsible, using sustainable resources.
  • I want to lock in my cost of energy.
  • I want to generate my own electricity.
Includes FAQs about PV systems. 
Your site must have clear, unobstructed access to the sun. Buildings, trees or other vegetation should not shade your site. South-facing roof exposure is best, but roofs facing east and west may be OK. If a rooftop is not available, your PV system can also be mounted on the ground.
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.
As you may know, solar panels come in many sizes. There are two basic types, photovoltaic and solar heating. Photovoltaic panels have solar cells that produce electricity. Solar heating panels can be made to heat either liquids such as water, or air. Most of my comments will refer to the photovoltaic or solar electric panels.The photovoltaic panels are more properly called modules by the solar electric industry. Most of the photovoltaic modules have a glass front called a superstrate) that provides protection from the elements (rain, etc.) while allowing sunshine to reach the solar cells. The solar cells are attached to the superstrate with a clear plastic that is in the form of a plastic sheet before the solar cells are laminated (stuck to) the glass by a combination of heat and pressure while a vacuum is applied to the assembly to minimize any bubbles in the plastic.

While this is in theory a simple process, it becomes more difficult the larger the photovoltaic module. This difficulty tends to limit the size of photovoltaic modules.

In general, the larger a photovoltaic module, the lower the cost per square foot, up until the maximum practical size is reached. There are some other considerations when considering the size of a photovoltaic module for any particular application (power plant, home, cabin, remote telecommunications site, etc.).

  1. The size limits shipping options. Large modules must be shipped by special truck in special packing. Smaller modules can be shipped by UPS or the mail. Optimum size depends of the total system size and how to best ship the modules. 2.
  2. Generally, the larger the module, the lower the installation costs due to a few number of wiring connections, mounting bolts, etc.
  3. In many areas where there is a high chance of hail stones, smaller modules are used because the damage of a single hail stone is limited to the module it hits. A single large hail stone can cause $200 of replacement damage for a small module, while the same hail stone hitting a large module may cause $4,000 of damage. With a large number of smaller modules, the system will usually continue to operate at a lower level of output when a few modules are damaged. With one large module, the system will most likely fail completely. This is important in some applications such as telecommunications.
  4. The weight per module can be very important during assembly. Most modules are of a size and weight that two persons can lift and install on the mounting frame. Larger modules become expensive to install.
  5. Some applications only require a few small modules. Any solar panel that is larger than needed is wasting money. This is one reason while there is a wide range of module sizes.
  6. Some applications require a voltage that is not generally available from a large module. In this case the system designer needs to select a combination of smaller modules that when wired together will have the required voltage and power.  Generally the person designing a solar system needs to select the panels that will accomplish the desired performance at the lowest installed price, while considering the impact of failures and the problems of the various sizes of modules.

This graphic summarizes how photovoltaic cells work.

The AZ Solar Center and AZ Solar Energy Industries Association provide lists of PV retailers. Retailers either can provide installation or can refer you to installation contractors in your area. Try to find a company located in the area where your system will be installed. Price is only one factor when selecting a PV company and/or contractor.

Here are some other considerations:

  • Does the company have experience installing grid-connected systems?
  • How many years has the company been in the business of installing PV systems?
  • Does the company use licensed Arizonacontractors?
  • Does the company have any judgments or liens against it?
  • Will the company provide references from previous customers?
  • If you get more than one bid, make sure that the bids are for the same identical system.

To estimate the best system size for your home or business, examine your electricity usage for the past 12 months.There are ‘Solar calculators’ on the web that will give ballpark cost and performance estimates.

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 normal ‘net metering’ does not allow the utility to fully credit you 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).
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 (called net metering). Net metering allows you to "bank" 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 banked on the grid, allowing you to use an equal amount of electricity later without incurring any additional cost. If you use more electricity from the grid than you have banked, your utility will charge you monthly for the difference. 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.
FAQs about solar water heating and other solar thermal technologies.
A power tower is a type of concentrating solar power (CSP) technology that uses flat mirrors which track the sun and reflect light onto a collector at the top of a tower. The PS10 and PS20 facilities have been operated since 2006 and 2009, respectively, in Spain by Abengoa Power. The PS20 plant utilizes 1255 heliostats spread across 210 acres to produce steam in a collector at the top of a 541' tower. The steam turns turbines to generate 20 MW of power.

This article explains in some detail how solar water heaters work.

Contains FAQs about passive solar and other green building topics.

Approaches to passive solar are contained within concepts of thermal mass design; thermal skin design; composite design; with direct gain; indirect gain; and isolated gain approaches for heating and thermal sinks and diurnal dispersal techniques for cooling. Please refer to the website section titled Solar Architecture for a tutorial on the variety of approaches and strategies for passive heating and cooling.

There are a variety of passive system solar buildings throughout the State of Arizona., and some are identified in the website section titled Solar in Arizona. Additionally, contact statewide solar organizations like the Arizona Solar Energy Association (Regional Director in your region), and/or local solar architects (listed in the website section - Products and Services) for locations of buildings incorporating passive design in your area. See this article

These articles contain descriptions of how Arizonans have used a variety of techniques to reduce their energy usage.<< Link not working

Contains FAQs about regs, laws, regulatory agencies, etc. 
The Arizona Legislature passed a bill in 2007 prohibiting homeowners’ associations (HOAs) from restricting the installation or use of solar energy devices. The legislation only authorizes an HOA to adopt reasonable regulations on the placement of the solar energy devices. This link  (HB 2593) provides the full text of the bill in a PDF formatted file.
The acronym SREC stands for Solar Renewable Energy Credit (or Certificate). SRECs exist as a result of the Renewable Portfolio Standards (RPSs) that have been implemented by many states, including Arizona, as policy measures which mandate the development of solar and other renewable energy sources. For example, Arizona’s RPS states that by 2025, 15% of the electric power generated in the state be derived from renewable sources such as the sun and wind. An SREC is produced each time a solar electric system generates 1000 kWh of electricity and it thus represents the benefits of clean solar energy. SRECs are tradable commodities in some states, such as New Jersey and Massachusetts, but for residential and commercial solar electric systems in Arizona, the local utilities generally retain them in return for the rebates provided as incentives for installing the systems.
FAQs of interest to solar/renewable energy practitioners.

The Arizona Registrar of Contractors does not have any specific solar license, but considers this to fall under the CR11 general electrical license. There is a special solar only domestic hot water license. A minimal bond is required. Arizona Registrar of Contractors

FAQs about the solar energy industry.
In the specific case of idling or lightly loaded electric motors, KVAR units (kilovolt-ampere-reactance units or power factor correction capacitors) actually do save energy. In this case, the KVAR units reduce the voltage and correct the power factor (a measurement of the phase difference from applied ac voltage and the resulting current), and save energy.  The motors also run cooler and last longer. But in most cases, such as air conditioning, refrigerators, and the like, the motors are fully loaded and there are no savings.

In the case of commercial accounts, the utility uses meters that measure both the real power (watts) and the reactive power (volt-amperes reactive or VAR) and charge for the VARs if they constitute more than a certain percentage of the meter reading.  This is important to utilities because while the VARs do not represent real energy, they do cause excessive currents that the utility needs to invest in larger equipment to handle.  Measurement of VAR in residential service is very uncommon.  These KVAR units do reduce the VARs and lower electric bills, but only for commercial service.  In the case of master metering for connected buildings such as apartment complexes, the utility may be charging for Power Factor, in which case the KVAR units could be beneficial.

We are not aware of any damage coming from KVAR units.