Good morning all,
I am considering getting an immersion heater controller (something like the Solar iBoost) but I'm reading conflicting views about the effectiveness of them.
I am just about to move onto Octopus Flux and really trying to squeeze the maximum benefit out of my PV system - we only use the gas at the moment for heating the hot water, twice a day for about 30 mins a time, but our gas bill is still around £80 per month, net of the standing charge (based on my old EDF figures, no Octopus figures yet).
Seems like a no-brainer to spend c£300 on a controller and heat my hot water for free during the summer.
I would really appreciate your thoughts and which controller you would recommend (as there seems to be lots to choose from).
Also, could a regular electrician be able to install it or would I need a 'specialist'.
Thanks in advance!
Immersion heater controller
Do the maths first. On flux you can export at 22p/kwh where gas is 10p/kwh. Also if you heat the water between 2am and 5am then it's 8p/kwh in electricity.
So even during the day if you heat the water by gas instead of electricity you are saving 11p/kwh as you will be exporting the excess electricity at 22p vs using gas at 10p.
If you paid £500 for a controller plus an electrician it might never pay for itself!
Before we had our system installed and went on to Flux we where thinking about getting air source aircon/heating to use up excess as we thought we would only get 5p/kwh. Then looking at Flux we decided it's more beneficial to sell to the grid. After our first month we are importing at an average of about 21p\kwh and exporting at about 24p\kwh! That's way above the kwh charge for gas! This month I am guessing that we will export 3 or 4 times as much electricity as we use!
Everyone's use is different but do some maths before you spend out on a controller and installation.
So even during the day if you heat the water by gas instead of electricity you are saving 11p/kwh as you will be exporting the excess electricity at 22p vs using gas at 10p.
If you paid £500 for a controller plus an electrician it might never pay for itself!
Before we had our system installed and went on to Flux we where thinking about getting air source aircon/heating to use up excess as we thought we would only get 5p/kwh. Then looking at Flux we decided it's more beneficial to sell to the grid. After our first month we are importing at an average of about 21p\kwh and exporting at about 24p\kwh! That's way above the kwh charge for gas! This month I am guessing that we will export 3 or 4 times as much electricity as we use!
Everyone's use is different but do some maths before you spend out on a controller and installation.
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SolarJunkie
- Posts: 29
- Joined: Wed Jan 04, 2023 9:54 pm
I have an iBoost system and it works very well, but always consider the overall cost of your energy and the way that you use it. My iBoost system is currently switched off, but it has paid for itself already in the first year by using over 1650KW of solar energy that would otherwise have gone to the grid for peanuts.
My system was setup before Flux was available and the iBoost, alongside my solar install, gave me all the energy I needed for half of the year and supplemented it for most of the rest.
Time of use tariffs, particularly those provided by Octopus, change the way we use our energy, by providing incentive (ie, money) to use energy outside of the normal peak times. Do the maths for you energy use (thoroughly) and you will see which is the most cost effective setup your needs.
My system was setup before Flux was available and the iBoost, alongside my solar install, gave me all the energy I needed for half of the year and supplemented it for most of the rest.
Time of use tariffs, particularly those provided by Octopus, change the way we use our energy, by providing incentive (ie, money) to use energy outside of the normal peak times. Do the maths for you energy use (thoroughly) and you will see which is the most cost effective setup your needs.
16x JA Solar 495 panels 8 East, 8 West, low pitch roof
H1-5.0 hybrid inveter
5x HV2600 batteries
Marle iBoost solar diverter
H1-5.0 hybrid inveter
5x HV2600 batteries
Marle iBoost solar diverter
You need to understand how much gas you're using to heat hot water (vs heating), and therefore how much you would realistically save with the solar diverter. When we had our gas boiler we averaged about 5kWh of gas per day (approx 50p at current prices) to heat water, for a family of four. However, in the winter we sometimes used over 100kWh for heating on the coldest days. So the vast majority of your gas usage will likely be space heating rather than hot water, unless your house is very well insulated. Your monthly gas payment is presumably set at a level that covers annual usage, so you're overpaying in summer and using up the account credit in winter? I cannot imagine you would be using anything like £80 of gas a month at this time of the year.
Just to add to this, I bought one of these diverter devices when I first got solar and when the price of gas was still low, so when factored against export payments I could get, it was a hard sell. I ended up with a low cost one (Solar Immersion) mainly as the thought of just not burning gas appealed. Then gas prices went up, and I was glad I had it, but it broke after just 14months 
. I was not going to buy another one and instead built my own with a SSR and Tasmota'd Sonoff device, so that I can now vary the divert myself, but more importantly, I can divert generation before the battery is full, which has the added benefit of reducing clipping by the inverter that I get once the battery is full. (7.8kWp array versus 6kW inverter)
. I was not going to buy another one and instead built my own with a SSR and Tasmota'd Sonoff device, so that I can now vary the divert myself, but more importantly, I can divert generation before the battery is full, which has the added benefit of reducing clipping by the inverter that I get once the battery is full. (7.8kWp array versus 6kW inverter)