Concrete example photovoltaic plant productivity: analysis of cost and convenience from installation to decommissioning
The photovoltaic systems in the service of domestic appliances, can provide enough electricity during the year to meet the entire demand of the home, thanks to the signing of an invention in trade regime in place with the GSE (National Manager of Electrical Services ), which allows the network to assign the excess energy produced by the plant during the sunniest hours of the day to pick it up during the hours in which the plant has reduced productivity or overnight.
The evaluation of the power to be installed is made according to the consumption of the user, detectable by the electric bill, and according to the characteristics of the surface on which the plant must be installed.
The best exposure for a photovoltaic system is to the south, with an angle of inclination of 30 ° to the central and southern Italy and 35 ° to the north.
So a south-facing roof at an angle of 30-35 degrees is optimal surface to install a photovoltaic system. The productivity remains high even when exposed to the south-east or south-west and variables for roof pitches between 15 ° and 45 °.
Here are some examples of productivity of a photovoltaic plant 3 kWp (kilowatt peak) installed on the roof in the province of Milan, for different exposures and inclinations of the surface of system.
Location: Milan
Rated power: 3 kWp
Type of PV modules: crystalline silicon (mono or poly)
Orientation angle of PV modules Yearly production plant
South 15 ° 3200 kWh / year
South 25 ° 3330 kWh / year
South 35 ° 3380 kWh / year
South 45 ° 3360 kWh / year
East / West 15 2840 kWh / year
East / West 25th 2780 kWh / year
East / West 35th 2690 kWh / year
East / West 45th 2570 kWh / year
The productivity of photovoltaic systems is not constant throughout the year, in fact, is highest during the summer months when the sun is above the horizon, and minimum in the winter months.
In general, if the exposure of the roof is not particularly unfavorable, a plant from 3 kWp will be sufficient to meet the energy needs of a dwelling with a counter from 3 kW.
Every kilowatt installed occupies an area of 8-10 square feet, so to make a plant of 3 kWp is necessary an area of 24-30 square meters (example system installed in Milan).
Revenues
Revenues arising from the installation of a photovoltaic system are given:
1. by government incentives in the Energy Bill,
2. savings resulting from the energy produced for own consumption
3. and, for plants with higher productivity, consumption of utilities associated with them, from the sale of the energy produced in excess.
For small-medium sized plants, built on the roof at the service of civil rooms and sized to cover a demand equal to (or less) than that to which users are connected, revenues are attributable only to the items referred to in points 1 and 2.
Below is an overview of the expected revenues under the net metering, a plant with a 3 kW partially architecturally integrated, installed in Milan with southern exposure, over a period of 25 years.
Productivity estimated annual year *
[KWh] Incentive for Energy Bill
€ / kWh Annual revenues from incentives in the Energy Bill [€] ** Average cost supply electricity [€ / kWh] Annual savings on electricity supply (consumption of energy produced) [€]
1 3300.00 0.422 1393 0.1600 528
2 3285.15 0.422 1386 0.1640 539
3 3270.37 0.422 1380 0.1681 550
4 3255.65 0.422 1374 0.1723 561
5 3241.00 0.422 1368 0.1766 572
6 3226.42 0.422 1362 0.1810 584
7 3211.90 0.422 1355 0.1856 596
8 3197.44 0.422 1349 0.1902 608
9 3183.05 0.422 1343 0.1949 621
10 3168.73 0.422 1337 0.1998 633
11 3154.47 0.422 1331 0.2048 646
12 3140.28 0.422 1325 0.2099 659
13 3126.14 0.422 1319 0.2152 673
14 3112.08 0.422 1313 0.2206 686
15 3098.07 0.422 1307 0.2261 700
16 3084.13 0.422 1302 0.2317 715
17 3070.25 0.422 1296 0.2375 729
18 3056.44 0.422 1290 0.2435 744
19 3042.68 0.422 1284 0.2495 759
20 3028.99 0.422 1278 0.2558 775
21 3015.36 0 0 0.2622 791
22 3001.79 0 0 0.2687 807
23 2988.28 0 0 0.2755 823
24 2974.84 0 0 0.2823 840
25 2961.45 0 0 0.2894 857
26693 16996
* Evaluated assuming a loss of efficiency of photovoltaic modules of 0.45% per year.
** Evaluated by estimating an increase in the cost of energy by 2.5% on an annual basis.
Costs
With regard to costs, it is important to consider that the main items of expenditure to be addressed to achieve and maintain activity in the system are as follows:
1. cost of design and installation of the system,
2. insurance costs of the plant against damage, theft or interruptions in productivity (the annual cost of insurance can be evaluated in the order of 0.6% of the cost of construction of the plant),
3. Extraordinary maintenance costs.
In relation to item 3, it is good to keep in mind that, although the plants do not require service of households, by type and size, special routine maintenance, compared with a useful life of 25-30 years, 'inverter has a life of 10-15 years, therefore, during the period of operation of the system will need to replace this component at least once.
17/09/2010
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Translated via software
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Source:
Italian version of CercaGeometra.it