User avatar
RegGuheert
Posts: 5547
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Online calculator for grid-tied photovoltaics and batteries

Sat Mar 11, 2017 9:40 am

Well, the Grid-Tied Solar & Battery Calculator is taking shape. I don't have the output calculations completed, yet, but I think the page for user input is in pretty good shape now. Unfortunately, it is VERY slow, so please be patient as you make entries in the form. All of the YELLOW cells should be accessible to you.

Here are my current thoughts on how I would like to structure it. Please give me your thoughts on these ideas and also let me know if you can provide a one-year hourly dataset of either PV production or your home's consumption or both that can be used in the spreadsheet.

(Please note that Google Sheets are limited to 2 million TOTAL cells, so that severely constrains the number of year-long hourly datasets I will be able to include given the number of calculations I need to make on each entry. I will try to optimize the flow to allow for the most entries possible.)

Assumptions:

- TVM is zero. (I don't think it is reasonable to try to estimate all of these things: future TVM, future electricity costs, future PV costs, future battery costs, so I will leave them all out and leave them up to your imagination.)

The user entry fields I intend to provide are:
- Dataset to use for home consumption (select from a list)
- Dataset to use for photovoltaic production (select from a list)
- Total Annual Consumption (kWh)
- Local electricity rates (sorry, no base rates, graduated rates or time-of-use metering for now)
- Monthly electricity connection fee
- Total Solar Installed (kWp(DC))
- Installed cost for solar per kWp(DC)
- Solar equipment lifetime (years)
- Number of Enphase AC Batteries (-)
- Installed cost per Enphase AC Battery (US$)
- Enphase AC Battery lifetime (years)
- Number of Tesla Powerwall 2 Batteries (-)
- installed cost per Tesla Powerall 2 Battery (US$)
- Tesla Powerwall 2 Battery lifetime (years)
- Initial charge contained in batteries (%)
- Capacity of other batteries installed (kWh)
- Power capability of other batteries installed (kW)
- One way energy efficiency of other batteries (kW)
- Installed cost per kWh of other batteries installed (US$/kWh)
- Other battery lifetime (years)

The results provided will include:
- Total installed cost for photovoltaics (US$)
- Total installed cost for batteries (US$)
- Total installed cost for both photovoltaics and batteries (US$)
- Total usable battery capacity (kWh)
- Total available battery power capability (kW)
- Total annual electricity consumed from the grid (kWh)
- Cost of all electricity consumed in the absence of net metering (sum of grid costs, photovoltaics and batteries) (US$)
- Overall per-kWh cost of electricity consumed from the grid. (US$/kWh)
- Total annual kWh NOT consumed from the grid due to photovoltaics (kWh)
- Total per-kWh cost of electricity NOT consumed from the grid due to photovoltaics (US$/kWh)
- Marginal per-kWh cost of electricity NOT consumed from the grid due to photovoltaics (US$/kWh)
- Total annual kWh NOT consumed from the grid due to batteries (kWh)
- Total per-kWh cost of annual electricity NOT consumed from the grid due to batteries (US$/kWh)
- Marginal per-kWh cost of annual electricity NOT consumed from the grid due to batteries (US$/kWh)
- Total annual electricity put onto the grid
- NET annual electricity consumed from the grid (kWh)
- Cost of NET electricity consumed in the presence of net metering (sum of grid costs, photovoltaics and batteries)
- Overall per-kWh cost of NET electricity consumed from the grid.
- Total annual NET kWh NOT consumed from the grid due to photovoltaics (kWh)
- Total per-kWh cost of NET electricity NOT consumed from the grid due to photovoltaics (US$/kWh)
- Marginal per-kWh cost of NET electricity NOT consumed from the grid due to photovoltaics
- Total annual NET kWh NOT consumed from the grid due to batteries (kWh)
- Total per-kWh cost of NET electricity NOT consumed from the grid due to batteries (US$/kWh)
- Marginal per-kWh cost of NET electricity NOT consumed from the grid due to photovoltaics
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

User avatar
RegGuheert
Posts: 5547
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Online calculator for grid-tied photovoltaics and batteries

Sun Mar 12, 2017 1:49 pm

I have added the link to the Grid-Tied Solar & Battery Calculator to the OP. The "Results" calculations are not quite complete, but please feel free to try out the "Input" section. Unfortunately, the spreadsheet is VERY slow given the amount of data involved. Please be patient with it!

In theory, the tool allows you to add an EV or two to your home to do the calculations, but I don't have any EV-only data that I can use. Does anyone have a years' worth of hourly data for charging an EV that I can use for the tool?
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

User avatar
RegGuheert
Posts: 5547
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Online calculator for grid-tied photovoltaics and batteries

Sun Mar 12, 2017 6:01 pm

At this point, the key results are all calculated on the 'Calculations' sheet, mostly in Row 9. But since those are the results from just a single condition (house, PV, EVs and batteries), what I think I will do is the following:

- Present some of the data at the bottom of the 'Input' sheet so that you can see key results without switching sheets.
- Present the "full" set of results at the top of the 'Results' sheet in a restricted area, but unlock the rest of that sheet.
- Create headers for a table so that it is easy to take individual results and use "Paste Special" to drop just the values one at a time into the table.
- Then anyone can populate the table one row at a time for whichever conditions they want to try out and possibly plot them.
- Also note that you can add your own sheet (tab) at the bottom if you want to record results. If you label it and it looks like someone is working there, I won't delete the data or graphs.

If there is a simpler way to populate a table with the results from a parametric sweep (or, better yet, a nested parametric sweep) please let me know.

Finally, I've seen a few people pop in to have a look, but no one seems comfortable changing the inputs. I assume this is because I am in there fiddling around. I want to say please go ahead and fiddle with the inputs. How the spreadsheet handles inputs is quite complicated and I would like everyone to see if everything works as they would expect. Thanks!
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

User avatar
RegGuheert
Posts: 5547
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Online calculator for grid-tied photovoltaics and batteries

Mon Mar 13, 2017 4:11 am

RegGuheert wrote:If there is a simpler way to populate a table with the results from a parametric sweep (or, better yet, a nested parametric sweep) please let me know.
It turns out that Excel has this feature, but I do not see a similar capability in Google Sheets. It looks like Excel can sweep a single variable and produce multiple sets of results or it can sweep two separate variables and produce a single set of results.

I'll run a few different parametric sweeps in Excel and upload them to the online spreadsheet. Of course those results can be duplicated in Google Sheets, but it will take some manual capture of the results to produce the output table.
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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