Is iBoost really worth it?

QrizB

RealtimeBlues said:

Petriix said:

RealtimeBlues said:

I am back again QrizB lol But if I use it (free solar) in a power diverter, then my free solar energy stops gas being burnt and reduces CO2 etc etc

And, as I already explained (twice, now three times), burning gas at home to heat water is likely more efficient than burning gas at a power station (plus the associated grid losses) to deliver that extra electricity to the grid. At best it's totally neutral, so no actual benefit.

And for the 3rd/4th time, free solar electricity going into an immersion heater, is better for the environment than burning gas 

What you keep missing (and I'm wondering whether it's deliberate) is that it might reduce your personal carbon footprint by feeding it into an immersion heater, rather than producing the same heat by burning gas, but if you export it you're reducing "the grids" carbon footprint.

paul991

so  the  electricity came  from my pv a few feet away on the roof and the gas half way round the world in a tanker 

Jrw90

I’m glad I got a iboost. Have to use electric to heat water and didn’t have to turn that on from April until last week

Screwdriva

psamatt said:

So we've recently had 4.8kw worth of Solar Panels fitted on our South facing roof, in addition to this, we have had iBoost fitted.

We are just about to sign up for Outgoing Octopus which pays 15p per KWH of exported Electricity, we are on the standard variable for gas (10.24p per KWH) and therefore am wondering if its any point in having iBoost? I know you can't quantify 1 KWH of Gas vs 1 KWH of Electricity, however, on the naive view, heating water (in a tank) is cheaper via the Gas boiler if you export the Electric to Octopus then to use the iBoost to heat the water?  

Thoughts?  

As far as diverters go, I would recommend a fully integrated smart diverter like the Eddi, especially if the Zappi EV charger and Libbi battery storage may become options in the future. The integration and connectivity of the 3 is Tesla rivaling and the product is leagues ahead of the iBoost. That said, you likely won't recover the cost but it can help with reducing your reliance on the grid. 

Niv said:

For me the diverter will reduce the number of loads of oil I need to buy so in my case has 'some' env benefit. But, being honest, I will be doing it to save money, env benefits are nice but money saving is the driver.

And with heating oil, it's a no brainer. As are Ground Source Heat Pumps

QrizB said:

I suspect @RealtimeBlues won't be back, but if they are they might like to consider that a kWh of gas has a carbon footprint of just over 200g CO2, while a kWh from the grid has a typical carbon footprint of ... about 200g CO2.

I'm not questioning the validity of this but am curious for the breakdown of how you arrived at this conclusion? I was always under the impression that the UK electricity mix is less CO2 intensive during the colder months when wind generation is at its annual high? Conversely, during the summer, I would think that this statement would be spot on. Fortunately, that's when diverters perform their best. 

QrizB

Screwdriva said:

QrizB said:

I suspect @RealtimeBlues won't be back, but if they are they might like to consider that a kWh of gas has a carbon footprint of just over 200g CO2, while a kWh from the grid has a typical carbon footprint of ... about 200g CO2.

I'm not questioning the validity of this but am curious for the breakdown of how you arrived at this conclusion? I was always under the impression that the UK electricity mix is less CO2 intensive during the colder months when wind generation is at its annual high? Conversely, during the summer, I would think that this statement would be spot on. Fortunately, that's when diverters perform their best. 

I usually look at https://electricinsights.co.uk (although you might be able to get the same from eg. https://www.carbonintensity.org.uk/ )

Looking at the last 12 months, the average is 177g/kWh. Breaking it down into seasons:

• Winter 21-22: 171g/kWh
• Spring 22: 181g/kWh
• Summer 22: 196g/kWh
• Autumn 22 to date: 164g/kWh
  

So in the summer, when you're most likely to be generating excess solar electricity, the grid is roughly as dirty as directly-burned gas.

I guess I should explicitly state that, as more renewable generation comes online and the grid becomes cleaner, so the grid carbon intensity will fall and export will become "less green" compared to displacing directly-burned gas.

RealtimeBlues

QrizB said:

RealtimeBlues said:

Petriix said:

RealtimeBlues said:

I am back again QrizB lol But if I use it (free solar) in a power diverter, then my free solar energy stops gas being burnt and reduces CO2 etc etc

And, as I already explained (twice, now three times), burning gas at home to heat water is likely more efficient than burning gas at a power station (plus the associated grid losses) to deliver that extra electricity to the grid. At best it's totally neutral, so no actual benefit.

And for the 3rd/4th time, free solar electricity going into an immersion heater, is better for the environment than burning gas 

What you keep missing (and I'm wondering whether it's deliberate) is that it might reduce your personal carbon footprint by feeding it into an immersion heater, rather than producing the same heat by burning gas, but if you export it you're reducing "the grids" carbon footprint.

I am glad you finally have agreed with me, it's up to us all, to reduce our own personal carbon footprint. Collectively then we make a difference.

Petriix

The notion of a 'personal carbon footprint' is, frankly, ridiculous if your action to reduce it actually causes more carbon emissions elsewhere. It's also a red herring to look at the overall grid CO2.

The CO2 saving from exporting (rather than self consuming) can only be the emissions from the last kWh, not the average. Your export has no impact on the nuclear base load or the wind (unless there's actually a surplus).

At the moment the last kWh is usually generated by burning gas, and relatively inefficiently at that. Choosing to ignore this doesn't change the reality.

Another factor, often overlooked, is that energy diverted to hot water is very often wasted. There's no particular benefit to having a full tank of hot water just sitting there all summer. If anything it probably encourages people to waste more water. It's far 'greener' to only heat the water you need. In that regard, on demand water heating is vastly more efficient.

paul991

so your saying if i turn my immersion off they will shut off a gas power station.my kw of electricity may  be  used by a neighbour or most likely  lost or wasted but the gas I save will definitely be used for heat cooking or water

Magnitio

paul991 said:

so your saying if i turn my immersion off they will shut off a gas power station.my kw of electricity may  be  used by a neighbour or most likely  lost or wasted but the gas I save will definitely be used for heat cooking or water

In theory, I could export 1kWh of electricity to the grid, which could save 1.5kWh of gas being used at a power station (assuming 1/3 loss in generation and transmission). It might then require 1.3kWh of gas from my boiler to heat the hot water cylinder to the equivalent of 1kWh of immersion heater. Thus there would be an overall saving of 0.2kWh of gas.

When there is a particularly high demand for electricity and renewable generation is low, some of the demand is actually met by burning of coal, so in theory the export  to the grid could have an even greater benefit.

What you export does not "get lost". It might well be wasted by a neighbour heating up their hot tub, but if they weren't using your exported electricity, it would come from a power station.

paul991

The way  to look at it if we all had sufficient pv for our own use and  to heat up water would you still want to burn gas?
to bring the argument about coal into it is a red herring as the times coal is being burnt 0.6% though as we are exporting 5% of our generation at the moment , so not  for uk use .
To manage the grid at times some renewables are switched off during high off during wind  output and some power companies have paid consumers to increase consumption for short  periods .The times of maximum demand are between 4 and 7 pm when this time of year no iboast will be working.