PV with battery

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Dirk De Keukeleere
PV with battery

Hi,

I would like to simulate the situation in which I already have bought and installed a PV-installation for some years. Now raises the question if it is beneficial to add a battery to the system increasing the self-consumption. How can I simulate this within SAM? When going into the PV battery module you can (to my understanding) only simulate the simultaneous installation of the PV and battery. not the situation in which the battery is installed later.

Best regards,

Dirk

Paul Gilman

Dear Dirk,

You are correct that you cannot model a situation in which you add storage to a PV system after some number of years.

However, you could create two cases in your file: One for the PV-only system, and one for the PV-battery system. You could then compare the two cases to explore the impact of adding storage to the PV system.

Best regards,
Paul.

Dirk De Keukeleere

Dear Paul,

Thanks for the answer. Your suggestion is valuable, but does not solve my problem. It gives an answer on what the best choice is between installing a PV-installation and installing a PV-installation with a battery. This will give also an idea on how the energy flows will be changed when installing a battery, but it will only give an answer on the operational costs and revenues of installing a battery, not of the entire economic feasibility. Perhaps something to consider in a new version as I think that the case is relevant for many projects.

Best regards,

Dirk

Paul Gilman

Dear Dirk,

Thank you for the feedback. I will share it with the rest of the development team.

SAM's cash flow models were originally designed on the assumption that the PV system in Year 1 is representative of its performance over the life of the project, with an optional annual degradation rate to account for module degradation. The model was designed to be used with typical-year weather data, where one year's worth of hourly data represents the solar resource over a multi-year historical period.

When we added batteries to SAM with explicit modeling of battery replacement costs and schedules, we added the "PV simulation over analysis period" option on the Lifetime input page, which causes SAM to run a separate simulation for each year of the analysis period so that SAM can account for the effect of replacing batteries. When you choose this option, SAM still uses a single weather file for the simulation.

Given that annual weather data with separate files for each year of a historical period is more readily available, it makes sense for use to move toward allowing SAM to run separate simulations for each year in the project life using a different weather file for each year (as it does for the P50/P90 analysis). That would make it possible to change the system design in the course of that period, for example to add or replace batteries, upgrade or replace inverters, add or replace modules, change the load profile, or make other changes.

We are aware of the benefits of this modeling approach, and considering ways to make that possible, hopefully without making the user interface too complicated.

Best regards,
Paul.

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