The Performance Check page allows user to run the power check method based on the uploaded data.
On the page the user can set the power-check settings (like safety factors and other parameters) and visualize the power check results.
The top of the page shows the toolbar containing all settings to run the power check.
In the first row, it displays the power check settings that are currently used.
On click on one of the settings or on click on the gear symbol on the right, a overlay will appear where user can adapt the settings (see further below).
If adapted, the settings are saved to the database as well.
In the second row contains a input field for specifying the start and end of the measurement period that should be used for the results.
By default, the full known range of the measurement data is used. However, user might want to specify smaller timeframes to speed up the exectution.
At the right end of the second row, the toolbar contains two buttons to execute the power check.
RUN: executes the power check and displays the information in the Web Interface in interactive plots.
PDF: executes power check and downloads a pdf report of the power method results.
Clicking on the RUN Button, the power check algorithm is executed.
After calculation, the results will be displayed in the Web-Interface.
The results page consits of 4 parts:
1. Results Table
The table contains the condensed information about the results - for each collector field (as specified in the configuration) and for the overall plant.
By clicking on a row, the corresponding data is shown in the other plots (2, and 3) as well.
The table displays the following information:
Selected - shows which of the rows is currently selected in the other plots
Name - shows the name of the component (either overall plant or name of the collector array).
Type - shows the type of the component (either overall plant or Array)
Gross Area - shows the gross area of the component
Measured - shows the average measured performance of the component within the valid intervals
Estimated - shows the average estimated performance of the component within the valid intervals
Ratio - shows the ratio of measured to estimated performance of the component within the valid intervals
Valid Intervals - shows the number of valid intervals found within the measurement data.
Note that there is a switch button on top of the table on the outer right which allows you to show the data without safety factor.
2. Measured Estimated Comparison Plot
The Measured-Estimated Comparison Plot shows the results of the selected component in a x-y plot.
Each point in the diagramm is a valid interval that has been detected in the data.
The x value shows the estimated power (by default including the safety factor), while the y-Axis shows the measured power within the intervals.
Hence:
if points lie exactly on the diagonal, it means that the estimated and measured performance of the valid interval matches exactly.
if points lie above the diagonal, it means that the measured power is higher than the estimated power of the valid interval.
if points lie below the diagonal, it means that the measured power is lower than the estimated power of the valid interval.
Hence, if the safety factors are set correctly, you would expect the points within the green area above the diagnoal,
while points below the diagonal would indicate a collector performance below expectations.
Note that there might be various reasons for under performance might be various:
incorrect settings (e.g. saftey factors or incorrect sensor units)
bad plant operation (e.g. pumps not running, no volume flow)
decreasing plant performance (e.g. accumulating dirt on collector)
low plant performance (e.g. damages)
…
3. Timeseries Plot
The timeseries plot allows to show the results versus time.
This is especially interesting to see any changes in plant performance over the lifetime of the plant.
Again, each point represents one of the valid intervals within the measurement data.
On the y-axis it shows the ratio of measured to estimated power.
Hence, values above 100% means that the measured performance is above the estimated performance.
The representation versus time sometimes allows to give more insights about the plant and the power check results:
Deteriorating Performance (slow decrease)
In case dust accumulates on the collectors, the performance initially will be very good, but gradually getting worse.
This can be identified with this plot, as you will see a slow decrease of collector performance versus time.
Collector Cleaning (sudden increase)
Assuming a dirty collector, a collector cleaning might increase the performance of the plant again.
Hence, after cleaning, the plot might indicate a sudden increase of the measured-estimated ratio,
with the collector producing more energy again.
Broken sensor (sudden change)
With a broken sensor used for the power check calculation, results might be wrong.
Hence, if a sensor break occurs, there might be sudden changes in the ratio reported by the Power Check.
No pump running (sudden drop)
If the pumps are not running even though irradiation is high the Power method might still yield results [*].
In such a case, the measured power will be zero as there is no volume flow.
Hence, the ratio of measured to estimated will be close to 0% for times
when pumps are not running despite high irradiation.
Internal-Shading (no points in timeframe)
The power check prohibits including intervals where collector are shaded.
Hence, some time periods will not show any valid intervals (e.g. during Winter with low sun).
(unaccounted) External Shading (yearly patterns)
In case of external shading the collector performance is lower compared to unshaded timeperiods.
If the information is not applied to SunPeek (through the is_shaded sensor slot),
the power check will yield lower ratio of measured to estimated in times where unaccounted external shading occurs.
This may result in seasonal pattern in the power check results.
[*] see discussion in Guide to ISO 24914 for more information about stagnation and “no pump running”
4. Tools
Finally, there is a small toolbar at the outer right of the plots.
TOOL: Zooming - when selected, click and drag over the plots to zoom into the selected area. Doubleclick to reset to the original zoom.
TOOL: Selecting - when selected, click and drag over the valid intervals in the plot to select them. As a result, the same valid intervals will be highlighted in the other plots as well, and the results in the table will adapt.
BUTTON: RESIZE - resets the zoom to the initial zoom.
BUTTON: EXPORT - exports the power check results as CSV data.
Example 1 - selecting time
Here you can see a example of the selection.
First, select the Selection tool from the toolbar.
Next, select a specific area for example in the timeseries plot.
As a result, the measured-estimated plot and the table will adapt.
Note this could be helpful for example if you only want to know the results of a specific period of time,
or to exclude outlier from the results.
Example 2 - selecting specific section
Here is another example, using the selection tool in the measured-estimated plot.
Again, the timeseries plot and the table will be adapted.
Note this could be helpful for example to see if results change when only taking into account higher measured/estimated power.
Example 3 - selecting outlier
You can also use the tool to select outlier in the measured/estimated plot and
find out when the outlier happened using the timeseries plot.
In the shown case, we use the selection tool to highlight one valid interval and hover in the timeseries plot to know
when the outlier happened
This assumes you have followed the Tutorial (Add a Plant).
Let’s assume that for this plant there is guarantee between the collector manufacturer, and the plant designer.
As part of the contract, it was agreed upon that the Power Check method according to ISO 24194 should be used,
to check if the collector performance matches its expectations.
Based on the hydraulics and sensors used, the two parties aggreed on the following safety factors:
Measurement Uncertainty: 95%
Pipes: 95%
Other: 99%
In addition, they agreed to use the ISO method as specified in ISO 24194 and use Formula 1 [*].
Unfortunately, there is no wind speed measurement available[*].
However, based on the typical weather of the location, wind speed above 10m/s as specified in ISO is uncommon,
and hence they agree to ignore wind speed in the analysis.
Hence, we adapt the settings accordingly (see screenshot above).
Note
[*] For simplicity, we assumed here that wind speed and beam/diffuse irradiation are not available.
They are in the DEMO dataset, but we haven’t used them in the sensor mapping yet.
Of course, this could be easily adapted without a need to re-upload data.
After clicking on RUN, we can see the results of the 1 month performance check (see screenshot above).
In the table, we can see that for the plant, 50 valid intervals have been found.
And in addition, the measured performance during the 50 interval exceeds the estimated performance according to ISO 24194 (including the safety factor).
This is also highlighed in the table with the Ratio showing a value above 100%.
The same can also be seen in the Measured Estimated Comparison and the Timeseries plots.
In all cases, the measured performance is above the estimated one - and inside the green area.
=> Hence, the power check has been successful - indicating that the collectors perform as expected!
