Economic analysis of a photovoltaic system, with the determination of payback.

Enter data of the photovoltaic energy, then the data estimated cost of the plant, then Data eletrica bill. Verifying the results of operations in the graph and table. Repeat the data entry when you have more accurate and definitive.
System
Power KWp
Annual Energy KWh/y
% Decay
Cost
Initial cost
Cost €/KWp
Annual cost
Contribution
Contribution €/kWh
initial contribution
Annual contribution
Analysis period
Years contributions
Years analysis
Invoice
Consumption kWh/y
Cost €/kWh
Loan
% Mortgage
Annual bill
Annual installment
Result
Pay back [year,month]:
YTD Return:
Compound:

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year	flow	revenue		Prod.	Bill	Cost	Loan
0	-19000	0		0	0	0	0
1	-16423	2577		2324	353	-100	0
2	-13863	5137		4631	706	-200	0
3	-11319	7681		6922	1059	-300	0
4	-8790	10210		9197	1412	-400	0
5	-6278	12722		11457	1766	-500	0
6	-3781	15219		13700	2119	-600	0
7	-1301	17699		15928	2472	-700	0
8	1164	20164		18140	2825	-800	0
9	3614	22614		20337	3178	-900	0
10	6049	25049		22518	3531	-1000	0
11	8468	27468		24684	3884	-1100	0
12	10872	29872		26835	4237	-1200	0
13	13261	32261		28970	4590	-1300	0
14	15635	34635		31091	4943	-1400	0
15	17994	36994		33197	5297	-1500	0
16	20338	39338		35288	5650	-1600	0
17	22668	41668		37365	6003	-1700	0
18	24983	43983		39427	6356	-1800	0
19	27283	46283		41475	6709	-1900	0
20	29570	48570		43508	7062	-2000	0
21	29823	48823		43508	7415	-2100	0
22	30076	49076		43508	7768	-2200	0
23	30329	49329		43508	8121	-2300	0
24	30582	49582		43508	8474	-2400	0
25	30836	49836		43508	8828	-2500	0
26	31089	50089		43508	9181	-2600	0
27	31342	50342		43508	9534	-2700	0
28	31595	50595		43508	9887	-2800	0
29	31848	50848		43508	10240	-2900	0
30	32101	51101		43508	10593	-3000	0

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Contents

  Initial cost, Cost €/KWp

  Annual cost

  Power KWp

  Annual Energy KWh/y

  Contribution €/kWh

  initial contribution, Annual contribution

  Consumption kWh/y, Annual bill

  Cost €/kWh

  Years contributions, Years analysis

  % Decay

  % Mortgage, Annual installment

  Result

  Comment

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Initial cost, Cost €/KWp

Represents the value of the initial investment, then the cost of the turnkey.
This information should be provided by an estimate of a designer, because the value is affected by many factors (eg: cost of natural building, plant engineering, integration, bureaucratic, etc.)that only after a careful evaluation may provide a precise value.
To give a rough idea, we could say that the average value is around 6000 €/kWp.
This value should take into consideration the cost of replacing the inverter which has an average lifespan of 12-15 years and costs about 5-8% of the value of the plant.

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Annual cost

Represents the sum of all costs such as electric charge of the operator, maintenance, cleaning, insurance, etc.

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Power KWp

The nominal power in kWp of a photovoltaic system is given by the sum of the peak of the modules used,
this value is declared by the manufacturer and is measured in standard conditions, with irradiation constant 1kW per square meter in the plane of the panel, at a temperature (modul) of 25°C.

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Annual Energy KWh/y

The output of energy in a year (kWh/y), the correct value is the extent made by the electricity meter (after one year of operation).
An estimate may be made known: the maximum power rating, the angle of inclination of PV modules from a horizontal plane, the angle of orientation of PV modules by the south, and the coefficient of performance, which represents the fraction of the power supplied by panel which will be introduced into the power grid. The difference is caused by losses in the cables and inverter, but also from reduced performance due to temperature effects. For a facility with a PV inverter efficiency can reach a value of 0.8 (total reduction of 20%). For small systems or systems with a match modules/inverter less optimal can still expect a value from 0.7 to 0.75.

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Contribution €/kWh

Contribution €/kWh

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initial contribution, Annual contribution

The contribution is a part that is paid from grants from municipalities, regions or nations that seek to fund the dissemination of photovoltaic energy. This contribution can be in a single installment or in annual installments.

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Consumption kWh/y, Annual bill

The annual energy consumption in kWh/y, is the amount of energy transferred from the distributor last year, can be derived by consulting the current bill and the previous year.

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Cost €/kWh

Represents the average cost for KWh of electricity charged by the operator, can be calculated by dividing the annual expenditure on consumption of energy for energy consumption for the same year.

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Years contributions, Years analysis

Years contributions represents the period in which the owner of the photovoltaic system will have a contribution to the energy produced, while the years of analysis represents the total period over which economic analysis is made.

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% Decay

The decay of the photovoltaic system did not yield a clear trend, in the first 2 years of the decade at most 2-3%, for the next 8 years maximum of 0.7% and then a maximum of 0.5%.
There are other factors that affect these values, first of all the material of photovoltaic panels, the monocrystalline silicon has lower values (about 0.1%) over the polysilicon, which in turn has lower values than the amorphous panels. Other factors are: the weather, the installation site, and type of installation.
The average life of a good solar cell is guaranteed for at least 25 years (with a decline below 80%), but can reach over 40 years.
The average values of decay ranging from 0.6% to a maximum of 1.1%, of course should be assessed all the factors that shaped him.

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% Mortgage, Annual installment

If you choose a loan or mortgage, for the purchase of the plant is necessary to include the interest of the funding.
The annual installment will be calculated assuming that the funding will last throughout the period of the incentives and covering the full amount of the plant.

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Result

Back to the time required to recover the initial investment (taking into consideration of all the annual expenses) is expressed in years and months.
The return on investment as interest is calculated using the expression of interest seplice:
interest = (Final capital - initial investment) / initial investment / years of analysis * 100
and a compound, which is the constant interest of an investment each year and is capitalized at the end of the period of analysis returns the same Final capital.

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