8 kW Solar + 11 kWh Battery + Ohme EV + Immersion Heater + Intelligent Octopus

[GaryMG4]

I will check the local oil club, but I have great difficulty in believing it will be significantly less than what I'm paying to CPL. Otherwise why is anyone using CPL at all (other than people like me who haven't checked the comparison).

I'm charging the car on that 3.5p/kwh price as we speak, although it's car charging only, not house load.

I found that the oil club price was marginally cheaper than the same supplier buying direct in most cases. What I did find was that neighbours that used the 'top up service' did pay more per litre for the 'I can't be bothered to check my oil level' service than myself. One of the suppliers would add an 'admin charge' at the point of payment 'to fund their community work' which would add another 2-3p per litre to the price. If you join the oil club there's no compulsion to use it, you can just ignore the emails and carry on as before.

 

[cgwhite]

Just to clarify, I have the EV charging on a separate circuit to the Solar and Battery, so using intelligent Octopus it only charges at the 7p rate and does not use the battery storage at all. The iBoost is scheduled to heat the immersion heater during the 7p cheap rate period so by the time we get to peak rate everything is topped up. But now that the oil price has come down and autumn is approaching, I will disable the iBoost and go back to oil for the hot water. That will also leave more Solar to export as it won't be topping up the tank during the day as we use hot water. As far as I know the GivEnergy solution is the only one that you can actually discharge the batteries back to the grid.

Must remember to disconnect the EV today so it doesn't charge tonight to get the 3.5p rate!

Regards, Chris.

 

[Rolfe]

So you have a special system wired up to let you do this? It's not possible with a system wired the usual way? Something very strange going on here.

 

[cgwhite]

It is a little special in that I have the EV Charger on its own separate circuit. I have a second set of tails out of the meter. That means I can have the Ohme CT clamp on its own tail. The Solar and Batteries have their own tails and hence the Inverters CT Clamp does not see when the car is charging. But even so, the car and batteries are charged during the cheap rate time so you will not ever get the battery charging the car. That is the beauty of the the Intelligent Octopus system, regardless of when the car is charging, even outside the cheap rate times, it still only costs the 7p rate. Think Solar Export in all of this. The more solar export you can achieve the better the payback. You even don't want the solar charging the batteries during the day, but as yet I have not found a way to avoid that. With an 8kw solar system I would like to have the solar only charge the batteries when the export hits the 4kw limit. Great in the summer but not so possible in the winter unless its a burning hot day. Something for the inverter manufacturers to think about.

 

[Rolfe]

Interesting response, thanks. There really should be a way to do this. At the moment I'm just chucking what's left in the battery by 11.30 pm back to Octopus as export. That actually covers it and a bit more. I'm not sure if Octopus really approves of this, but we'll see. In fact it means they're getting some export right at the time a lot of people are turning on their washing machines and dishwashers, so it may suit both parties.

 

[Rolfe]

It is a little special in that I have the EV Charger on its own separate circuit. I have a second set of tails out of the meter. That means I can have the Ohme CT clamp on its own tail. The Solar and Batteries have their own tails and hence the Inverters CT Clamp does not see when the car is charging. But even so, the car and batteries are charged during the cheap rate time so you will not ever get the battery charging the car. That is the beauty of the the Intelligent Octopus system, regardless of when the car is charging, even outside the cheap rate times, it still only costs the 7p rate. Think Solar Export in all of this. The more solar export you can achieve the better the payback. You even don't want the solar charging the batteries during the day, but as yet I have not found a way to avoid that. With an 8kw solar system I would like to have the solar only charge the batteries when the export hits the 4kw limit. Great in the summer but not so possible in the winter unless its a burning hot day. Something for the inverter manufacturers to think about.

I have a potential 8 kw generation and a 5 kw limit. It has been interesting to see the generation recorded shoot up when the battery has been below 100% in the middle of a sunny day!

I think I am more or less sorted. I don't mind that the battery can charge the car, because this is sometimes useful and I can prevent it from happening if I want to. John has very kindly explained to me how to stop the Eddi grabbing solar without turning it off, and I think this will work for the Zappi too. So I'm only left with the house and its battery grabbing the solar.

As I said, my solution to this, until and unless Octopus say don't do it, is to export whatever is left in the house battery at 11.30 pm. That represents the solar generation the house and battery took when I would have preferred to export it up front. And a bit more sometimes, but we also have to consider losses. As I said, Octopus might not mind some export at the time when a lot of people are turning on their washing machines etc. We'll see.

 

[cgwhite]

Shouldn't be an issue exporting the battery to the grid. There is nothing in the T's & C's from Octopus to say you can't do that that I can see. They don't know where the electrons are coming from. How do you tell if you are using green or black electrons when your electric company says that their energy is 100% renewable? Octopus is one of the only leading electricity companies that seems to want to innovate as far as renewables is concerned. They will take everything you can produce.

 

[Rolfe]

Seems to be working perfectly this morning. The water was at temperature just after 5 am, then when the sun rose export started as soon as the battery was at 100% without any interference from the Eddi and without any intervention from me.

The battery emptied itself from 11.30 then recharged from 2.00. It was almost done when the water heating started. Current situation, water quite hot enough, car at 100%, home battery ditto, panels generating 5.21 kw and exporting 4.81 kw, subject to cloud cover.

I think this is as good as it's going to get.

 

[Bam Bam]

I have a potential 8 kw generation and a 5 kw limit. It has been interesting to see the generation recorded shoot up when the battery has been below 100% in the middle of a sunny day!

I think I am more or less sorted. I don't mind that the battery can charge the car, because this is sometimes useful and I can prevent it from happening if I want to. John has very kindly explained to me how to stop the Eddi grabbing solar without turning it off, and I think this will work for the Zappi too. So I'm only left with the house and its battery grabbing the solar.

As I said, my solution to this, until and unless Octopus say don't do it, is to export whatever is left in the house battery at 11.30 pm. That represents the solar generation the house and battery took when I would have preferred to export it up front. And a bit more sometimes, but we also have to consider losses. As I said, Octopus might not mind some export at the time when a lot of people are turning on their washing machines etc. We'll see.

Hmmmm, so there is an advantage to having a battery not full during the middle of a sunny day so you can get more out of your solar system by putting it in the battery? I guess there won't be so many of those as we move to the dark half of the year, but that is an extra complication.

On the previous version of the Givenergy app there were: pause, go, plus (import) and minus (export) options for the battery at the bottom of the home page, but I found they didn't really work reliably (maybe that is why they got removed).

So a good schedule for you might be: Import overnight - export during breakfast - top-up battery in the middle of the day - export in the late afternoon - use grid in the evening

Octopus just set times for export and import, but I don't think you can set up more than one export option at a time so you'd have to update it twice per day. Maybe you could set it up for export in the morning peak and the afternoon peak and it would run off and get filled up with solar during the middle of the day.

You could do what Octopus do with for us on the Intelligent Flux and fully export your battery from 5pm-7pm. Electricity prices shoot up from 4pm-7pm so I'm sure Octopus would appreciate you exporting then!

 

[Rolfe]

I'm exporting what's left at 11.30, but I'm open to suggestions.