The P50 - P90 evaluation is a probabilistic approach for the interpretation of the simulation results over several years.
This requires several additional parameters, which are not provided by the simulation process, and should be specified (assumed) by the user.
Procedure summary
For activating the P50 - P90 tool, please open the button "Energy Management", page "P50 - P90 estimation" in the grid's project dialog.
This should be done after a first simulation, since by default the P50 value corresponds to the simulation output.
First choose the "Kind of Data", which will impact how the P50 value is determined.
Then determine the shift, weather data annual variability, and other simulation uncertainties.
Finally, you may specify whether you want P90 or other values. The result will appear on the report if the parameters are correctly specified (no warning).
NB: This feature is not available for Stand-alone and Pumping systems, where it is more difficult to define.
Probability law
This approach supposes that over several years of operation, the distribution of the annual yields will follow a statistical law, which is assumed to be the Gaussian (or "normal") distribution.
P50/P90 represent different yield levels, for which the probability that the production of a particular year is over this value is 50%, resp. 90%.
The problem is now to establish the 2 parameters of this Gaussian distribution, i.e. the Mean value and the Standard deviation (named sigma or RMS).
The main contribution to those parameters will be the uncertainty and variability of the meteo data. But other uncertainties in the simulation process and parameters should be taken into account.
Uncertainties on Meteo data
Commonly available meteo (climatic) data have usually some uncertainties, of different kinds, which may produce very significant differences between sources, or years in a same source. These may be:
- The yearly variability, which is supposed to have a Gaussian distribution,
- The quality of the data recording, care of the operators, positioning, calibration and drift of the sensors, perturbations like shadings, dirt or snow on the sensors, etc.
- The presence of a not negligible horizon for terrestrial measurements,
- The location difference (distance of measuring station) for terrestrial measurements,
- The quality of the models used for interpreting the satellite data, which is in continuous improvement since 20 years,
- The evolution of the climate. In Europe, it seems that the irradiation has increased by as much as 5% since the beginning of the 21th century.
See the differences in the PVGIS data between the old database and the more recent "Climate-SAF" database.
Another example: in Geneva, for official measurements of the ISM, the 2003-1011 average is 10% above the 1980-2002 average, which is probably an extreme situation.
However if you have averages of years mostly after 2000, you can let this value to null.
Details
P50 determination - Kind of data
The simulation result is closely related to the Meteo input used for the simulation. This may be of different kinds, which has to be entered as the parameter "Kind of data":
•If the data are representative of an average over several years ("Monthly averages" or "TMY, multi-year"), the simulation result should be considered as an average, and generally corresponds to P50 (mean value of the Gaussian).
However PVsyst gives the opportunity of taking a specified climate change into account: this will displace the mean value P50 of the Gaussian with respect to the simulation result. This is useful for interpreting simulations performed with old average data (Meteonorm, PVGIS classic, etc), which are known to be lower than the present climate.
•If the data are for a specified year ("Own measured", or "Specific year"), these cannot be considered as representative of the P50 value. In absence of further information you cannot determine a reliable P50-P90 indicator. But if you have some information about the usual average of the site, you can introduce an estimation of the deviation of this particular year with respect to the average. Again, this will displace the P50 value with respect to the simulation result.
Note that the software will determine automatically the kind of data for most known sources.
Variability determination
The annual variability (sigma value) will be dominated by the meteo year-to-year variability. This information is not commonly available.
| - | A report of Pierre Ineichen (2011) gives some evaluations for about 30 sites in the world. PVsyst proposes default values according to these data. |
| - | The new version of Meteonorm 7.2, 7.3 and 8.0 provide this information for your site (see the "site definition" dialog, page "Monthly Meteo"). |
| - | Several meteo data providers can now deliver multi-year meteo data (sets of 15 to 25 years), that you can directly import in PVsyst (for example SolarGIS, 3-Tiers Vortex, Soda-Helioclim, or other). If you avail of such meteo data for your site, you can calculate the RMS of the annual GlobInc distribution. You have a tool for doing this in PVsyst: please use "Databases > Compare Meteo Data", and here choose the corresponding MET files for different years. You have an option "Histo and Probabilities" which shows the Gaussian distribution, average and RMS. |
Additional uncertainties in the simulation process could eventually be taken into account. These deviations should represent random variability of the uncertainty from year to year, not the absolute uncertainty !
- PV modules model and parameters (the main uncertainty after Meteo)
| - Inverter efficiency | (negligible) |
- Soiling and module quality loss (highly depending on the site conditions)
| - Long term degradation | This is not compatible with the P90 evaluation concept. |
| We don't know how to handle this in the present time. |
- Custom other contributions
All these random contributions will add quadratically, giving a global standard deviation which may be applied for constructing the final Gaussian distribution function, and give estimation of the P90 or any other Pxx indicator.
This is for very special uses: in usual situations, all these values may be let to null values.
NB: In the Gaussian distribution function, P90 represents a shift of -1.28 sigma, P95 => -1.64 sigmas, and P99 => -2.35 sigmas.
PVsyst shows a graphical representation of your choices, either as a Gaussian probability distribution for several years, or as the corresponding cumulative distribution (the integral of the gaussian).
On this example, the simulation was performed using a specific year, which was supposed to be -3% below the yearly average. Therefore the P50 value is higher. A positive climate evolution would have the same effect.
Playing with the uncertainty parameters is highly instructive about the representativity of the simulation result for the future years. It is interesting to observe that according to your interpretation of the simulation result (i.e. E_Grid, fixed), the forecast productions distribution may move around your simulation result !
P90 estimations for monthly or daily values
The P50-P90 statistical estimations are based on yearly values. Defining P90 for hourly or daily values (or even for monthly accumulations) doesn't make sense !
When the variations of annual meteo data is of the order of 3-4% (RMS), the variability of monthly data from year to year is much higher, and defining a probability profile for each month will give erratic results.
By the way the probability profiles for the determination of P90 are statistical estimations, which should be based on significant weather series (at least 15-20 years of meteo data).
But we don't avail of such generic data for monthly values, and this would be very dependent on the climate and the season.
If you want to do such evaluations, you should find monthly meteo data of 15 years or more for your site, and evaluate the probability distribution month-by-month.
Correction of Hourly values
For defining P90 hourly values, some people think to simply diminish the yearly hourly results by the ratio of the yearly yields P90 / P50.
This is not correct, as the behavior of your system will be exactly the same for clear conditions. The eventual P90 "correction" would affect the distribution and frequency of bad weather conditions, not the absolute yield of each hour.
Some meteo data providers propose Meteo Time series corresponding to P90 (or other Pxx). We don't know how these data are elaborated, and we don't know the significance of such data.
FAQs
What does P50 mean in project management? ›
There should be at least a 50% probability (P50) that the quantities actually recovered will equal or exceed the best estimate. There should be at least a 10% probability (P10) that the quantities actually recovered will equal or exceed the high estimate.
What is P10 vs P50 vs P90? ›P90 refers to proved reserves, P50 refers to proved and probable reserves and finally P10 refers to proved, probable and possible reserves.
What is the P50 mean? ›p50 is a shorthand representation of hemoglobin-oxygen affinity. A lower p50 is protective in ambient hypoxemia, whereas increasing the p50 should be beneficial in hypoxia due to lung disease, anemia, and tissue ischemia.
What is P50 and P90 in solar? ›For example, a P50 value of 10,000 kWh for the annual output of a solar power system means that there is a 50 % likelihood that the system's out put will be greater than 10,000 kWh. Similarly, a P90 value of 10,000 kWh would mean that the system is likely to gener ate over 10,000 kWh 90 % of the time.
What is P50 performance ratio? ›The P50 figure is the average level of generation, where the output is forecasted to be exceeded 50% over the projects life. The P90 figure is the level of generation that is predicted to be exceeded 90% of the projects life.
Is a P50 a best estimate? ›P50 is the most probable value, also called best estimate, and it can be exceeded with 50% probability. P90 is to be exceeded with 90% probability, and it is considered as a conservative estimate.
What is p99 p90 P50? ›The p90 latency of an endpoint is a latency number higher than 90% of calls to that endpoint. The p50 latency is the median latency, so it is higher than half the call latencies to that endpoint. A higher latency metric, say p99, for your endpoint means that 99% of calls to that endpoint were faster than this number.
What is P50 P70 p90? ›P50 refers to 50% of the years exceeding the value. Accordingly, the P70 (P90) value defines the DNI, which is exceeded in 70% (90%) of the years. Accordingly, the DNI value related to P90 / P70 for a given site are lower compared to P50, which represents the long-term average.
What is a P50 contingency? ›For instance, a P50 cost is the Project cost with sufficient contingency to provide 50 per cent likelihood that this cost would not be exceeded.
What is the P50 project schedule? ›When we look at results of the schedule analysis, we often talk about confidence levels, where as p50 means that there is a 50% chance the project will finish “at or before” the date.
What is P10 P50 P90 schedule? ›
By definition, P10, P50 and P90 are values on an ascending or descending scale, representing the point where the integral (total area) from one end of the statistical curve to the define value would have equaled to 10%, 50% and 90% of the total area respectively.
Is P50 the average? ›To be clear P50 is different than average. Technically speaking P50 is called median and it roughly says half the elements have higher value and half the elements have a lower value.
What is the p50 duration? ›The p50 threshold is the value at which 50% of transaction durations are greater than the threshold. This is also the median. For example, if the p50 threshold is 10 milliseconds, then 50% of transactions exceeded that threshold, taking longer than 10 milliseconds.
What are the three types of solar PV? ›There are three types of PV cell technologies that dominate the world market: monocrystalline silicon, polycrystalline silicon, and thin film.
What are the 4 Ps for solar energy? ›Presenting this set of slides with name 4 Ps Of Solar Marketing Model. The topics discussed in these slides are Product, Price, Place, Promotion.
What is a good performance ratio for solar? ›In real life, a value of 100 % cannot be achieved, as unavoidable losses always arise with the operation of the PV plant (e.g. thermal loss due to heating of the PV modules). High-performance PV plants can however reach a performance ratio of up to 80 %. 2 What is the function of the performance ratio?
What is P50 p90 evaluation? ›The P50 - P90 evaluation is a probabilistic approach for the interpretation of the simulation results over several years. This requires several additional parameters, which are not provided by the simulation process, and should be specified (assumed) by the user.
What does kWh per kWp mean? ›Values such as the kilowatt hour and the kilowatt peak provide information about this. While the kWh tells you how much electricity your system generates, the kWp tells you how high its output is. Combined, the two values stand for the PV yield you can expect.
Is P50 50%? ›p50 — The p50 is the pressure at which hemoglobin is 50% saturated (27 mmHg on the X-axis). Arterial blood — Hemoglobin is approximately 100% saturated at an oxygen pressure of 100 mmHg.
How fast does P50 go? ›Capable of a top speed of 38 mph, the P50 features a 49-cc 4.5-horsepower single-cylinder two-stroke Zweirad Union engine mated to a three-speed gearbox. The Peel P50 has no reverse gear, simply a handle on the rear to enable the driver to pick up the car and maneuver it as required!
What is the difference between P50 and average? ›
It is a common misunderstanding that the P50 is a synonym for the Mean or Average. If the probability distribution for activities were symmetrical, this this would be the case, where the Mode, Mean and P50 all would be the same. It might be better to provide the alternative name to P50 which is the Median.
What is P50 vs p95 vs p99? ›p50 shows the experience of 50% of the users. p95 shows the experience of 95% of the users. p99 shows the experience of 99% of the users. If you were looking at places to improve the performance of your application, then it would make more sense to look at p95 response time values than to look at p99 values.
What does p95 mean? ›Per column, select one of the following performance indicators: Avg: average value. P50: median. P90: 90th percentile. P95: 95th percentile.
What is P50 P90 cost? ›P90 represents the estimate of costs such that there is a 90 per cent probability of the project being delivered within that cost estimate. P50 represents the estimate of costs such that there is a 50 per cent probability of the project being delivered within that cost estimate.
What does P50 and P80 mean? ›Defining P50 / P80. P50 and P80 refer to a confidence level regarding the probability of the cost not being exceeded, and does not indicate a quantum of cost or proximity to the actual cost realised. That is, P80 is not a cost plus/minus 20% but instead it is a cost that will not be exceeded 80% of the time.
What is P90 P10? ›The P90/P10 ratio is the ratio of the upper bound value of the ninth decile (i.e. the 10% of people with highest income) to that of the first. The P50/P10 ratio is the ratio of median income to the upper bound value of the first decile.
What is 20% contingency? ›This contingency is normally calculated as a percentage. If the phase is 100 days of effort, contingency at 20% would be another 20 days. As the project progresses, the level of risk reduces as the requirements and issues become known, so the percentage will be reduced.
What is a P70 estimate? ›As an example, a cost P70 means that, based on uncertainty and risk applied to the model, there is a 70% probability of completing the project within the P70 figure (and therefore a 30% probability of exceeding it)
What is a P80 schedule? ›The P80 date on the Risk Exposure histogram simply means that "80% of the Risk iterations finish on or before this date." The P80 date is not one single schedule; it is just a "line in the sand" date. There is no logical way to back a schedule into this date.
What is the new project cycle? ›The project life cycle is made up of five project stages: project initiation, project planning, project execution, monitoring & control and project closing. Each of these phases is necessary for the effective delivery of the project.
What is the most common project schedule? ›
The most common form of project schedule is a Gantt chart. Both a milestone schedule and a detailed project schedule can be created as a Gantt chart.
Does a project charter have a schedule? ›A schedule is created by the PM during the Project Charter process, which provides a timeline of high- level project deliverables during each of the Project Process Phases. The schedule developed at this stage is not intended to be as detailed or precise as the construction schedule maintained by the contractor.
How many days is p90? ›P90X is a set of 12 high-intensity online workouts that you do over the course of 90 days. You've probably seen the infomercials about it on TV.
What is the difference between p50 and p90 latency? ›p50, p90, pxy are metrics to measure the latency of your services. The number here denotes the percentile of total requests. p50 – The 50th latency percentile: 50% of the requests will be faster than the p50 value. p90 – The 90th latency percentile: 90% of the requests will be faster than the p90 value.
How is p90 calculated? ›What is the 90th percentile value? Multiply the number of samples by 0.9: 0.9 X 10 samples = 9 Therefore, the 9th highest ranked sample is the 90th percentile result to compare to the Action Level.
Why is P50 so expensive? ›The reasons for its price tag are many – first, it's the only product that guarantees a glow like no other and second, it's a god-send for pigmented skin. We all know that Indian skin is more prone to pigmentation and that's one good reason, right there to pay an arm and a leg for the formula.
What is the strongest P50? ›BEST FOR PURISTS, ACNE PRONE AND COMBINATION SKIN: LOTION P50/P50 1970. P50 1970 is what many call the OG editions in the P50 line. Hence, it's also the strongest formula available.
How often can I use P50? ›You can use the Lotions P50 daily, morning and night after you cleanse. There is no need for rubbing your skin with the Lotions P50. Simply pat the formula on your skin.
Is P50 same as average? ›To be clear P50 is different than average. Technically speaking P50 is called median and it roughly says half the elements have higher value and half the elements have a lower value.
What is p99 and P50? ›p50 shows the experience of 50% of the users. p95 shows the experience of 95% of the users. p99 shows the experience of 99% of the users. If you were looking at places to improve the performance of your application, then it would make more sense to look at p95 response time values than to look at p99 values.
What is P50 P90 evaluation? ›
The P50 - P90 evaluation is a probabilistic approach for the interpretation of the simulation results over several years. This requires several additional parameters, which are not provided by the simulation process, and should be specified (assumed) by the user.
What are P50 and P90 in a cost estimate? ›For instance, a P50 cost is the Project cost with sufficient contingency to provide 50 per cent likelihood that this cost would not be exceeded. A P90 cost is the Project cost with sufficient contingency to provide 90 per cent likelihood that this cost would not be exceeded.
What is P80 in project management? ›Generally, P80 or 80% is the total project value to use for setting the final total project cost. P90 or 90% is often used to include the management reserve. Most Monte Carlo simulation software allows the user to configure the graphs and charts to indicate the P80 or P90 amounts.
What is the P50 schedule? ›When we look at results of the schedule analysis, we often talk about confidence levels, where as p50 means that there is a 50% chance the project will finish “at or before” the date.
What P50 should I use? ›Lotion P50: Keratinized & Oily Skin
I typically recommend the original Lotion P50 to clients with keratinized (thick skin) or skins producing an excess of oil, as it regulates oil production. This multifunctional lotion exfoliates, cleanses, and purifies the epidermis, helping it maintain its acidic pH balance.
Biologique Recherche Lotion P50 Capillaries is a purifying lotion that helps strengthen hair, improves texture and makes it shinier and more manageable. It balances PH, regulates the sebum and gently exfoliate the scalp.
What is the difference between P50 and P90 in project finance? ›P90 represents the estimate of costs such that there is a 90 per cent probability of the project being delivered within that cost estimate. P50 represents the estimate of costs such that there is a 50 per cent probability of the project being delivered within that cost estimate.
What is P50 and P90 metrics? ›The p90 latency of an endpoint is a latency number higher than 90% of calls to that endpoint. The p50 latency is the median latency, so it is higher than half the call latencies to that endpoint. A higher latency metric, say p99, for your endpoint means that 99% of calls to that endpoint were faster than this number.
What is P90 P50 and P99? ›This TMY should be considered as an average and thus corresponds to P50. P50 represents the "best estimate" but in some cases, you can need a prediction with lower risk, like the P90 (estimate exceeded with 90 % probability) or P99 (estimate exceeded with 99 % probability).
What is the P50 duration? ›The p50 threshold is the value at which 50% of transaction durations are greater than the threshold. This is also the median. For example, if the p50 threshold is 10 milliseconds, then 50% of transactions exceeded that threshold, taking longer than 10 milliseconds.
What is P50 P70 P90? ›
P50 refers to 50% of the years exceeding the value. Accordingly, the P70 (P90) value defines the DNI, which is exceeded in 70% (90%) of the years. Accordingly, the DNI value related to P90 / P70 for a given site are lower compared to P50, which represents the long-term average.
What is P90 in project finance? ›The Basic Definitions. P50 and P90 are probability figures. The P50 figure is the annual average level of generation, where the output is forecasted to be exceeded 50% over a year. The P90 figure is the level of the annual generation that is predicted to be exceeded 90% over a year.