Anyone got solar panels and Tesla Powerwall ?

  • Thread starter Thread starter Robert Clark
  • Start date Start date
mikebeaches said:
The funny thing was, our property was built 36 years ago on an infill plot, and the guy from Western Power said "I just needed to check because your house doesn't appear on any of our maps!!" :rolleyes: Gobsmacked was an understatement - I couldn't believe it. If nothing else, have they not heard of Google Maps... :LOL:
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Trust me, most utilities don’t know where half their cables and pipe runs are.

They may have drawings but they arnt accurate a lot of the time.

Ask. As any ground work contractor 😉😊
 
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For a 22 Panel 8.6KW system with 14KW of battery storage I've just been quoted 15,250.00 Plus Vat! 😲
 
Jim said:
For a 22 Panel 8.6KW system with 14KW of battery storage I've just been quoted 15,250.00 Plus Vat! 😲
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Gold plated I’m guessing to suit your standing in the community 😉😊

They must be paying the fitters a fortune 🤔😊
 
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Silver-Fox said:
Ask. As any ground work contractor
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What like the large sum of money the council paid a homeowner for a small patch of land for me to widen and build a new bridge only to find an 11kv cable going right through the bit of land where a retaining wall was going😂😂

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Just had a chat with our solar fitters

mikebeaches said:
No special permission required - our array has a potential 7.2kWh generation capacity.
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They suspect your fitters did not do the DNO application, unless you have a 3 phase supply, it is possible without DNO approval if the output is too high they can make you turn off the solar panels. Whether that just means any output to the grid or in total I didn’t ask

mikebeaches said:
You must use a fair bit of electric if 13kWh wouldn't last you until midnight! :LOL:
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We consume close to 1Kw all the time increasing at night with lights and cooking , typically 40 Kw/day in winter 🤔😳

Mrjenben said:
Unless things have changed, you need permission from the grid DNO (District Network Operator) to connect any Solar Migrogeneration to the national network if it’s over 4kw. Most are normally ok but some rural areas might have capacity problems. Even with just 4kw our friends had to get them out to ‘adjust‘ the local transformer as they were pushing the supply voltage over the allowed limits.

We’re thinking about adding battery storage to our Solar PV. The Tesla energy plan sounds interesting, but if I’m reading it right I’m not sure it’s worthwhile if you currently have the best FIT rate which is over 50p kwh. Sounds good for new installs though!
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The DNO info was pretty much as I recalled it 👍

We are new to solar, only fitted in October, Best Buy back rate we can get is 4.5p, but we only paid £8K for the dual systems fitted, I understand this is a lot less than when you could get 50p + buy back

Our installer fit 8Kw battery packs for about £4K, the Tesla unit would cost £7.5K fitted

Even with the amazing rate of 11p to buy and sell our electricity, we reckon it would be a minimum of 8 years to break even, and by 10 years fear the batteries may be getting ready for changing , even with our higher than average usage / costs I don’t think it will make financial sense for us to add the Tesla option or any battery for that matter

Our suppliers have had complaints that in winter, the batteries barely take any charge.

We are still weighing up putting a battery on one half of our property where we use by far the most power

Will follow this thread with interest 👍
 
mikebeaches said:
We have no gas, so all electric cooking, and yet our average daily consumption throughout the year is around 5.25kWh
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I find that amazing! I have one fridge , & 2 new small top rated freezers , The lights are all led's & even if on 24hrs/day consume only 0,75kw. Apart froma couple of lap tops there is no other electric consumption & we cannot get it below 4 kw/day?

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gus-lopez said:
I find that amazing! I have one fridge , & 2 new small top rated freezers , The lights are all led's & even if on 24hrs/day consume only 0,75kw. Apart froma couple of lap tops there is no other electric consumption & we cannot get it below 4 kw/day?
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That sounds about right - we use, on average, 5.25kWh per day. So circa 2,000kWH a year.

BUT, we aim to use more now we have the solar and battery set-up. Although cold today, there was a bit of bright sunshine for a couple of hours, so we switched on some electric convector space heaters. :giggle:
 
mikebeaches said:
Interesting! I assume our installer Infinity Renewables https://infinity-renewables.com/ must have taken care of it with the District Network Operator.
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Its a while since we had ours fitted, but all the installers we looked at included this as part of their work. They had to register with the DNO for you to get the FIT payments anyway.

Although they didn’t have to register installs under 4kw, most used to check with the DNO as part of the initial survey. The DNO cant reject the install if it’s under the limit but they sometimes have to carry out work to upgrade the network to handle it. It’s normally only a problem in rural areas or residential where a lot of houses are adding solar at the same time.
 
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DavidG58 said:
We are new to solar, only fitted in October, Best Buy back rate we can get is 4.5p, but we only paid £8K for the dual systems fitted, I understand this is a lot less than when you could get 50p + buy back
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£11k for a 4kw system back in the day. Although the payback at over 50p per kWh for 25 years is pretty good.

Our installer was obviously on to a good thing. Just before the rate was cut he was installing 4-5 systems a week. He quit a career in IT to work with his dad installing Solar PV and has never looked back:-)
 
Silver-Fox said:
If the switch doesn’t see a feed from the grid it could drop out.

I’ve worked with a few guys that work on the cables.
There are plenty of safety things in place to prevent electrocution.

Plus most of them work on live cables anyway 🤷‍♂️
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Quite correct, as part of our safety rules we use LV shorting kits and HV drain earths against any inadvertent back feeds, normally PV but any renewable.
A solar panel could potentially produce up to 11kV.
Most of our work on the LV network we do live to save Customer Minutes Lost.
We also work live on the 11kV network for the same reason.
If the HSE had their way we would have to knock the power off every time we touched it.
 
Anorak warning: The equipment needs to meet G98 (or 99/100) approval to be connected to the mains, to ensure it cuts over safely in case of power cut. Victron and Tesla Powerwalls do, for example.

Interestingly (for some!), if you have solar panels, they can continue to work when off grid if they have control mechanisms set up. SMA and Fronius can do this with a Victron unit. So if there is a power cut the panels will still work, and charge until the batteries are full.

This is all my understanding from my system and the research I've done.

Cheers

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Update

Had a guy round to measure up for a ground mounted solar system and Tesla power wall.
He’s promised a price by the end of next week.

I asked Octopus if they’d need to replace our old smart meter as it never worked due to crappy mobile signal here. They’ve said that we can’t join their scheme unless their meter can get a decent signal. They’re now checking to see if it will work here.

If they say we can’t join the TEP I’m now wondering whether to get just the battery, to avoid power outages. Or to get some solar too and not get paid for any electricity I feed in
 
Robert Clark said:
If they say we can’t join the TEP I’m now wondering whether to get just the battery,
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These days they just pay you for electricity you feed back - in the old days you got paid for what you generated, whether you fed it back or not!

It's called the Smart Export Guarantee (SEG) - see here - "If you generate renewable electricity in your home or business, you can feed back into the grid any electricity that you don’t use. Under the Smart Export Guarantee (SEG) you will be paid for every unit of electricity that you feed back. You won’t be paid for any that you use yourself"

I reckon it's worth having panels installed at the same time at the same time as a battery if you qualify for 5% VAT - if you are over 60 :) or have a war pension etc - for examples see here - "If you’re eligible, you’ll pay a reduced rate of VAT (5%) when certain energy-saving products are installed in your home".

Cheers
 
cbrookson said:
These days they just pay you for electricity you feed back - in the old days you got paid for what you generated, whether you fed it back or not!

It's called the Smart Export Guarantee (SEG) - see here - "If you generate renewable electricity in your home or business, you can feed back into the grid any electricity that you don’t use. Under the Smart Export Guarantee (SEG) you will be paid for every unit of electricity that you feed back. You won’t be paid for any that you use yourself"

I reckon it's worth having panels installed at the same time at the same time as a battery if you qualify for 5% VAT - if you are over 60 :) or have a war pension etc - for examples see here - "If you’re eligible, you’ll pay a reduced rate of VAT (5%) when certain energy-saving products are installed in your home".

Cheers
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The generous Feed In Tariffs (FITs) for solar were withdrawn in 2019 for NEW installations.

And the replacement Smart Export Guarantee (SEG) which is now available, requires all medium and large electricity suppliers (100k+ customers) to offer it. However, there is no standard or minimum rate, so each electricity supplier can decide how much they are going to pay for every killowatt hour of electric they receive from homeowners exporting solar. eg I believe British Gas currently pays a miserly 3.2p.

Whereas, Octopus energy will pay a flat rate of 7.5p, provided you also purchase your electricity from them and of course pay their standing charge (even if consuming very little from the grid).

-----------------------------

Reference the application of VAT on battery storage systems, I learned a lot from a website I linked to previously about the Tesla Powerwall.

Battery installations in the UK generally attract VAT at 20%. So the total cost to the residential purchaser (Powerwall) would be £10,200 inc. VAT @ 20%.

Please note: after the new VAT laws introduced on 1 October 2019, if a home battery is installed at the same time as a solar PV system, you might be able to secure VAT @ 5% on the Powerwall. That would bring the price down to £8,925 inc. VAT @ 5%. This is only possible if the materials element of the invoice (ex VAT) is less than 61% of the total invoice value. Ask your local installation company for more details.

If you don’t meet the 61% threshold, it’s cheaper to have the solar panel installation put on one invoice @ 5% VAT, and then the battery installation submitted on a separate invoice @ 20% VAT.

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The system we had installed - solar pv panels, lithium batteries and smart hybrid inverter - all attracted 5% VAT. (Nothing to do with our age, as far as I know?).
 
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gus-lopez said:
If you are all electric I can't see that you only use 1,25kw/day for cooking & heating?
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We've got oil-fired heating, so only using electric for space heating when we've got excess solar generation. Which would of course take us over 5.25 kWh - that's the idea - to use more electric when it's available now we can make our own. ;)

And we have just one cooked meal a day, frequently prepared using a standard Remoska rated at 400 watts. Obviously, we also use electric hobs on the range and electric kettle (although we've long kept a large thermos jug of hot water to use through the day, so the kettle isn't on too often). :giggle:

We've always been very careful with energy, although we like to stay warm and generally live comfortably. The solar and batteries just provide more flexibility and the ability to reduce our oil bill a little too. (y)

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Rob Turner said:
Quite correct, as part of our safety rules we use LV shorting kits and HV drain earths against any inadvertent back feeds, normally PV but any renewable.
A solar panel could potentially produce up to 11kV.
Most of our work on the LV network we do live to save Customer Minutes Lost.
We also work live on the 11kV network for the same reason.
If the HSE had their way we would have to knock the power off every time we touched it.
Click to expand...
cbrookson said:
Anorak warning: The equipment needs to meet G98 (or 99/100) approval to be connected to the mains, to ensure it cuts over safely in case of power cut. Victron and Tesla Powerwalls do, for example.

Interestingly (for some!), if you have solar panels, they can continue to work when off grid if they have control mechanisms set up. SMA and Fronius can do this with a Victron unit. So if there is a power cut the panels will still work, and charge until the batteries are full.

This is all my understanding from my system and the research I've done.

Cheers
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Is it legal to install your own solar system connected to the grid, as long as it is under 4Kw?
 
It is critical that the frequency and phase of the 240V AC power formed by the domestic PV inverter in the home matches exactly that of the power at that location provided by the national grid (which varies all the time), otherwise there will be a great gnashing of teeth.

To ensure this condition is met the inverter continuously monitors the grid frequency and phase and matches them in its AC inversion process. Without this feed from the grid the standard inverter cannot function and hence is a no go during a power cut.

So simply isolating your PV set up from the grid to try to use it during a power cut is not enough, you would also need a replacement input signal.
 
We have a 4 kw system and two pylontech batteries which fill up on a good sunny day as well as doing the washer, dryer and dishwasher so it's rarely we see much going back to the grid if we use it properly and we only get 3p per Kw from our supplier anyway. Even at 11p which Tesla are paying it would seem difficult to justify the very high cost of the Tesla wall versus the cheaper alternatives. Anyone worked that out?

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We have 8.6kWh of solar on order, along with Tesla Powerwall. The whole thing has been very expensive, not least because we live on an island, but long term it will payback. We are high users as we have electric (ASHP) heating as well, no mains gas on the island so the options are oil heating or storage heaters.

The Powerwall looks expensive, but by the time you match the spec (especially discharge rate - some systems have barely enough to run a kettle) it’s not too bad. The Tesla Energy Plan makes it a no-brainer, ironically if it wasn’t for that we would need two Powerwalls, but there is no point having more than one.
 
Don Campbell said:
We have a 4 kw system and two pylontech batteries which fill up on a good sunny day as well as doing the washer, dryer and dishwasher so it's rarely we see much going back to the grid if we use it properly and we only get 3p per Kw from our supplier anyway. Even at 11p which Tesla are paying it would seem difficult to justify the very high cost of the Tesla wall versus the cheaper alternatives. Anyone worked that out?
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I guess everyone’s situations are different.

For example our solar array can only be 2-3kw and we own two electric cars, so being able to consume electric at 11p is a major saving compared to current prices.
 
Backlanes said:
So simply isolating your PV set up from the grid to try to use it during a power cut is not enough, you would also need a replacement input signal.
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Me being a simpleton I’m struggling with not being able to use pv when the grid is down.

We only use solar and battery in the Moho.

Can you explain in simple terms why you need a grid feed to use the solar and battery set up in a house.

Thanks
 
Silver-Fox said:
Can you explain in simple terms why you need a grid feed to use the solar and battery set up in a house.
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It is because the home solar system feeds power into the grid so it has to match it.
Your van power stands alone and does not have to match anything.
You can have an ‘island’ switch for your home which isolates it from the grid properly at which point it no longer needs to match, but the inverter will need to have a mechanism for setting its own AC phase without an input in that case.
 
Silver-Fox said:
Me being a simpleton I’m struggling with not being able to use pv when the grid is down.

We only use solar and battery in the Moho.

Can you explain in simple terms why you need a grid feed to use the solar and battery set up in a house.

Thanks
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For safety reasons most inverters need there to be mains power to trigger them to run.

Tesla and Victron don’t as they isolate the incoming power feed as soon as it loses power.

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