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How solar PV plant owners optimise their O&M

image credit: Courtesy Scatec Solar
philip LEijTEN's picture
Director Soka Solutions

Energy professional with comprehensive skill-set in the project development cycle across the technical, commercial and economic modeling space. Available to take on responsibilities for renewable...

  • Member since 2020
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  • Jun 11, 2020
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Just over eight years ago we invested in 16 250W PV panels on our south facing roof with a 30-degree pitch. Sure, the FIT regime took care of a big chunk of the investment risk in a 4kW system. Recently though, the inverter has been playing up. Back in 2012 internet connectivity of household installations did not appear to be a big thing. Or at least it was not a feature that was tabled as a prominent option by my system provider, now long bankrupt. So, when there is trouble, the system does not flag an alarm on my smart phone, nor in my computer. A (daily) visual inspection of the Elster A100C generation meter is required: is the LED pulsing? Yes? That’s good as each pulse equates to 1 Wh produced. If not and it is permanently lit, it is bad. Unless it is night of course in which case the LED signals the PV system is off.

For some troubleshooting a trip to the attic is needed. Thus far, I have been able to reset the system and bring it back up and running. This has not prevented hours, even days where no power was generated, especially in periods of absence. A comparison between actual power produced since day one in 2012 and the P50 investment case revealed system performance is 9% higher. Phew! But that is not to say the system could do even better if optimised. This way of operating might be acceptable for a household installation. Even though this ‘analogue’ way of monitoring a system is cumbersome, it is not clear yet that the cost to digitise (~10% of the initial investment) justifies the benefits. But even that is not going to help me decide how often to clean the panels

So I wondered how operators of utility scale (100’s of MW) solar PV farms, at the other end of the spectrum, do this. My curiosity did not take long to be satisfied: I joined a webinar a few weeks ago, hosted by GreenPowerGlobal and delivered by Prediktor, a global IT-solutions provider in the solar power sector who is helping operators optimise production yield with an integrated asset management platform. The webinar featured cases studies with one of their clients, Scatec Solar, a large emerging markets IPP with over $1bn and 1.9GW of solar assets in operation and construction.

The block diagram of a solar PV plant is simple compared to that of a hydropower plant, or a combined cycle gas turbine (CCGT) fired power plant. Yet, as argued by one of the speakers at the webinar, they are more difficult to optimise. The hundreds of thousands (millions for very large plants) of solar panels are driving this, with inverters and transformers labelled as ‘relatively easy’ by the presenters. Each solar panel behaves as an individual power generator and so many of them are needed to get to utility scale capacities of 100’s of MW. Clearly then, from the panel level up it is a data heavy operation, even more so when considering companies like Scatec Solar operate not one but many such plants across the world.

Consequently, the two key challenges faced by any PV Asset Management Platform are (1) how to ensure quality & reliability of all this data and (2) how to distil operational insight from ‘big data’. In light of the scale, the number of individual generators as previously mentioned, seeing the wood for the trees, is a particular problem: where are the biggest losses, how well is the plant actually doing compared to what it could do in the (ever changing) weather conditions? The large, geographically diverse portfolio of plants most utility scale companies run adds the need to handle vast data sets, to enforce standardisation, to enable immediate access to data anywhere and give the asset managers the toolset to maximise operational performance of all plants, drilling down to component level.

(1)   Data

Illustrated by several diagrams, Erling Fledsberg, Product Manager for Prediktor’s PV software platform PView, explained how data is collected locally, cleaned (filtered), replicated over a VPN to a central store where it is structured in a common information model to maintain consistency and traceability across the portfolio and facilitate easy analysis. The cleaning requires outlier filtering, statistical techniques and using median to remove noise.

(2)   Creating operational insights

The asset management platform then transforms the very large datasets into actionable insights by providing a user interface with real time performance indicators, alarm management, the ability to drill down to individual components like inverters and obtain details, e.g. time series and alarms for troubleshooting. It also enables simulation to compare real production with what is theoretically possible, given parameters such as time of day, weather, panel ageing, soiling. A platform is not complete without the ability to generate automated reports, scheduling of operator / maintenance interventions, budget monitoring and perform KPI calculations to benchmark plants and their components across the entire portfolio. If battery storage is present on site, the platform can also support decisions when to charge or discharge – both a function of electricity spot prices.

 

Status Screens and drill down. [Images: courtesy of Prediktor and Scatec Solar]

Impressively, Scatec Solar’s entire portfolio of plants down to single panels and other pieces of equipment is controlled from one central location in South Africa. There, the asset management platform answers for each facility, across multiple countries, questions like: what components are underperforming? When best to intervene? Where is money lost? When best to do maintenance? It can extract operational data, including real-time weather parameters from onsite stations, prepare datasets for analysis and validate then deploy algorithms to analyse the data with the help of Artificial Intelligence. The platform also ensures local grid code requirements are met, has a flexible interface to 3rd party control and allows operators to schedule maintenance and despatch work orders for each local facility. With labour cost one of the main opex drivers in running solar PV plants it is imperative interventions are well focused, effective with minimal time impact.

The speakers, Thomas Pettersen, Erling Fledsberg and Pál Strom, presented three use cases in the webinar which to me read like a 101 of solar PV operations management. It raised pertinent questions in my head about how the 16 PV panels on my roof perform against potential! If only my 16-panel array could upload to PView and benefit from Scatec Solar’s O&M scale and know-how.

String performance map [courtesy of Prediktor and Scatec Solar]

Three sets of questions I would like to finish with:

a)      How many utility scale solar PV portfolios are controlled to this ‘standard’? What does the investment case for upgrading 'legacy assets' to handle big data look like?

b)     Apart from providing supplier recommendations (based on equipment failure rates experienced in the plants) and the appropriate module cleaning methodology – both of which were mentioned in the webinar - what others insights from O&M are transferred to the beginning of the development cycle? Will they inform conceptual design choices? How much improvement is Scatec Solar seeing in the design and ultimately O&M and profitability of new plants as a result? In my experience in upstream oil and gas, this is a key knowledge development process with the challenging task to balance the need for standard solutions, supply chain economies of scale against adjusting designs to incorporate lessons learned in the field

c)      A utility scale PV developer in southern Europe is looking into the potential for complementing one of its plants with an electrolyser to produce hydrogen (very topical and likely to remain so). How easy would it be to create a common platform to optimise the entire production system, electrons and hydrogen alike? And what about hybrid solar PV and wind?

philip LEijTEN's picture
Thank philip for the Post!
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Matt Chester's picture
Matt Chester on Jun 11, 2020

If properly implemented, what's the scale of impact on the bottom line these types of measures can have? Is it enough to tip some potential projects from non-viable to commercially profitable?

philip LEijTEN's picture
philip LEijTEN on Jun 12, 2020

Good question Matt, Prediktor's business model is premised on the capturing some of this value. They assured me that there are many legacy solar PV plants which do not match the standard followed by Scatec Solar. As to turning potential projects from non-viable to commercially profitable, I shall see if I can get an opinion from Prediktor on that. In a development cycle, the asset management strategy encompasses a number of choices  as to scope and technology. Somehow I would qualify a project that would only fly on its O&M philosophy rather marginal. I will ask Prediktor. 

Jim Stack's picture
Jim Stack on Jun 12, 2020

I own a 130 kW Solar PPA. It provides Power and cooling shade at a church in my area. 

I monitor it with a simple app called Ted Comander. It's not worth the time and efgort to monitor down to each panel. As long as the output is in line things are fine. If not then you can go on site and check each string and get to each panel.

  I also have a system on my home since 2001 with a very reliable SMA  inverter. I also just watch the overall output for each day. It has made more than we use each month since 2001 and saved us over $50k so fsr. It still produces like new after 20 years and is good for 30 more years.  

  Both systems have been great investment and run perfectly. Here in Chandler Arizona they oroduce more than almost any place on earth. The littke rain we get cleans the panels. It produces all of it's power duringvthe high Peak Time of Day hours and we use a small amount during Off Peak to use the excess in the GRID at night. I plan to use V2G with our 2 electric cars to be have back up power in case of an outage. We use no fossil fuel at anyvtime. Our system uses no water. 

philip LEijTEN's picture
philip LEijTEN on Jun 12, 2020

Jim, that is helpful. I shall investigate.

Impressive your numbers of money saved and your state of decarbonisation. The UK and our latitude of London has no where near Arizona's irradiation levels. I'm envious! My inverter is a Fronius and is now coming up with various error modes. Not too impressed. When I enquired with a local installer I was quoted £800 to replace the PCB, supposedly to eliminate the problems. I'm not convinced. And certainly not happy with the cost of a like for like PCB replacement that is ~ 10% of the original investment. 

Thanks again for your insights. 

Philip 

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