What size are you quoting on DNO forms - Peak or Instantaneous output?

[whlphil]

Had a meeting with One of the northern DNO's today and they were as helpful as ever, we were actually talking about over 50kw but this question also applies to the 3.68 to 4kw range.

On the ENA DNO application form it asks for the net plant size - what are you filling in for this figure? as I suspected and confirmed with them today they are interested in the Instantaneous peak output not the Installed STC Kwp

Now Initially they said you cant install a 4Kwp system without a DNO app, then changed their mind and finally ended up on they weren't sure. But as they are definitely interested in Instantaneous output and resultant voltage rise I came away with the view that a 4Kwp system will most likely never actually achieve 3.68kw.

The system after losses from inverters, cables, panel efficiency and irradiance and its Instantaneous output at the AC terminal on the inverter is what they are interested in which gives an Interesting problem how do you calculate the (worst case - Jun/July) Instantaneous output at the AC on the inverter?

 

[Worcester]

TIC or DNC, depends what they ask for.

The Inverter is the generator, the panels are merely the fuel source, as you say the sun moves around.

Now, as a large organisation, MCS registered, you do know what those terms mean don't you. (and where they are defined)

Just in case you don't, dig through the threads here, the question has been answered many times, and in depth.

 

[whlphil]

yep aware of the definitions, read through the threads, aware of the AC output of inverters restrictions but the DNO was talking about instantaneous and I'm taking it that people are assuming that an array will output at its given Kwp STC at an Instantaneous condition but is that the case? and how do you calculate it? not so much of an issue on a small system but significant and dependent on technology of the install on larger.

Like youve said before an East or West system output isnt just the Array DC output less system efficiency to give the AC output its a function of irradiance aswell

 

[Worcester]

@whkphil, that's all you can do, use STC, we're not climatologists, what if it gets sunnier and colder, efficiencies go up...

kWp is just that PEAK.
We use kWp x inverter efficeincy, STC tends to overestimate, as it's based on a flash test, in real like the panels will run hotter (even in winter) and so the output is likely to be lower.

 

[whlphil]

Spoke to a guy from Fraunhofer ISE today, Kwp at 15 min average is about the best you can get which I can get off PVSOL.

 

[Former Sponsor TM]

Hey guys,
Sorry for the delay getting back to you, we were in talks with Chauvin Arnoux. I'm now pleased to announce that we are to sole UK distributors for the FTV-100 that I think fits the bill perfectly!

The Chauvin Arnoux FTV-100 Photovoltaic Imprint Verifier measures all the physical and electrical parameters of a single and three phase solar power installation so that correct operation and optimum efficiency of a pv system can be achieved.


Chauvin Arnoux FTV100http://www.test-meter.co.uk/product...-greentest-ftv100-pv-system-efficiency-meter/ Solar Efficiency Tester features include:
► Measurement of voltage, current and power produced by photovoltaic panels
► Measures AC/DC voltage, current and power at the inverter
► Performs all measurements simultaneously along with temperature and solar irradiance
► Calculates pv panel performance and AC/DC energy conversion efficiency
► Displays temperature coefficient for panel performance correction
► Simultaneously stores test results for later analysis
► Non-reflective 5.7" colour LCD for clearly displayed results
► Straightforward set up and operation


In a solar pv installation each row of solar panels is designed to achieve a specific level of efficiency. The FTV100 will instantly measure AC and DC voltage, current, power, panel temperature and solar irradiance to calculate the overall efficiency of a solar photovoltaic installation. The Chauvin Arnoux Green Test will perform an electrical power survey, calculation of solar panel efficiency and a calculation of the inverter efficiency simultaneously, in compliance with the European Directive 2001/77/CE.

If you have any questions, would like a demo or are interested in hiring the FTV-100 then please do not hesitate calling us on: 0113 248 9966

 

[DurhamSparky]

how much!!!!!

 

[Former Sponsor TM]

Considering it's the only tester on the market to check all the environmental parameters, monitors both the AC & DC output and is able to give you an overall numerical. What price can you put on a tester that checks the efficiency of a complete PV system that's going to be left to its own devices for 25 years? Imagine being able to offer this service to your customer. You could charge a premium service to customers who have had a system installed already that isn't performing as well as it should. It helps identify where the faults on systems are that have not being correctly installed. You could get contract work for checking the systems efficiency every 5 years or so and you would be able to hire the unit out to other PV installers. With all that in mind I think it's reasonably priced.

 

[JD6400]

Sounds good , but like Durham said how much ?