Electronics design for PV systems

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Linda Liu offers some PCB design tips for photovoltaic systems

When designing photovoltaic electronics for outdoor use, durability, performance and energy efficiency are the essential factors you should consider. Every designer dreams of balancing these three factors, but how can that be achieved?

The way you design your PCB layout significantly determines the photovoltaic systems’ functionality, efficiency and durability. Innovative concepts integrated into the design at the layout phase can dramatically improve the manufacturability of photovoltaic products.

PCB design tips

Involve your PCB manufacturer earlier in the design

Ensure you inform your preferred PCB manufacturer early about your solar panel project. Partner with a PCB manufacturer that has rich experience in the electronic industry and can assist in solving issues that are unseen from a designer’s point of view. Failure to detect and solve minor issues from the initial development stages can lead to costly long-term hitches that may hinder the production, performance, and certification processes.

Take into account the efficiency of the photovoltaic system

Basically, the energy efficiency of small photovoltaic devices is influenced by various factors, such as the type of panel used. Studies have shown that monocrystalline photovoltaic systems are more effective than thin films or polycrystalline panels. It is advisable to confirm the efficiency of your solar panel before designing your circuit board. 

Check the battery and panel sizes

A photovoltaic device designed to function continuously requires a battery backup system. An important point to remember when creating your circuit board for photovoltaic systems is the working duration of the system when the solar panel power source drops to 0% efficiency.

Various environmental factors affect the photovoltaic system’s performance. Therefore, you require a battery with adequate capacity to sustain the functioning of your system for an extended period. After determining your system’s power needs, you can estimate the right photovoltaic system and battery sizing through: the highest number of successive dark days will help you figure out the battery capacity your system needs; and the she smallest number of sunny days will help you figure out the solar panel size you require to recharge the battery and power the system.

Evaluate the need for power-intensive modules

Some applications such as thermal printers, WiFi, and GSM require power-intensive modules. When designing PCBs for such use cases, try to comprehend and estimate the power usage of the module precisely. Evaluating the requirement for power-intensive modules will enable you to find out the power you need to operate your photovoltaic system faultlessly.

Consider firmware architecture

Ensure you find the appropriate firmware structure that regulates the microcontroller to “deep sleep” mode when it is not working. The right firmware design will help your photovoltaic system to work for an extended period during cloudy days.

A correct design should offer a distinct power channel to logistics and marginal unified circuits regulated by a microcontroller. This will inhibit unnecessary power use when the system is not working.  

Create a corrosion-resistant box

Photovoltaic electronics are mostly mounted in the open air. Therefore, put temperature control measures in the box to certify all photovoltaic devices inside to handle high/low temperatures. The rule of the thumb is building a corrosion-resistant box to protect against extreme environmental conditions like snow, hurricanes, and drastic temperature changes.

Create a faultless current flow

During the circuit board design process, build an appropriate width to streamline the flow of current. Generally, you can use different online calculators to establish the optimal line width for good current transmission. Selecting the correct line width that facilitates easy current flow is a good way of maximising the layout efficiency. It is also suitable for the systems’ optimal energy efficiency.

Additionally, create distinct wiring directions for any consecutive layers when designing your layout. For instance, if you apply horizontal wiring on one layer, use vertical wiring for the second layer.

Have the right PCB component sizes

Selecting undersized components during the designing stage will, beyond doubt, affect the equipment’s manufacturability process. If your PCB contains adequate space, use more extensive parts to improve the device’s manufacturability. Basically, you should invest more time and resources in the initial design stages to warrant a quick production with minimal defects.

Go lean

A lean photovoltaic design eventually results in a minimal requirement for engineering, quality testing, processing, handling, and stock management. Fewer components also imply minimal expenses and assembling time.

Complicated circuit designs such as those applying surface mount technology (SMT) on both sides can be expensive. Likewise, avoid creating through-holes on both sides unless you can’t do without them.

Select an appropriate surface finish

Choosing a suitable surface finish is a crucial factor in the circuit board design process. An ideal surface should prevent the circuitry from corrosion and offer a solderable anchor area for mounting components. When selecting your PCB surface, consider:

●          The parts you are using

●          Your estimated production volume

●          Durability requirements

●          Environmental impact and cost

One of the surface finishes you should avoid is the RoHS-compliant hot air solder levelling (HASL) method. While HASLE is a standard surface finish method, it wipes out solder on the photovoltaic circuit board.

The recommended surface finish method is the electroless nickel immersion gold (ENIG). This method is cheap and effective for most circuit board designs. Besides, it is flat and easier to solder than other surface finish methods. Still, most PCB manufacturers can store ENIG in their stores safely, saving production time and expenses.

Space your layout well

The location of parts in your circuit design layout is an essential aspect. Positioning parts closer to the edges can hinder the efficiency and durability of your solar panel. Ceramic capacitors seem to crack more when located on the borders. Additionally, parts that are located close to the edge display low performance. Wiring such parts is challenging and can lead to defects that may hinder the general system performance. Therefore, place a route around any component close to the edge and along with the PCB layout.

Conclusion

Photovoltaic system design for manufacturability will build your electronics faster, easier, and more proficiently. Partnering with a reputable PCB manufacturer in the initial stages of your product design will streamline and enhance the whole production process.

Linda Liu is with MKTPCB

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