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PV, EV, heatpump, outdoor spa bath - ecoMode

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(Morten Gjedrem) #1

Hi,
New here and seeking advise.

I am currently in the process of building a house and I recently received an offer for a massive solar installation. PV panel with a total of 24 kWp.
Calculations indicate that this plant should produce my yearly needs of energy.
I am planning on getting a battery storage in the future but will not be getting one right away.

Since I live in the south-west part of Norway, a lot of this energy production will take place mid summer and peak mid-day.
Which of course is the time of day one would need it the least.

So entered google and found EmonEVSE with eco-mode. I can divert surplus power into EV. Fantastic!
But I want to take it another step. In case EV is not present or EV is fully charged the power should be diverted to one of my three water storage tanks. 1. hot water tank 2. heat accumulator tank 3. outdoor spa.

Another issue could be the minimum 6A output for the EV. How does this work with a 3-phase feed to the EV? Do I need at least 400 * sqrt(3) * 6 = 4150 W surplus to activate EV charging? Or if it starts charging EV if less than this surplus then will it draw from the grid?

See floor plan here Floor plans with energy storage components.pdf (219.7 KB)
Basically I have main intake cabinet which feeds one fuse box inside house for appliances and one in garage for EV and jacuzzi.

What Hardware will this require and how to set it up?

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(Robert Wall) #2

Welcome, Morten,

Excuse my asking, but why, in your user profile, have you put Afghanistan as your country of residence? You’ll find us giving you advice suitable for the Afghan electricity supply, not the Norwegian one. :roll_eyes:

Which do you have, 4-wire 400/230 V or 3-wire 230 V line-line?

And
Please don’t link to files on external sites. Unlike others, we want you to attach your screenshots, log files, etc to your post. If the external site goes away, the material is likely to be lost forever. If that happens, when someone reads your post, your question and our answer will have little or no value.
If you need to post more than one attachment, tell us you have more information to post, and we’ll change your user account settings to enable you to do so.

I suggest, as you have a 3-phase operation, that you look at https://mk2pvrouter.co.uk for diverting your PV energy into the water heaters. There is a 3-phase variant, Robin Emley developed that here, and so we know a lot about it and it works well.

Unfortunately I can’t answer the question about the EV, so I’ll leave that to others.

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(Morten Gjedrem) #3

I have the 4-wire 400/230V.

I will check out the mk2pvrouter

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(Dave Howorth) #4

I don’t know for sure but if you have a device that has a minimum current draw, such as an EV or a heat pump or whatever, then yes you will need to have that amount of surplus power available before switching the device on if you want to avoid drawing power from the grid. You will also have to maintain that power continuously whilst the device is switched on, so if a cloud covers the sun you either switch the device off or draw grid power. Repeated switching of loads is often bad for them so grid power may be necessary.

A way around the problem is to use a battery as a buffer to store enough energy to cover periods whilst clouds cover the sun. An EV has a large battery of course, so getting a suitable charging system that allows it to be trickle charged at arbitrarily low levels if necessary is a useful ability if possible. Vehicle-to-grid technology also allows the EV to serve as a source of energy to e.g the heat pump if required.

This is one big reason that heating water with resistive heaters is a good, easy target for surplus energy. It’s a very flexible and low-cost approach.

edit: PS If you’re building your own house, why not insulate it some more to reduce the heating demand? It looks like your load is a bit less than 50 W/m² which seems quite high.

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