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--- drafts:dynamic_ess [2024-09-04 10:36] – [FAQ] dfaber
+++ drafts:dynamic_ess [2024-11-09 15:16] (current) – [Q: My providers changes price at the half hour instead of the full hour] aleximb
@@ Line 1: / Line 1: @@
 ====== Dynamic ESS - manual ======
-===== What is Dynamic ESS? =====
+===== Smarter energy, bigger savings with Dynamic ESS =====
-Dynamic ESS is an algorithm that aims to minimise the costs made on the grid and battery:
+With Dynamic ESS, your Victron system becomes even smarter. It optimizes your battery's charge and discharge cycles by leveraging electricity prices, solar production forecasts, and your unique consumption patterns. Dynamic ESS will help you save money on your energy bill.
-  * By scheduling charge/discharge cycles of the battery,
-  * While taking grid limitations, battery specifications and day ahead energy prices into account,
-  * When it can, it also considers the consumption and solar yield forecasts when scheduling.
-Also check these community posts for remarks and further troubleshooting:
+Whether you're managing a home or a larger installation, Dynamic ESS helps you optimize your solar and battery system for maximum efficiency, while actively contributing to a more sustainable future.
-  - [[https://community.victronenergy.com/articles/232720/dynamic-ess-on-beta-vrm.html|Dynamic ESS on Beta VRM - part 1]]
-  - [[https://community.victronenergy.com/articles/236792/dynamic-ess-on-beta-vrm-part-2.html|Dynamic ESS on Beta VRM - part 2]]
-  - [[https://community.victronenergy.com/articles/245772/dynamic-ess-on-beta-vrm-part-3.html|Dynamic ESS on Beta VRM - part 3]]
-  - [[https://community.victronenergy.com/articles/256073/dynamic-ess-on-beta-vrm-part-4.html|Dynamic ESS on Beta VRM - part 4]]
-  - [[https://community.victronenergy.com/articles/266992/dynamic-ess-on-beta-vrm-part-5.html|Dynamic ESS on Beta VRM - part 5]]
-==== Can I use it? | Eligibility Criteria ====
+If you have dynamic energy rates or off-peak energy prices, start configuring now to take full advantage of your setup!
-Dynamic ESS is only eligible for the installations which fits the following criteria:
+{{:drafts:phone_mocks.png?600|}}
-  * Be an ESS;
+==== Two modes: green or trade ====
-  * Not use Generator connection outside of power outages;
-  * Run Venus OS v3.30 (or newer)
-For best results:
+We offer two operating modes to cater to different preferences for managing energy. Not everyone is comfortable with the risks of the energy market, so we have created modes to fit various needs:
-  * Have a variable or dynamic energy contract.
-  * Use a supported energy meter (especially if your system setup has heavy loads (EV charger, heat pumps) in front of the Victron system). See [[drafts:dynamic_ess#qwhy_does_the_system_exceed_the_configured_power|here]] for more information on this.
-Note:
+=== Green Mode ===
-  * Only the dynamic energy contracts of the following countries are supported for day ahead prices: //Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Montenegro, Netherlands, North Macedonia, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine and the United Kingdom.//
-  * If you have fixed prices (which may differ weekends/weekdays/daytime/nighttime), you can also use it outside these named countries.
+Sell surplus solar power back to the grid after covering your consumption and charging the battery.
+Reserve battery energy for your own use.
+Charge your battery when prices are low to save more.
-===== How can I get started? | Configuration =====
+=== Trade Mode ===
+Always sell surplus solar power back to the grid.
+Use the battery energy to take advantage of trading opportunities.
+Charge your battery when it’s most beneficial for trading.
-{{:drafts:dynamic-ess-settings.png?direct&200 |}}
+Green Mode is ideal for those who prefer a safer, more predictable approach, while Trade Mode is perfect for those looking to maximize their gains through trading. You can always switch between modes to find what works best for you.
-To get started, you need to provide VRM with the necessary configuration Dynamic ESS requires. To do this, you can navigate to //Settings -> Dynamic ESS// and follow the instructions on the page. This should take 15 minutes of your time.
-From the page, you can configure the settings in 5 steps. All filled out values can always be adjusted later.
+====== Let’s get started ======
+Setting up Dynamic ESS happens in 5 steps. All of these settings can be adjusted later, so no worries if you make a mistake. Head over to settings → Dynamic ESS in VRM to get started!
-Also make sure that you have set the location of your device (so we can do the correct solar forecast) and have "Two-way communication enabled" on VRM. This is needed for injecting the Target SOC schedules on to the device.
 ==== Step 1: System ====
-First thing we need to know is whether or not you can sell back to the grid or not. If you can, you get additional questions on the power limits when selling back. This is the lowest one of either your grid connection or what your system is capable of. So if your grid connection can do 4 kWh and your system 2.5 kWh, fill out 2.5 kWh.
+First, confirm whether you can sell excess electricity back to the grid. If so, you'll be asked to provide details on the power limits for selling. The limit will be the lower value between your grid connection capacity and what your system can handle. For example, if your grid connection supports 17 kWh but your system can only handle 10 kWh, enter 10 kWh.
-Note that this is part is setting the capabilities, not actually setting limits for the system to use. See [[#qwhy_does_the_system_exceed_the_configured_power|here]] for info on setting limits for the system.
+Note: This step defines the system’s potential capabilities, not the actual operational limits you'll set later.
-Then you need to set the operating mode:
+{{:drafts:step_1_config.png?400|}}
-  * Green mode:
+==== Step 2: Battery information ====
-    * Only sell surplus solar back to the grid after consumption and battery charging
-    * Energy in battery is reserved for consumption
-    * Charge battery when prices are low
-  * Trade mode:
-    * Always sells surplus solar back to the grid
-    * Energy in battery is used to trade
-    * Charge battery when it is beneficial for trading
-You can always adjust this mode at a later stage, so pick the one that best suits your needs.
+Next, provide key details about your battery:
-==== Step 2: Battery ====
+  * Battery Capacity – To calculate what 1% of the battery's State of Charge (SOC) represents, we need to know the battery’s total capacity.
+  * Maximum Charge and Discharge Power – This determines how much energy the battery can handle for charging or discharging in an hour.
+  * Battery Costs – These reflect the cost of charging and discharging the battery, usually expressed in €/kWh.
-Then we need to know information on your battery:
+To calculate battery costs, you can input the purchase cost of the battery, the estimated number of charge cycles, and the battery’s capacity. Use the formula:
-  * //Battery Energy Capacity// - In order to calculate how much 1% of SOC of the battery is, we need to know how much capacity the battery has.
-  * //Maximum charge and discharge power// - This is used for determining the maximum amount we can (dis)charge the battery in an hour
-  * //Battery costs// - Battery costs indicate how expensive it is to use it for charging and discharging, expressed in €/kWh. A typical calculation for this is:
-    costs for buying the battery in € / (charging cycles * battery capacity in kWh)
+Battery cost (€) / (Number of charge cycles * Battery capacity in kWh)
-One battery charge cycle equals full battery charged to 100% and fully used to 0%. If you only use half of the battery power, then recharge it and repeat it the following day — it will also count as one charge cycle instead of two. The number of charging cycles is a number that differs per brand. The battery costs is usually somewhere between € 0.02 and € 0.06 /kWh.
-Some feedback of users is that they don’t care about the battery costs, as they already paid for it, so technically there’s no additional costs to charge it. In that case we still advise to put a small amount in as battery costs. E.g. 0.01 €/kWh.
-In order to make the calculation for you, you can also fill out the invoiced battery cost and the estimated amount of cycles the battery can do. Together with the filled out battery capacity this will calculate the price for you.
+For example, if your battery cost €2,000, has a capacity of 10 kWh, and supports 6,000 charge cycles, the calculation is:
-==== Step 3 and 4: Buy and sell prices ====
-For buying and selling you can either have dynamic (day ahead) prices or fixed prices (which can differ at different times / weekend vs weekdays). So first you need to fill out if you have fixed or dynamic pricing.
+/ (6000 * 10) = € 0.03/kWh
-=== Dynamic prices ===
+  * Charge/Discharge Restrictions – You can also configure settings to control when your battery can charge or discharge to the grid. For instance, you may want to restrict discharging to the grid during specific times or days due to national laws.
-Each country and provider uses their own formula for pricing. As the system grows, we will have more and more pre-filled out formula's to select from, but you may need to adjust or fill out your own formula.
+{{:drafts:step_2_battery.png?400|}}
-Unfortunately getting the buy and sell formulas right isn't always straightforward. As all calculations, on when to buy and sell from the grid, are based on the formulas, getting it right is important. Most of the details of your formulas are located somewhere in the contract you signed with your provider. Quite often these contracts are not the most clear documents to read and dissect.
+==== Steps 3 & 4: Buying and Selling Prices ====
-We can give you some general rules and show you what other users have filled out as their formula. With these instructions, you should be able to approximate the actual price you are paying and receiving for your energy.
-Generalised over countries and providers a formula typically something like: //(p+0.02+0.13)*1.21//. It this example it breaks down to:
+For energy transactions, you can use either **dynamic** (day-ahead) prices or **fixed** prices that may vary by time of day or between weekdays and weekends. Indicate whether you're using fixed or dynamic pricing. You can find these rates in your energy contract.
-  * p - the dynamic price / kWh
+For the UK, Spain and France, Dynamic ESS provides an out of the box connection with your energy provider. Refer to the list below to see if that applies to you.
-  * € 0.02 - energy provider profit share
-  * € 0.13 - DSO working price + contributions/levy/transportation fees
-  * 21% - tax
-The sell price formula looks often identical and in common cases looks something like (//p-0.02+0.13)*1.21//. So the energy provider profit share works the other way around.
+=== Your Dynamic Price Formula Made Easy ===
-If the provider takes a 15 % percentage of the day ahead buy price and the taxes are 6%, the formula becomes: //( p * 1.15 ) * 1.06//.
+Getting your dynamic pricing formula is important, but it might not be easy to find in your energy contract. Let’s break it down with an example:
-This is a bit weird, because in case of negative buy prices, the provider is going to pay you extra for all of the energy. Knowing providers, this is quite unlikely. So the more plausible formula becomes:
-//(p + abs(p * 0.15)) * 1.06//, which makes sure that the provider takes its share, even when the prices are negative.
-Also note that, if you don't use euro's, you can set the sites currency in the general settings for your site.
-You can also get some ideas from [[https://github.com/victronenergy/dynamic-ess/issues/72|this issue]].
+When you sell energy back to the grid, you get the base rate from your energy provider. But when you buy energy, you also pay VAT and an extra charge of 11 cents per kWh.
-=== Fixed prices ===
+**Selling Energy**: Your selling formula is just: P
-If you have a fixed prices contract, you can still have different prices at different moments of the day. In some cases you can have different prices between weekdays and weekends. So that is the first question to answer.
+**Buying Energy**: Your buying formula is: P * 1.21 + 0.11
-Then, you can fill out the price per hour (more granularity is currently not possible).
+If you’re not sure about your rates, start with a simple P for the price. You can compare the numbers in VRM with those in your energy provider's app to check if they match.
-==== Step 5: Confirmation ====
-In the final step you see the filled out values summarised. If you need to make adjustments, you can do so. Otherwise you can //submit// the form.
+{{:drafts:step_3_buy_prices.png?400|}}
-Now navigate to the installation’s Dashboard and click the button shown below to open the Controls menu. Under the ESS section, you will find Dynamic ESS controls.
+==== Step 5: Confirmation ====
-{{:drafts:controls-screen.png?nolink&600 |}}
+In the final step, review a summary of all the settings you’ve entered. Make any necessary adjustments, then submit the form to activate Dynamic ESS.
-==== What's next? | After configuration ====
+===== Tracking your daily energy schedule =====
-As the configuration flow points out, you can navigate to the //Installation Controls// -> //ESS settings// to see the running state of Dynamic ESS. The switch is green when Dynamic ESS is on and red when it is switched off.
-{{ :drafts:dess-control.png?direct&200 |}}
+Once you've configured Dynamic ESS, a new section will appear at the bottom of your VRM dashboard. This section displays a graph showing today's energy prices alongside the Dynamic ESS plan. Starting from around 3 PM each day, you'll also be able to view the prices and the plan for the following day. Dynamic ESS will be on by default. In the controls panel, you’ll be able to enable and disable Dynamic ESS. Note that Dynamic ESS saves most money when left on for extended periods of time.
-The //Auto// (green) mode is the usual mode in which Dynamic ESS should operate. If you want to disable Dynamic ESS, toggle the switch to //Off// (red).
-The state of Dynamic ESS will also show on the dashboard, just after the title. As a side note: If you run [[https://github.com/victronenergy/dynamic-ess|the Node-RED implementation of Dynamic ESS]], here it will show "Node-RED".
+===== Want to know more? =====
-====== Operational ======
-==== Data Visualisations ====
-Once operational, you can find Dynamic ESS visualisations that appear below the installation data charts on the //Dashboard// page. There you can find a graph showing the current forecast:
+For more information on Dynamic ESS, check out our frequently asked questions. For some countries, Dynamic ESS provides an out of the box connection with your energy provider. Refer to the list below to see if that applies to you.
-{{ :drafts:dess-forecast.png?nolink&800 |}}
-On the left side of the vertical line, you see the recorded values. On the right side of the line it shows the solar forecast, the consumption forecast and also the target SOC that will be followed (as scheduled during the last calculation for the site).
+===== For Victron installers =====
-By clicking on the legend, you can enable or disable shown data sets in the graph.
+As a Victron device installer, Dynamic ESS allows you to offer enhanced value to your clients while unlocking new sales opportunities. By intelligently optimizing battery charging and discharging based on dynamic electricity prices, Dynamic ESS helps users achieve significant cost savings.
-Below you first find a summary on the totals for the day and then there are three tabs which visualise:
+These savings can be further amplified with larger battery capacities. As customers see the financial benefits of increased battery storage, they are more likely to invest in expanding their energy systems. For you, this presents a straightforward path to upgrading your service with advanced, seamlessly integrated features, positioning you as a provider of efficient, cost-effective solutions that can drive additional device sales and strengthen customer satisfaction.
-  * Costs and earnings made as a result of Dynamic ESS usage;
-  * Schedule of battery and grid usage;
-  * All energy factors which are taken into account when scheduling
-=== Costs and earnings ===
-This tab begins with a summary that compares the system using Dynamic ESS with the system using regular ESS.
-=== Schedule ===
-{{ :drafts:dess-buy-sell-prices.png?nolink&800 |}}
-The prices graph is available on both this tab and the //Energy// tab. It shows the buy and sell prices per hour.
-{{ :drafts:energy-usage.png?nolink&800 |}}
-The usage graph shows the energy usage of the grid and of the battery in kWh.
-=== Energy ===
-The prices and graph is the same one as on the //Schedule// tab. It shows the buy and sell prices per hour.
-{{ :drafts:dess-energy-graph.png?nolink&800 |}}
-Then there is the energy graph, which summaries everything the system has done and is planning for.
-==== Warm-up period ====
-Dynamic ESS uses consumption and solar yield forecasts to schedule ahead, when the forecasts are available. Depending on the historical data available prior, the accuracy of these forecasts can vary. As it stands now, optimal consumption forecasts need 28 days of past consumption data and optimal solar yield forecasts need 28 days of past solar data. Thus, if there is not enough data the forecasts might be suboptimal which makes the performance of Dynamic ESS suboptimal. However, despite lower accuracy in forecasts, turning Dynamic ESS on in this period is still more cost-efficient and it gets better every day until it reaches its optimal state after 28 days of warm-up period.
-==== Unexpected behaviour? ====
-It is possible that you deem the behavior of Dynamic ESS to be unexpected or suboptimal. Depending on when it happens, there are two possible causes:
-  * If the suboptimal scheduling is in the future plan, it is probably due to the configurations set by the user. For instance, battery costs being high leads to limited usage of the battery.
-  * If the suboptimal scheduling is in the past, then it is mostly due to the inaccuracies that come from consumption or solar yield forecasts. It is important to note forecasting will always come with its inaccuracies and even with these inaccuracies at distinct hours, Dynamic ESS minimizes costs compared to Default ESS mode in the longer run.
-  * Make sure you have the formula's right. The system uses these to determine the price per hour and, if they are not correct, the system will make the wrong decisions.
-You might also want to read the chapter on [[#determining_the_target_soc|determining the target SOC]], to get some more idea on how the algorithm determines the optimal (dis)charging path.
-If you feel like the behavior that you are observing is not explained by above points and you cannot find the answer in the [[#faq|FAQ]] below, you are encouraged to visit the [[https://community.victronenergy.com/articles/232720/dynamic-ess-on-beta-vrm.html|community thread]] dedicated to this. If needed, please also report your issue [[https://github.com/victronenergy/dynamic-ess/issues|here]], containing the VRM tag.
-====== Implementation ======
-This part of the documentation is about how the system works on a technical level, as it might help troubleshooting for the more advanced users. The system works by taking all of the available data (day ahead pricing/fixed prices, solar forecast, consumption forecast, current SOC and minimum SOC) into account and calculating the optimal planning for the next hours. It looks as far ahead as it has information on the pricing. In case of day ahead prices until the end of the known prices (midnight when the prices are not in yet, tomorrow midnight once the prices get available). In case of fixed prices, the system always plans 48 hours ahead.
-The planning is being converted into a target state of charge for the batteries per hour and whether or not the system can feed in to the grid during that hour. If the target SOC is lower than the current SOC, the batteries discharge (either to consumption or the grid; if feed-in is allowed), if the target SOC is higher than the current SOC the batteries get charged (either from solar or from grid). The upcoming four hours schedules are put into the GX device via the two-way VRM communication channel. On the dbus these schedules can be found under `com.victronenergy.settings`, path `/Settings/DynamicEss/Schedule/[0-3]`. Each schedule has a unix timestamp as starting time, a duration (typically 1 hour, 3600 seconds), a target SOC and a boolean value for if feed-in is possible.
-Every few seconds the GX device will compare the target SOC with the current SOC and determine the power to use to reach that target before reaching the timestamp + duration. So it takes the full hour to reach the target SOC.
-In all cases, when the target SOC changes, it will calculate the charge current required to get there, and then distribute that over all the chargers, with the solar chargers getting priority.
-If it needs more current to get there than solar provides, it will charge from the grid for the rest, but only if the price of the grid is not too high.
-===== Determining the target SOC =====
-Several people want to know how the algorithm determines the target SOC. This is done by taking 4 steps for each site running Dynamic ESS on each re-calculation of the schedule. This is typically done each hour.
-  - Obtain data;
-  - Set boundary conditions (battery, grid and the consumption/pv yield boundaries);
-  - Find the most optimal charging cycle according to the data at hand and the battery/grid costs;
-  - Attempt to reach the target SOC for the current hour by the end of this hour
-We've ran a lot of simulations to check if we needed to increase the frequency of re-calculation, but that does not help much. In hindsight it is easy to conclude when the algorithm was off in its prediction. But usually it matches it quite well.
-We keep the battery stable and not the grid: in our internal testing keeping the battery usage stable (basically the same as the plan) has been a lot more cost-effective than otherwise, because of the battery costs that pile up.
-Also keep in mind that, when doing a consumption forecast, the system does not known when during the hour that consumption will be done. If the forecast does not match the reality, Dynamic ESS does keep the planned battery usage stable while punishing the forecast inaccuracies on the grid (selling the excess to grid, buy the additional need from the grid). This can be less ideal, but it is an issue of the forecasts being inaccurate, nothing that the Dynamic ESS decided.
-===== The Node-RED implementation =====
-There exists also a [[https://github.com/victronenergy/dynamic-ess|Node-RED implementation]] of Dynamic ESS.
-The Node-RED flow uses the VRM API to get the calculation for the site and inserts the hourly schedules into the GX device. If you have specific needs, the Node-RED implementation gives you a lot more options than the current VRM implementation.
-You should only be running one implementation at the same time. If you want to run the VRM version, disable the Node-RED flow. You can read on how to do that [[https://github.com/victronenergy/dynamic-ess/blob/main/VRM-BETA.md|here]].
-====== Country / provider specific ======
-It turns out that some countries have specific pricing rules and regulations. Most of these quirks that affect dynamic ESS have been added below.
-==== Czech Republic ====
-In the Czech Republic there are dynamic transport charges work the same as Denmark, working with peak-tariff and off-peak tariff transport fees.
-==== Denmark ====
-In Denmark there are dynamic transport charges, depending on the time of day. At the moment there is no support for this in our system, but we will plan to add it later on.
-==== Germany ====
-German regulation does not allow feeding in from the battery into the grid (even if the power came from solar). From Venus OS version 3.20~17 it is possible to set certain [[https://github.com/victronenergy/dynamic-ess#restrictions|restrictions]].
-==== Portugal ====
-At least one provider in Portugal only allows feeding in solar to the grid during daytime. This looks a lot like the German regulation.
-In order to set this up, you can select charge or discharge restrictions to be effective at certain times.
-==== UK ====
-In the UK, (fixed) prices are known to change at the half hour instead of the whole hour.
-For dynamic prices in the UK, we are supporting users with Octopus contracts. Setting up Dynamic ESS in the UK is simple. All you need is your Octopus API key, which you can easily obtain by following the steps in [[https://www.youtube.com/watch?v=lEfry72-vdQ|this video]].
-In addition to your API key, VRM will need your account number and information about your payment method (e.g., direct debit), as these factors influence your energy pricing. Once you’ve entered this information, you’ll be able to see your Octopus energy prices displayed in the Dynamic ESS graphs on your dashboard.
-At the moment (4-9-2024) this functionality is only available via [[https://betavrm.victronenergy.com/|beta VRM]].
-If you’re living in the UK but don’t have a dynamic energy contract, you can still use Dynamic ESS with fixed prices.
 ====== FAQ ======
@@ Line 239: / Line 108: @@
 ==== Q: Why can't I find dynamic ESS on VRM? ====
-Right now (early March) Dynamic ESS is still in beta and only available via the beta VRM site. We expect to have Dynamic ESS ready for the officially launch in March 2024, after which it will no longer be needed to use VRM beta.
+There are some pre-conditions a site must fulfill in order to get the “Dynamic ESS” menu option. Make sure that the site's system type is set to ESS or Hub-4. If it is not set to this, you need a different ESS assistant, which can be configured through VE.Configure. When in doubt on how to do that, please ask your installer for help.
-For those of you who aren’t familiar with beta VRM, you can log in through [[http://betavrm.victronenergy.com/|this link]] with your normal credentials.
-==== Q: Why can't I find dynamic ESS on Beta VRM? ====
-There are some pre-conditions a site must fulfill in order to get the "Dynamic ESS" menu option. Make sure that the sites system type is set to //ESS// or //Hub-4//. If it is not set to this, you need a different ESS assistant, which can be configured through VE.Configure. When in doubt on how to do that, please ask your installer for help.
 ==== Q: Which energy meters are supported? ====
@@ Line 251: / Line 115: @@
 [[https://www.victronenergy.com/upload/documents/Datasheet-Energy-Meters-Selection-Guide-EN.pdf|energy selection guide]] for supported meters.
-Things like the Dutch P1 meter are not sampling fast enough and not supported right now.
+==== Q: What is the default behaviour if the VRM connection is lost longer than 12 hours? ====
-==== Q: What is the default behaviour if the VRM connection is lost longer then 12 hours? ====
 The system will run out of its schedule after 12 hours and revert to standard ESS operation. Once the connection is reestablished, new schedules will get added again and the Dynamic ESS will commence its operation.
 As the system is partly depending on third-party services (e.g. for retrieving the day ahead price information). If we are somehow unable to fetch new pricing information, the calculations can no longer be done and the system will run out of schedule too. We have monitoring in place to check for this.
 ==== Q: Can the system handle charging my EV or other heavy loads? ====
-The short answer is no. The longer answer is that we are working on this, but as it is not that straight forward to come up with a solution that is user friendly and works for everyone, it can take a while before support for this will appear.
+It will be able to in the future.
 See [[drafts:dynamic_ess#qwhy_does_the_system_exceed_the_configured_power|here]] for information on the options of limiting power.
 ==== Q: Is there an API available? ====
@@ Line 310: / Line 174: @@
 Under the //Settings -> General// part of your site, you can set your currency.
-==== Q: My providers changes price at the half hour instead of the full hour ====
-Some (UK) providers offer fixed prices that change on the half hour instead of at the full hour.
-Unfortunately the 30 minute interval has some more implications than just allowing it to be entered into the fields.
-The calculations and forecasts are currently done on the whole hour, so that needs to be accounted for as well. And the same goes for the graphs. All not impossible to solve, but not trivial either and needs a fair bit of testing.
-So the 30 minute interval will be added eventually, but it will take some more time.
 ==== Q: Why does (dis)charging slow down or speed up towards the end of the hour? ====