Short answer
At an irrigation well that has an electricity subscription, the panels can be connected to the grid. In this case, the electricity produced during the day goes to the pump first, and the surplus is fed to the grid and netted against consumption. The time period on which the netting is based and how surplus production is valued are set by regulation; because the rules have changed in recent years, the current procedure is checked at the time of application.
How does a grid-connected system differ from a battery-backed or direct pump system?
On the Harran Plain you see two kinds of solar irrigation. In the first, the panels are connected directly to a pump drive and there is no grid; the pump runs while the sun is out and stops when the sun goes. In the second, the well already has an electricity subscription, and the panels are connected to this subscription through a grid inverter. This article describes the second case.
In a grid-connected system, the pump is supplied from the grid as usual. When the sun is out, the electricity produced by the panels takes the place of the power the pump draws. If the pump is not running or production is more than consumption, the energy flows to the grid and the meter records it separately. On a cloudy day, or when you irrigate at night, the pump keeps drawing from the grid and irrigation is not interrupted.
If your well has no subscription and bringing the line to the field is troublesome, a direct pump system may make more sense. If there is a subscription, a grid-connected system also makes it possible to use the production in the winter months.
What does netting mean?
Netting means comparing the energy you give to the grid with the energy you draw from the grid over a certain period, and issuing the bill according to this difference. The meter measures both ways: it records what you draw and what you give separately. The distribution company, Dicle EDAŞ in Şanlıurfa, calculates this data according to the procedure in the regulation.
The detail that affects the result most is the time period on which netting is based. There have been changes in the unlicensed generation regulation in recent years, and arrangements such as a move to an hourly basis have been introduced. In an hourly calculation, the energy you give at noon is not balanced one to one against the energy you draw at night; each hour is calculated on its own. This directly affects the size and the return of the system.
Which subscriber group, which installed capacity, and which connection date the rules apply to is a detailed matter. At the project stage, the current regulation is read and the calculation is made accordingly. For a detailed legal and financial interpretation, consult a specialist or the distribution company.
Expert note: Before installation, collect the last year's bills and, if possible, the hourly consumption data. The hours at which the pump runs show how large the system should be better than the monthly totals on the bill.
What are the panels for outside the irrigation season?
Cotton and corn irrigation peaks in summer, and in winter the pump does not run on most days. In a direct pump system, the electricity produced in these months is wasted. In a grid-connected system, winter production is fed to the grid and is used to the extent the regulation allows.
However, the credit for surplus production is not unlimited. There are regulations that limit the energy fed to the grid by tying it to consumption. For this reason, building the system as large as the space allows, without looking at the well's annual consumption, is not the right approach. The capacity is determined together with the real consumption and the connection conditions.
- 1Collect the bill and consumption data
- 2Check the well and subscription documents
- 3Apply to the distribution company
- 4Set the capacity according to the connection opinion
- 5Get the project approved and install it
- 6Meter replacement and acceptance
What is the size of the system based on?
The calculation starts with the pump's power and the annual consumption. The Agricultural irrigation option in the solar calculator on our site gives the approximate installed capacity from the monthly kWh value on the bill; for Şanlıurfa it assumes a production of about 1,600 kWh per year per kW. This is for a first idea; the exact value comes out on site.
The following information is clarified on site:
- That the subscriber group is registered as agricultural irrigation, and the subscription capacity
- The pump's nameplate power and the hours of the day at which it runs
- Monthly consumption for the last year and, if available, hourly consumption data
- The size of the area where the panels will be installed, the shading, and the ground structure
- Transformer and line capacity, that is, whether the connection opinion will come out positive
- That the well license and the water use permit are current
How does the application process go?
Every grid-connected system is installed through an application and connection process. You apply to the distribution company, and the company gives a connection opinion by looking at the capacity of the transformer and the line in the area. Then the project is prepared and approved, the installation is done, and the acceptance procedure is completed with the meter replacement.
Transformer capacity can be limited on rural lines. If other producers are connected to the same transformer, the connection opinion may come out for a low capacity or may be negative. For this reason, the panel order is not placed before the connection opinion is obtained.
A solar system does not complete the well's permits. A system installed on an unlicensed well causes problems at the application stage. If you gather your documents in one file before the site survey, the process goes more smoothly.
What should be watched when installing in the field?
In a field installation, the mounting structure is fixed to the ground with driven piles or concrete footings; which is suitable is chosen according to the soil structure. The lower edge of the panel is kept at a height where it does not touch splashing soil or grass. Because dust gets heavy during harvest and plowing periods, access to cleaning water is planned from the start.
The inverter and the panel board sit in a shaded, ventilated, and locked cabinet. In the noon heat of August, the temperature inside a board in the sun rises quickly and the inverter cuts its output. The site is surrounded with a fence, and cables are run through protected conduit where farm machinery passes. Because it is valuable equipment, a camera can also be considered in suitable places.
The most common mistakes
A common mistake is sizing the system by copying the installation in the neighboring field. If your neighbor's pump, well depth, and irrigation schedule are not the same as yours, the same capacity will not suit you. If the subscriber group or connection date differs between two fields, the netting rules may also be applied differently.
The second mistake is choosing the panel and inverter by looking only at the installed capacity. In the field, the inverter is exposed to dust, heat, and voltage fluctuations. On rural lines, when the grid voltage rises around noon, the inverter can cut production to protect itself. This is largely prevented with settings and the right cable cross-section, but only if it is taken into account at installation.
The third is forgetting maintenance. In a grid-connected system, because the pump runs even without sun, it becomes hard to notice that the panel is producing less. Have the monitoring app installed, and at the start of the season and the middle of the season compare production with the same month of last year.
Frequently asked
I have a subscription at my irrigation well; does my existing pump need to be replaced?
In a grid-connected system, the pump generally stays as it is, because it continues to be supplied from the grid. If the pump breaks down often or its power is much more than needed, replacing it is assessed separately.
Can I irrigate at night?
Yes. In a grid-connected system, the pump draws from the grid at night. How night consumption is netted against daytime production depends on the current netting procedure.
What happens if the connection opinion is negative?
Options such as applying for a lower capacity, a different connection point, or an off-grid pump system are assessed. Which of them is possible depends on the distribution company's response.
Let's calculate the right system for your well
Share your bills and well information; Desa Bilişim will inspect the site and prepare a written quote.
