Article - Greenbyte

September 8, 2021 — Product News

Are solar strings tying you in knots?

You can now use the Greenbyte Platform to monitor the output of strings of panels in your solar farm to see which are underperforming. Johanna Renman, Data Scientist at Greenbyte, explains.

Data Scientist, Greenbyte

What’s the issue here?

The solar industry is growing fast. Global installations were 132GW in 2020 and are due to exceed 200GW in 2021, according to Bloomberg New Energy Finance. We’re also seeing solar farms getting bigger, which makes it more challenging for operators to find faults and keep their projects running optimally.

This increases the pressure on operators to find sources of power loss at projects with hundreds, or sometimes even thousands, of solar panels, and then fix them quickly so they can protect their profits. That is where string monitoring helps.

We all hear that ‘knowledge is power’, but in this case it’s not just an expression. If you know what’s broken and how much it’s costing you, you can take the actions needed.

What is String Monitoring?

A solar farm can be made up of thousands of photovoltaic panels. Groups of these are connected to each other in strings which are in turn, often via combiner boxes, connected to a solar inverter. The inverter is where the direct current from the panels is converted into alternating current that can be used by the electricity grid.

At present, if one of those panels in the string breaks then the whole string can go down. If left unchecked, this could do major damage to the project’s profitability.

That’s where string monitoring can help. Using string data, owners and operators can see how their strings of solar panels are performing so they can identify issues with underperformance and address them.

As well as identifying underperforming strings, Greenbyte now also estimates the amount of lost production resulting from underperforming or broken strings. That is vital information when you analyze the financial performance of your projects.

But why monitor the strings? Wouldn’t this show up at inverter level?

Not necessarily. String monitoring helps you find losses that wouldn’t show up when looking at the data at a solar inverter. For example, let’s say you have an inverter of 800kWp with 20 combiner boxes attached to it, and each combiner box is connected to eight strings of panels. That means 160 strings of panels linked to one inverter.

Now let’s say that one sunny day, one of the panels in those strings stops producing – perhaps due to a loose connection or blown fuse. That could stop the full string of panels from producing but, if you looked at the inverter, that blown string would only represent a 0.6% dip in inverter capacity. You could just write that off as a measuring error. You’d have no clue there was an issue until your next site inspection.

How does Greenbyte Platform help?

Put simply, the Greenbyte Platform now helps you monitor the output of your strings so you can see which are working and which aren’t. Providing this data enables you to carry out manual monitoring of strings and set up alerts to highlight string failures.

But if that sounds simple, it isn’t! There’s no standard size for strings, so one thing we have to do in the Greenbyte Platform is to include a normalization step. This helps us to compare strings of different sizes, and provide a reference signal that we can use to compare the performance of the strings to.

Monitoring the strings helps you identify which ones are underperforming, but we have taken this one step further, by also estimating how much production you are losing from your broken or underperforming strings. This can help in planning and prioritizing maintenance as well as in explaining what part of your total losses are coming from string issues.

Of course, loss estimation isn’t the only benefit. It’s also useful for operators to be able to see when solar farms are working perfectly, as that gives peace of mind to both their operational teams and other stakeholders.

What do we need to do to monitor our strings?

For you to be able to leverage the advantages of string monitoring, we need two things – data and metadata. By ‘data’ we mean that the data needs to exist in the Greenbyte Platform on string level. By ‘metadata’ we mean the rating of the strings so that we can perform the normalization step, which makes the whole difference. We’re happy to talk you through how we can get hold of both.

And what about if you’ve lost your specification sheets for your sites and have no clue about the ratings of your strings? There’s no need to worry. We’ve still got you covered – but we’ll save that explanation for another day (hint: using historical data we can help you find the ratings of your strings).

Please get in touch. We’d love to explain more.


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