Smart switch

[user 37014]

We have solar panels and I've been trying to figure out how I might activate my emersion heater when excess power is going back in to the grid.
Then found a vague snippet pointing to this forum.
Can anyone offer any further pointers, or does such a device exist commercially these days.

Thanks

 

[monkey5]

Hi yes there are a couple of things I know of, the solic 200 and the myenergi eddi. I've got the solic which seems to work fine but think the eddi is more superior, others will know the pros and cons

 

[binky]

Hi yes there are a couple of things I know of, the solic 200 and the myenergi eddi. I've got the solic which seems to work fine but think the eddi is more superior, others will know the pros and cons

Solic aren't brilliant for reliability.

 

[johnb2713]

We have solar panels and I've been trying to figure out how I might activate my emersion heater when excess power is going back in to the grid.
Then found a vague snippet pointing to this forum.
Can anyone offer any further pointers, or does such a device exist commercially these days.

Thanks

Devices like MyEnergi EDDI arent just simple switches, they adjust the amount of power fed to you Immersion heater. So for example, if your solar PV had 1800w of surplus power that was being fed back to the grid, EDDI would feed that 1800w into your immersion heater even though the element is rated at 3000w. It drives your export to zero and uses as much of the power your system has generated as it can within your home. In my case, it charges the house batteries first, then the car and last the immersion.

 

[user 37014]

The Eddi sounds like the perfect device, however at £450 i wonder how long it would take to pay for itself.

How does it determine what's excess ??

 

[johnb2713]

The Eddi sounds like the perfect device, however at £450 i wonder how long it would take to pay for itself.

How does it determine what's excess ??

It has a CT on the meter tail, if it sees export it starts to feed the immersion, if it sees import it reduces the power being fed to the immersion. In terms of break even, it will take 1500kW of energy (assuming 30p kWh). Thats 28kW per week over a year, 4kWh per day which would seem about right for normal use. The Caveat of course is that you have 1500kWh of excess energy in a year. They are very effective and minimise your export.

 

[user 37014]

With no hungry devices running today, I'd just short of 3kw spare. Emersion heater switched on manually. My tank of hot water cost me about 15p.
But in bleak mid winter on a sunny day, I'm lucky if I get about 1200w spare, of which I'll burn off with the washing machine or dishwasher.
I try to be clever (manually) but if I'm not in for instance, it gets wasted.

 

[user 37014]

That would e 3kw per hour by the way, peak times between about 11.30 to 2.00pm

 

[Murdoch]

The Eddi sounds like the perfect device, however at £450 i wonder how long it would take to pay for itself.

How does it determine what's excess ??

You want to keep the excess energy for your own use. Switching the immersion on isn’t great as it will draw 3kw for as long as its on

We have the Solic device and it only sends the excess current to the immersion meaning it should never draw power from the grid

As for payback, who knows what power will cost going forward so just think you’re doing your bit for humanity and the planet

 

[David FIRTH]

We have solar panels and I've been trying to figure out how I might activate my emersion heater when excess power is going back in to the grid.
Then found a vague snippet pointing to this forum.
Can anyone offer any further pointers, or does such a device exist commercially these days.

Thanks

Try Solar iBoost - it detects when the power starts flowing back to the grid and diverts the power to the immersion heater - fully automatic

 

[Sparkless]

You want to keep the excess energy for your own use. Switching the immersion on isn’t great as it will draw 3kw for as long as its on

We have the Solic device and it only sends the excess current to the immersion meaning it should never draw power from the grid

As for payback, who knows what power will cost going forward so just think you’re doing your bit for humanity and the planet

The immersion heater will not draw 3kW for as long as it is on. It will not use energy (whether from solar or grid) once it is up to temperature and the thermostat operates.
If it "never" draws power from the grid then when there's no solar excess there's no hot water unless there's another heat source e.g. gas.

 

[David FIRTH]

The problem is that, unless you heat the water, you have loads of power in the middle of the day when usage is at its lowest normally. I charge my EV, use the dishwasher in the afternoon and use the Solar iBoost and, in the summer, have a virtually zero electricity account except for the standard charge. You do need to micro-manage the energy usage, however, to get the best outcome.

 

[wgoldie]

I got an Eddi installed with our solar panels a year ago. Works away with no problems. Virtually all our hot water heating is electric now. Set the Eddi to boost during the Octopus Intelligent 23:30 - 05:30 cheap rate, uses solar what available and during the winter we have one boost around 4pm if required. Solar diverted by Eddi has been around 746kWh from solar and the nighttime boost has used around 200kWh @ 7.5p. I also fitted a relay board to the Eddi which, using a PTC1000 can monitor the hot water temperature in Home Assistant.

 

[Chandelia]

I have an iboost, had it installed with my panels etc. It's been great so far (10 months). I have been switching it off in the afternoons recently though to max export payments (Octopus flux) Probably will programme it to heat water from off peak grid supply from October. I've decomissioned old inefficient gas boiler. So payback will depend on how you use it, like everything!

 

[brummydave]

The Eddi sounds like the perfect device, however at £450 i wonder how long it would take to pay for itself.

How does it determine what's excess ??

Here's a calculator to show all you need to know.
https://garydoessolar.com/utilities/solardivertercalculator/solar diverter calculator

'Gary does solar' has lots of helpful and interesting videos including this one:



In which he concludes that solar power diverters are normally worth it.

He also has a follow up that argues they may not be!

Nothing in this micro controlled domestic energy world is simple now. You have to find out all the information, decide what's relevant and affordable for you.

 

[brummydave]

We have solar panels and I've been trying to figure out how I might activate my emersion heater when excess power is going back in to the grid.
Then found a vague snippet pointing to this forum.
Can anyone offer any further pointers, or does such a device exist commercially these days.

Thanks

There's several products out there now. a quick internet search will bring up lots of sites that evaluate the pros and cons and different models. They've been around for many years so some information is out of date, and some units are defunct. Some diverters connect to one immersion (solic 200). Some connect to two or three loads (Eddi, immersun, solar iboost,)

Eg
http://www.totnesenergy.co.uk/solar-immersion-controller-review/

https://www.thesolardoctor.co.uk/immersion-diverters/

Also consider an export tariff from octopus to get paid for your excess.

 

[user 37014]

We normally heat dhw with the gas boiler, but now we are retired and at home more, I can make better use of the surplus solar, by switching things on and off as required. So for instance as I type, I've about 2.5kw going back in to the grid, so I put emersion heater on and now drawing 500w. So whilst it might cost me about 30p to heat the tank, it would have cost about 97p via gas. Of course winter is a different story. I like the idea of the smart switches diverting surplus though (and inly surplus). When I hot up this morning 1kw was going back in to the grid, this could have been going towards my hot water if I had the switch.

 

[user 37014]

I like the idea of the iboost, fits in line between the fused spur and emersion heater with a battery operated remote ct. Seems like a simple enough install for someone competent.
Does this send only surplus ?
So if I have 1kw surplus, iboost will use it and then does it ramp up or down as the surplus changes

 

[user 37014]

I just had a play with the gary does solar calculator, and it has me down for about 2 years payback.
However, there are a number of unknown variables, like how much water we use and how many days insufficient solar excess.
So im still none the wiser

 

[user 37014]

Just ordered the iboost.