David Jenkins
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| posted on 21/2/23 at 07:36 PM |
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I've had a 9.6kW/h home battery installed just before Christmas - even during most dismal February days I can recharge the battery off the PV
ready for the evening. If the weather is truly bad and it doesn't get fully charged I top it up during the 00:30 to 04:30 cheap period via
Octopus Go.
The result is that I don't take any power off the grid during the typical day, apart from the top up in the wee hours, which (currently) is at 5p
per kW/h - but will be up to just over 10p when I renew the contract in a few months. We normally charge our cars either off solar, or with the
cheap-rate night tariff - I can't remember the last time I charged a car using the normal day tariff.
Note that I get paid for all power that comes off the roof, as I'm on an old FIT contract, so it literally pays me to use as much solar as
possible.
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craig1410
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| posted on 22/2/23 at 05:49 PM |
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quote:
Originally posted by tegwin
quote:
Originally posted by craig1410
Hi,
I installed an "ESS" (Energy Storage System) a few.......
Thats pretty much what I was contemplating doing but I couldnt quite get the numbers to add up for me.
Now you have a handle on your consumption etc - at today's power prices what do you think your payback period is looking to be?
There are various ways to do this but let me look at it this way. Firstly here are my actual energy consumption and costs from my Nov, Dec, Jan bills.
I'm not including standing charges since they are the same. I am including VAT at 5%. These calculations are also taken BEFORE deducting the UK
govt £66.67 subsidy.
Nov: 44.9 kWh @ £0.4013 = £18.02 + 780.7 kWh @ £0.0825 = £64.41 (Total £82.43)
Dec: 74.2 kWh @ £0.4013 = £29.78 + 793.2 kWh @ £0.0825 = £65.44 (Total £95.22)
Jan: 25.1 kWh @ £0.4013 = £10.07 + 845.6 kWh @ £0.0825 = £69.76 (Total £79.83)
Taking the worst case scenario of consuming all electricity on a variable rate capped at £0.34/kWh it would be:
Nov: 825.6 kWh @ £0.34 = £280.70
Dec: 867.4kWh @ £0.34 = £294.92
Jan: 870.7kWh @ £0.34 = £296.04
So the average monthly savings over those three months is the sum of the respective totals divided by 3 which is £204.73
Therefore the annual saving would be £204.73 x 12 = £2456.73
My capital outlay was something like £6600 for the main ESS kit plus a few extras such as new consumer units, earth rods, cabling etc. So let's
call that £7000. That means a payback period of 2.85 years.
In reality, since we have an EV then we'd be on Octopus Go even without the ESS solution and I did a calculation for that as well. It has a few
extra assumptions but basically I'm assuming 230kWh of EV charging per month, all at off-peak rate plus a pro-rata of non EV consumption applied
to the 5 hour Octopus window. Without delving into the spreadsheet details that comes out as an annual saving of £1524.37 and payback period of 4.59
years.
My projections show that adding solar is basically cost neutral in terms of the pay back horizon but there are a lot more variables there in terms of
actual energy received (central Scotland). But since it is a DC coupled system, efficiency is 99% in the DC-DC converters and I really only need to
buy the actual panels, mounting brackets, cables and the charge controllers. I don't need any further DNO approvals etc. and can add as many
panels as I want.
I'm probably going to go for 20 x 415w Trina or Canadian Solar panels for a total power of 8.3kWp. Of course I won't see 8.3kW even in the
summer in Scotland but in the winter the oversized array will come in handy to capture whatever is available. My batteries are limited to 80A
recommended max charge rate each so 160A between the two which is just under 8kW anyway.
Anyway, I'll stop there but let me know if you have any further questions.
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craig1410
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| posted on 22/2/23 at 05:52 PM |
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quote:
Originally posted by JoelP
I spent a long time reading up on solar. I concluded its absolutely viable, but that a stove for heating would have a much quicker payback time and
would reduce my bills by a similar amount. The heating has been off since the stove went in, and we're back in tee shirts most evenings. The wood
is free from work.
I'll look into solar again during summer - it's pretty dismal in winter. 1 sun hour equivalent.
Yeah, we've used our log burner heavily this past winter. Unfortunately it doesn't have a back boiler so we still use oil fired central
heating but we added Tado Smart TRVs and control unit to that last winter and it has reduced oil consumption significantly. Probably by 30% plus we
have economised further by other means to get our oil consumption to about 50% of what it was 2 years ago.
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HowardB
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| posted on 22/2/23 at 06:29 PM |
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I am looking at solar too - a bit sunnier in the midlands but not as good as the sunny spots further south.
My neighbour has a system he is very pleased with - I asked the same company and was quoted £14k for 3.7kw of panels and 9.5kwh battery.
Since my usage is low - about £75 a month even over winter it is not adding up just yet. Especially as I have economy 7 (yes it is still a thing) and
so do most of the energy intensive washing etc over night.
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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JoelP
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| posted on 22/2/23 at 07:21 PM |
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quote:
Originally posted by HowardB
I am looking at solar too - a bit sunnier in the midlands but not as good as the sunny spots further south.
My neighbour has a system he is very pleased with - I asked the same company and was quoted £14k for 3.7kw of panels and 9.5kwh battery.
Since my usage is low - about £75 a month even over winter it is not adding up just yet. Especially as I have economy 7 (yes it is still a thing) and
so do most of the energy intensive washing etc over night.
The quoted prices just seem so crazy compared to what the equipment actually costs. I priced up a massive system at about 7 grand. I concluded
I'd be better off forgetting the feed in side and just fit it myself.
My stove came to £750 all in, and may well pay for itself within a year.
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JoelP
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| posted on 22/2/23 at 07:24 PM |
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quote:
Originally posted by craig1410
quote:
Originally posted by JoelP
I spent a long time reading up on solar. I concluded its absolutely viable, but that a stove for heating would have a much quicker payback time and
would reduce my bills by a similar amount. The heating has been off since the stove went in, and we're back in tee shirts most evenings. The wood
is free from work.
I'll look into solar again during summer - it's pretty dismal in winter. 1 sun hour equivalent.
Yeah, we've used our log burner heavily this past winter. Unfortunately it doesn't have a back boiler so we still use oil fired central
heating but we added Tado Smart TRVs and control unit to that last winter and it has reduced oil consumption significantly. Probably by 30% plus we
have economised further by other means to get our oil consumption to about 50% of what it was 2 years ago.
I've been weighing up a heat pump, unvented cylinder and make my own heat exchanger to wedge in against the stove. Makes so much sense, and
there's a grant too.
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HowardB
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| posted on 22/2/23 at 07:25 PM |
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quote:
Originally posted by JoelP
quote:
Originally posted by HowardB
I am looking at solar too - a bit sunnier in the midlands but not as good as the sunny spots further south.
My neighbour has a system he is very pleased with - I asked the same company and was quoted £14k for 3.7kw of panels and 9.5kwh battery.
Since my usage is low - about £75 a month even over winter it is not adding up just yet. Especially as I have economy 7 (yes it is still a thing) and
so do most of the energy intensive washing etc over night.
The quoted prices just seem so crazy compared to what the equipment actually costs. I priced up a massive system at about 7 grand. I concluded
I'd be better off forgetting the feed in side and just fit it myself.
My stove came to £750 all in, and may well pay for itself within a year.
I have not looked at a DIY option - where did you get your massive system?
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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craig1410
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| posted on 22/2/23 at 08:09 PM |
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Hi,
Yeah I was quoted £8000+vat for a 7.2kWp solar array and £9500+vat for a Tesla Powerwall battery system. And those prices were assuming I did the
groundworks to lay the armoured cables between house and garage! VAT would probably have been zero and there is an interest free loan scheme available
(in Scotland at least) which would fund £5k + £6k of the costs respectively, to be paid back over something like 11 years.
But, £17500+vat just seemed crazy expensive, and the lead times were about 6 months at that time, perhaps worse now! In fact the Tesla Powerwall is
very hard to get hold of now from what I'm told, and quite honestly I'm not a fan of Elon Musk and don't want to put any money in his
pocket. That's what initially set me on the Victron path and I have to say I'm very happy with my decision. It is highly customisable and
compatible with a wide range of batteries including the Pylontech batteries I chose.
Here is the kit I bought, configured with 5kVA inverter, 2 x Pylontech US5000C batteries, Cerbo GX, GX Touch 50 and Busbar.
https://essandsolarsolutions.co.uk/products/multiplus-ii-48v-230v-bundle.html
Even though I self installed and did not get MCS certification, I *might* still be able to get paid for exports. I have heard from at least one
person who was able to get Octopus to put him on a SEG export tariff on the basis of the DNO approval letter only. I've not had that conversation
yet with Octopus because it doesn't affect my decision to self-install anyway but I will certainly do so when the time comes.
HTH
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HowardB
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| posted on 22/2/23 at 08:18 PM |
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quote:
Originally posted by craig1410
Hi,
Yeah I was quoted £8000+vat for a 7.2kWp solar array and £9500+vat for a Tesla Powerwall battery system. And those prices were assuming I did the
groundworks to lay the armoured cables between house and garage! VAT would probably have been zero and there is an interest free loan scheme available
(in Scotland at least) which would fund £5k + £6k of the costs respectively, to be paid back over something like 11 years.
But, £17500+vat just seemed crazy expensive, and the lead times were about 6 months at that time, perhaps worse now! In fact the Tesla Powerwall is
very hard to get hold of now from what I'm told, and quite honestly I'm not a fan of Elon Musk and don't want to put any money in his
pocket. That's what initially set me on the Victron path and I have to say I'm very happy with my decision. It is highly customisable and
compatible with a wide range of batteries including the Pylontech batteries I chose.
Here is the kit I bought, configured with 5kVA inverter, 2 x Pylontech US5000C batteries, Cerbo GX, GX Touch 50 and Busbar.
https://essandsolarsolutions.co.uk/products/multiplus-ii-48v-230v-bundle.html
Even though I self installed and did not get MCS certification, I *might* still be able to get paid for exports. I have heard from at least one
person who was able to get Octopus to put him on a SEG export tariff on the basis of the DNO approval letter only. I've not had that conversation
yet with Octopus because it doesn't affect my decision to self-install anyway but I will certainly do so when the time comes.
HTH
Yes thank you,.. diy has been my go to mantra for most things so I b should have thought about it before
Thanks again
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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JoelP
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| posted on 22/2/23 at 08:42 PM |
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Hi Howard!
I think I looked at voltacon for inverters and panels. They had done crazy cheap ones - £250 for a 400w panel rings a bell. Didn't find anywhere
cheaper. Inverter depends on size but I was aiming for a pair of 5kw hybrid inverters for redundancy.
Batteries I didn't ever decide between 'proper' 48v ones ready built with bms etc, or just getting 200ah lifepo 12v batteries off
amazon and assembling myself. Didn't really get to t bottom of that one - separates work out much cheaper but maybe there's a reason why
pylontech etc are more expensive.
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JoelP
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| posted on 22/2/23 at 08:43 PM |
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Someone on a solar forum put me onto these guys.
https://www.fogstar.co.uk/collections/lithium-leisure-battery
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David Jenkins
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| posted on 23/2/23 at 02:06 PM |
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Perhaps I was lucky - Suffolk County Council had a scheme called "Solar Together", where people declared an interest in solar PV and/or
batteries and they gathered it all together and sought quotes from reputable companies (using some external company to administer it all). I had the
PV installed about 5 years ago and it was significantly cheaper than the companies I'd looked at myself.
I declared an interest in batteries about 2 years ago, but covid and the resulting Chinese industrial shutdown meant that they didn't get
installed until the end of December. Fortunately for me, they stuck to their 2-year-old price quote, because the cost of the components had risen
considerably since.
Tesla Powerwall is probably the most expensive option on the market - it's work looking around as there much cheaper options available, such as
Givenergy or myenergi's Libbi.
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craig1410
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| posted on 23/2/23 at 02:18 PM |
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quote:
Originally posted by JoelP
Hi Howard!
I think I looked at voltacon for inverters and panels. They had done crazy cheap ones - £250 for a 400w panel rings a bell. Didn't find anywhere
cheaper. Inverter depends on size but I was aiming for a pair of 5kw hybrid inverters for redundancy.
Batteries I didn't ever decide between 'proper' 48v ones ready built with bms etc, or just getting 200ah lifepo 12v batteries off
amazon and assembling myself. Didn't really get to t bottom of that one - separates work out much cheaper but maybe there's a reason why
pylontech etc are more expensive.
I've not really done much of a comparison between building up discrete battery packs from generic modules but to give a price comparison between
the Pylontech US5000 which I bought and the 12V modules you link in your next post, it's as follows
Pylontech US5000 from ESS & Solar Solutions = £1824.57 ( I think I paid a bit less than that back in August )
Fogstar Drift 12V 105Ah * 4 = £1476 (Not sure if shipping is free or not - it was with the Pylontechs)
So that's a difference of £348.57 and you'd need to also buy some sort of BMS or battery monitoring gear and ideally some sort of enclosure.
You'd also need additional battery cables to daisy chain the four 12V batteries into a 48V config.
The Pylontech has a 15 year design lifetime and has a 7 year warranty as standard plus you can extend this by a further 5 years by registering with
them. So to me buying the Pylontech still seems like an attractive option but time will tell in terms of reliability, service, performance, warranty
etc.
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HowardB
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| posted on 23/2/23 at 04:52 PM |
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quote:
Originally posted by JoelP
Hi Howard!
I think I looked at voltacon for inverters and panels. They had done crazy cheap ones - £250 for a 400w panel rings a bell. Didn't find anywhere
cheaper. Inverter depends on size but I was aiming for a pair of 5kw hybrid inverters for redundancy.
Batteries I didn't ever decide between 'proper' 48v ones ready built with bms etc, or just getting 200ah lifepo 12v batteries off
amazon and assembling myself. Didn't really get to t bottom of that one - separates work out much cheaper but maybe there's a reason why
pylontech etc are more expensive.
Thank you everyone - very useful discussion as ever
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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JoelP
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| posted on 23/2/23 at 05:33 PM |
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Fogstar were in the process of making their own 48v devices. Might be interesting to see the price when it's released.
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David Jenkins
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| posted on 23/2/23 at 05:56 PM |
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quote:
Originally posted by JoelP
Batteries I didn't ever decide between 'proper' 48v ones ready built with bms etc, or just getting 200ah lifepo 12v batteries off
amazon and assembling myself. Didn't really get to t bottom of that one - separates work out much cheaper but maybe there's a reason why
pylontech etc are more expensive.
Pylontech have a communication bus that can be used to manage multiple batteries, and to communicate with the inverter - it's much more than a
collection of cells in a box. They also come with software to allow controlled starting and stopping and, when used with the bus, all batteries can
be started with one button press (background: I currently have 4 Pylontech battery packs!).
They are also very well packaged, in solid units specially designed for 19" racking.
One thought: in all these discussions, no-one seems to have mentioned that any household battery and inverter has to be wired in a specific way to the
house electrics, with isolator switches, fuses, and other legally-required paraphernalia - if you want to go it alone you will have to do a LOT of
research - and your setup may not get approved. Apart from the batteries and inverter, my system has a consumer unit of its own, current sensors, a
data transmitter to allow me to monitor how it's functioning, a hell of a lot of safety stickers... the list is endless.
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craig1410
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| posted on 24/2/23 at 11:33 PM |
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quote:
Originally posted by David Jenkins
quote:
Originally posted by JoelP
Batteries I didn't ever decide between 'proper' 48v ones ready built with bms etc, or just getting 200ah lifepo 12v batteries off
amazon and assembling myself. Didn't really get to t bottom of that one - separates work out much cheaper but maybe there's a reason why
pylontech etc are more expensive.
Pylontech have a communication bus that can be used to manage multiple batteries, and to communicate with the inverter - it's much more than a
collection of cells in a box. They also come with software to allow controlled starting and stopping and, when used with the bus, all batteries can
be started with one button press (background: I currently have 4 Pylontech battery packs!).
They are also very well packaged, in solid units specially designed for 19" racking.
One thought: in all these discussions, no-one seems to have mentioned that any household battery and inverter has to be wired in a specific way to the
house electrics, with isolator switches, fuses, and other legally-required paraphernalia - if you want to go it alone you will have to do a LOT of
research - and your setup may not get approved. Apart from the batteries and inverter, my system has a consumer unit of its own, current sensors, a
data transmitter to allow me to monitor how it's functioning, a hell of a lot of safety stickers... the list is endless.
Agree with everything you said including the last bit about the regs. To this end, I did do lots of research plus I bought and read the BS7671 blue
book (it's brown now I know) and on-site guide. I also bought another publication from the IET called "Code of Practice - Electrical Energy
Storage" which was a useful book to read as well. I also bought a second hand but calibrated multifunction tester (MFT) and even recently bought
a Brother PT-E550WVP label maker to produce all the required labelling. I've also spent countless hours watching various YouTube channels where
professional electricians are installing this type of gear and are themselves learning and sharing the knowledge they gain.
I've already described my setup but the key things from a safety point of view are:
1. It has an 63A AC lockable 2 pole (actually 4 pole but only needs 2) isolator leading from the 50A MCB on the primary consumer unit
2. It has a 275A DC isolator (not lockable as such but you can remove the knob when turned off) just after the 200A "MegaFuse" which is in
turn connected to the battery positive lead.
3. It has a supplementary earth rod installed which is a requirement if you want to go into "island mode" when the grid fails.
4. The inverter has G99 approved protections internally to ensure that there is no possibility that energy can be fed back onto the grid in the event
of a grid outage. It also connects neutral and earth via a relay on the battery backed output to ensure that downstream RCBOs will disconnect in the
event of a fault condition.
5. I also have a CT clamp around the main tails to try to avoid grid export, at least until I get set up with a SEG tariff. That may or may not be
possible since this is not an MCS certificated system but some people have done this on DIY systems. In addition, I have an energy meter installed on
my critical loads consumer unit to measure consumption.
5. As you say, everything has to be labelled although the regs do allow now for a more aesthetically pleasing labelling regime where you can provide
information on for example a laminated card attached nearby rather than plastering labels all over everything. You can also attach some labels under
the consumer unit lid rather than always having to have them on show.
6. I performed the equivalent of a very thorough EICR on my property before and after installation and found some pretty serious faults which have now
been resolved. Of my three ring final circuits, only the kitchen sockets ring was intact. The downstairs ring was severed on all three conductors and
the upstairs had a continuity fault on the CPC. Upstairs was an easy fix where someone had got the earth sleeving too far under the terminal screw on
a socket but the downstairs was apparently a completely broken wire or perhaps more likely was never actually a ring in the first place! I ended up
splitting it into two 20A radial circuits and just tested R1 + R2 to ensure compliance. Fortunately the break in the ring was near the middle so it
was easy enough to split up.
7. Lastly, the fact the Pylontech batteries use LiFePo4 battery cell technology means that I am more than happy to have these batteries in my house,
even under my stairs. These are totally different to the NMC batteries which we've all seen videos of going into thermal runaway and
spontaneously combusting. Well, LiFePo4 batteries simply don't do that and although they can be punctured and emit smoke, they are very unlikely
to actually catch fire.
So, yeah, lots to think about and even more details when moving onto adding solar. You need to worry about sizing the cable depending on the lengths
and current plus the various ways of splitting an array into series and parallel strings. You need to think again about lockable isolators, surge
protection, ensuring you are not susceptible to the EMP from nearby lightning strikes causing the PV wiring to act like an antenna and cause massive
surges. Think about whether your panels have partial shading in which case you might need optimisers installed. All sorts of things.
I'm not suggesting I know everything - far from it - but I know a hell of a lot more than I knew 12 months ago and I suspect I'll learn a
lot more again in the next 12 months. So if you're not willing to put in the time and effort to learn then you are definitely much better off
getting someone to do it for you.
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russbost
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| posted on 1/3/23 at 07:50 PM |
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" It has a supplementary earth rod installed which is a requirement if you want to go into "island mode" when the grid fails."
Can you describe exactly what you have as I need to install one for my off grid setup, most available seem to be either 5/8 or 3/8 by 4' or
1200mm, however I have seen regs (not sure they are UK?) suggesting an 8' length?
How do you decide what length is required to give adequate earthing & when measuring earth resistance once installed, what are you actually
measuring between to get the Ohms reading, I keep reading all sorts of conflicting information?
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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craig1410
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| posted on 1/3/23 at 08:53 PM |
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quote:
Originally posted by russbost
" It has a supplementary earth rod installed which is a requirement if you want to go into "island mode" when the grid fails."
Can you describe exactly what you have as I need to install one for my off grid setup, most available seem to be either 5/8 or 3/8 by 4' or
1200mm, however I have seen regs (not sure they are UK?) suggesting an 8' length?
How do you decide what length is required to give adequate earthing & when measuring earth resistance once installed, what are you actually
measuring between to get the Ohms reading, I keep reading all sorts of conflicting information?
Full disclosure - I’ve bought my rods but haven’t installed them yet as I’m laying a patio in this area and am waiting to see where the pattern of
various sized slabs would most easily accommodate the earth pit. I’m using the steel structural columns of my garage as a temporary earth in the
extremely unlikely event that I lose the DNO earth during a fault.
My earth rods are 5/8” diameter but tbh the difference between 3/8” and 5/8” is not that much in terms of conductivity to earth. I only got the larger
rods because the ground is quite stoney and I wanted the extra strength of the larger rod to help when driving it past stones.
There are various ways to test earth rods including the 3 wire method which you can read about on YouTube in the “John Ward” channel if interested,
but the easiest for a site which is already energised is to use a Multifunction Tester (MFT) on earth fault loop impedance mode and simply test
between the line conductor and the new earth connection. Essentially it applies 230V to the rod and measures the current passing in order to calculate
the total impedance back to the substation. It’s called “external loop impedance” or “Ze” because it literally measures the total impedance of the
line/live conductor all the way from the substation and back again via the general mass of the earth. Ultimately it must be below 200 ohms but really
you want it much lower than this if possible. I’m hoping to get mine down to 20 ohms or lower if I can.
However, if you are in a fully off grid situation then you’ll probably need to use the three wire method instead which I’ll let John Ward explain for
you on YouTube. You’ll need an MFT for this as well.
To install, basically you need to dig down to the depth of the bottom of your earth pit and then drive the earth rod into the ground in the middle of
this area. You can get a rod coupling adapter and a matching bolt to protect the end of the rod when driving it. You can also use an SDS drill on
hammer only mode to drive the rod if you want. Once you get the full 4 foot length of rod driven in, you can attach your earth cable and run a test.
If the impedance is low enough then you don’t need to add any more rods but if not then you can use the coupler to attach another 4 foot length and
drive it in as well. If you do this then you’ll need a second coupler to use with the bolt to protect the end of the second rod while driving. How
many rods you need depends on ground conditions and you may be limited by the depth of the ground. Note that both ends of the rod will be threaded but
one will also be pointed and this should go downwards obviously. Don’t be tempted to drive multiple rods in side by side because this does not have
the same effect as connecting them together and driving them deeper. The earth is less inclined to dry out deeper down and you will get better
readings as you go deeper.
Obviously you need to be very careful not to drive the rods through any service pipes and cables, and you should try to avoid having an earth rod
within around 5m of any buried services. This is because in the event of an earth fault, the earth rod will be energised to around 230V and the ground
next to the rod will be at a range of voltages between 230V and 0V as you get farther from the earth rod. This is also why you must enclose the earth
rod in a pit of some sort to avoid any chance of someone touching it. You’ll also need to use 16sq mm cable if buried directly in the ground but you
can use thinner cable if it is protected by trunking or conduit. I’m using 10mm cable inside conduit because I already had a roll of 10mm but I think
you can use 4mm for an earth rod as long as it’s mechanically protected because the prospective fault current will be relatively low. I’d need to
check the regs though. If you don’t have any cable already then I’d suggest just buying a cut length of 16mm from CEF or similar.
This is the earth pit I bought: https://www.tlc-direct.co.uk/Products/TLPT205.html
but you can use smaller ones if you want to. Just make sure they are labelled correctly with something like this:
https://www.cef.co.uk/catalogue/products/335941-80mmx35mm-safety-electrical-connection-do-not-remove-label-pack-of-5
Disclaimer: I’m not an electrician so if in doubt get a qualified spark in to keep you right.
HTH
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JoelP
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| posted on 2/3/23 at 07:24 PM |
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Can't understand the need for an earth rod myself - if you've lost the supplier's connection, the current from the inverter isn't
trying to get to earth anyway!
In the past I've intentionally broken the supply head to force them to upgrade to a tncs supply. Felt a bit bad when they sent out 5 guys and a
digger to avoid doing it live!
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craig1410
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| posted on 2/3/23 at 09:43 PM |
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quote:
Originally posted by JoelP
Can't understand the need for an earth rod myself - if you've lost the supplier's connection, the current from the inverter isn't
trying to get to earth anyway!
In the past I've intentionally broken the supply head to force them to upgrade to a tncs supply. Felt a bit bad when they sent out 5 guys and a
digger to avoid doing it live!
There’s a good answer to this question on the Victron Community Forum. I’ve quoted the answer below for convenience but have also provided the link as
there is further discussion on this topic which might be of interest. This was mostly talking about an off-grid scenario but it also applies to grid
failure in a grid parallel system.
quote:
There is a common misconception that the earth rod is there to carry fault currents. This is not the case. Rather it is there to drain off static
energy that might built up on the system safety ground so the safety ground voltage is at earth potential.
Separate to the earth rod, the safety ground is connected to the system neutral AT ONE POINT in the system. The purpose of this connection is so that
if there is a hot to chassis short in some piece of equipment, the circuit breaker for that branch circuit will trip in stead of elevating the chassis
to hot line voltage. Line voltage on a chassis could kill a person.
There is never a connection between neutral and the earth rod. The connection is made from the safety ground wiring and the earth rod. This does make
an indirect connection between earth rod and neutral through the above mentioned connection.
The neutral to safety ground connection is made at the service entrance if there is one. In off grid with generator this bonding is often made inside
or close to the generator. When the Multi is inverting, it disconnects both neutral and hot legs from the grid and makes a local safety ground to
neutral connection internally at the AC output.
Another misconception is that the neutral must be at zero volts relative to the safety ground. I practice, this is seldom the case due to current flow
in the neutral wiring. Safety ground to neutral voltage is typically under a few volts and does not indicate a fault or safety issue of any kind.
You should never make any connections from the Multi AC output neutrals to anything up stream (e.g., the grid or generator). The Multi isolates the AC
output from the AC input when inverting and it must remain isolated, including the neutral. As mentioned above, the safety ground to neutral bond is
made inside the Multi in this case.
ALL PE (safety ground connections) ARE connected together. Always. While the Multi has PE connections for each AC input and output, they are all
connected internally. External connections to the same point in the system is expected and does not create any ground loop or safety problems.
Source: https://community.victronenergy.com/questions/181262/relying-on-earth-rod-in-off-grid.html
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