Net Billing

[Leonidas]

After searching quite long, i cannot figure out if there is the possibility to study and evaluate systems under the condition of net billing. Sepcifically we are talking about self consumption systems, but the excess of energy is stored and sold to the network in a daily basis.

The tricky part here, is that we need to focus and evaluate the system in a daily basis in order to maximise the silmutaneous production and consumption (meaning it is a good exercise for cost..)

I can upload to pv syst not only the prices of the equipemnt but also the energy consumption per hour.

Can you please guide me how can i Set a system like that or even better if there some video tutorials?

[Linda Thoren]

Hello,

In PVsyst it is possible to define an hourly self-consumption profile and in the economic evaluation you can also define precise tariffs for electricity sale as well as calculating the gain from self-consuming compared to grid consumption. I link 2 video tutorials below.

A large enough system will fulfill the energy need by day, as well as injecting the excess energy into the grid. For example, below you see the loss diagram for the DEMO Residential system at Geneva variant VC4 : The result is divided in to user from grid, to user from solar and to grid. 

You can also include a battery storage solution to increase the self-consumption, though it is not yet possible to inject energy stored in the batteries to the grid (unless you use the peak shaving strategy, that can not be combined with a self-consumption profile)

In the Advanced Simulation window, you can then create an Output file with all the relevant parameters for your project in Daily or Hourly timesteps.

I hope this helps to get started with your Net billing project,

Kind regards

 

 

[Leonidas]

Thank you for your remarks.

Currently, the new legislation referers to net billing strategey but with 15min timesteps. So we are talking a model with selfconsumption while the excess of energy either stored or sold to the network but in 15minutes timesteps. That means that we need to compare the energy with this large frequency.. Is this possilble to PvSyst? (the enerfy from batteries cannot be injected to the grid)

Moreover the cost of the electricity that is sold is something unstable and depends on many factors which change it every month. I believe that this is something that cannot be defined in pvsyst, right?

Lastly, in order to design the most suitalbe solution for a client, I am a little confused of how pv syst work. We make scenarios to pvsyst (with different kW or battery capacities) and compare these scenarios in terms of cost adn WE decide the most suitable solution OR we enter data to pvsyst and we wait from Pvsyst the most suitable solution in terms of cost?

[Linda Thoren]

Dear Leonidas,

Sub-hourly simulations are under development, but in the current version of PVsyst the simulation will be done in hourly time-steps.

For the self-consumption profile, you can import a CSV file with sub-hourly values. In the economic evaluation you can import a CSV file with hourly time-steps for each hour of the year. In the following PVsyst help page you find more information about the custom feed-in tariffs:
https://www.pvsyst.com/help/custom_feed-in_tariff.htm

PVsyst will simulate the values you as a user put in, thus it is up to you to define the system that best correspond to your requirement. The input values suggested by PVsyst should be considered as suggestion and not as an optimization or most suitable solution.  

[Leonidas]

Thank you very much. 

 

One more queistion. The feed-in tarrif price is the price teh consumer buys from the grid? Where do we put the price of the energy that the produced sells to the grid (the excess of energy in net billing systems)

Moreover, if there prices of buying from the grid and sellign to the grid, is changinf throught the year, where do we put those data?

 

Thanks

[Linda Thoren]

If you have self consumption you can in the economic evaluation calculate the electricity sale as well as the self-consumption saving, see the two print screens below, where the first one correspond to the electricity sale (feed in tariff price) and the second, the price for the consumer to buy from the grid and thus an estimation of how much money is saved by avoid buying energy from the grid but self consume energy from the PVsystem. These can be in hourly values is you import a CSV file.

 

In the following youtube tutorial, you have more information about how to use the Economic Evaluation in PVsyst (though this example is without self-consumption):

 

[Leonidas]

Thank you very much.

Moreover, please let me know how can I add more than one type of inverter in my installation?

[Linda Thoren]

Hello,

You can define multiple sub-arrays and assign different inverters (as well as lengths of strings etc) to each sub-array. You find a list of the sub-arrays to the right in the system window. In the following youtube tutorial about Multi-MPPT and Power Sharing, you see a few examples of how different inverters have been used in one system configuration.

Kind regards