The client who was working for the energy department of a power company in the US requested us for making a feasibility study for installation of a 3MW solar PV power system at a given location in the state of California and making a complete report on the project and all its aspects such as cost-effectiveness, environmental impacts, needed accessories such as implementation of PV cleaning system, etc. The report was to be delivered to the board of directors of his company to decide on it. The request included:
- Field calculation of the area for installation of the solar power plant
- Choice of quality and durable, yet cost-effective PV panels
- Sourcing other components such as inverters, transformers, MPPT charge controllers, phase digital power meters, smart grid requirements, etc. for a good solution
- Compatibility of the plan with the state of California electrical code
Considering the large area of the land under consideration, the following issues had to be carefully resolved.
- Analysis of the area and how the area under the installation could be shrunk.
- Finding the most efficient while cost-effective solution with all the components
After carefully reviewing the field, an initial design was worked out and simulated by different simulation software such as RETScreen, HOMER energy software, and PVS. For the input data, online NASA Surface meteorology and Solar Energy data was used and based on the results of the simulations, different options were compared to find the optimum solution. In order to find the best solution many parameters were to be considered including,
- Highest energy output and monthly power production of the system
- Ambient temperature impacts on the efficiency of PV cells
- Ideal Components to be used (considering the quality, lifetime and cost)
- Cost estimation and economic performance of the optimal solution considering such financial parameters as,
- Inflation rate
- Annual cash flow
- Incentive and grants in the state of CA
- The annual income of the design
- Cumulative cash flow of the project during its lifetime
- The final return on the investment and the payback time
- Infrastructure changes and its cost (making roads, water supplies, …)
Based on the above analysis, the optimal solution was proposed. Some of the main features of the final solution were the followings
- Using 250W PV solar panels
- Panel arrangement for every one MW unit consisting of 100 Parallel rows with each row containing 20 double panels in series
- Total plant area: 50,000 m2 including:
- Power plant area for just modules: 30,000 m2
- Area between the modules for the maintenance roads and concrete bases of the grids, transformers and etc: 20,000 m2
Upon the request of the client regarding the cost of the design, aside from using such solar design software as RETScreen and HOMER that are powerful tools for such calculations, a research on the capital cost of grid-connected PV cells in different countries was made. Some of the main points of the final report were the following
- As a guide, the typical installation cost of a PV power plant in the USA in mid-2010 (excluding tax) ranged from about $9,000 for a 1 kWp domestic system ($9 per Wp) to about $2.2 million for a 500 kWp utility-scale system ($4.4 per Wp).
- The PV solar panels accounted for just over half of this cost, and the inverter, frame, wiring, and labor for the rest. The costs had decreased substantially over the past three decades.
- Although the mentioned cost calculations for a 3MW power plant was amounted to about $13 million; however, due to the falling cost of the construction of solar power plants in recent years, the final cost excluding the price of the occupied land was calculated to be approximately $5 million. This figure included 10% of total costs for such issues as payment to the project employees, commissioning consumables, infrastructure such as power cables and logistical services, and so on.
- The research also indicated that the Total costs for a European solar PV plant average around $1.7 million per MW.
- After carefully choosing the components for the design, the following table showing the detailed costs of the components was offered to the client.
The relation between costs of a PV power system to the corresponding cost of produced electricity depends on a number of factors. One major factor is the local solar irradiance in the location under consideration. For example, a 1 kWp PV system on a South-facing roof in the UK supplies about 800 kWh/year of AC electricity (20% of average UK household electricity use), compared to about 1,700 kWh/year in the state of California.
Another major factor is how the system is financed. For California, assuming 5% interest and 20-year payback time, the above-mentioned utility-scale PV system the generated electricity contributes to about 19 cents/kWh, and the domestic system at about 39 cents/kWh.
Also, when the installation is completed, the annual income of a 3MW PV power plant would be about $1,000,000.
In addition to the installation costs, there are also maintenance costs associated with a solar PV installation. These costs include such items as
1.PV cleaning cost.
Every solar PV power systems should be cleaned for at least twice a year to ensure their efficient working
2.Inverter replacing cost
Although solar panels have a typical lifetime of 20+ years, the inverters’ lifespan is about 10 years. The cost of maintenance and replacement of inverters is normally about 10 percent of the total income.