Preliminary design

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This is the easy pre-sizing of a project, in 3 simple steps:
1. - Choose the location (you may also define an horizon line
2. - Define the system parameter (see below)
3. - See the results, may be saved or printed.
For grid-connected systems, and especially for building integration, this level is architect-oriented, asking for available area, nominal power or energy yield desired. Further parameters are general properties about PV technology (mentioning colours, related to technology; transparency, etc), mounting disposition, ventilation.
For stand-alone systems, this tool proposes a sizing for the required PV power and battery capacity, given a user's load profile and the acceptable probability that it will not be satisfied (called "Loss-of-load" probability, equivalent to the inverse of the "solar fraction").
For pumping systems, the user should specify the water needs and the pumping conditions (pumping depth). For a desired "Loss-of-load", the tool will estimate the required power of the pumps and PV array.
In this "Preliminary Design" mode the system yield evaluations are performed instantaneously in monthly values, using only a very few general system characteristics, without specifying specific system components. A rough estimation of the system cost is also available.

Project design

This engineer-oriented part is aiming to perform a thorough system design using detailed hourly simulations. This level offers to the user:

A large database of PV components, location and meteorological sites.
Definition of the plane orientation (with possibility of tracking planes, double-orientation or shed/sun-shields mounting).
An expert system to facilitate the PV system layout definition.
Detailed parameters allowing fine effects analysis, including thermal behaviour, wiring and mismatch losses, real module quality loss, incidence angle losses.
Horizon definition for "far shading" calculations.
A 3-D CAO tool for "near shading" detailed studies.
A detailed economic evaluation performed using real component prices, additional costs and investment conditions, in any currency.
Condensed result forms which summarise all system parameter and the most significant result plots and tables for one given simulation. These forms are readily available on the printer, or can be inserted in documents through the clipboard.
Other detailed results available for several dozens of simulation variables, which may be displayed in monthly, daily or hourly tables or graphs, printed or transferred to other software.

The 3-D CAO tool

The 3-D CAO tool allows the user to draw the geometry of the complete system. It computes a shading factor for beam component as a function of the sun's position. The shading for the diffuse is taken into account using an integral of the shading factor over the sky portion "seen" by the array. It is also possible to partition the array in order to evaluate the electric losses due to the string layout.
Animation over a whole chosen day clarifies the shading impact of a given situation.

Orientation

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The plane orientation can be defined in several configurations. PVSYST computes the irradiation available on the collector field for fixed tilted plane, tracking planes, double-orientation or shed/sun-shields mounting.

The expert system

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For grid connected system, the user has just to enter the desired nominal power, to choose the inverter and the PV module types in the database.The program proposes the number of required inverters, and a possible array layout (number of modules in series and in parallel). This choice is performed taking the engineering system constraints into account: the number of modules in series should produce a MPP voltage compatible with the inverter voltage levels window. The user can of course modify the proposed layout: warnings are displayed if the configuration is not quite satisfactory: either in red (serious conflict preventing the simulation), or in orange (not optimal system, but simulation possible). The warnings are related to the inverter sizing, the array voltage, the number of strings by respect to the inverters, etc.
The procedure is similar for stand alone systems, but requires a more refined sizing process, which in fact uses the same monthly optimisation as in the "pre-sizing" level. The user should first quantify the system needs (choosing domestic-appliances, powers and operating times). Then he has to decide the acceptable LOL ("loss of load probability", i.e. the duration when load cannot be satisfied), and the required battery autonomy in days. According to the load level, the program also advises a system (battery) voltage.Then the program computes the required storage capacity and PV array power. The user has just to choose the battery model and the PV module in the database, and the program determines the PV array and battery pack configuration. In the same way as above, the user can adjust this configuration. Again, warnings are displayed according to the system design consistency: PV array sizing by respect to the battery pack, right choice of the regulator (voltage, input or output currents), etc.
For pumping systems, the design is a little more complex. You can choose among 3 types of systems: deep well, lake/river/pond, or pressurizing. Then you specify your water needs, and eventually some pumping level variations along the year. After choosing a pump in the database (colors guide the choice of suited pumps), you have to decide of the system configuration (direct coupling and its improvements like booster, cascading or array reconfiguration, MPPT converter, battery buffered). The rest of the system determination is analogous as for stand-alone: the program proposes a PV-array arrangement, that you can of course modify. At each stage the program displays warnings indicating the next step to be performed. Simulation will become possible only when all the parameters are consistent, i.e. when the program doesn't display any "red" warning.

Economic evaluation

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A detailed economic evaluation is performed using real component prices, additional costs and investment conditions, as well as maintenance, in any currency. The component prices may be defined by the user, within the concerned component parameters. Of course PVsyst cannot propose component prices, as they may vary in time, with countries, quantities or other shipping conditions. The program computes the investment, annual cost and end-user electricity (or water) price.

Tool

Tools include the meteo database management, with graphical displays or tables of data.
PVsyst includes a database of around 330 sites in the world. Since PVsyst version 4.3 you can easily import meteo data from many popular meteorological sources (Meteonorm, Satellight, US TMY2, Helioclim-2, WRDC, NASA-SSE, PVGIS-ESRA, and the complete database of the Retscreen software). Custom meteo files can be easily imported in any ASCII format (as for instance from the NSRDB).

The component database holds over 1750 PV modules, 650 inverters, nearly 100 solar pumps and dozens of batteries or regulator models.

Custom updates of the database are very easy, on the basis of usual manufacturer data sheets.

This part also provides other specific graphical or tabular tools. Most of them yield results which can be exported to other software:

extensive output of solar geometry (sun paths, incidence angles, etc.),
clear sky irradiation yields on tilted planes,
quick meteo calculations on tilted planes, with horizon, sheds or sun-shields shadings,
transposition factor plots, for plane orientation optimisation,
generation of meteo hourly synthetic files from monthly values,
hourly meteo plots, and calculations of irradiation on tilted planes, also with on-graph comparison with clear day model.
various graphs of the component's behaviour (PV modules, batteries, pumps),
electrical PV-array behaviour under partial shadings, mismatch or double-orientation,
operating voltage optimisation tool.

This constitutes a powerful didactic facility, for education as well as for experimented solar engineers.

This part also offers a general tool for importing measured data recorded on real PV systems (in almost any ASCII format).

It performs close comparisons between measured and simulated values, allowing for detecting and analysing even very little misrunnings of real systems.

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Software

Preliminary design

Project design

Tool