VPP Mechanics

1 Reply 5119 Views

I’m approaching my first year with AGL’s VPP plan and have been watching it at work as activity has gradually increased and the reasons why and when it activated become clearer in terms of weather etc.


So far as it’s possible for me to see there have been only grid to battery direct interventions, no battery direct to grid.


I’ve read the VPP contract and don’t have any fears about it. It’s easy to buy out if the situation ever arises and the limits on what AGL can do are clearly set out. It’s not compulsory, locked in or whatever, and better than that it’s possible to see how it can work to the mutual benefit of the parties.


Now I’m seeking to confirm some more details of the game, things that I’ve assumed so far are the way they are in the contract on the basis of fairness, and my own cross check calculations using daily results recorded from AGL Accounts, and monitoring data via the Tesla App and the website provided by the supplier of panels and inverter.

I’ve got a time of day rate contract for energy supplied, - peak, shoulder and off peak, plus a feed in rate below the off peak supply rate.


Once again, as far as it’s possible for me to be sure, significant direct grid to battery events have always happened during night time off peak and cross checking from a couple of directions suggests the supply into the battery is provided at the off peak supply rate.


The strategy seems clearly one of making sure that on days of low panel energy generation the battery will be close, or at least much closer than it might otherwise have been to full when the morning shoulder supply rate begins, also with a good chance of getting through to the evening off peak begins when another battery VPP top up commences.


I’m pleased to report that the strategy seems to work. In mutual benefit context the negative to me of getting power during off peak VPP events that can and does occasionally mean a burst of sun during the ensuing day can see me selling one or two kWh back to the grid at about a third less than I paid. The positive for me is that I am almost never in a situation of having to significantly access daytime peak supply rates and not very often called on to use shoulder rate supply either.


Until I get some good information from AGL on how much the VPP trial is costing and benefitting me in reasonably quantified terms I’m not ready to declare trial over and count me in, so I’d like to hear from you AGL about the validity of my assumptions and how realistic my impressions of experience are of VPP operation with what you see of my account from your side.


Whether or not AGL respond and how generous they are with information I’d very much like to hear from any other member of this VPP Community.

I am already encouraged by some of the contributions but understand the more cautious approaches others have.

Thank you in anticipation.


AGL Employee
AGL Employee
1 Reply 5071 Views

Hi GPS2119, thanks for your message! Have sent you a private message so that we may be able to assist you further. From what you are saying it seems that your solar battery is set to time of use tariff which means that it charges during off peak hours and discharges when energy prices are high to power your home. This is a setting on your solar battery. Alternatively, it could be set to self consumption mode which will prioritise self consumption of your stored energy. VPP events very rarely involve charging your battery from the grid, they are normally about discharging your battery to the grid to support grid events so this is most likely your TOU setting doing this. Look forward to helping you understand what's happening with your battery further, thanks Jen

1 Reply 5062 Views

Thanks. I hadn't realised I had any level of influence / control at all over VPP. Not at all unhappy to learn that I do have, and at how those interactions are happening as a result.


As a comment, I observe that there are very few occasions where the battery discharges to the grid, and that such discharges which I accept as well within the parameters of the VPP agreement are very modest. Conversely charging from the grid directly to the battery are obviously in line with the TOU plan I'm on, and my comment is that they work very well for me, and I'm happy to have them continue, perhaps even art an increasing level. I understand that the risk to me is that diet charges from grid to battery could from time to time result in sales by me of stored energy back to the grid if subsequent home usage is lower than expected while solar charging in the same ensuing 24 hour period is greater.


Modifying the Tesla App, or developing a new AGL system monitoring App to identify battery grid energy flows as direct source and destination points. AGL accounts could help wth that as well with kWh and cost for such slows alongside the same info already supplied for Solar to Grid and Grid to Home.


Regards, GPS2119



0 Replies 4971 Views

The Tesla App doesn't provide an appropriate level of information for battery charge sources and discharge destinations.

For example, the App only shows "From Solar" as the one source when in fact it's charging from both "Solar" and the "Grid" as a retail consumer from time to time, a feature that's easily enough understood and displayed by the App in the graphic above the tabulated figures.

Also, the App only shows "Energy Discharged", a piece of data for which there's a duplicate data value at the top of the "Powerwall Discharge" display, when in fact it's can discharge to both the "Grid" as a solar generator and to the "AGL VPP" from time to time.

I appreciate is might not be an easy thing to get Tesla to alter their App, and if not possible than that information could usefully be provided in the AGL App / Overview / Battery - as more informative displays of direct values within the VPP (when activated and other than "temporarily unavailable") and / or Energy System pages