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Solar PV Guide: Prices, Design,

Installation & Pay-off Period

(ROI)

Solar Photo-voltaic (PV) technology is the way of

the future, for generating and supplying electric power for hom es and businesses in the US and across the world. Despite the great potential of Solar PV, current cost and efficiency of solar panels makes them a green, yet expensive alternative to conventional ways of generating electricity, such as Coal, Gas and Oil fired power plants as well as Nuclear and Hydro electricity.

Main obstacle that is holding the wide-spread of solar PV is the long ROI (return on invest m ent) that in som e situations m ay exceed 10 years. Fortunately, US federal government and local and state governm ents have a multitude of incentives and rebate programs for solar and other renewable energy projects.

Planning a Solar PV system

When considering installing a Solar PV system , you as home or business owner will need a to know the future size of your solar system in kW ( 1 kilo watt is 1000 watts) and the cost associated with this solar system . You also need to establish your current annual electricity usage and decide if you want to reduc e or com pletely eliminate the use of electricity that you purchase from your utility company.

First, gather your electric bills for the last 12 m onths, record your total electricity consum ption – the number of kW-hours, and your the total am ount you had to pay, excluding any late fees and other miscellaneous fees. Divide your total cost by the total num ber of kWh – this will give you real cost per kWh.

In Massachusetts, average cost of electricity for residential use is 19-24 cents per

kWh, and 15-17 cents per kWh for commercial use. Both are set to increase by 20% in near future, as announced in April 2008, by local utility com panies.

Designing a Solar PV system, tailored for your need

In Massachusetts and surrounding states, we have an average of 4.5 sun hours per day annually. This accounts for rainy and cloudy days as well as long, sunny summer days and short winter days.

To m ake best use of your solar system, you will need to capture as m uch sun-light as possible, therefore the best location to place your solar system is on the south-facing side of the roof. You also want them to be installed at a certain angle – about 20-30 degrees. Assuming the 4.5 hours of sun per day, a 1 kW Solar PV system will produce 4.5 kWh per day, and 135 kWh in a 30-day m onth (4.5 x 30 days). Please keep in mind that the energy produced is in DC volts, and when it goes through the conversion into AC, you lose about 20-25% of that electricity.

Average household electric consum ption is 750 kWh per m onth for a single family hom e. To cover 100% of this consum ption with solar electricity, you will need about 8 kW solar PV system. 135 kWh DC x 8 = 1080 kWh – 25% =810 kWh AC at 100% production output of solar panel. Note that ALL solar panels loose an average of 0.5% of production output per year, or 10 % through its 20-year warranty period.

Average residential solar installation is 2-4 kW system which usually eliminates 50-70% of electric power that you purchase. How ever those installations are still dependent on additional electricity.

Commercial solar installations can range from 10 kW to over 1 MW (1 megawatt = 1000 kW). Commercial Solar PV system s can supply power to the building they are installed on or they m ay be a so called solar farm – or a solar power plant supplying electric power directly into electric grid. For purpose of this guide, we will concentrate on sm aller, roof-top solar installations for individual home or business use, as solar farms topic goes way beyond the scope of this guide, and is considered a power utility for taxes and other purposes.

Solar PV Cost

National average cost to install a Solar PV system ranges from $9 to $12 per watt or $9000-12000 per kW DC (direct current) of solar system installed, with sm aller installations being at the top for this price range due to fixed costs such as equipment, setup, installation, permits and paperwork.