I have been told for years that solar photovoltaic panels will soon be cheap enough and abundant enough for every building in the U.S. to have at least one or two sitting on the roof or hanging on the wall. The promise has always been that, any day now, costs will come down so much that solar PV will be affordable to the masses. Year after year that promise goes unfulfilled, and my roof and walls remain uncluttered with solar panels.
Why So Much?Reason 1: Raw Materials. The most common material used to make solar photovoltaic panels is polysilicon. For years, manufacturers of polysilicon have made and sold it to their biggest customer-the computer industry. Total production of polysilicon has been traditionally produced to match the demand of the computer industry, with all of its economic ups and downs. Polysilicon manufacturers have not increased production in a significant way to account for the increase in production of PV, which has resulted in competition between the two industries for this critical ingredient-keeping demand, and prices, high. Even more exotic ingredients, such as gallium, indium and nanocrystalline metal oxides, also used in the production of PV panels, are also expensive and available in limited amounts.
Reason 2: PV Panel Fabrication. Building a PV panel is a very delicate, highly technical, multi-step process involving many kinds of materials-all put together by people with white coats and gloves working in a laboratory setting. Building a solar PV panel is not the same as building a microwave oven, and cheaply producing PV panels on a massive scale remains a huge challenge to the industry.
Reason 3: Design and Installation. PV panels generate Direct Current electricity. Our homes and offices use Alternating Current electricity. A traditional PV array on a home or building consists of several PV panels wired together and into a box, called an inverter, which makes DC into AC and requires expertise to design and install, expertise that the average citizen does not possess. Inverters are one of the more expensive components of any PV system, and typically last no more than about eight to 10 years.
Owners of these types of PV systems can expect to replace the inverter at least once during the life of the system, which adds even more cost. Each PV array must be designed specifically for the amount of power generation desired, solar exposure, and location on the building or building site. Adding or removing panels is not something that can be done easily or simply without additional design and installation costs. PV arrays are permanent, and there is little flexibility built into them.
Reason 4: Long Payback. The average installed cost of a solar PV array is about $8 per watt. A 4kW system would cost approximately $30,000 and take up about 400 square feet of space on the roof or wall. According to the Solar Power Calculator on the NREL PV Watts Web site, this system in Seattle, including federal and state incentives, would pay for itself in approximately 32 years. A system half this size in Tucson, Ariz., would pay for itself in 11 years. Census records show that Americans move once every five years.
Proponents of solar power have suggested that costs for PV systems will come down as the cost of electricity goes up. But even if electricity doubles in cost for the Seattle area, to continue with the example given above, the payback for a 4kW system would be 16 years; still too long for most people to seriously consider. PV proponents have also claimed that efficiencies will dramatically increase as technology improves, and new and better panels will soon be developed and available. While it’s true that increase in efficiencies have been realized, it is also true that the greater a PV module’s efficiency, the greater the cost.
Getting to Critical MassWe are repeatedly told by PV-believers that, in order to reduce the cost of PV systems, more of them need to be produced and installed. It’s all about economy of scale; reduction in cost per unit resulting from increased production, realized through operational efficiencies. But how do we get there?
With the emergence of something called a microinverter, a refocusing has occurred within the industry; one that might finally allow solar PV to take off, in a big way. Instead of having to string several panels together on a rooftop, all wired into an expensive inverter box, a microinverter is a small inverter installed with each individual panel. A PV panel with a microinverter produces AC power right where the wire leaves the panel.
Microinverters are being produced with a 20 year warranty, which matches the average expected life of a PV panel. A PV panel with a microinverter can be placed anywhere on a building-or a building site, completely independent of other panels. In a strung-together, single inverter PV array, if one panel is shaded, or dirty, of otherwise working less than optimally, all of the other panels’ performance is subsequently affected. Connecting each panel to its own inverter allows each panel to operate independently of the others, and a poorly performing panel has no impact to those adjacent.
A California company called Enphase Energy has been producing microinverters for a couple of years now. Their product is designed to be installed on a rooftop array of solar PV panels, one microinverter per panel, and claims the following advantages over a traditional PV array with a single inverter:
- Energy harvest gains of 5 to 25 percent
- Greater production in low-light conditions
- No single point of failure
- Quick and simple installation
- No central or string inverter to install or design
PV panel manufacturers are exploring the possibility of fabricating panels together with a microinverter to simplify design and installation, reduce cost, and sell to a potentially huge market-the average homeowner.
The New Solar ApplianceClarian Technologies, based in Seattle, claims to have just such a product, which will be available in 2011 and sold through big box home improvement retailers. It hopes to be able to offer the panels to customers for as little as $600 per panel. Clarian will be making panels that are designed to be plugged into any home’s electrical receptacle, and deliver power directly to the home, through the home’s electrical wiring grid. Clarian’s “solar appliance” is a 200W solar panel called the Sunfish. According to the Web site, it functions just like any other appliance but instead of drawing power from the home’s grid, it feeds power into it. Additional features and advantages include:
- Unlike existing micro-inverters, the Sunfish has built-in circuit protection and doesn’t require a dedicated electrical panel
- No contractors, no installers, no additional wiring-up and running in about an hour
- Same cost as a household appliance with a payback in three to four years or less
- Web-based tracking and monitoring with onboard WiFi, upload data directly into Google PowerMeter
ConclusionMost people are deeply concerned about the state of the environment, and want to do the right things to help improve it. Most are also subject to the economic realities of life. Very few can afford a solar PV array that costs tens of thousands of dollars with a long payback. I would wager that most homeowners, however, would be willing to part with $600 for something that they can purchase at appliance retailers, load into the mini-van Saturday morning, install on the patio trellis by noon, plug into the wall, and watch the power being generated at the computer the rest of the day. I would also wager that the average homeowner will likely install more than one of these solar appliances as funds become available.
One of the biggest attractions to the average homeowner is that, like any other appliance in the home, the solar appliance can easily be removed and reinstalled in the next home (or apartment).
The availability of these innovative products allows any homeowner to generate renewable power, and further reduce energy use, at an entry level price.