Circular reasoning

[Bam Bam]

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.

Oooh you're getting an Eddi as well - that increased our quote substantially so I didn't bother with it. We came up with our own hot water solution which is working as intended but probably not worth the hassle we had to go through.

Givenergy works well for us.

The only thing I would query is whether you will get much clipping with the 3.6kw inverter.

Installers like the 3.6kw because they don't have to do as much paperwork.

I asked for a 5kw (it is only £40 more expensive) but that created a lot of extra delays! If there were delays then you'd then be missing out on the fantastic generation over the Spring and Summer.

On the other hand, in the winter the 3.6kw might be better though and in the Summer you'll have loads of generation so I doubt it is a major issue.

So I would say go for it, but check you are getting a recent generation (ie Gen 3) GivEnergy inverter.

 

[SimonS]

Two suggestions. Firstly, I would go for a 5kW inverter which will only add £150 or so. With a 3.6kW you will be drawing from the grid when you turn on the oven and the hob or kettle. We have a 5kW and it's very rare that we exceed that during the day when drawing from the battery but regularly get above 4kW.
Secondly I would question if you need the Eddi. We have one and before we were registered for export we used the Eddi to divert solar to the immersion rather than giving it to the grid. Now we have the battery and an export tariff. we send as much solar as possible to the grid as Octopus pay us 15p/kWh. We rarely use the immersion now as it is more cost effective to use gas. If you are not on mains gas then your priorities might be very different.

Something else to add... Do you have a smart meter? If not, it's easy to get one fitted (usually no cost) but allow a couple of months as there is a backlog.

 

[Bam Bam]

Two suggestions. Firstly, I would go for a 5kW inverter which will only add £150 or so. With a 3.6kW you will be drawing from the grid when you turn on the oven and the hob or kettle. We have a 5kW and it's very rare that we exceed that during the day when drawing from the battery but regularly get above 4kW.
Secondly I would question if you need the Eddi. We have one and before we were registered for export we used the Eddi to divert solar to the immersion rather than giving it to the grid. Now we have the battery and an export tariff. we send as much solar as possible to the grid as Octopus pay us 15p/kWh. We rarely use the immersion now as it is more cost effective to use gas. If you are not on mains gas then your priorities might be very different.

Snap!

Eddi ?
I know what you mean about the Eddi, I didn't go for it myself, but in the future I think there will be more of the 'free green electricity sessions' where you get free energy at times of plenty (windy and/or sunny).

A smart device like an Eddi could potentially just dump some of that lovely free electricity in the hot water and save the need to buy gas.

5kw?
You've also given @Rolfe another reason to ask for a 5kw inverter, though that would cause delays.

You might be right about the extra cost being more than the difference (£40) - it might require thicker cabling as well for all I know.

Worth asking the installer what the pros and cons are of going for the 5kw instead I think.

 

[Rolfe]

Thanks for all that. I already have a smart meter.

The Eddi, with built-in wifi and ethernet, is only adding £410 to the cost. I wasn't sure about it, but it's not a huge amount, and another neighbour (not the neighbour who recommended this installer) spontaneously said to me that his installer had fixed it so that excess solar went to his immersion heater and he thought it was a great idea.

The inverter is a Gen 3. I can ask about the 5 kw part.

I'm not on mains gas, my heating comes from a tank of kerosene, and sparing the usage of that would probably be worth it both in terms of saving a bit on the oil bill and enhancing my green credentials. I'm also going to look at some way to use some surplus to heat somewhere, maybe the main living room, though I don't know the practicalities.

 

[SimonS]

Thanks for all that. I already have a smart meter.

The Eddi, with built-in wifi and ethernet, is only adding £410 to the cost. I wasn't sure about it, but it's not a huge amount, and another neighbour (not the neighbour who recommended this installer) spontaneously said to me that his installer had fixed it so that excess solar went to his immersion heater and he thought it was a great idea.

The inverter is a Gen 3. I can ask about the 5 kw part.

I'm not on mains gas, my heating comes from a tank of kerosene, and sparing the usage of that would probably be worth it both in terms of saving a bit on the oil bill and enhancing my green credentials. I'm also going to look at some way to use some surplus to heat somewhere, maybe the main living room, though I don't know the practicalities.

Without mains gas then I agree that the Eddi is a good idea.

Re the inverter, 3.65kW would be a 'G98' approval which basically means that you only have to tell your DNO that you are installing it. For a 5kW it becomes a 'G99' which means you have to ask permission which can take a bit longer. Your install can give you more details.

 

[johnb80]

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.

The inverfter is too small, switch on the kettle and the toaster or washing machine and cooker you will be importing from the grid. Installers go for 3.6 kW because it makes their paperwork easier. Go for at least 6 kW inverted, theres minimal increase in price and it will fit your system so much better. You have around 7 kW of solar panels on your roof and an inverter that can only handle half of that. EDDI and Zappi work really well together.

 

[Rolfe]

Thanks. However, apparently there is a £900 fee to go to the higher rating.

 

[SimonS]

My DNO application for G99 approval cost £200 last September.

 

[johnb80]

Thanks. However, apparently there is a £900 fee to go to the higher rating.

To the best of my knowledge there isn’t a fee attached to the applications, well, not down here in England. I would check with you DNO, give em a quick call and ask what the fees are for G98 and G99.

J

To the best of my knowledge there isn’t a fee attached to the applications, well, not down here in England. I would check with you DNO, give em a quick call and ask what the fees are for G98 and G99.

J

I’ve had a search around, Scottish power allegedly charge £750 for a G99 application, if you protest however, they reduce it to £250. You could apply for export up to 3.6 kW with a 6kW inverter, DNO shouldn’t have any objections to this. The other aspect is during a power cut, you’re limited with the small inverter to 3.6 kW even though your batteries are full etc. With a 3.6 kW inverter you may as well reduce the number of panels to be nearer the inverter capacity.

 

[SimonS]

I’ve had a search around, Scottish power allegedly charge £750 for a G99 application, if you protest however, they reduce it to £250. You could apply for export up to 3.6 kW with a 6kW inverter, DNO shouldn’t have any objections to this. The other aspect is during a power cut, you’re limited with the small inverter to 3.6 kW even though your batteries are full etc. With a 3.6 kW inverter you may as well reduce the number of panels to be nearer the inverter capacity.

Backup on both the 3.6 and 5kW inverters is limited to 16A. https://givenergy.co.uk/wp-content/uploads/UK-Datasheet-Hybrid-Gen-3-3.6.pdf

 

[Bam Bam]

My DNO application for G99 approval cost £200 last September.

Thanks. However, apparently there is a £900 fee to go to the higher rating.

I'm guessing they are charging you for the extra time it will take them to put in the application?

I asked for a 5kw despite a smaller array (and E-W so never both full-on at the same time) and I don't think our local supplier increased the cost too much (though perhaps I'm wrong). It did really increase the time it took.

 

[johnb80]

Backup on both the 3.6 and 5kW inverters is limited to 16A. https://givenergy.co.uk/wp-content/uploads/UK-Datasheet-Hybrid-Gen-3-3.6.pdf

Find a better quality unit then, I ended up in the same boat with an SPH6000 (6 kW Inverter), only 3 kW on battery. That's what started me off on designing and building an AC coupled battery, now I have 9 kW plus of inverter power and my meter registers very little on peak consumption.

 

[Bam Bam]

Find a better quality unit then, I ended up in the same boat with an SPH6000 (6 kW Inverter), only 3 kW on battery. That's what started me off on designing and building an AC coupled battery, now I have 9 kW plus of inverter power and my meter registers very little on peak consumption.

The all-in-one is Givenergy's AC coupled offering. Basically a Powerwall but much cheaper. That provides a better backup option than the hybrid inverter.

However, you'd then need a separate solar inverter. The hybrid units do solar and battery in one and thus are cheaper, plus fewer losses from converting DC-AC-DC-AC so many times. Pros and Cons really.

The 16A limit only applies when using the off-grid backup facility. The 5kw inverter we have can output 21.7A when on the grid. The 3.6kw does have a 16A limit generally though.

Personally I found that the roughly 4kw output (5kw when the sun is shining) saved us using the grid. Just try to time the big-draw items (immersion heater, kettle, oven, dishwasher, washing machine) where possible so that they aren't on at the same time.

16A backup means you'd have to give a bit more thought to usage, but the Givenergy EV charger is pretty good as you can limit the amps and it does solar divert so should work well even on backup mode. We've not had a power cut since the backup was installed 6 weeks ago and ideally we never will! Nice to know that we can run the lights/fridge freezer and continue to get solar energy if the grid does go down.

During the Summer we are on IO where the entire grid is your battery so no need to worry about solar divert, or even if you go over the inverter's limit.

In the winter you are happy to draw from the grid overnight when it is cheap anyway, so time some big-draw items like the dishwasher and hot water immersion (via eddy for instance) for then and you're golden.

 

[Bam Bam]

The inverfter is too small, switch on the kettle and the toaster or washing machine and cooker you will be importing from the grid. Installers go for 3.6 kW because it makes their paperwork easier. Go for at least 6 kW inverted, theres minimal increase in price and it will fit your system so much better. You have around 7 kW of solar panels on your roof and an inverter that can only handle half of that. EDDI and Zappi work really well together.

Hmm looking at the datasheet perhaps the 3.6kW can take in more solar, it just can't output at the same rate. But it is DC coupled with the battery.

Am I right in thinking that means it could take in more than 3.6kW as long as there is spare battery capacity available? https://givenergy.co.uk/wp-content/uploads/UK-Datasheet-Hybrid-Gen-3-3.6.pdf

 

[Gomev]

The all-in-one is Givenergy's AC coupled offering. Basically a Powerwall but much cheaper. That provides a better backup option than the hybrid inverter.

However, you'd then need a separate solar inverter. The hybrid units do solar and battery in one and thus are cheaper, plus fewer losses from converting DC-AC-DC-AC so many times. Pros and Cons really.

The 16A limit only applies when using the off-grid backup facility. The 5kw inverter we have can output 21.7A when on the grid. The 3.6kw does have a 16A limit generally though.

Personally I found that the roughly 4kw output (5kw when the sun is shining) saved us using the grid. Just try to time the big-draw items (immersion heater, kettle, oven, dishwasher, washing machine) where possible so that they aren't on at the same time.

16A backup means you'd have to give a bit more thought to usage, but the Givenergy EV charger is pretty good as you can limit the amps and it does solar divert so should work well even on backup mode. We've not had a power cut since the backup was installed 6 weeks ago and ideally we never will! Nice to know that we can run the lights/fridge freezer and continue to get solar energy if the grid does go down.

During the Summer we are on IO where the entire grid is your battery so no need to worry about solar divert, or even if you go over the inverter's limit.

In the winter you are happy to draw from the grid overnight when it is cheap anyway, so time some big-draw items like the dishwasher and hot water immersion (via eddy for instance) for then and you're golden.

The Givenergy AIO does have solar input out of the box as far as I'm aware, no need for any other inverters.

 

[Bam Bam]

The Givenergy AIO does have solar input out of the box as far as I'm aware, no need for any other inverters.

That would be great, and artisan electrics had a video recently where they installed solar and all-in-one and I didn't note any other inverter.

However, I can't see anything about solar input on the product datasheet.

 

[EVsince2016]

I decided to do this 20+ years ago but the maths didn't add up.

In 2011 I switched from an oil boiler to wood pellets & solar thermal. I got a 200%+ return on the wood pellets thanks to a grant but still have got just 69% back on the thermal so have a way to go, probably a 20y return.

Sums added up for an EV in 2016 when I switched, as it was cheaper to own than my elderly diesel Vauxhall estate.

In 2019 I added solar PV, Zappi & Eddi. I got my full return on Zappi, so far 48% on the PV but an amazing 136% back on Eddi, so Eddi is a winner!

This year I've added a Ripple wind turbine and expect a 7-11 year return.

A battery never had a good return until the last 2 years, but as prices went up for electric, so did battery costs, it was a fine balance. Now as long life LFP batteries at lower unit rates and future Sodium Ion batteries arrive, maybe that will bring a return?

 

[Gomev]

..

A battery never had a good return until the last 2 years, but as prices went up for electric, so did battery costs, it was a fine balance. Now as long life LFP batteries at lower unit rates and future Sodium Ion batteries arrive, maybe that will bring a return?

Not forgetting the removal of VAT for standalone batteries and installation recently.