Correctly connecting PV modules in series for the S1-700 system is essential not only to ensure proper installation and optimal pump performance but also to prevent damage to the controller.

Before we explain how to make series connections, here’s a quick and easy way to make sure you don’t exceed the controller’s maximum voltage rating:

Identify the Voc (open circuit voltage) of your PV module:

You’ll find this value on the label of the solar panel. Example:

For the S1-700 system, let’s use a 330 W PV module. On the label, the Voc is listed as 45.6 V (See the picture below)

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Add the Voc values of the PV modules you intend to connect in series:

Make sure the total does not exceed 220 V.

Recommendation:

For the S1-700, we recommend connecting at least three (3) 330 W PV modules in series. This ensures two important things:

• The total Voc remains safely below the 220 V limit.
• The system meets the minimum Vmp (voltage at maximum power) requirement of more than 85 V DC, which ensures optimal pump performance.

Read more information here:

• Required solar power input

Important: In this example, you must not connect more than five (5) PV modules in series. Doing so would exceed the controller's voltage limit and may result in permanent damage to the S1-700 controller.

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By connecting PV modules in series, you increase the total voltage of your PV system while the current remains the same.

To make the series connection, connect the positive (male) cable of one PV module to the negative (female) cable of the next module (as shown in the image below). Be careful not to exceed the maximum input voltage allowed by the controller (refer to the three steps outlined at the beginning of this article). Exceeding the controller’s voltage limit may result in permanent damage.

In this example, we use three (3) PV modules of 330 W each. Because they are connected in series, their voltages are added together, while the current stays constant.

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Important: We recommend using a properly sized DC disconnect switch for the PV generator. The switch must be installed between the PV generator and the controller. For more information, please refer to the following article:

As shown in the previous example using 330 W panels, we recommend using at least three PV modules connected in series for the S1-700 system. However, the minimum number of panels required depends on the size and electrical specifications of each module, especially the Vmp (voltage at maximum power). The key requirement is that the total Vmp of the series connection must be higher than 85 V DC to ensure proper operation and good performance of the pump.

If you are using larger PV modules, and the combined Vmp of fewer than three (3) panels still exceeds 85 V DC, then this configuration may also be suitable.

Always check the specifications of your PV modules and ensure that the total Voc does not exceed 220 V, which is the maximum allowed input voltage for the S1-700 controller.

Read more information here:

Technically, it is possible to connect PV modules in parallel. However, for the S1-700 system, we do not recommend using parallel connections.

Series connection is sufficient to meet both the voltage and power requirements of the system. Adding a parallel connection would only increase costs without improving performance.

Therefore, for optimal and cost-effective operation, we recommend connecting PV modules in series only.