Project Planning

Ensuring feasibilty

During operation, comprehensive monitoring and short reaction times in the event of failures result in a short payback period.
Photo: Tom Baerwald/Belectric Trading GmbH

Good and thorough preparation by experienced planners can make or break a large solar park project. Owing to the size of the project, neglecting small points may soon lead to large quantities of money being lost. Careful planning does not only concern the assessment of yields and capacity or building permits. Other significant factors that determine the success of a project include on-site support, grid access inspection and certification of the feed-in management system.

Performance ratio

The inverters’ design has a considerable influence on the plant’s profitability.
Photo: Tom Baerwald/Belectric Trading GmbH

The ratio of actually generated power to the theoretical yield in a certain location is decribed by the performance ratio (PR). It serves as a measure of plant efficiency for evaluating different plants in different locations Top priority is being given to optimizing a plant’s PR when operating in profitable conditions. Excellent PR values amount to between 80 and 83 percent (for crystalline silicon solar modules) or between 82 and 85 percent (for thin-film solar modules).

Based on the values for a 1 MW PV plant in the south of the USA (PPA: 0.2 US dollars/kWh, specific yield: 1,800 Wh/ Wpeak, performance ratio 80 percent), an increase of ten percentage points in PR will earn an additional 396,000 US dollars annually.

Comparable calculations can be made for Germany. For instance, a PV power plant with a peak output of 1 MW, connected to the grid at the beginning of 2010 with a PR of 75 percent, would produce 863 MWh of electricity each year. Increasing the PR by ten percentage points to 82.5 percent by optimizing the system components would represent a total of 949 MWh. At a remuneration tariff of 13.5 euro cents per kWh, this would yield increased profits totaling 232,200 euros.

Expert opinion

Monitoring devices are another way of monitoring and analyzing the various inverters within a plant.
Photo: Tom Baerwald/Liebherz

Planning always starts with a survey to help determine what the solar yield, the foundations, the best modules, inverters and mounting technology will be. If the installation is planned on a former military or brownfield site, extensive preparatory work is needed to remove any ammunition or hazardous substances that may be present. Ensuring that the land is safe has top priority. Yields from the PV plant must be able to cover the purchase price or the rent for the land.

Certification of feed-in management systems

Before a solar farm can be connected to the grid, the future operators or project developers must submit a certificate issued by an authorized, independent test institute. This confirms that the plant technology complies with all technical specifications and grid-feed management guidelines issued by the German Association of Energy and Water Industries (BDEW ). Other important documents must also be submitted, the installation must be simulated and an expert report must be commissioned. The whole procedure lasts several weeks.

Grid authorities in China impose strict regulations on plant operators, who must provide proof that these have been met (inverter certification). Stringent requirements are also laid down in the USA. For example, inverters must be able to recognize when subgrids continue to operate independently despite higher grid levels being shut down and maintain the voltage. This can happen when generation and consumption are equally balanced in the subgrid (active islanding). Solar power plants must prevent this from happening.

How to start a project – Some important questions

Assessment of yield and capacity

  • Which technology is necessary to achieve the highest possible yield?
  • What is the module area required?
  • Is it possible that additional shading from new buildings or plant growth will occur at a later point in time?

Local support

  • Will the project be supported by representatives from local government and the local community?
  • How can skeptics be won over?

Building permits, development plans and compliance testing

  • Has planning and building permission been granted?
  • Does the land development plan permit the installation of a photovoltaic plant?
  • Does the project conform to the national feed-in requirements?

Grid connection testing

  • Is a suitable grid connection terminal available on site?
  • How long will it take to obtain grid-related information and to process the application?


Early involvement of utilities

The greater the level at which photovoltaic capacity is expanded, the more important it is for grid feed-in to be controlled precisely, especially in terms of large-scale solar parks.
Photo: Tom Baerwald/Belectric

Rough technical planning is followed by submitting the feed-in application to the local utility. This has the purpose of determining the location of the entry point and whether it will actually be possible to feed the projected yield into the grid. Involving grid operators in planning at as early a stage as possible is therefore a must. If it is later discovered that additional investment is needed for grid feed-in, this can become very costly and jeopardize the entire project. If there are several possible entry points, the most cost-efficient point will be selected – no matter which part of the costs must be paid for by the plant investor, and which by the utility. The basic principle is: Grid connection costs must be borne by the investor, grid development costs by the utility. The utility also sets specific parameters for keeping the grid stable when power is fed in. The sooner grid operators are involved in the planning process, the quicker and more smoothly different connection scenarios, and the costs associated with them, can be investigated to find the optimum solution.

A word on logistics

The turnkey implementation of large PV installations poses great logistical challenges to project planners.
Photo: Tom Baerwald/Parabel AG

Solar parks are complex building sites covering a large surface area. Transport logistics for modules alone requires careful planning. Crystalline modules, for example, are delivered in containers of 500 each (appr. 100 kW). A solar park with a capacity of 25 MW requires around 250 containers which can only be moved using designated lifting equipment (cranes, forklift trucks, etc.). Just-in-time delivery is vital to avoid costs for idle periods. The handling of modules – especially frameless modules – in particular calls for extreme care so as to avoid breakage or damage.

Monitoring systems increase the lifetime of solar plants and allow malfunctions to be detected promptly.
Photo: Tom Baerwald/Skytron Energy GmbH


The operation of a solar park also necessitates great care. First of all, the smooth running of the plant must be ensured to avoid any interruptions. A sophisticated plant monitoring system will document operation, providing the basis for quarterly reports to investors and helping to identify the causes of any shortfalls. Faults at the entry point or the inverter are particularly critical, and engineers must respond quickly to minimize any yield losses. Since modern inverters provide remote monitoring options, faults do not always require a trip to the site.

Regularly checking plants on site is essential.
Photo: Tom Baerwald

Regular checks

PV plants in the MW range also require regular checks by staff. Regular visual checks, on-site thermal imaging, remote monitoring of strings and inverters as well as the evaluation and storage of data are indispensable. Operation and maintenance costs account for between three and five percent of the solar yield. If well planned and executed, they can increase the yield by a significant amount. To enable inspections to be carried out in a single day, it can make sense to employ helicopters or service drones.

Protection against theft

Theft protection provided by video monitoring
Photo: Tom Baerwald/Skytron

Ground-mounted systems need to be protected from theft and vandalism, the minimum requirements being a fence with climb-over protection and a secured access gate. Video monitoring and microwave or infrared sensor barriers with alarms via cable or radio complete the security concept. Of course, costs and benefits must be weighed up against each other in each individual case. Investment in such equipment will have paid for itself if it prevents just one occurrence of large-scale module theft. In the event of such theft, not only components are lost; consequential damage to the electrical system is common, as are significant yield losses. If such occurrences become frequent, there is a risk that insurance cover will be withdrawn, meaning that the investment will no longer be protected. At the very least, costs will be incurred to fit expensive anti-theft systems or employ additional security staff.