Solar cell optimisers: what are they? How do they work?

Solar panels in an electricity producing system are usually connected in a string of series-connected panels. This may carry a risk of system output underperformance when, for example, shading on one or more of the panels results in lower power production in the specific panel, and  also as the panels are connected in a string, the rest of the panels in the string, potentially the entire solar PV system.

You can think of it as a water hose - even a small knot stops the flow of water across the whole hose. In other words, it is the weakest link in the string that determines how much current the other panels can produce;a little shade on one panel risks the output of the whole system which becomes quite a big problem!

To avoid this issue, we recommend installing optimisers on the shaded panels (i.e., the weakest links). An optimiser is a device that helps optimise the output of the panel it is installed on by bypassing current around a subperforming panel so the whole system is not affected. In this article, we will take a closer look at optimisers and how they operate.

Specifically, we will focus on the following sections:

• How do solar optimisers work
• The difference between optimisers and inverters
• The different type of solar optimisers 
• Solar optimisers brands we work with at Otovo
• Frequently Asked Questions

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How do solar optimisers work

An optimiser is a small box (DC-DC converter) which is mounted on the back of the panel so it is hidden from plain view. The way a solar panel optimiser works is by using Maximum Power Point Tracking (MPPT) technology. Every solar panel has a point during the day (“maximum power point”) where it generates the most electricity. This point may vary due to external factors such as climate and shading which impact panel efficiency.

Using an optimiser ensures that the panel continues to operate to the potential of the maximum power point. Moreover, an optimiser ensures that the other panels in the system aren’t negatively impacted and can continue to operate in the peak output.

Quick facts - benefits of power optimisers:

• You only need to install optimisers on the panels that are shaded from, for example, chimneys, aerials or trees.
• An optimiser maximizes the power production from each individual solar panel it is mounted on.
• Where ordinary solar systems require that you have no shade on the panels, by using optimisers you can have solar panels mounted in different directions, if you have a complex roof.
• If all solar panels are connected with optimisers, you can monitor the performance of each individual solar panel in real time.

The difference between optimisers and inverters

A common confusion among consumers is with regards the difference between an optimiser and an inverter. In fact, it can be argued that optimisers take over a part of the inverter’s tasks. In a system without an optimiser, it is the inverter’s built-in MPPT that keeps strings apart so that these strings can produce power independently of each other. This is key, especially, if you have strings of series-connected solar panels on different parts of the roof.

However, when it comes to performing this task, an optimiser actually does a better job, especially if you have a roof with many angles or have varying shading conditions during the day.  Also, it is important to remember that even in a solar panel system with optimisers for the solar panels, having an inverter in the system is vital as the inverter’s main function is to convert the energy generated by solar panels, which comes in the form of direct current (DC), into usable electricity for the home or business, which is in the form of alternating current (AC). 

Different types of solar optimisers

There are three main types of solar optimisers:

• DC optimisers
• Smart solar panels
• Microinverters

DC optimisers, de-facto, operate as mini power stations responsible for optimising DC electricity from the solar panel it is installed on before it is converted to AC electricity. Further, DC optimisers are classified as module-level power electronics (MPLEs).

Smart solar panels on the contrary, are solar panels that have built-in optimisers, so no additional equipment is needed in order to optimise the solar panels in the system.

Finally, with microinverters, the solar panels are connected in parallel with each solar panel having its own “microinverter”, and, hence, allowing each panel to function independently without impacting the other panels. 

At Otovo, our experts will work with you closely and advise you on whether you need to include any optimisers in the system all with the objective of providing you with the system that will produce the most output and provide you with the best return on your investment.

Solar optimisers brands we work with

At Otovo, we work with a wide variety of high-quality manufacturers of solar panels optimisers adapted to the needs of any home. 

The manufacturers of solar panels optimisers that we work with in Otovo are:

• Huawei - SUN2000-450W-P
• Tigo - TS4-AO

Frequently Asked Questions

Do you always need to have optimisers in your solar system?

The answer is that definitely not. In fact, in most cases optimers are not required. If they are not required it will be a waste of money. When you talk to us in Otovo, we will look at your roof and its shading. We know from experience that not everyone needs to invest in optimisers for  their solar system. Most often, it is also one or a few individual solar panels that are affected by shading.

Our solar panels are of high quality and use technology that reduces energy loss even when shaded by utilizing bypass diodes. However when bypass diodes are not enough to compensate for loss of efficiency our team will suggest the installation of optimisers. 

How long of a warranty do you provide on optimisers?

We provide the optimisers we install with workmanship and product warranties of 5 years in addition to a manufacturer’s warranty of 25 years.