The whole nine yards?

Hi All,

Now that I have my emonPi up and running, It’s time to move to the next phase.

However, I’ll outline the full plan to help people put advice in context.

Where I want to end up is with the ability to monitor my grid input/output, solar generation, diversion to hot water via an existing Immersun, 2x openevse car charging points, my heat pump and (in future) battery storage (probably with a Victron inverter.)

I have the emonPi monitoring the house in/out and the solar PV generation.

My PV setup is 10KW via 2x SolarEdge 5kW inverters. SIngle phase.

The inverters connect at the meter via Henley Block and don’t go through a distribution board. This is where the emonPi (and sensors) are connected.

I have a distribution board for the house which has the Immersun immersion feed on it.

I have a separate distribution board in the garage which has the heat pump and will have the car charging points attached to it.

I have the openevse charging points and I’m want to install those next.

Do I need any further hardware to be able to control diversion of excess solar to the car charging points or is connection to the emonPi sufficient?

(As regards the Immersun, I’m hoping to be able to prioritise diversion by setting different limits on how much excess energy is produced before they turn on. If not, it’s not much of a problem because the system tends to heat the tank to maximum after about 90 mins, so the cars can wait until then.)

If I can’t independently control the diversion to two different places, does adding immersion diversion monitoring help? (I’m hoping I can set up some logic that says that if the Immersun is taking energy to the hot water, don’t divert excess to the cars or something like that.)

Next, if you’re still with me, I want to add heat pump monitoring to the system. I have the heat pump already installed. Do I just need the heat pump kit or do I need anything extra.

Then, if the wife hasn’t killed me or chucked me out for my constant meddling with the house, I want to be able to install an inverter/battery system. I don’t need to buy anything for that at the moment but I also don’t want to buy one thing now and another later if I could just buy one, better, thing now.

Sorry for such a long and rambling thread. It’s difficult to know how much information to provide to help paint the picture without doing too much.


First of all, the emonPi does not and cannot control anything. All it can do is monitor a couple of currents, accept data from other sensor nodes and record and make that data available for display, or send the data elsewhere via (usually) your LAN. It’s other things that will use the data to make control decisions and issue the appropriate instructions or do the switching.

It reads as if you will need an emonTx to monitor the inverters and water heating, and another in the garage to look after the car chargers. I don’t know what the heat pump monitor can do in addition to monitoring the heat pump - my understanding is it cannot handle the chargers as well, hence the need for the second emonTx4.

The emonTx 4 has 6 current inputs, expandable to 12, so looking only at the things you’ve mentioned, two emonTx4s (one with the full emonVs, one maybe with a stripped-down version sharing the emonPi’s 5 V power supply) and the appropriate c.t’s is all you need, no matter where you locate the battery - always assuming the battery system needs a c.t. and can’t provide data via a data bus (Modbus or similar) or Ethernet.

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That’s brilliant, thanks.

Have ordered the emonTx 4 and associated bits.

Will post on another thread how it all goes.


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