# Newbie: dynamic contract + solar +battery +heat accumulators +boiler +PHEV +smart thermostat **URL:** \ **Category:** Energy\ **Created:** [February 24, 2025, 1:02pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479 "2025-02-24T13:02:48Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Tanguy\_Legrand](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/tanguy_legrand/32/121589_2.png) [@Tanguy\_Legrand](https://community.homey.app/u/Tanguy_Legrand)\ **Post date:** [February 24, 2025, 1:02pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/1 "2025-02-24T13:02:48Z")
Dear, I am a complete newbie with Homey, and I need some guidance for the first project for my parents. They live in a house that used to be heated solely by heat-accumulators (they used to have a special contract for the accumulators). (model: Dimplex CXL S24N) Location: Belgium Since some renovations they also have a gas fireplace. They currently have solar panels with a non hybrid inverter. They also have a Mercedes PHEV. The plan is to: -convert to dynamic energy contract (power by the hour) -install an hybrid inverter (probably Growatt) with 10 kW of battery power (and a smart meter) -install a homey compatible smart thermostat What I want to achieve (all through AI and smart usage of the dynamic contract): -charge the heat-accumulator during the cheap hours (mostly during the night, if needed around 12h we also have a pricedip) -charge the boiler at night and with any excess solar production -charge the PHEV at night -charge the battery at night (if no or little solar is expected) and use the battery for all electrics untill we are back at low cost energy What I think I need. Homey Pro DIN Rail Smart Switch for charging the heaters at night DIN Rail Smart Switch for the boiler Smart Plug for the PHEV Questions: -what app is the best to use to predict the solar production (no need to charge the boiler/PHEV if the next day the sun will shine) -can Homey/the smart thermostat “calculate/adjust/learn” how much we need to charge the heat-accumulators at night in order to have a good temperature during the next day? I still need to check if the Gas-Fireplace can be automated (to use it if it’s cheaper then charging (recharging around 12h) the accumulator, offcourse it’s always a good backup! Thanks Tanguy ---
**Author:** ![Rmb](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/rmb/32/79135_2.png) [@Rmb](https://community.homey.app/u/Rmb)\ **Post date:** [March 19, 2025, 9:45am UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/3 "2025-03-19T09:45:45Z")
I would suggest to start with a more simple project. So you get an idea of the complexity of your question and the required hours of effort. ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [March 19, 2025, 10:42pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/4 "2025-03-19T22:42:24Z")
I agree with RMB, this is very complex to build. Usually this is how it works: you show the flow(s) you could come up with, and we can help improve and/or share ideas on how to proceed > [@Tanguy\_Legrand](#): > > what app is the best to use to predict the solar production > [@\[APP\]\[Pro\] Solar Forecasts (SolCast + Forecast.Solar)](https://community.homey.app/t/app-pro-solar-forecasts-solcast-forecast-solar/46842): > > Solar Forecasts Homey app using the Solcast API or Forecast.Solar to get solar forecasts customized for your location and installation Links You can download the app here: [Solcast](https://homey.app/nl-be/app/com.solcast/Solcast/)Usage You could use the app to switch on electric appliances or charge a car or battery based on the forecast solar power, to maximize self-consumption. You can compare the daily forecast with your actual production. Solcast Setup Sign up your solar installation at [Solcast Toolkit](https://toolkit.solcast.com.au/live-forecast) You have to setup the … > [@Tanguy\_Legrand](#): > > -can Homey/the smart thermostat “calculate/adjust/learn” how much we need to charge the heat-accumulators at night in order to have a good temperature during the next day? Homey can calculate “anything” you like. But _how_ to calculate this, is out of my league ---
**Author:** ![Rmb](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/rmb/32/79135_2.png) [@Rmb](https://community.homey.app/u/Rmb)\ **Post date:** [March 19, 2025, 11:02pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/5 "2025-03-19T23:02:23Z")
> [@Peter\_Kawa](#): > > But _how_ to calculate this, is out of my league This gives a hint: > **[Predict your gas/energy usage for heating using degree days from Netherlands...](https://community.home-assistant.io/t/predict-your-gas-energy-usage-for-heating-using-degree-days-from-netherlands-knmi/800762)** > > This solution relies on data from the Dutch Meteorological Institute (KNMI) and as such is only relevant for people living in the Netherlands. There a several different implementations on this forum. See this post for some of them. I believe this... ---
**Author:** ![Tanguy\_Legrand](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/tanguy_legrand/32/121589_2.png) [@Tanguy\_Legrand](https://community.homey.app/u/Tanguy_Legrand)\ **Post date:** [March 20, 2025, 1:40pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/6 "2025-03-20T13:40:26Z")
thanks for the reply’s! I have some homework to do now 😉 ---
**Author:** ![FKey](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/fkey/32/14793_2.png) [@FKey](https://community.homey.app/u/FKey)\ **Post date:** [March 20, 2025, 8:42pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/7 "2025-03-20T20:42:04Z")
> [@Tanguy\_Legrand](#): > > -charge the boiler at night and with any excess solar production You can use my car [charging flow](https://community.homey.app/t/app-amina-power-up-your-smart-home-with-amina-s/114193/6) on surplus solar as inspiration. Its really working well to reduce excess solar to almost zero ---
**Author:** ![FKey](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/fkey/32/14793_2.png) [@FKey](https://community.homey.app/u/FKey)\ **Post date:** [March 20, 2025, 8:45pm UTC](https://community.homey.app/t/newbie-dynamic-contract-solar-battery-heat-accumulators-boiler-phev-smart-thermostat/131479/8 "2025-03-20T20:45:22Z")
> [@Tanguy\_Legrand](#): > > -charge the boiler at night > -charge the PHEV at night > -charge the battery at night Sounds like you also need to think about load balancing… Ttyese are all high power devices, you do not want to blow you main fuse.