Grid Power Limitation - Truncation of Input Value

[JMBalGrp]

Hi All,

I have been doing some modelling for a large single axis tracking solar farm recently which notably has an grid input limitation of 27.17MW. When specifying this value to two decimal places the menu appears to immediately truncate the value to a single decimal place (as per below). Most of the time the PVsyst report shows the same truncated vaue(although, very few times it has shown the untracated value). However, the hourly output data shows that the 27.17MW grid limitation is indeed in effect, as desired (as per below).

 

showing truncation menu and hourly output

 

It would be fantastic if the next update corrected (the appearance of) this issue, to reduce confusion when interpreting PVsyst reports.

Cheers,

Jake

[André Mermoud]

If you choose the option of applying the limit at the injection point, you will very probably obtain a clean output E_Grid of 27'200 kW.

[JMBalGrp]

Hi André, yes you are correct, but that's not the issue. Put simply, if I input a 27.17MW injection point grid limit PVsyst rounds this limit in the report to a single decimal place value (27.2MW), even though the simulation was done to 27.17MW.

[André Mermoud]

The 4th decimal is really not significant here. A limit of 27.2 or 27.17 MW will probably have exactly the same results.

[linkeshd]

The 4th decimal is really not significant here. A limit of 27.2 or 27.17 MW will probably have exactly the same results.

 

HI André, I have struggled with PVsyst's grid power limitation implementation as well.

It looks to me like all the pieces exist for accurate modeling of the grid power limitation, however, whether I choose "Inverter Level" or "Grid Injection Point" does not change that the loss is applied to the "Inverter Loss over Nominal Inverter Power" instead of "Inverter Loss due to Power Threshold".

I'm also curious about your statement above. Per my calculations, the difference between 27.2 and 27.17 can easily be a difference of over $100,000, which can significantly affect a project's ROI. (I have assumed 3 hours of clipping for 120 days per year with $3/MWh electricity price).

Your thoughts? Perhaps the Grid Power Limitation has improvements scheduled in PVsyst's development plan?

Thank you.