Programable Smart Load for Ac and Water Heater

I have a EG4-18K and the Smart Load function isn't complex enough.

I have more solar capacity than I can use during the day, and I have more loads than I can run all at once.
I'd there any device that can communicate with Smart water heaters, Smart thermostats?

I have more solar than I can use, so I'm looking for smarter ways to consume.

I'd like to be able to say, when the battery is full during the day, make the AC 2 degrees colder to chill the house. Or, if the battery is full, turn the hot water temperature up 10 degrees.

I'd also like a way to say, if the car is charging, and the AC is on, don't let the water heater turn on until AC is off.

Any ideas on where to start w this project?

Thanks ya'll! I appreciate it.

bob.longmire said:

I have more solar capacity than I can use during the day, and I have more loads than I can run all at once.
Is there any device that can communicate with Smart water heaters, Smart thermostats?

Click to expand...

Depends on the brand of "smart device" and if its an open system that can communicate with other brand home automation system protocols or RS485 or CAN or MQTT. If the answer is yes to more than one of these communication standards than what controller do you use that can integrate all of them under one control system. A programmable logic controller is fairly flexible but would take a lot of ground level programming and integration. A home automation controller is generally easier to set up and use but may not talk to ALL of the devices you listed.

Perhaps something like Node-Red that is MQTT and Modbus capable.

bob.longmire said:

I have more solar than I can use, so I'm looking for smarter ways to consume.

I'd like to be able to say, when the battery is full during the day, make the AC 2 degrees colder to chill the house. Or, if the battery is full, turn the hot water temperature up 10 degrees.

I'd also like a way to say, if the car is charging, and the AC is on, don't let the water heater turn on until AC is off.

Click to expand...

Interesting project, sounds like something I'd want to try if presented with the same situation.

bob.longmire said:

Any ideas on where to start w this project?

Click to expand...

Make a spreadsheet with a line item for each device or parameter you want to either measure and/or control then list the possible methods and format for reading the data and likewise the communication protocol of the device you want to turn on or off or dynamically control. Does the device even have a means of external control?
1) Water heater:
2) T-Stat:
3) Batt Voltage or Charger state.
4) Car Charger:

bob.longmire said:

I have a EG4-18K and the Smart Load function isn't complex enough.

I have more solar capacity than I can use during the day, and I have more loads than I can run all at once.
I'd there any device that can communicate with Smart water heaters, Smart thermostats?

I have more solar than I can use, so I'm looking for smarter ways to consume.

I'd like to be able to say, when the battery is full during the day, make the AC 2 degrees colder to chill the house. Or, if the battery is full, turn the hot water temperature up 10 degrees.

I'd also like a way to say, if the car is charging, and the AC is on, don't let the water heater turn on until AC is off.

Any ideas on where to start w this project?

Thanks ya'll! I appreciate it.

Click to expand...

In my opinion, the topic of coupling a solar system with a SmartHome system receives far too little attention. There is still a lot of potential in combining both worlds.

Before I've started my off-grid DIY PV solar project, I've already running a DIY smart home system running to control/monitor all important devices and parameters. After the idea with the off-grid DIY PV solar project was born, it was clear for me to integrate it into my existing smart home system to be able to do like a smart energy management.

In my situation, the most important thing was to control the loads in the night or near the end of a night before the batteries are completely empty. To do this I've implemented a lot of different rules in the smart home system. Here are some examples (depending on time of day/night, solar forecast, current SOC, whole house energy consumption, temperatures, etc.):

• Increase the central heat pump cooling setpoint a bit to conserve energy if the new solar production is not too far away
• Increase the RV garage mini split setpoint (here the inverters/batteries are located)
• disconnect the water heater via contactors
• etc. much more is possible (I don't own an EV until now)

So in my opinion, the key is to get as much as possible sensor data into a smart home system and be able to control all important loads via smart home integration to be maximum flexible about the controlling of the solar system.

I my case I'm using Solar Assistant to get all individual inverter and individual battery data and publish them via the integrated MQTT feature of Solar Assistant to my existing smart home system (in my case it's OpenHAB but it could be HomeAssistant or something else). Now I have all the solar system data also (load, PV power, SOC, BUS voltage, cell delta, inverter and battery temperatures, ...).

With all the sensor data from your solar system and from other sensors of your house, you can develop any thinkable rule to control your actors (AC's, mini spits, EV chargers, relays, contactors, etc.) depending on the current situation and goals.

Thank you! These are great places for me to start.

bob.longmire said:

I have a EG4-18K and the Smart Load function isn't complex enough.

I have more solar capacity than I can use during the day, and I have more loads than I can run all at once.
I'd there any device that can communicate with Smart water heaters, Smart thermostats?

I have more solar than I can use, so I'm looking for smarter ways to consume.

I'd like to be able to say, when the battery is full during the day, make the AC 2 degrees colder to chill the house. Or, if the battery is full, turn the hot water temperature up 10 degrees.

I'd also like a way to say, if the car is charging, and the AC is on, don't let the water heater turn on until AC is off.

Any ideas on where to start w this project?

Thanks ya'll! I appreciate it.

Click to expand...

I do it manually thru my phone. The hybrid heat pump water heater has an app and the mini splits do too. I also have some Shelly smart plugs I can turn on/off using my phone.

All of these apps have programming so they can automatically turn/off or adjust the settings. During colder months, the Shelly smart plug connected to a resistive heater was programmed to turn on at 5:30 AM, the heat pump was programmed to turn up temp to max at 5:00 AM. The house was warmed up when I arose at 6:00 AM.

It doesn't have to be a fully automated house system. You can get by with just a phone or tablet thru wifi and set up each appliance to do what you want.

Zwy said:

I do it manually thru my phone. The hybrid heat pump water heater has an app and the mini splits do too. I also have some Shelly smart plugs I can turn on/off using my phone.

All of these apps have programming so they can automatically turn/off or adjust the settings. During colder months, the Shelly smart plug connected to a resistive heater was programmed to turn on at 5:30 AM, the heat pump was programmed to turn up temp to max at 5:00 AM. The house was warmed up when I arose at 6:00 AM.

It doesn't have to be a fully automated house system. You can get by with just a phone or tablet thru wifi and set up each appliance to do what you want.

Click to expand...

I do this too, but there are a few times a week where my loads are too variable outside my control. For example, if I'm doing laundry, and the AC is trying to hold a temp, it's possible my water heater, AC, and Dryer would all kick on at the same time. This would overload my AC output (the inverter could probably surge long enough to handle the dryer as that heating element doesn't stay on long, but i don't want to risk it consistently).

I don't want to forget to do something one time and risk an overload. I'd like to program the water heater to not run when the AC is on or the car is charging, and be all set. That 1 piece of logic should get me to within a comfy safety margin.

I agree doing it manually would get the job done, I just don't want to be traveling, or forget about it.

I have Solar Assistant on my phone too, this helps me determine: The loads on the inverters and what SOC currently is and if we will hit full or close to full SOC before the end of the day.

If it warm enough to run the AC, we don't need to run the dryer. If the heat pump mini splits are running for heating, we have enough battery capacity and inverter capacity to run the dryer plus the washing machine and the well pump kicks on/off as the wash cycle completes.

The heat pump water heater in heat pump mode takes such little power (less than 400W when running) that I don't need to turn it off. Only time I turn it off is if we get a string of cloudy days.

I'm still on the fence when it comes to a heat pump dryer. Might be another year or so as energy efficiency tax credits are capped each year at $2000.