Net Billing for Spain

Hello,

my name is Antonio, I work for CEN Solutions (Spain), where we are studying whether or not to install a PV. Working with SAM I reached the next doubt,

In Spain the bill works the following way. In subhourly (each 15 mins) the correspondant electricity company sees how many kWh you have consumed from grid, and how much kWh you have sold to grid. Each of those terms have differents prices, just because probably you might have to be represented by a electricity company in order to sell energy to the grid, and they will get a piece of your sell income.
So, in this case, lets put the example of a month of July. In this month, we know from other studies, that if we install 600 kWp, we would consume aprox 20 000 kWh from grid, and sell 10 000 kWh to grid. In this case, and with the following prices (sellprice=0.04 and buyprice=0.10) the bill would be:

 20 000 * 0.10 - 10 000 * 0.04 = 1 600 €.

Instead, if I am not wrong, SAM would do the next calculation:

[20 000 (buy) - 10 000 (sell)] * 0.10 =1 000 €. Doing the calculation as a Net, so when I get into the "Data tables" of the simulation, the "Excess generation"  of July would be 0, when that is not true. 

I hope I explained myself crearly enough, and I am looking forward for some help. 

Best regards,

Antonio

PD: I attach images from SAM, where you can see that the excess generation in most months is 0, when we actually will export to grid every month.

Hi Antonio,

The data you show in your table is the monthly kWh excess generation in kWh/month. A better indication of how the electricity bill calculations work is the appropriate $/month value for excess generation, which depends on the metering and billing option you choose:

Billing Option	Monthly Output Variable
Net energy metering	Excess generation (kWh)
Net energy metering with $ credits	Net metering credit ($)
Net billing	Net billing credit ($)
Net billing with carryover to next month	Net billing credit ($)
Buy all / sell all	Buy all sell all electricity sales to grid ($)

You can find more descriptions of these output variables in the "Electricity Bill Results" Help topic under "Electricity Rates and Load" in the table of contents. You can find descriptions of the billing options in the Electricity Rates Help topic.

I think the Buy all / Sell all option may best represent your situation.

Best regards,
Paul.