How to design an optimal solar PV system

Roll up your sleeves and learn how to design an optimal solar PV system. Get a perfect project layout easily with pvDesign.

Gabriel Cañadas

9 Sep, 20 / UPDATED 14 Apr, 21

pvDesign is a tool that allows you to optimize your solar pv designs quickly and efficiently. In the last few months, we have implemented some game-changing innovations which have helped shorten the simulation time and improved the structure grouping algorithm. These new parameters will help you make sure that your site is completely filled with structures to the most optimal design configuration.

In RatedPower, our aim has always been to ease and simplify the work of solar PV engineers through the automation of all the different tasks they perform on a daily basis.

Since the start, our goal was for pvDesign’s algorithm to focus greatly on certain aspects of the design of a PV plant. These include the automatic positioning of structures, roads, power stations, cables, and so on. Other important aspects are the calculation of cable cross-sections in accordance with different electrical standards, the energy production calculation, the design of the substation engineering, and the generation of all the necessary documents and drawings related to each design.

This algorithm has always been and keeps being in a constant process of evolution. With our latest blog post, we hope to shed light on some of the latest developments that the layout algorithm has experienced and to provide advice on how to optimize your design.

So, buckle up and enjoy the ride!

Structure Grouping Algorithm

We have centered our attention immensely on the structure grouping algorithm. This implies giving so much importance to how the different blocks of structures connected to a string box or to a power station are defined.

With such a goal in mind, we have implemented a new update to our algorithm that tries to ensure a more regular shape for these blocks while avoiding the creation of any stretched out blocks or any blocks being divided between far areas in the case of complex sites. This also resulted in an improvement to the positioning of these blocks, which are now more centered with respect to the roads, thus saving up on low voltage cables.

This process used to take an average of approximately 66 seconds with the old version of the algorithm and has now been cut down to 0.6 seconds, lowering the p95 of the complete simulations’ duration from 2 minutes to slightly over a minute.

This time reduction makes pvDesign’s iterative process even more simple and quick despite the great level of detail that its simulations provide.

Layout Parameters and Optimization

Our team has also added some new layout parameters with which you, our user, can play a bit and see how they affect the final output for the layout. Combining this with pvDesign’s quick process of creating different iterations of the same simulation, you can reach an optimal design within a short period of time.

This section should help you understand how these parameters affect the layout for you to get the best use out of them.

Roads

There are currently four road options in pvDesign:

  • Horizontal roads: this option draws horizontal roads that end at the power stations.
  • Horizontal with perimetral roads: this option draws horizontal roads that connect to the perimeter and a perimetral road around each available area.
  • Vertical roads: this option draws vertical roads that end at the power stations.
  • Vertical with perimetral roads: this option draws vertical roads that connect to the perimeter and a perimetral road around each available area.

Based on the needs of your PV plant, you can select one of the above options. The two possibilities without perimetral roads install PV modules all the way till the border of your parcel thus allowing you to install more total capacity.

Perimeter

Here, you can opt between 2 options:

This parameter gives you the option to decide between a linear uniform positioning of the structures or adapting your structures to the parcel’s border, which could help increase its total capacity at the expense of it being more irregular and thus more complex to construct.

Your choice of horizontal or vertical roads will affect this parameter because this border adaptation will only take effect when said roads are parallel to your structures’ axes. This would be when vertical roads are used with trackers or when horizontal roads are simulated with fixed structures.

Power stations

You can select one of two options for the positioning of your parcel’s power stations.

Placing the power station inside the DC field will take out a structure from the block connected to it but will result in shorter distances between structures and thus more total installed capacity.

Structure position

Here you can opt to rotate or offset your parcel, thus optimizing the layout with respect to the parcel’s borders.

You have four options to choose from:

  • Layout standard: structures follow their usual axis direction.
  • Layout rotated: structures are rotated in blocks.
  • Layout offset: rotates the axis of the block while keeping the structures aligned.
  • Layout Turning angle axis: structures are rotated while keeping the block aligned.

In the case of linked-row trackers, the last two options are not available.

Layout Configuration

You also have the following options for configuring your layout:

  • Regular blocks: this option defines a rectangular block of structures belonging to one power station and repeats it throughout the whole layout.
  • Adaptive design: this option defines smaller blocks made up of a few structures thus adapting much better to the irregularities of the site and resulting in more total installed capacity.

Once all the structures are installed, in the last two options, the Group Grids algorithm groups these small blocks into bigger ones corresponding to the different power stations and then allows for the definition of the low voltage cables.

The size of these blocks can be selected in the table of electrical configurations.

DC/AC Ratio

The table of electrical configurations allows you to define the Ratio of DC/AC which depends on the PV module, the inverter, and the structure that you have chosen. It also depends on the number of strings per structure, per string box or inverter, and on the respective size of the block of structures.

This table will give you thirty different electrical configurations while taking the above parameters into consideration. You will only have to select one of them. The order in which they are shown takes into account the ideal DC/AC ratio and the number of strings per box that you have previously defined and places the closest ones to them at the top.

The preview tab will show you, in red, the zones or portions where your selected inverter cannot be installed due to the available DC field being too small. In the following image, you can observe how a small change in the DC/AC ratio of an inverter can achieve a much better filling of your PV plant.

Using Secondary Inverters

Another option to consider, when trying to fill in those last portions where the chosen inverter cannot fit in, is to utilize a secondary inverter with a smaller size.

This option will allow you to use the same inverter with different DC/AC ratios, thus permitting you to reach more flexible electrical configurations.

What you should do now

Whenever you’re ready, here are 4 ways we can help you grow your solar business and reduce LCOE of your PV plants.

  1. Get hands-on with a free pvDesign demo. If you’d like to learn the ins and outs of how top photovoltaic software can help your engineering team, go ahead and request your free demo. One of our solar experts will understand your current design and engineering workflows, and then suggest practical tips on how to speed up them though the right tool.
  2. If you’d like to learn insights, ideas and inspiration for the low-carbon energy transition for free, go to our blog or visit our resources section, where you can download guides, templates and checklists solar successful pros use.
  3. If you’d like to work with other passionate experts on our team, or learn more about our purpose and corporate values, then see our Careers page.
  4. If you know another solar designer, developer or engineer who’d enjoy reading this page, share it with them via email, LinkedIn or Twitter.

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Gabriel Cañadas

Business developer

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