Solar Divert should I be concerned?

[Nicky pies]

Hi all

I’m waiting for installation for a system including an Iboost solar divert, however a touch of concern has crept in while watching a YouTube video just now. From what the YouTuber is saying is that if your batteries are DC coupled then the solar divert will almost definitely struggle to read when to begin diverting any energy to immersion heater. I have seen an install of the same Growatt 6.5kwh battery I am due to have installed and the installer has installed them on the DC side according to him far more efficient that way(?) So I suppose my question is should I bother going ahead with solar divert or is it likely to be more chew on than it’s worth? YouTube video below around 4.10 in.



Cheers Nick

 

[johnb2713]

Hi all

I’m waiting for installation for a system including an Iboost solar divert, however a touch of concern has crept in while watching a YouTube video just now. From what the YouTuber is saying is that if your batteries are DC coupled then the solar divert will almost definitely struggle to read when to begin diverting any energy to immersion heater. I have seen an install of the same Growatt 6.5kwh battery I am due to have installed and the installer has installed them on the DC side according to him far more efficient that way(?) So I suppose my question is should I bother going ahead with solar divert or is it likely to be more chew on than it’s worth? YouTube video below around 4.10 in.



Cheers Nick

I have a Growatt SPH6000 inverter and a Growatt 7kWh battery. My system uses EDDI for the solar diverter and it has no issues at all, works perfectly with the DC coupled battery.

I don't see how there can be an issue, the inverter supplies the house first, then the battery is charged when more power is available. Only when the battery is full and the house is supplied does it start the export, this is spotted immediately by EDDI which then ramps up the immersion heater. The CT on the meter tails is all it needs to run and as far as I can see, it doesn't matter whether you have DC or AC couple batteries.

 

[torbrowser]

Looking at doing this to my system, 6kWh went down the loo on friday, my battery filled up by noon and nothing much running in the house, i manually put the immersion on to catch the escaping kWs.

How has it been performing for your system john, do you get hot water every day ?
I am running the same inverter with slightly less battery power, and i am in the same irradiance zone, so whatever you are achieving on hot water i should expect very similar.

 

[johnb2713]

Looking at doing this to my system, 6kWh went down the loo on friday, my battery filled up by noon and nothing much running in the house, i manually put the immersion on to catch the escaping kWs.

How has it been performing for your system john, do you get hot water every day ?
I am running the same inverter with slightly less battery power, and i am in the same irradiance zone, so whatever you are achieving on hot water i should expect very similar.

We always end up with some hot water from the solar, even overcast / dark / rainy days. I run my tank quite hot at 85 degC in order to store more energy, the insulation is good and I have fitted a blending valve to reduce the hot water temperature to the house supplies (50 degC). I have also added a small circulation pump between the tank outlet and the tank inlet, this ensures the whole tank is heated, the pump runs when the immersion is on.

The way we set our system is to use the off peak to run everything between 00:30 and 04:30, at that point it runs on battery until the PV starts. The PV then runs the base load and usually charges the battery by lunchtime it's charging the car and topping up the hot water. When the PV stops were back onto battery until 00:30.

I have set the car as 1st priority and the immersion as second priority within the MyEnergi system because the minimum excess solar for the car is 1.4 kW so when we exceed 1.4kW the car charger starts up anything less EDDI feeds into the immersion heater. If it's done the other way round the immersion will take all excess PV up to 3kW until the tank is hot before starting the car charger.

I'm delighted with the whole system, Octopus Energy wanted to increase our monthly payment from £178 to £565. I've had the solar and battery installed along with EDDI and ZAPPI, I reduced our payment to £140 per month but the actual monthly bill has been less than £70 per month since installation.

 

[Mrjmegson]

John, how long have you had your system setup as it is?

 

[johnb2713]

John, how long have you had your system setup as it is?

Since the end of April

I'm almost ready to commission my DIY 14kWh battery so that should keep us away from peak rate electricity through winter, charging during off peak (I will be just about maxing out my gris supply when its done).

 

[Mrjmegson]

So you've done a summer with it.

Look forward to hearing how your battery goes, that would put you on 20kwh wouldn't it?

 

[johnb2713]

So you've done a summer with it.

Look forward to hearing how your battery goes, that would put you on 20kwh wouldn't it?

21kWh of which 18 will be usable

 

[Mrjmegson]

Excellent, that's amazing that you've made your own battery.

Have you got a thread about it anywhere, or are you intending on putting a thread up about it?

 

[johnb2713]

Excellent, that's amazing that you've made your own battery.

Have you got a thread about it anywhere, or are you intending on putting a thread up about it?

I'll maybe do a bit of a writeup if anyones interested.

I've used LifP04 batteries, assembled them into 4 cell modules so there will be 16 batteries in total. A Seplos BMS looks after them connected to a Victron Multiplus IIGX inverter all to be housed in a little shed down the side of my house.


This is one of the four battery modules mechanically assembled, the grey Anderson connector carries the heavy current the smaller silver plug is the BMS connection with voltage and temperature sensor data.

The price will be slightly under £5k for the 14kWh including the Victron 5 kW inverter / charger. Payback on straight electricity use grid charging etc is 2.7 years, based on my average export that reduces to 2.2 years and hopefully even less when I take into account the reduction is gas usage due to running heatpumps from battery.

 

[Mrjmegson]

John, I for 1 would definitely be interested in a write up.

That looks a fantastic job from what I can see so far.

Cheers