Circular reasoning

[Ferretusmaximus]

Thanks for all the contributions. Obviously the system I'm pricing up is the Full Monty, and the supplier suggests the Zappi with Octopus Flex. If I was only going for a charger I'd re-think that.

I'm a bit surprised by the scarcity of "it's great, go for it!" posts compared to the "nah, not worth it" ones, especially in this forum section. Where are the enthusiasts?

Possibly because it all depends on personal circumstances. I invested in a Powerwall when interest rates were 0.1% and house batteries looked as though they could deliver an equivalent interest rate of about 5-10% - not sure if I would have done it if I didn't have the funds. As to "go for it" - if you can afford it then definitely a big yes as you save a lot in the long term, you have some insulation against power cuts and you are being good to the planet.

 

[Archev]

Possibly because it all depends on personal circumstances. I invested in a Powerwall when interest rates were 0.1% and house batteries looked as though they could deliver an equivalent interest rate of about 5-10% - not sure if I would have done it if I didn't have the funds. As to "go for it" - if you can afford it then definitely a big yes as you save a lot in the long term, you have some insulation against power cuts and you are being good to the planet.

Go for it

 

[GaryMG4]

Obviously the panels are going to provide bugger-all in the winter. So there must be some compensatory mechanism. The system the installer is proposing is predicted to supply 6618 kwh pa, which is actually more than I use at the moment. I'm trying to get my head round how this works.

Here in Norfolk our 16 panel 4kW array (no battery storage) has produced 3700-4200 kWh pa over the last 8 years. As a result we buy around 3000 kWh pa, currently costing around £82 per month. I expect the DD will need to increase a bit as this time last year I was in credit by £100 or so, this year it's flat. Oil provides heating and hot water.

 

[Rolfe]

Thanks for all the input. Could anyone specifically clarify two things.

First, how come the projected payback time is less than the time it would take me to pay the capital cost for electricity at my current direct debit rate, and

Second, given that solar generation only really happens in the summer, how is it possible not to rack up a lot of expenditure from the grid in winter?

 

[Bam Bam]

Thanks for all the input. Could anyone specifically clarify two things.

First, how come the projected payback time is less than the time it would take me to pay the capital cost for electricity at my current direct debit rate, and

Second, given that solar generation only really happens in the summer, how is it possible not to rack up a lot of expenditure from the grid in winter?

Not sure I've understood your questions.

1. Does the projection assume that you will cash in some of the credit? You can get an income during the Summer from selling the electricity, though if you keep it as credit you won't have to declare it for tax purposes (at least that is my understanding).

One company was convinced we should get much more solar and battery than the others. I looked through their spreadsheet and they were assuming that energy prices would continue to rise at pandemic rates forevermore. Perhaps they will but it seemed like a big assumption to me! I now wish I had got as many panels as they suggested, though not the expensive powerwall.

2. We built up around £300 credit last summer and gradually got through it over the winter. Having the battery is great for savings sessions in the winter as well - full export and you are paid handsomely.

 

[Rolfe]

What you have said has answered the second question, I think. I'm still a bit hazy on the first.

If I go for this, and it's looking more likely than not, I will get the 18 panels suggested by the installer.

 

[Bam Bam]

What you have said has answered the second question, I think. I'm still a bit hazy on the first.

If I go for this, and it's looking more likely than not, I will get the 18 panels suggested by the installer.

18 panels is a very decent amount if south facing. We have East-West so get about 80% of a South array over the year.

You could interrogate their numbers if they haven't provided you with the full breakdown:
1. Are they assuming you will be selling your summer surplus and getting an income from it?
2. Are they assuming future increases in energy prices in their calculation? (That might happen for various reasons like devaluation of the pound, but who really knows?)

 

[Rolfe]

Honestly, there's pages and pages of technobabble there. This is the relevant page I think. They're only talking about the payback time for the panels themselves. The installer says the standard calculations for the full system don't cover systems expected to generate over 6,000 kwh pa, but he estimates the payback for the full system (including battery etc) to be 6-7 years. The array is to be on a roof that faces slightly east of south.

As my current electricity use is about 6,000 kwh pa another thing I'm struggling with is how it works when I'm generating more than I use from solar alone, but of course mostly in summer when I'm using less. I suppose there are some big assumptions about getting paid to export surplus to the grid in the summer, building up credit, and living on that over the winter as Bam Bam said.

 

[salty]

Honestly, there's pages and pages of technobabble there.

On this thread, agreed, I'm totally lost.

 

[Bam Bam]

Honestly, there's pages and pages of technobabble there.

Well we contacted 6 or so companies and three quoted. Was hard to get quotes at the time as the companies had big backlogs and there were supply chain problems.

Went for the cheapest option and they delivered - eventually.

Your quote sounds reasonable to me, but you could seek out a few more and see what they suggest.

 

[Rolfe]

This guy did my next-door neighbours in an identical (mirror-image) house a year ago, and they're happy with him. The quote is about par for the course. I'm inclined to go for it, as my neighbours did all the multiple quotes and so on, and picked this one. Why keep a dog and bark yourself?

 

[SimonS]

When spec'ing a new install I would insist on the following:

1. A charger that is compatible with IOG (currently the Zappi and Ohme).
2. The charger to be wired from its own separate consumer unit which is fed direct from the supply meter.
3. All communications from charger/inverter/battery etc to be hard wired via ethernet.

Reasons. Do some reading around Forums, Facebook etc and you will soon realise that there are way more issues with vehicle to IOG integrations (and with other electricity suppliers) than with the charger. If you integrate the car you are adding two extra layers of complexibilty. Firstly the control needs to go via the car manufacturer's servers and secondly from these servers to your car via mobile data or your wifi. The one plus side to this is that you can use any charger.

Integrating with the charger means the control signals either go from the supplier to the charger direct or via the charger manufacturer both of which have a vested interest in keeping your systems working and with ethernet to the charger the mobil network and wifi are eliminated from the system.

On Forums/Facebook you will see with monotonous regularity people ask why their charger 'stole' all the electricity out of their battery. Having the charger on its own consumer unit means the Grid CT clamp can be placed between the two consumer units so that a house battery system (if fitted) will not see any current drawn by the charger and you with avoid the house battery being drained.

NB You can ignore this is you have a Zappi/Libbi system as they will communicate with each other to avoid this draining the battery.

Again, comments about communication problems usually come down to owners being overly optimistic about the quality and range of their wifi signals. Wire everything back to your router with ethernet if you want a trouble free installation.

 

[GaryMG4]

Honestly, there's pages and pages of technobabble there.

As my current electricity use is about 6,000 kwh pa another thing I'm struggling with is how it works when I'm generating more than I use from solar alone, but of course mostly in summer when I'm using less. I suppose there are some big assumptions about getting paid to export surplus to the grid in the summer, building up credit, and living on that over the winter as Bam Bam said.

I've had a look at our quarterly generation figures for a sample year.
Spring 700kWh, Summer 1800, Autumn 1000 and winter 300. So, sadly it is probably the inverse of your consumption.

 

[Bam Bam]

I've had a look at our quarterly generation figures for a sample year.
Spring 700kWh, Summer 1800, Autumn 1000 and winter 300. So, sadly it is probably the inverse of your consumption.

I put the stats of our first year here and you are right there is a slight inverse of consumption (though we got a dehumidifier and EV in January which account for an increase in consumption).

First year of solar generation

We had out solar and battery system installed a year ago and so I thought I would share the stats! Yes, we generated 4.64 MWh and we use...

dougstaxappeal.blogspot.com

If you are getting credit for the Summer generation that you can use in Winter it doesn't really matter if they don't match up.

 

[Bam Bam]

This guy did my next-door neighbours in an identical (mirror-image) house a year ago, and they're happy with him. The quote is about par for the course. I'm inclined to go for it, as my neighbours did all the multiple quotes and so on, and picked this one. Why keep a dog and bark yourself?

That is reassuring if the company did a good job with your neighbour and your system would match theirs. Ours were the cheapest quote but poor communication/customer service.

 

[Rolfe]

When spec'ing a new install I would insist on the following:

1. A charger that is compatible with IOG (currently the Zappi and Ohme).
2. The charger to be wired from its own separate consumer unit which is fed direct from the supply meter.
3. All communications from charger/inverter/battery etc to be hard wired via ethernet.

Reasons. Do some reading around Forums, Facebook etc and you will soon realise that there are way more issues with vehicle to IOG integrations (and with other electricity suppliers) than with the charger. If you integrate the car you are adding two extra layers of complexibilty. Firstly the control needs to go via the car manufacturer's servers and secondly from these servers to your car via mobile data or your wifi. The one plus side to this is that you can use any charger.

Integrating with the charger means the control signals either go from the supplier to the charger direct or via the charger manufacturer both of which have a vested interest in keeping your systems working and with ethernet to the charger the mobil network and wifi are eliminated from the system.

On Forums/Facebook you will see with monotonous regularity people ask why their charger 'stole' all the electricity out of their battery. Having the charger on its own consumer unit means the Grid CT clamp can be placed between the two consumer units so that a house battery system (if fitted) will not see any current drawn by the charger and you with avoid the house battery being drained.

NB You can ignore this is you have a Zappi/Libbi system as they will communicate with each other to avoid this draining the battery.

Again, comments about communication problems usually come down to owners being overly optimistic about the quality and range of their wifi signals. Wire everything back to your router with ethernet if you want a trouble free installation.

Perhaps I should bounce this off the installer. He is quoting for a Zappi and it is a Zappi that my neighbours have, but I don't know what a Libbi is.

 

[Archev]

Perhaps I should bounce this off the installer. He is quoting for a Zappi and it is a Zappi that my neighbours have, but I don't know what a Libbi is.

I think the Libbi is the storage battery made by Myenergi.

 

[GaryMG4]

I put the stats of our first year here and you are right there is a slight inverse of consumption (though we got a dehumidifier and EV in January which account for an increase in consumption).

First year of solar generation

We had out solar and battery system installed a year ago and so I thought I would share the stats! Yes, we generated 4.64 MWh and we use...

dougstaxappeal.blogspot.com

If you are getting credit for the Summer generation that you can use in Winter it doesn't really matter if they don't match up.

My panels have been in for 9 years now so I'm fortunate to be on the FiT scheme. because the panels were there when we moved in I don't have an idea of our actual consumption, only what I have to pay for. When we moved here the FiT payments covered our total electricity bill but the hike in prices means it was less than half at the peak closer to 3/4 currently.

 

[SimonS]

Perhaps I should bounce this off the installer. He is quoting for a Zappi and it is a Zappi that my neighbours have, but I don't know what a Libbi is.

As Archev has said, the Libbi is Myenergi's battery system. Having a battery and inverter from another manufacturer is not a problem and long as the charger and CT clamps are installed correctly to avoid battery drain. The installer should be aware of this.

https://support.myenergi.com/hc/en-gb/articles/4716922623633-Hybrid-PV-Battery-Set-up-Avoid-Draining

 

[Rolfe]

I've pretty much made up my mind to accept this quote, as it seems reasonable, the installer seems knowledgeable, my neighbours are happy, and he says he can start work in 4-5 weeks if I order now.

He was showing me his phone with current prices from Octopus Flux while he was looking at the job, and is quoting for a Zappi.

The panels are Trina Vertex S
The battery is GivEnergy Giv-Bat 9.5
The inverter is also GivEnergy hybrid inverter 3.6
There is also a MyEnergi Eddi microgeneration energy diverter

If anyone has any experience of these things, or any comment, fire away.