太阳能投资回报率计算共12页文档

http://coolflatroof/solar-power-guide.phpSolar PV Guide: Prices, Design,Installation & Pay-off Period (ROI)Solar Photo-voltaic (PV) technology isthe way of the future, for generating andsupplying electric power for homes 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 investment) that in some situations may exceed 10 years. Fortunately, US federal government and local and state governments have a multitude of incentives and rebate programs for solar and other renewable energy projects.Planning a Solar PV systemWhen 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 associatedwith this solar system. You also need to establish your current annual electricity usage and decide if you want to reduce or completely eliminate the use of electricity that you purchase from your utility company.First, gather your electric bills for the last 12 months, record your total electricity consumption – the number of kW-hours, and your the total amount you had to pay, excluding any late fees and other miscellaneous fees. Divide your total cost by the total number 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 companies.Designing a Solar PV system, tailored for your needIn 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 make best use of your solar system, you will need to capture as much sun-light as possible, therefore the best location to placeyour 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 month (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 consumption is 750 kWh per month for a single family home. To cover 100% of this consumption 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 systems can supply power to the building they are installed on or they may 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 smaller, 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 CostNational 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 smaller installations being at the top for this price range due to fixed costs such as equipment, setup, installation, permits and paperwork.Most expensive component of the solar PV system are the solar panels themselves, however equipment such as inverter (which converts DC into AC and feeds it into your meter) also add considerable amount to a smaller size PV systems. Therefore for a 3 kW residential solar system, the cost will be around $11 per watt or $33000 total system cost when using conventional solar panelsFortunately the $33000 price tag is not you actual cost, as many states have a wide range of rebates for solar PV installations as well as federal tax credits, available for both commercial and residential systems.ROI and pay-off period for Solar PVFor purposes of this guide we will use two hypothetical solar PV systems – one being a 4 kW residential system and the other being a 25 kW commercial system. To simplify this guide and to avoid any confusion both of those systems are installed in Massachusetts. This way we know exactly what the MA state rebates are for each system and what the local electricity costs are from N-Star and National Grid utility companies. These two utility companies have the widest presence in MA market.太阳能光伏指南：价格，设计，安装及收费期率（ ROI ）太阳能光voltaic （光伏）技术是未来的方向，创造和提供电力的家庭和企业在美国和世界各地。