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Magnus Pernemark avatar image
Magnus Pernemark asked

Enhancement feature: Peak shaving feature

fIn Sweden and maybe other countries an effect tarif is introduced. This means you pay an extra fee based on the maximum kWh per hour you buy from grid during a whole month. Eg, if you buy 2kWh every hour for one month, but one single hour during that month you buy 5kWh, you will pay a fee for 5kWh times 3-5 euro per kWh, just because of that hour that month.

When using ESS you can set a grid point. Usually you want that to be 0W so batteries charge when there is an excess of energy, and discharge when more grid power is needed.

Settinggrid point to 1500W, will make victron to discharge above 1500W, but charge below 1500W. Not very effective when being charged hourly rates for the electricity.

It would be a nice feature to extent the ESS grid settings with more parameters.
Like having two grid points. One for charging, and one for discharging?
Grid point 1: 0W
Grid point 2: 1500W

Charge batteries when below grid point 1, discharge when above grid point 2, when in the middle do nothing, no charge/no discharge.
If both grid points are the same, use it as if there was only one grid point, like today?

What do you think, Victron?

EDIT: One other possible feature for peak shaving could be, discharge enough power to meet a hourly goal. Eg. you allow the system to import a maximum of 2kWh per hour. After this, batteries take over and discharges enough so no more power is bought during that hour.

Some power companies have different fees for different times during the day.
Eg, duing peak hours (7-19) high fee, rest of day no fee, others have fee 24/7. So a time intervall would be nice too

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·
Sounds interesting; anyone else has comments or ideas about this?




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daryl avatar image daryl mvader (Victron Energy) ♦♦ commented ·
I feel that over time ESS needs to become smarter to deal with the change in network tarriffs like this one and variable export rates (eg you get more for your exported power early in the morning and late afternoon than the middle of the day).


I do worry about the Venus UI becoming unusable as many complex configuration items are added to it. It doesn't have any real help inside it to describe the options that can't be described in a couple of words.

I wonder if Node-Red is a better way forward for more edge case complex configuration scenarios. Perhaps with a Victron catalog common of Node-Red flows?


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Magnus Pernemark avatar image Magnus Pernemark daryl commented ·
@daryl I agree, the more 'clutter' the harder it would be to use. In the nordic european countries, electricity is fixed at a market price, every hour. The price differance could be huge. Some nights electricity is basically free, even negative prices have occured (you get paid to use electricity) and some hours during the day the price could be 30 US cents (the latter is extreme prices here).

A way to charge and discharge based on fees is a very welcomed addition, but such a feature would diverge from the core funtionallity and would fit perfectly in a node-red environment. The fetching of prices would probably differ quite much from region to region, country to country.

My proposal for a "peak shaving feature" would probably not divigate to much from the existing functionallity, and in my opinion would fit nicely with the existing ESS functionallity.
My battery is big enough for me to keep a zero-feedin policy between april and september, but october to mars I would very much like it to charge only if excess power is available (grid exports), but only discharge if needed power is above x kW. (that would be, charge if grid is below zero, do nothing if needed power is between x and y watts, discharge if above y watts)

And a more advanced feature would be to monitor grid usage and have a hourly maximum of imported electricity. Eg. buy a maximum of 2kWh per hour. Then you could use 5000W for 20 minutes and inverters would not discharge, The remaining 40 minutes you have 0.3kWh left, before inverters would "shave the peak" so total for that hour never exceeds 2kWh import

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r2d2 avatar image r2d2 mvader (Victron Energy) ♦♦ commented ·

In reply/addition to Magnus' nice to have feature :

My battery is big enough for me to keep a zero-feedin policy between april and september, but october to mars I would very much like it to charge only if excess power is available (grid exports), but only discharge if needed power is above x kW. (that would be, charge if grid is below zero, do nothing if needed power is between x and y watts, discharge if above y watts)

I'd like to add that this feature becomes more or less a 'Must have' for the Belgian market as from July 2022. In short : a setpoint for grid export and a grid setpoint for shaving combined with a date-window when to be applied (e.g. october to mars).

This is a must have feature as all recent competitor systems have it already in place

and it will be a determining factor when choosing an ESS system.

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Kevin Windrem avatar image Kevin Windrem commented ·

Here in California (Pacific Gas and Electric grid), there is about a 15% rate difference between "peak" (currently 4-9 PM) and "off-peak" (during summer months only!). It would be nice to shift most or all of the consumption from the grid away from the peak time period. (The timing of the peak period is such that grid-tie solar really is not much help.)


Actually getting an ESS system designed and approved for use on the PGE grid is yet another issue but grid power consumption shifting should be possible without ESS.


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