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Solar power optimisers open new opportunities for mixing panels at different angles, installing panels in places prone to shading, or mitigating heat inefficiencies.
What is the Best Solar Power Optimiser?
Two big brands supply solar power optimisers. They both perform a similar job but some variables may tip the choice in one direction or another based on what you are looking for.
Tigo power optimisers
They are easy to install and small enough to tuck away at the back of a panel. They also come with clips for secure mounting. Another feature I like is the longer leads they have for attaching the next panel.
Positives
In a white paper Photon test Results published by Tigo they claim that:
| Condition | Improvement | Value |
|---|---|---|
| No shading at all | Increased the energy yield | 1.5% – 1.7% |
| Horizontal shade | Energy gain improvement | 20.8% |
| Shade from pole | Energy gain improvement | 9.7% |
| Shading from a tree | Did not provide values | Did not provide values |
Independent of Inverter Vendor: Each inverter operates independently and can work on any string with any inverter. Therefore, you can install Tigo solar panel optimisers on strings.
Negatives
Expensive Monitoring Equipment – Monitoring the optimisers requires an additional hub to be purchased. This is not necessary for the operation of the optimisers. However, if you want to know what every panel is doing you will have to pay roughly as much as the equivalent of 4-5 optimisers to buy the hub.
SolarEdge power optimisers
Small enough to fit at the back of a solar panel, this optimiser comes with pre-wired MC4 connectors making it easy to install. Comes with clips for secure mounting too.
Positives
In a white paper PV Performance Separating Fact from Fiction published by SolarEdge they claim that:
| Condition | Improvement | Value |
|---|---|---|
| No shading at all | Increased the energy yield | 1.5% – 1.7% |
| Horizontal shade | Energy gain improvement | 34.6% |
| Pole | Energy gain improvement | 9.7% |
| Shading from a tree | Negative effect reduction from 24% | to 9% |
They also claim that at light, moderate and heavy shading a system with SolarEdge optimisers improves the energy harvest by 1.9%, 5.0%, and 8.4% respectively, compared to a string inverter system without optimisers.
Monitoring Directly From The SolarEdge Hub – The solar panel optimisers can be paired with the SolarEdge monitoring hub
Negatives
Only Works With SolarEdge Inverters – SolarEdge power optimisers operate in a closed system, which means they only work on strings connected to a SolarEdge inverter.
Independent Verification
This study performed by the University of Southern Denmark names SolarEdge and Tigo optimisers in their experiments on power optimisation. Their finding are in line with the finding quoted in the white papers by Tigo and SolarEdge when it comes to shading effect reduction. This study however tests the optimisers in both uniform sunny condition and cloudy condition, and finds solar panel optimisers pose negative effects in such conditions.
On the other hand a paper published in 2019 by School of Electrical and Computer Engineering (FEEC) University of Campinas (Unicamp) Campinas, Brasil suggests a general positive effect from using optimisers in all conditions. Their premise is that panels are affected differently from thermal inefficiency or internal components underperformance and in a large string all panels operate at the current of the worst performing panel.
My Take
I used Tigo power optimisers on a north-west facing string with intermittent shading.
In my experience, Tigo’s optimisers perform in line with the stated benefits. I cannot speak to their longevity as I have had them since May 2023, and so far, they are working well.
Summary
We looked at the offering from SolarEdge and Tigo as the two most popular and easy to buy on the market. The advantages of seamless integration of the SolarEdge solution are appealing to SolarEdge inverter owners. On the other hand Tigo’s versatility renders them the only choice for retrofitting or expansion of an existing system.
