Last week, I went to the PV Operations conference in Munich, organised by NewEnergyUpdate. Besides pleasant talks with attendees during the networking breaks, I had the opportunity to speak about the importance of irradiance and soiling measurements for utility solar plants.
When I was doing research on satellite derived irradiance data I spoke to more than just my colleagues at Kipp & Zonen and providers of satellite data; I also contacted other stakeholders in the solar energy industry. And that is when I came across different myths that were going around in the industry. Here’s my list of the top myths on the subject of satellite and pyranometer measurements that I would like to dispel.
That’s not a question: we need both! As a result of a fruitful co-operation, 3E and Kipp & Zonen present a joint white paper, indicating that satellite and pyranometer irradiance data can both co-exist and do even complement each other.
Although the Milan airport Malpensa is not the nicest place to be, it is just an airport and 50km (!) from Milan city centre, it was exciting last week; being the venue of the Solar Asset Management Europe conference. It was also a perfect platform to present our DustIQ Soiling Measurement System.
On evenings and weekends with beautiful weather, I tend to jump on my old-timer scooter and ride the winding roads in the neighbourhood. The scooter is from 1962, and my father used to drive it to work in the sixties. It is still rolling along due to its high build quality and my ongoing good maintenance.
You might have read that the oldest operational Kipp & Zonen pyranometer we found is located in Freiburg (Germany) and 46 years old. Like my scooter, it is still operational due to its build quality and good maintenance! You have to clean the dome, ideally at least every 2 weeks (or as soon as it gets dirty) and at the same time check the levelling and inspect the desiccant colour (and change it when required). With many of our recent instruments you don’t even need to check the desiccant, it is sealed inside.
Part of pyranometer maintenance – and luckily not part of old-timer scooter maintenance – is regular re-calibration. Under the influence of solar radiation, mostly the UV light, the sensitivity might have changed slowly over time.
The world of utility-scale solar energy is becoming a global market; many investors, asset managers, EPCs and O&M parties operate on an international scale, or they intend to do so.
Many of the parties I meet have global strategies and policies and they buy centrally to benefit from large volume prices. An example is a German monitoring firm, which installs worldwide, but puts all the monitoring elements together in Germany and tests the systems before shipment.
I used to train installers of (mostly residential) PV systems, and tell them that half of the quality of a PV system is in good materials and design, and the other half is in proper installation. For utility solar systems there is even a “third half” (if there is such a thing); maintenance!
A good measure of the quality of a PV plant is the Performance Ratio: it separates “the good, the bad and the ugly” solar systems from each other. Find out more in our whitepaper: 6 key influences that determine PV performance ratios.
Irradiance measurements to calculate the Performance Ratio (PR) for solar parks sometimes cause controversy: A few years ago, I visited an O&M conference, where cheating with irradiance measurements was openly discussed on the podium. There were about 200 attendees in the room; And after a presentation on irradiance measurement at a solar conference, our R&D manager was asked whether Kipp & Zonen could make instruments that were less (!) accurate.
This shows that irradiance measurements can cause headaches; but they are absolutely necessary for calculating the Performance Ratio. Besides the output generated relative to the solar irradiance received on the panels, PR is the figure looked at by most players involved in the PV power plant business.
In most PV plant monitoring software you can choose the definition of the Performance Ratio (PR). So, a specific PV plant can have different Performance Ratios at the same time? Yes, and no…
Puzzled? Is Performance Ratio misleading? You don’t have to be puzzled, and no, Performance Ratio is not about misleading, it is about facts! Read our whitepaper – 6 key influences that determine PV performance ratios – to get a better understanding.
What is DustIQ, and why do you need to find out all about it at Intersolar in Munich?