{"id":118842,"date":"2020-11-12T08:48:20","date_gmt":"2020-11-12T07:48:20","guid":{"rendered":"https:\/\/www.sma-sunny.com\/?p=118842"},"modified":"2020-11-16T08:37:55","modified_gmt":"2020-11-16T07:37:55","slug":"how-to-design-east-west-polystring-pv-arrays","status":"publish","type":"post","link":"https:\/\/www.sma-sunny.com\/en\/how-to-design-east-west-polystring-pv-arrays\/","title":{"rendered":"How to design East\/West polystring PV arrays"},"content":{"rendered":"

Have you ever heard about polystrings? Did you know that PV plants with this special plant design benefit from more energy yield over the course of the day? Sunny Design Web will help you easily design a polystring PV Array. Find out all you need to know about this key but often overlooked feature. <\/strong><\/p>\n

Imagine a scenario with limited roof space. The PV system designer may want to maximise the number of modules used. For sites in the Southern Hemisphere, this could mean PV modules are placed on North, East and West orientated roofs. Below is an example of what would be entered into Sunny Design.<\/p>\n

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Fig 1. Screenshot from Sunny Design Web<\/p><\/div>\n

In this scenario, it may appear that two Sunny Boy Inverters must be used (e.g. two SB3.0-1AV-41), since each inverter has two MPPTs. However, as a benefit of polystrings, the need for a second inverter can be eliminated. This will significantly reduce costs whilst achieving a similar annual energy yield (see figure 2).<\/p>\n

What does polystrings mean?<\/h2>\n

The installation of polystrings means that two different PV arrays (same type of PV modules but with different orientations) can be connected in parallel at one common MPPT.<\/p>\n

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Fig 2. Screenshot from Sunny Design (Note: to compare the two alternative designs in Sunny Design , use the tabs on the top right corner of the PV system section labelled \u2018add alternative\u2019 and \u2018compare alternatives\u2019).<\/p><\/div>\n

As an added benefit, systems with only one PV inverter can be export-controlled more easily and cost-effectively via the use of the SMA Energy Meter.<\/p>\n

Visual Roof Planning<\/h2>\n

When configuring the PV arrays for the system design, Sunny Design\u2019s visual roof planning tool may be a preferred alternative to the manual planning option shown in Figure 1. It provides a more visual solution and allows the installer to precisely layout modules and plan around obstacles such as chimneys and skylights. It also allows for the design to be traced around specific roofing locations by using Google satellite images.<\/p>\n

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Fig 3. Screenshot from Sunny Design Web<\/p><\/div>\n

How to find and apply Polystrings in Sunny Design?<\/h2>\n
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Fig 4. Screenshot from Sunny Design Web<\/p><\/div>\n

1. In the PV system design section of the project, click on the tile shown below to configure the strings connected to the inverter.<\/p>\n

2. This will then take you to a tab in which you can configure strings as shown below.<\/p>\n

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Fig 5. Screenshot from Sunny Design Web<\/p><\/div>\n

3. Click \u201cConnect an additional PV array to the input (Polystring)\u201d (highlighted in Fig 4) to add in a Polystring on MPPT A. Sunny Design Web automatically inputs the same number of modules on both polystrings. Additionally, click on the \u201ci” symbol for more information on connecting polystrings.<\/p>\n

4. After applying the polystring, you can check whether the inverter is compatible with the design choices.<\/p>\n

Restrictions on Polystrings (Australia\/New Zealand)<\/h2>\n

Polystrings are generally allowed in Australia\/NZ so long as other requirements in the standard are followed. The most essential clauses from AS\/NZS 5033:2014 related to polystrings are paraphrased below. It is important that you directly consult the standard holistically before making any design and installation decisions.<\/p>\n