Basic considerations for photovoltaic water pump system selection

Basic considerations for photovoltaic water pump system selection

Choosing the right solar water pump system for your home or farm requires more than just product power and price. Correct selection requires a comprehensive assessment of core factors such as water demand, solar resources and water source conditions to ensure cost-effective and long-term stable operation of the system.

1. Clarify water needs and working conditions

This is the basis of all selection calculations and must be quantified first.

Determine the total head: This is the total height difference that the pump needs to overcome. Includes:

Vertical lifting height: the vertical distance from the water surface to the highest point of the water outlet.

Pipeline friction loss: the pressure lost due to friction when water flows through pipes, elbows, and valves, usually estimated at 10%-25% of the vertical lift (the longer, thinner the pipeline, and the more elbows, the greater the loss).

The formula is simplified: total lift ≈ vertical lift × (1.1 ~ 1.25).

Determine daily water consumption: Based on the irrigated area, crop water demand or household daily consumption, calculate the average number of tons (or cubic meters) of water needed to be pumped every day.

Confirm the water source: is it a deep well, river, pond or tank? This determines the pump type (submersible or surface pump) and whether the sustainability of the water source needs to be considered (whether it will dry out).

2. Assess local solar resources

Solar energy is the only source of power for the system, and its strength directly determines the system scale and investment.

Query key data: Get the local “annual peak sunshine hours” (can be queried through meteorological data or professional apps). This value represents the abundance of local solar resources and is a key input in calculating the required photovoltaic panel power.

On-site survey of the installation location: The location where you plan to install solar panels must ensure that there are no shadows from trees, buildings, etc. during the main hours of the day (especially 9 am to 3 pm). The best orientation is due south.

3. Matching and Selection of System Core Components

Based on the above two points, match key components.

Water pump selection:

Type selection: Submersible pumps are suitable for pumping water from deep wells or directly from deep water sources; surface pumps such as centrifugal pumps are suitable for pumping or pressurizing water from water sources above the water surface (such as rivers, reservoirs).

Lift and flow: The selected water pump must be able to provide the flow required to meet daily water consumption under the total lift. Look at the water pump's "Performance Curve" to make a match.

Determination of solar panel power:

The total power of photovoltaic panels required is determined by daily water consumption, total head and local sunshine conditions. A simplified logic is: under the same water demand, the worse the sunshine conditions, the greater the power of the solar panels required to ensure that the water pumping task can be completed on days with average sunshine.

It is recommended to reserve 10%-20% margin for power to compensate for photovoltaic panel aging, dust coverage and line loss.

Controller selection:

A dedicated photovoltaic water pump controller must be selected, which can efficiently drive the DC power from the solar panel directly to the water pump and has a maximum power point tracking function to maximize the use of sunlight.

For occasions where stable water pressure or flow is required, a controller with frequency conversion function can be selected.

Energy storage and water supply methods (key recommendations):

It is highly recommended to configure a water reservoir or water tower. The system pumps and stores water during the day when there is sunlight, and draws water from the pool at night or when water is needed. This perfectly solves the contradiction between "pumping water only when the sun shines" and "all-weather water demand". It is the most effective way to ensure water convenience and reduce system complexity and cost.

Summary: Start from needs and match with data

The successful selection path is: first calculate "how much water is needed and how high it is" (demand and working conditions), then find out "how much sun" (resources), and finally match the water pump power and photovoltaic panel power based on this. Be sure to provide your calculated head, daily water consumption and local sunshine data to the professional supplier and ask them to assist in accurate configuration. Remember, a system with water storage facilities and a slight margin is far more reliable and durable than a system that is "stuck" at the theoretical limit.