Growatt iboost and battery

markpb1978

Hi All,
Newbie here... only found this site a couple of days ago!
I have a question regarding the iboost system and battery combined. We were informed by our installers that the two systems do not work well together, and therefore we only installed the battery at the time of the solar install.
I'd like to divert the excess energy generated to the hot water tank (via the iboost system) and before general export back to the grid.
Does anyone know if this works well for them like this? What are the settings within the growatt portal to run effectively?
Thanks
Mark

kerregan

markpb1978 I think your installers are wrong. I have iBoost and battery and it works very straightforwardly. The iBoost is triggered by a clamp on the mains cable which detects when you start to export. Effectively battery is first priority, then iBoost, then export.

That said, I can get 15p per kWh export on Octopus which is much more than the cost of heating hot water with gas. So I now rarely use the iBoost. I am shortly upgrading to a heat pump which means even less reason to use an iBoost.

markpb1978

kerregan Thanks. This is what I thought to be honest.
Do you have an example of the dashboard settings for the iboost to kick in for future reference?
The more I think about it, especially as my export tariff does not achieve 15p per kWh then i'm just more tempted to go ahead with the purchase of iboost.
The way you've described it as battery first, then iboost to heat the water tank then export is how i want ours to be set up

kerregan

markpb1978 What do you men by dashboard settings? The inverter / battery doesn’t know you have an iBoost and the iBoost doesn’t communicate with the inverter. So there’s nothing to set.

psiloc

iboost works fine with a battery. There is a setting on the newer models to raise the export threshold to decrease the risk of it draining the battery but I wouldn’t lose any sleep over it. It may pull from the battery by a small amount as it adjusts to clouds coming over etc but it really is minor.

psiloc

All that being said, you should think long and hard about whether it's a false economy. Even if you don't get a great export rate, it's this you need to compare to the import price of gas (assuming that's your alternative heating fuel) which is a lot lower than the price of electricity.

The difference between your export rate and the price of gas per unit is how much your iBoost can potentially save you per unit. You can then use this to work out your payback rate - and it might be a very long time. If you're lucky enough that your export rate is more generous than your gas unit price, then an iBoost actually costs money to run.

We have one, but we have a rent-a-roof scheme meaning we get nothing for export. Even so, our payback rate was about 6 years and this was when an iBoost cost about £250.

KevinD

I fitted a programmable wireless immersion heater instead of an iBoost device. We're on the gas tracker tariff with Octopus that's been consistently less than 5p so it doesn't make sense to use electricity that I can sell to the grid for 15p to heat the water. I only use the immersion heater when the electricity prices are either a couple of pence or negative.

felmer

I have iBoost+, it was installed by default when I had my solar/battery installed so I didn't have a chance to research it. Had I known at the time it wasn't modern and smart I would have have looked for alternatives...

I'm on Agile and as others have written, no point in using it if the export price is above your kWh gas price (so _7p/kWh for me).

As per KevinD I swapped the manual dual-pole isolator switch for a smart one ("Wifi Timer Fused Spur Wall Controller For Electric Towel Rail" from CompanyBlue). This allows me to schedule turning off iBoost+ between 4PM and 7PM (actually through to 10AM) when I get most price for export and don't want my battery heating water. You can use the Tuya App to control its schedules and also to manually turn on/off, and get power consumption figures.

It's worked fine even when its had just over 3kWh flowing through it to the immersion.

I have also deleted all the iBoost+ Boost schedules, and set the trigger threshold at 250W.

Also, iBoost+ doesn't easily allow me to make use of grid electiricity (Boost feature) when its well below the price of gas/kWh, as it is sometimes overnight. I think I might set Boost schedule on all night, and then use Tuya schedule to turn it on during the extra cheap times (aslo need to make sure batteries aren't discharging into it). A bit of a hassle...