Cost of Solar

Overview

The cost of a standard home solar electric system can be anywhere from $20,000 to $60,000 depending on these factors:

• System size
  A larger system will be more expensive and system size depends on how much energy you need. System size is the biggest factor that determines how much solar costs.
• Brand of equipment
  As with everything, some brands are more expensive than others.
• Equipment quality
  Less efficient solar panels are less expensive but you also will need to buy more to produce the same amount of power.
• Cost of labor
• Federal and local solar rebates

Larger state rebates make for a less expensive system. Most solar installation companies will let you pay the after-rebate price and then they'll take the rebate when it comes. In other cases you may have to pay the full price of the system and wait for the rebate yourself

The costs of solar energy can be high. Overall, the cost of a solar system is usually between $8 and $10 per AC watt and this adds up to a high total price tag. But, when you buy a solar system, you're paying in advance for 25-30 years of power.

When you think of it that way, the cost of solar energy is not much compared to what this power will cost from the utility company over the next 25-30 years. This is especially true when you think about solar as an investment in your home.

Plus, with new and innovative options for home solar financing, solar power can be surprisingly affordable.

Cost Breakdown

When you buy a solar electric system, here's where your money goes:

• Solar panels are 60% of the cost - they're mostly made up of pure silicon, which is expensive and takes a long time to make.
• The inverter makes up about 10% of the cost
• All the other parts, like wires and racking, is about 15% of the cost
• Labor is also about 15% of the cost

More Information

• Read about the federal solar tax credit and how it factors into the cost of solar.
• Learn how to save money on the upfront cost to go solar withSunRun Power Plan.
• Contact SunRun to find a solar solution for your home.

http://www.sunrunhome.com/

Solar Photovoltaic Rebate Program Introduced into Senate

Ten Million Solar Roofs In Ten Years
U.S. Senator Bernie Sanders (I-VT) has introduced a new bill into the Senate to help ease the cost for homeowners wanting to install solar panels. The 10 Million Solar Roofs Act of 2008 will offer rebates for up to half the installation costs of solar photovoltaic systems, and would be in place for the next ten years. In addition to private homes and businesses, non-profit organizations, and state and local governments would be eligible for the rebates.

Read More

SOLAR FAQ'S

• What is the recommended size??
  
  In colder climates, a 500 square foot collector area is appropriate for domestic hot water heating in a single family home. In warmer climates, a 300 square foot collector can often do the job. For space heating, a minimum of 800 square feet of roof area is recommended.
  
  
• What is the proper orientation of a solar energy system??
  
  Ideally, the solar collectors should face as close to south as possible. However, east and west orientations can still provide significant solar energy. A system facing east or west is approximately 20% less effective than one facing south. The ideal slope for a solar energy system is roughly equal to the geographic latitude. The slope is generally not as critical as the orientation. A 10 degree change in slope will typically affect performance by 2-3%.
  
  
• How does the system integrate with my domestic hot water system??
  
  The water from the main water supply is preheated as it passes through the storage tank on its way to your primary water heater. Each BTU of solar energy used offsets a BTU that would otherwise be generated by fossil fuels or electricity. Typical solar domestic hot water systems utilize a circulating pump, solar storage tank, miscellaneous fittings and a solar differential control, specified in conformance with SRCC OG 300 requirements.
  

SOLAR ELECTRIC (video)

SOLAR PAYS BACK

BuildingGreen.com features a story on the value that renewable energy can add to a home. Amy Levin, a realtor who completed a LEED platinum registered gut rehab in Washington, DC, had her home appraised at 10% higher value than comparable properties. Interested buyers made offers that exceeded her green investment costs, even though the house wasn’t listed. People wanted to rent her house, even though she built it for her own residence.

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.

Solar Hot Water

Case Study - Solar Hot Water

The incorporation of domestic solar hot water system into residential homes has become increasingly popular over the last several years. The basic concept of all solar hot water systems is to use the sun’s energy to heat or preheat water, thereby reducing the gas or electric requirements to produce hot water.

In general all solar hot water systems have a solar collector (to collect the sun’s energy), and a storage tank (to store the hot water). From this however, the systems can be separated into two different categories, active and passive systems.

Active systems rely on pumps and valves to circulate the water or heat exchange fluid through the solar collector, while passive systems rely on the natural tendency of water to rise when heated, and thereby circulate through the system.

Figure 28: Schematic of a Closed Loop Solar Hot Water System

While active systems are slightly more complicated than passive systems, they can be more flexible in terms of the placement of the components since the location of the storage tank is not dependent on the physics of hot water buoyancy. On the other hand, passive systems, because of the lack of pumps have been argued to be more durable and less prone to problems.

Active Systems

There are three main types of active systems, direct, indirect, and drain back.

With direct systems, the domestic potable water is circulated directly through the solar collector. The pump circulates the water from the storage tank through the solar collector when the temperature of the solar collector is greater than that of the tank. Direct systems are generally not recommended for climates where the exterior temperature drops below freezing or for areas that have hard or acidic water.

For cold climates, the need for freeze protection of the system is important. The recommended systems would either be an indirect (closed loop) or drain back system. The indirect (closed loop) systems use a propylene glycol heat exchange fluid in the solar collector. The low freezing temperature of the propylene glycol provides the freeze protection for the system allowing the solar systems to be used in climates prone to longer freezing times. These indirect systems require a check valve to prevent reverse thermosiphoning at night, since the hot water in the tank could convect heat back up to the typically roof mounted solar panels.

The drain back system uses water as the heat exchange fluid. In order to provide for freeze protection, the pump shuts off when the temperature of the collector cools down below that of the tank, and the water in the system “drains back” into storage reservoirs. The panel then fills with air protecting the system from freezing when the pump is turned off.

For both indirect and drain back systems, the solar collection loop is run to a heat exchange coil around a water storage tank. In that way, the systems are decoupled from the potable water delivered to the house.

Passive Systems

There are generally two types of passive systems; thermo-siphon, and integral collector storage.

A thermo-siphon system uses the tendency of water to rise as it is heated. In this system a storage tank is installed at elevation above the collector. As the water is heated, it becomes lighter, and naturally flows up and into the top of the storage tank. The cooler water from bottom of the tank flows down pipes to the bottom of the collector, creating the circulation through the system. As the temperature in the panel drops below the temperature of the storage tank, the circulation through the system stops as well. This prevents the cooler night time temperatures from removing heat from the system.

Thermo-siphon systems can also be designed with a closed loop and heat exchange fluid as well, in areas where freeze protection is required.

In the integral collector storage system, the storage tank is integrated into the solar collector. The cold water supply is connected directly to the collector. As water enters into the panel it is heated up by the sun. However, unlike other systems, the water remains in the panel until there is a call for hot water, and then the water is drawn directly from the panel to fulfill the demand. Since the hot water is stored in the panel, integrated systems require larger storage tubes in the collector (to increase collection ability) than a normal direct system, which also helps prevent freezing. This is likely the simplest solar hot water system available.

Design Considerations

The solar collectors should be placed on the South side of the building with the optimum tilt for the collector to be set to the azimuth angle for the location of the house. This is to provide the best year round performance of the system.

Due to the potential for high temperature water leaving the solar hot water system, a mixing valve must be installed on all systems to regulate the water temperature delivered to the house, and prevent any concerns about scalding. In addition, it is generally required to install some means of providing back up heat with any solar hot water systems to ensure that hot water demands can be met all year round. The simplest way to provide the back up heat is with a small electric heating coil inside the storage tank. Alternatively, instantaneous water heaters can also be used. If instantaneous water heaters are used for a back up, they must be designed to handle the potentially elevated water temperatures from the solar panel.

Energy Model Results

The system used in the energy model is based on a closed loop glycol system with a SunEarth Empire EC40 solar collector plate with an 80 gallon Rheem Solaraide HE (heat exchange) tank. The collector was oriented to the South and the angle was set to the angle of the roof slope in order to approximate the most realistic installation of the panel on the roof. The resultant energy savings was a 3.0% decrease in the overall whole house energy consumption. Part of the reason for the small savings is the relatively high efficiency of the tankless heating unit it replaces.

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