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PV, diverter, AC and emoncms

(Dan Padure) #1

I have an grid-tie system.
I have a CT on PV inverter output, one on house import (I am not allowed to export)

I am thinking of a system to use all available PV power that is left unused at the moment

I will use a hardware diverter with a CT on it
when diverter diverts more than 800W of power, I want to command the AC to start up to heat/cool the house.
Then when house import draws more than…~200w of power turn OFF AC

This way if I have more unused power AC will make better use of it, and for small amounts the diverter will heat up the water

That’s my plan.
What do you think about it?

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(Craig Fryer) #2

I have been wanting to do something similar.

Just to clarify, are you not allowed to export or just don’t obtain any credit (Feed in tariff).
How do you control your air conditioner?

I have partial control of the air conditioners via WiFi to InfraRed bridged. I have two commercial ones, but I have also built two using ESP8266 and control with ESP Easy. When I say partial control, none of the WiFi controllers can change the Powerful/Quiet/Normal mode. There are many different IR protocols used for air conditioners even within the same brand.

To make the controlling of the air conditioners more complicated, I have found the available power can be highly variable. I am not just talking about 3 or 4 minutes when cloud comes over, but days when it is overcast and the light varies greatly over 30 to 60 minutes. By controlling the temperature setting of the air conditioners the power demand can be varied, however there can be a 5 minute delay for the demand power to drop off.

Just to make my situation more complicated, I also want to run our pool pump when sufficient power is available. I already have the system working to run the pool pump to run when there is sufficient power and this works well if the air conditioners are controlled manually.

In the period between the transition between summer and winter, I want to control the air conditioners depending on available power and a set of predetermined conditions.

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(Dan Padure) #3

I have to pay for exported power, so better not to :slight_smile:

Currently I have a sonoff controlling the AC based on my manual input.
Sonoff also works with ifttt and I will reasearch on controlling it this way

Alternatively I could controll AC with a stand-alone light intensity sensor that would tell me how much sunt is available

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(Craig Fryer) #4

Ouch! That hurts.

This is one way of doing it. I would suggest using Node-Red running on a RPi.

How do you change the temperature?

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(Dan Padure) #5

will surely look into that

I don’t need to change the temperature. During winter I set it high.
During summer I set it low.

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(Craig Fryer) #6

That makes it easy.

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(Alastair D'Silva) #7

If you have a Solax inverter, I have software that can help. As well as micromanaging the inverter, it also provides instantaneous and 5 minute rolling average values for your power budget (being how much extra you can draw before pulling from the grid). I haven’t used it in a zero-export scenario before, so some tweaks may be necessary. https://github.com/InfernoEmbedded/PowerScraper

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(Dan Padure) #8

nice work.
But I have a different inverter, with a wifi module connected on a serial port

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