I have had some past experience in dealing with a Solar Panel installation client working in commercial business. I had a look at the different grants and tax benefits as I have had some past experience in dealing with these things.
I can help you in preparation of the summarized excel spreadsheet which will help you in calculating customized sales proposals for a number of clients.
I can see that the first part of calculation of cost of Kwh wouldn't be a problem as they can be derived from the area. Tax and Grant calculations will take time as there will be many conditions involved in claiming the grant. If you could provide me all the information to apply for a grant and tax credit then it will reduce most of my time. If I need to consider that the client fulfils all the conditions then I will have to walk through the whole area for all the different grants and tax credits conditions. If that can be considered by you manually then it would be great.
Third part needs to be robust as these are variable calculations as someone might prefer to have the add ins. I can help you with that as well. My time on this will also depend on the level of variable add ins sold by the company. If around 20 to 30, it's fine. If more than that, it will consume a huge amount of my time.
Also, we can add the number of sunny days in a year to show the cost savings to the client per year and the cost recovery period.
Approx. project time depending on below conditions:
1. Information of grants and tax credits is provided by you. If not, then researching minimum will take 5 to 10 hours of my time.
2. NOT adding any conditions to fulfil the grant. This will be evaluated by you on the site by your knowledge. I would prefer this be done by you.
3. Variables are not more than 30.
4. Cost information of parts involved in installation is provided by you.
Approximately it will take 5-15 hours depending on the information.
End result will be, you only need to input area and variables in the excel sheet, excluding conditions requirement assuming that the client can get hold of all the grants and tax credits.