Circular reasoning (Rolfe's solar energy system)

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.
 
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.
 
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
 
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.
 
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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.

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? :unsure: https://givenergy.co.uk/wp-content/uploads/UK-Datasheet-Hybrid-Gen-3-3.6.pdf
 
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.
 
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.
 
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?
 
..

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.
 
Well, it's all go. My installer has upgraded the inverter to 5kw at no extra charge. I have signed on the dotted line and paid a 10% deposit. Work is scheduled to start in two weeks.
Hey, well done, thats good to hear, I'm sure you will be impressed with the end result.
 
Just had a real stroke of luck. The corner of the garage where the installer wants to put the battery and other toys was occupied partially by a couple of really old bicycles I was never going to ride again. Neighbours who have recently moved in across the road have a big skip in their driveway full off all sorts of junk. I plucked up the courage to ask, and the husband helpfully lifted the bikes into the skip for me. Saved me the chore of getting them into the MG4 without scratching anything and driving them 15 miles to the council tip. Result.
 
Well, it's all go. My installer has upgraded the inverter to 5kw at no extra charge. I have signed on the dotted line and paid a 10% deposit. Work is scheduled to start in two weeks.
Result!

Are they going to de-tune the 5kw until they get the G99 permission?

Glad you won't have to wait months like we did.

Our solar was great today - made nearly £4 export even after filling the car to 100% (from 80% so 10kwh)!
 
I sent off the "Letter of Authority" to get this done this afternoon. (For some reason the original email requesting this didn't get to me.) He's very hopeful it will be fine.

It has only just started to warm up here today, a bit of sun, got my bed linen washed and dried, hopefully these fatuous sunbeams will be toiling to greater effect by the end of the month.
 
I sent off the "Letter of Authority" to get this done this afternoon. (For some reason the original email requesting this didn't get to me.) He's very hopeful it will be fine.

It has only just started to warm up here today, a bit of sun, got my bed linen washed and dried, hopefully these fatuous sunbeams will be toiling to greater effect by the end of the month.
Here in sunny Norfolk I've added 31 kWh this month (2 charges) at a total estimated grid cost of £1, those sunbeams are doing there job here.
 
Just calculate the payback period, for us solar and batteries, plus the orientation of our rook is a no go. Now if we were 20 years younger it would be very different story. The EV changer alone will take a few years to payback, but we bought it for convenience.
 
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