Plant, Cell & Environment

Cover image for Vol. 39 Issue 11

Edited By: Keith Mott

Impact Factor: 6.169

ISI Journal Citation Reports © Ranking: 2015: 10/209 (Plant Sciences)

Online ISSN: 1365-3040

PCE Calculator Help

This help page is intended to provide users with a source of information concerning any issues that may arise during the use of the application. This is by no means exhaustive, so if there is an issue that you are having which is not mentioned here, please get in touch with us and we will endeavour to answer your questions.

Getting Started

Error message: “Compile error: Can’t find project or library”.

This error has been found on computers running Microsoft Office Excel 2007. The error is caused when the Microsoft Visual Basic compiler is unable to locate the Solver reference file.

Click here to view more information >>

Application Help


  1. Use a freshly downloaded copy of the utility, the cells are not locked and can be inadvertantly changed.
  2. As a first approximation, assign all points below 200 ppm as rubisco-limited, points above 300 ppm as RuBP-regeneration limited, and the last point as TPU limited. Assign points between 200 and 300 ppm as 0 and see if the curves fit those points.
  3. Add points at the top of the curve that are constant or declining with CO2 to the TPU limited category.


Solver is not automatically loaded when Excel is installed. The first time Solver is invoked you will get a message saying that it cannot be run but will ask if you want to install it. You will likely need the installation disks during the install.
Advanced User Tips

If you have independent information about mesophyll conductance or day respiration, enter the value in the output region, then invoke Solver from the tools menu and adjust it so that the values you entered are not changed during fitting of the model.

If you want to explore, for example, how photosynthesis would change if rubisco were genetically engineered to go twice as fast, change the Vcmax and observe the effect on the lines. The data to draw the lines are at the bottom of the Calculations page.

It didn't work!

If Solver is unable to find a solution no changes will be made and the lines will not fit. Try adjusting the values manually to get an approximate fit and then try the "Solve" button again. Sometimes this allows Solver to find a realistic solution.

It still didn't work!

Estmate gm as 0.1 times A at 25 Pa and Rd as 1. Then, using solver as described in Advanced use tips estimate Vcmax, J, and TPU (do not allow gm and Rd to be changed by solver). This allows you to get some information out of the data. Use other estimates for gm and Rd if you have information about these.

If there are any issues that are not covered, please feel free to contact us to discuss further at