On-grid domestic battery storage

Starfrog

Yeah I see when the shower is on it draws a lot of power 8k from solar, battery and grid. Its very early days (last Friday!) so I'll see how the system performs first before putting more money into it. The main reason for it is to offset a future air source heat pump so I can get rid of the old Oil boiler.  Here are my settings let me know if theres anything I should be doing thanks for the help (Fife ? where ? )

EVandPV

Those settings look fine to me. Don't see anything that would cause a problem.
Do you mean where is Fife ?
East coast of Scotland, just north of Edinburgh.

Starfrog

thanks for checking and I meant where in Fife, Glenrothes here ! but talking about my solar setup in Lochinver 

Starfrog

Raspberry Pi immersion controller
Raspberry Pi Lux charge controller

What are these two units and how do you interface them with the setup ? just via the internet, I have a load of Raspberry Pi's but would I need two to do what you are doing with your setup ? sorry lots of questions but great to get answers thank you

EVandPV

Starfrog said:

Raspberry Pi immersion controller
Raspberry Pi Lux charge controller

What are these two units and how do you interface them with the setup ? just via the internet, I have a load of Raspberry Pi's but would I need two to do what you are doing with your setup ? sorry lots of questions but great to get answers thank you

The Lux controller is basically my own version of Octolux written in Python. We're on Octopus Go at the moment (was on Agile but switched due to hike in pricing) and the script checks a pv forecast for the following day using the api on solcast.com then works out how much to charge during the cheap period. 
It controls the Lux over the internet using some of the original Octolux Ruby code.
It's not doing a lot at this time of year but should come into it's own over the coming weeks when the sun's out.

The immersion controller Pi controls a solid state relay to switch our immersion on when the batteries get above 80% then turns it off when they drop below 70%. So uses the batteries like a kind of buffer. The Pi gets the state of charge directly from the batteries via serial cable.

I'm in Crossgates by the way. 👍
I know Lochinver too, been up that way many times in the past. Your not into fishing by any chance ?

Starfrog

So would your recommendation when i switch to octopus is to use the Go tariff ? As I aim to have an air source heat pump with a hot water heater do you suggest using the raspberry pi for that to heat it or a iBoost which I’ve been reading about and maybe its doing the same job but i think the raspi would give me more precise control to provide a boost to the heating of the water.

the last time I went fishing was back in the 1980’s maybe I’ll take it up when I’m up there full time  

EVandPV

Starfrog said:

So would your recommendation when i switch to octopus is to use the Go tariff ? As I aim to have an air source heat pump with a hot water heater do you suggest using the raspberry pi for that to heat it or a iBoost which I’ve been reading about and maybe its doing the same job but i think the raspi would give me more precise control to provide a boost to the heating of the water.

the last time I went fishing was back in the 1980’s maybe I’ll take it up when I’m up there full time  

At the moment, Go is working out cheaper than Agile if you have batteries but the prices change constantly so you might find Agile is better once you've switched. During the last lockdown, Agile was extremely cheap and quite often the price was negative meaning you actually got paid for what you used !

If I'm not mistaken, an iboost is a proportional controller which adjusts the amount of power it sends to the immersion depending on how much surplus pv you have.
My DIY Pi controller just turns the immersion on at full power then off when the batteries reach 70% so not quite as 'intelligent' as an iboost.

mickyduck55

EVandPV said:

Starfrog said:

So would your recommendation when i switch to octopus is to use the Go tariff ? As I aim to have an air source heat pump with a hot water heater do you suggest using the raspberry pi for that to heat it or a iBoost which I’ve been reading about and maybe its doing the same job but i think the raspi would give me more precise control to provide a boost to the heating of the water.

the last time I went fishing was back in the 1980’s maybe I’ll take it up when I’m up there full time  

At the moment, Go is working out cheaper than Agile if you have batteries but the prices change constantly so you might find Agile is better once you've switched. During the last lockdown, Agile was extremely cheap and quite often the price was negative meaning you actually got paid for what you used !

If I'm not mistaken, an iboost is a proportional controller which adjusts the amount of power it sends to the immersion depending on how much surplus pv you have.
My DIY Pi controller just turns the immersion on at full power then off when the batteries reach 70% so not quite as 'intelligent' as an iboost.

A lot of the "intelligence" is lost when you have batteries.. the clamps on the live seem to get confused and don't respond quickly enough.   If for a brief period you start to export to grid, my Solic says OK stop that and diverts power to immersion.  The issue is that it sometimes detects the batteries as extra and may then pour 3 kW from my batteries into the tank.  Not an issue when the sun is shining but a bit irritating if I have just charged them on "GO".  My Solic is now turned off, I believe some of the diverters allow you to set a threshold so only diverts when over "X" W being exported so these maybe better.

chamelion

Very limited and specific use case here but I've found something interesting...
I had switched to go faster tariff from agile. I have the batts charge up to 100% during the 5.5p 830pm - 130am slot, and from 130 onwards they contribute to the house. 

I previously had it trickle contributing - approx 300/350 watts to lower my profile for the day. However last night I bumped that to 1500w (my home baseline over 2500w) and got 15% more power out of them... 
I'll try again tonight with 2kw output. 

Sum of it is if you're doing something similar on go, sounds like you get more efficiency at higher wattage contributions rather than trickling. 

Starfrog

Chamelion not sure exactly what you mean ? Sorry I’m real new to this but want to understand it, any help is always appreciated