I want to change the global solar resource for each time period. How do I do that?

[Rishabhvarma25]

I am trying to look at a scenario where the global temperature changes in future and it affects the total solar potential of a region. The change in solar potential is based on various calculation done out of the model which includes changing climate factors. Till now I have only used the model to change the solar potential which is fixed for all time periods, but for this exercise I want to change the Solar potential for each time period. How do i do that in GCAM?

[pkyle]

The way solar power production is represented in GCAM is not very amenable to this sort of change. The model does not track the flow of energy from the sun into a solar panel; rather, the PV technologies are represented by their power output, and the total costs of producing the power. One of the key input assumptions that determines this cost is the capacity factor, which is currently region-specific but is not assumed to vary over time. One could easily revise that assumption, by increasing the capacity factor over time in order to represent more power production per unit of installed capacity, which will lower the levelized costs of electricity production. That said, the model is not well set up to represent the increased power output of an installed base. Increasing the capacity factor over time will make the technology more competitive (for the structrure just see the electricity_water.xml file and search for the string capacity-factor), and allow it to gain more market share, but in GCAM an existing stock of capital would not similarly change over time. There is a survival curve that is assigned to each cohort, but the functional form that is used for the survival curve does not allow for an increase in output from the initial level. There is a parameter called exogenous-shutdown-decider in the more recent versions of the model that does allow a user to prescribe the output of an individual cohort over time; each future year in which a cohort is operating can be assigned a multiplier called output-scalar. I don't know if the multiplier is allowed to exceed 1, but if that works then that could allow a user to increase the electricity output of a cohort over time. Here is what the XML looks like:

                    <period year="2015">
                        <s-curve-shutdown-decider delete="1" name="s-curve"/>
                        <exogenous-shutdown-decider name="exogenous-shutdown">
                            <output-scalar year="2015">1</output-scalar>
                            <output-scalar year="2020">0.38</output-scalar>
                            <output-scalar year="2025">0.48</output-scalar>