太阳能投资回报率计算

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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

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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.

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Most expensive com

ponent of the solar PV system

are the solar panels them

selves,

however equipment such as inverter (which converts DC into AC and feeds it into

your meter) also add considerable amount to a sm

aller size PV system

s. 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 panels

Fortunately the $$33000 price tag is not you actual cost, as m

any states have a wide

range of rebates for solar PV installations as well as federal tax credits, available for

both commercial and residential system

s.

ROI and pay-off period for Solar PV

For purposes of this guide we will use two hypothetical solar PV system

s

–

one

being a 4 kW residential system

and the other being a 25 kW commercial system

.

To sim

plify this guide and to avoid any confusion both of those system

s 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 com

panies. These two utility com

panies 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）< /p>

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。

尽管潜力巨大太阳能光电，

目前的 成本和效率的太阳能电池

板使他们的绿色，

但昂贵的替代传统的 发电方式，

如煤，

天然气和石油发电厂以

及核能和水电发电。

主要障碍 是持有广泛的太阳能光伏是一项长期的投资回报率（投资回报）

，在

某些情况下可能会超过

10

年。 幸运的是，美国联邦政府以及地方和国家政府的

多种奖励和退税计划的太阳能和其他可再 生能源项目。

规划太阳能光伏系统

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