Feature/financial tool implementation

[paulapreuss]

The approach so far consists of:

• I set up a class for the financial tool
• Upon initialization, the financial tool collects system and financial params (some params still missing)
• System and revenue over lifetime tables and capex calculation already works (some tweaking needed to collect some cost parameters that are not there yet)
• Some other tables still don't work in the tool, but I have been able to reproduce everything from the excel table manually

Will try to get it far enough to be able to actually show something from it on the GUI on tuesday, so will probably focus on making some graphs for the things that already mostly work (CAPEX including all costs or revenue flows)

[paulapreuss]

Things pending to discuss about the financial tool:

• Variables that are present in the excel table / code but not as inputs in the tool:

  • Growth rate for OM costs (excel D31)
  • Diesel fuel price increase (included in tool but default does't match, should we set default to 3.8%?) (excel D32)
  • Transformer, substation and mounting structure are set to 0 in excel - will it stay like this?
  • SHS OM costs in excel are set to $7 / SHS system / year. Is this correct and should it stay in the background?
  • Loan tenor = 10 years and grace priod = 1 year in excel. Is this correct and should it stay in the background?
  • Should there be only one loan or multiple (junior and senior)? → currently loan according to capex*debt_share
  • Depreciation years = 20 in excel. Is this correct and should it stay in the background? Or should this always be equal to project duration?

• Calculations that are still unclear:

  • In excel, VAT is calculated from labour, logistics, transformer and mounting structures. Is this correct? If transformer and mounting structure stay as 0, current setup doesn't need to be changed (only accounts for labour and logistics)
  • Is there a reason why SHS is not included in Power Supply System total CAPEX? Is this a mistake or should it be calculated like this? → in current class setup, SHS is included in System CAPEX
  • Community / Project developer equity cannot be input, only debt share and grant share
  • → Should the equity be calculated as100% - grant share - debt share? Should this be communicated in some way or should there be another input parameter?
  • → Do we need to set up a constraint so thatdebt share + grant share cannot be higher than 100%? Is it allowed to be lower than 100%?
  • WACC in excel is calculated from loan and equity amounts and interest rates instead of static (C64). What should we be doing here?
  • What values does the wanted goal seek function for the tariff need to be applied to?
  • Excess generation can't be calculated over project lifetime → this is not important until we include demand / consumer growth and only if we consider feed-in tariff, which we are not as of now, correct?

• Needed for implementation plan / results:

  • What graphs should be displayed from these calculations?
  • What tables should be displayed from these calculations?

Resulting tasks after clarifying (either here or merge and handle in separate PR:

• [ ] Set up output graph functions (If like FATE, line graph for revenue, opex, cash flow over lifetime, bar/pie for costs. Best double check what is wanted but graph type according to output table format could already be set up), also clean up outputs view when this is set up
• [ ] Set up output tables (check what is wanted)
• [ ] Set up goal seek function
• [ ] Set up default values or input fields for unclear variables
• [ ] Double check / fix unclear calculations

[paulapreuss]

One thing I notice as a reviewer of the code, is that it is still not very easy to follow the steps of pandas transformations for certain costs calculation. It is maybe a nice to have but I think it could also help communicate around those calculations (and possibly help finding bugs/errors in the model) if we could write them as mathematical formulas with variables

I originally translated the excel into python in a jupyter notebook that also includes the written out formulas :) I didn't think it really belonged in the repo so I didn't upload it, but we can talk about where best to save it so it is accessible to people who want to look into it.