tegwin
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| posted on 9/11/22 at 01:56 PM |
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Solar panels and batteries
We're all fairly technically minded here so I wonder what your take is...
Evidently energy costs are going up with electricity at 34p/kwh. I am assuming that from April '23 that might be around 40p?! Or more/less? What
do people think?
I am trying to figure out the economics of fitting solar panels. I would do it DIY as once you add the sky high installation costs it becomes a non
starter in my eyes.
I think I could fit a 4KW array on my garage roof which faces south.
Panels are around 34p/w so a 4000W array is around £1400
An standard inverter is around £600
A hybrid inverter for use with batteries is around £1400
5KW of battery storage would be around £1800.
So without battery = £2000ish
with battery = £ 4600ish.
Currently have an electric shower (12KW) but the ideal would be to get a 200L storage tank and use the solar to heat the tank rather than exporting at
the pathetic 5.5p/kwh
House is currently heated by gas. (one only speculates what the cost of gas will do)
Really struggling to workout exactly how much energy I would get, how much I use, how much I would save etc....
I want to split fact from fiction - it would be fun to install a setup and tinker with it but it does have to be financial viable.
Anyone have similar setup? How is it performing for you?
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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cliftyhanger
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| posted on 9/11/22 at 02:57 PM |
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5kw battery sounds small unless I misunderstand how they are rated.
On a sunny day it would recharge in 75 mins (or so)
Recon you want triple that to be worthwhile.
5kw of electricity at (say) 50p is £2.50 Payback time is about 7 years. 15kw rather faster, depending on battery cost.
Better is to buy a car you can use as a house battery (nissan only I think, but that will change) so you can charge teh car during the day and use it
at night, or to drive or whatever.
Solar heating water sounds sensible but not if it needs substantial replumbing.
All very tenious, and I am not being helpful
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coyoteboy
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| posted on 9/11/22 at 03:08 PM |
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A normal system size for a house using 6.4MWh a year is a battery of about 12kwh. The average house uses 10-15 kwh per day and mostly in the evening.
Bear in mind that if you DIY the system, you likely can't declare it to your power company for export as they usually require MCS certs, and
those can't be granted on legacy hardware, only fresh installs. Ie you can't call your friendly spark and ask him to look over it and sign
it off, in theory.
Bear in mind the insolation in winter will be incredibly low - you can expect something like 4 hours full daylight equiv mid winter. If you want your
system to handle that, you need a big array.
Battery is sized by house daily usage.
Array is sized by location and battery size.
Any excess of energy will get exported, and you'll only get paid for it if you're MCS certified or you have a friendly power supplier.
[Edited on 9/11/22 by coyoteboy]
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tegwin
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| posted on 9/11/22 at 03:11 PM |
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Tenuous is pretty much how my thought process is going...
My very loose thinking is that
I am guessing I use on average around 2800Kw/yr (7KW/day). Mostly in the evenings for cooking/lighting/shower
If I can fully charge the battery during the day I would be able to provide about half of my daily consumption from battery. so say saving £1.60ish a
day.... £570/year... Minus say 1/3 for the days the sun isn't out... £380 That's a 12 year payback for a battery based system!? Not
sure the batteries will still be useable after 12 years.....
Buying an EV is a non starter- a cheap efficient second hand IC car is a lot more cost effective at the moment.
Re MCS - I don't expect to get any paying tarrif - by the time you pay for the MCS certified installation the cost has almost doubled and the
economics of it just don't make sense.
[Edited on 9/11/22 by tegwin]
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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David Jenkins
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| posted on 9/11/22 at 03:13 PM |
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I have had solar panels for some time - professionally fitted - the 'expected earnings' are fiction, but that's not the real benefit
for me. Although I'm not always earning money by pushing electricity to the grid, I am running the house most of the time on anything better
than a bright, overcast day, if you ignore heavy occasional loads like ovens, tumble drier, etc. On a sunny day they'll even power them. So,
basically, unless it's a really gloomy day I'm not buying power from the grid until the evening. Any income is a bonus.
I also have an EV charger (myenergi Zappi) that is intelligent enough to charge the car almost entirely by solar, if it's a bright day. If the
weather's not bright, it will use the cheap overnight rate from Octopus Go (00:30 to 04:30) to top itself up.
I am currently waiting for the installation of a 10kWh battery that will also be charged either from solar on good days, or overnight on Octopus Go if
necessary. This will mean that my evening consumption will be from solar (free) or cheap overnight rates (currently 5p/kWh, will be 7.5p/kWh
soon).
The key thing here is to get your electricity from a supplier that has a much cheaper overnight rate, such as Octopus (there are others). This means
that even ignoring PV, you can use the cheap overrnight rate throughout the day in most circumstances.
I should add that Octopus are really happy for their customers to use batteries as they balance the load on the grid. They have just announced a
system where they will offer a longer period of cheap rates, as long as you let them decide when that period will be. I haven't yet worked out
if that's beneficial for me!
[Edited on 9/11/22 by David Jenkins]
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Dingz
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| posted on 9/11/22 at 06:57 PM |
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I had a system installed at my last house, just over 4kw of panels and a 4kw battery. In the 2 years I was there it generated just over 4mw per year,
I used roughly half that the remainder went to the grid at between 3 to 5 pence per kw. I did it partly to be green? And thought then, 2020, it would
take 10ish years to break even. Now it would be better but not sure of the current installation costs. We had 2 inverters, one for the panels one for
the batteries. There are a couple of system certifications for feed in tarrifs, make sure you get one that the suppliers accept. Can’t really fit them
to the new house otherwise I would.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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ianhurley20
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| posted on 9/11/22 at 09:53 PM |
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Interesting discussion. I have a number of friends who have solar PV and after talking to them I decided to go for a PV array. I should say we
installed a solar hot water heating system 15 years ago and May to September it handles all our hot water use without need for a top up. No it needs a
top up the rest of the year but it does take the water coming in from cold to 30 + ish dergrees so the top up is just what it says. My roof is not
ideal as it has a ridge facing due North /south so the 45 deg sides face East and west. No trees etc to obstruct either direction. It does mean
earlier and later solar works well but peak power is reduced. Swings and roundabouts. I'm not up to DIY so I have had a comercial instalation
that has sorted G99 aproval etc. BTW I am terified of heights so there is no way I would go onto my roof !!
So I should add that our power consumption over the last 6 years has been 3217Kwh or just under 9 kwh per day. Based on those figures I have a hybrid
inverter (sorts DC from panels to mains and charges battery at appropriate volts and then changes that to mains again) with 5kw of solar panels with a
6kw battery. Here we are in November with rain and very overcast days and its doing about 5kw/day. May to September it will run the house completely.
Feed in tarif - not interested as I would like to use all the power but accept that in summer a lot of power will go to the grid at a staggering 3p
per kw - until we can swap tariffs I am stuck with this one. Payback at current prices should now be about 8 years but I think with price increases
that will come down.
The solar hot water (west facing) has been a winner for 15 years and I hope the PV + battery will be but ask me again in 12 months and I'll give
a proper answer.
To answer an earlier question about battery life - 6000 cycles is specified which makes about 20 years at one charge per day - ish and it comes with a
10 year warranty
[Edited on 9/11/22 by ianhurley20]
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BenB
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| posted on 9/11/22 at 10:14 PM |
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For a new install tempting to go hybrid water and pv. PV panels make more juice when cold and less when hot so my taking away the heat into water you
increase the PV output by about 20% while also making hot water using the same roof space.
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coyoteboy
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| posted on 10/11/22 at 12:01 PM |
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Aye, but in reality in the UK it isn't that much of a boost, and it's really just "actually making the rated power" not
"making 20% more". My all-black PV panels get to about 40C on a peak summer's day. You lose 0.5% per degree C on silicon cells, approx,
so 10% for me. But if I could use that heat to pre-heat the boiler water, grand.
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coyoteboy
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| posted on 10/11/22 at 12:04 PM |
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quote:
Originally posted by ianhurley20
Interesting discussion. I have a number of friends who have solar PV and after talking to them I decided to go for a PV array. I should say we
installed a solar hot water heating system 15 years ago and May to September it handles all our hot water use without need for a top up. No it needs a
top up the rest of the year but it does take the water coming in from cold to 30 + ish dergrees so the top up is just what it says. My roof is not
ideal as it has a ridge facing due North /south so the 45 deg sides face East and west. No trees etc to obstruct either direction. It does mean
earlier and later solar works well but peak power is reduced. Swings and roundabouts. I'm not up to DIY so I have had a comercial instalation
that has sorted G99 aproval etc. BTW I am terified of heights so there is no way I would go onto my roof !!
So I should add that our power consumption over the last 6 years has been 3217Kwh or just under 9 kwh per day. Based on those figures I have a hybrid
inverter (sorts DC from panels to mains and charges battery at appropriate volts and then changes that to mains again) with 5kw of solar panels with a
6kw battery. Here we are in November with rain and very overcast days and its doing about 5kw/day. May to September it will run the house completely.
Feed in tarif - not interested as I would like to use all the power but accept that in summer a lot of power will go to the grid at a staggering 3p
per kw - until we can swap tariffs I am stuck with this one. Payback at current prices should now be about 8 years but I think with price increases
that will come down.
The solar hot water (west facing) has been a winner for 15 years and I hope the PV + battery will be but ask me again in 12 months and I'll give
a proper answer.
To answer an earlier question about battery life - 6000 cycles is specified which makes about 20 years at one charge per day - ish and it comes with a
10 year warranty
[Edited on 9/11/22 by ianhurley20]
How big is your solar thermal collector?
6000 cycles at one charge per day is 16 years, but in reality if it's a lithium battery it's degraded by both cycle quantity and depth of
discharge - 6000 cycles at 20% depth of discharge is a LOT less damaging than 6000 cycles at 80% depth.
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tilly819
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| posted on 10/11/22 at 12:33 PM |
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Ok so we have just installed a very similar system on our house. It's been running about a couple of weeks now.
Our system is:
16 Off 325W Panels = 5200W
Panels are ground mounted approx 60m from the house. Combiner box with isolation on the frame. DC comes back to the house underground in armoured
cable (big fat one to minimise volt drop) The frame and cable did bump up the price but since we built it all our self in the workshop it wasn't
too bad. Maybe £1000 extra but the Mrs didn't want it right behind the house and we cant really put them on the roof as it's an old
property.
Isolator in the house then into an off grid inverter. Inverter is rated at 4000W continuous. But will do about 5000W for 15 mins.
(As an aside it also has a generator input which I intend to use for micro hydro in future)
Battery is LiFe-P04 5280W 100AH 48V.
Panels/inverter and battery were about £6500 IIRC
Additionally to this we have an automatic change over switch that goes on the inverter output and can switch the house between 'grid' and
'off grid' mode. There is a few hundred quid in the change over as I built it to work how we wanted it rather than just getting an off the
shelf unit. Also a lot of the off the off the shelf units from china are not properly interlocked which is a big no no.
A few other bits as well: Bracketry, cable, connectors, conduit etc. RCD as we are TT earth. Few hundred quid there as well.
So all maybe £8000. That's not paying anything for labour.
How we run it>
The house runs off grid with the ability to switch to the grid if we need it. Since it's a 4kW inverter that's the same as having a 4kW
mains incomer. Since the change over switch is properly interlocked it is impossible for us to feed in. Our supplier said we can only have a feed in
if we have a smart meter but they wont give us a smart meter because there is no reception here... We live in the middle of nowhere, and the feed in
tariffs are rubbish unless you get a business one anyway.
As others have said the battery is sized based on daily load. We use about 5 - 6 KWh/day and I specked the battery for ~1 Day of autonomy.
Inverter is sized based on maximum load but there is a design loop here as the battery inverter interaction is important (you don't want to be
pulling max amps from the battery all the time) Our max load is an induction Hob theoretically 7.2kW but it never runs at that due to diversity.
Realistically its about 3.5kW with a couple of rings on. If we ever needed the full whack we can just switch to grid mode... xmas dinner maybe.. We
run the washing machine fine. We don't have tumble dryer... that's what wind is for. 3kW Kettle. All the normal stuff really.
Now this is the crux of it. We heat with wood. Solid fuel Rayburn does the hot water and central heating in the winter. We tried this week to heat the
tank 180ltrs IIRC with the immersion. Just to stress test the system. The system did it fine but we did it late in the day so it didn't have
chance to recharge before bed. ( I wanted to kill the battery to test the automatic change over part of the system) Ran the battery down to about 30%
that evening.... No sun the next day...or the next... So we had to run on grid for a bit. When it's a grey day we only get 100-300W from the
array. So if you want to heat water you either need to do it only on sunny days or have a very big array. In the summer it wont be a problem for us as
there is plenty of sun and hot water demand is lower so we can use the solar for hot water duty but in the winter it's more difficult to do it
with solar.
Now going back to that aside about micro hydro earlier.. The long term plan for the winter is to be able to generate enough hydro power in the winter
that it will charge the battery on the wet rainy days in winter thus reducing out dependence on wood. Then we can just do the central heating with
wood and heat the tank with the immersion all year round.
Just looking at the OP
That 12kW shower will likely be your biggest problem
12kW @ 48v (battery voltage) is 250A (that's a lot to be pulling from a battery for maybe 15 mins) Our battery is rated for 100A continuous or
150A peak for 15 seconds.
The thermal store idea is a good one providing you have the energy available to heat it in the first place. A spreadsheet is definitely going to be
needed.
A couple of things to consider.
Don't underestimate all the *extra* costs - brackets, cable, etc etc
You get very little from the panels on cloudy days. 5-10% of there rated power if you are lucky. That's only 250-500W on a 5kW array. add that up
over 7 hours of day light and you only collect 1.75 - 3.5 kWH/Day
Read all the data sheets!!!!
Make a spreadsheet
Payback for our system
Based on the current price of electricity @£0.34/kWH and our typical usage of 6kWH/Day
6kwH*365 days = 2190 kWH/Year
2190 kWH/Year *0.34 £/kWH = 744.60£/Year
Investment £8000 / 744.60 £/Year = 10.75 years for payback. Obviously this does include some additional costs for us like the frame and long armoured
cable that you would not incur but the equations are still the same.
I did shoot a video of the install and it should be going up on my youtube in a week or two once it has been edited. Ill post a link when its done.
Hopefully the video will also bring in some add revenue which should also help reduce the payback time.
hope that helps. Sorry it was a bit of a long one.
Tilly
F20C Haynes roadster 440 BHP/Tonne www.youtube.com/handmadeextreme
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ianhurley20
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| posted on 10/11/22 at 04:24 PM |
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quote:
Originally posted by coyoteboy
How big is your solar thermal collector?
Its the round tube type connected to a manifold at the top with a totl of 24 tubes. It was installed 15 years ago and feeds a code L hot water tank
with two heating coils. The lower heats all the tank and is the solar part giving 165 litres of water at 60 deg C when full. The upper one runs from
our oil fired boiler (no gas available here) and will heat 115 litres of water with the bottom coil doing a pre heat which usually achieves 30 deg on
a poor day. When we get sea fogs rolling in we get nothing but that only a few days a year!
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Mr Whippy
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| posted on 11/11/22 at 09:58 AM |
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I have an EV but am now heating the house with coal  the stuff is so cheap and one shovel full heats my house for the whole day  Used wood before
but it cost a fortune for kiln dried stuff and it takes up loads of room to store.
Have looked at solar but the cost is so much and the weather is rubbish where I live, hardly see the sun. Personally I think plowing the money into
insulating your house is the best bet and will get better returns in the end.
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James
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| posted on 11/11/22 at 11:10 AM |
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Just been having this conversation with the missus so will watch this thread with interest!
2013 we moved into our house, got a quote from an installer who said it'd be a 7 year pay-off. We thought we might not be here long enough to
benefit so didn't go ahead...
9 years later we appear to be staying still! lol
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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HowardB
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| posted on 11/11/22 at 01:31 PM |
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watching with interest too
Friends have 5kw installed and 4kw inverter - £4500 installed - no battery. They just use what they can when they have it, washing machine etc on
sunny days. This is their generated output so far
 
Description
they are on the south coast
I am in the miserable midlands but thinking that 5kw with a battery would be good - something that covers the base load of 250w and the occasional
kettle etc - my consumption on a full day is circa 5kWh
envious of your install Tilley
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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russbost
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| posted on 12/11/22 at 06:27 PM |
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You might find this as interesting reading, tho' my installation has moved on by a loooong way since that was posted
Link to previous LCB thread
I would agree you need to self install if you want a sensible, reasonably quick return on the investment
My system now is as follows, I have an original 4kW MCS installed array done back in 2011, on the original & best FIT tarrif, the return is
ridiculous, I get over £2k a year payments, plus the benefits of the free leccy
I've installed a Solic diverter to take any excess power that would be returned to the grid & dump it into the hot water immersion tank, I
didn'y use any gas for heating my hot water from April thro' to 2nd week of October, the Solic still provides some power to the immersion
thro' the Winter months if we get a sunny day, cuts down on gas usage
When I saw what was happening with the energy prices l;ast year, I bought a load of SH solar panels & self installed on my flat roof, it would be
illegal to add these to the existing system, so I decided to atke as much off grid as I could, started out with 4 SH 12v solar telecoms batteries,
lead acid, 170Ah each, a couple of cheapy solar charge controllers & a cheap Chines 3kW (supposedly!) inverter which had a simple 3 pin plug
connection
This has subsequently been updated with a "proper" off grid Powland inverter whci is vastly more sophisticated & has a charge facility
for the batteries, which as I get 6 hours of 10p/kW leccy overnight allows me to top the batteries up cheaply, particularly useful when the solar is
insufficient to have the batteries fully charged. I've gradually taken circuits off grid, but have the facility to swap plugs around &/or
switch some circuits from grid to inverter or vice versa
When I did the first off grid installation talked about in the thread above, it cost me around £1400, I've now spent a further £600 or so on the
upgraded inverter & cabling/switchgear, so currently stands me in around £2k for just under 3kw of power to the batteries
My total gas & leccy bill from start April through to end Oct has been around £160 for the 7 months & that includes charging my all elecric
Kona on the overnight cheap leccy, which was previously 5p/kW now 10p, day tariff has also nearly doubled from 24p unit to 44p unit since start Nov,
so. I'm going to be very glad of the amount I'm NOT having to pay for!
I've just bought some used Leaf batteries at around 80% of their original capacity, arriving Monday, £550 to make a 2.5kWh 48v battery pack,
which I'm intending to put in parallel with the existing batteries, will almost double available capacity as with LA, you don't want to take
them below 50%, whereas with Li you can take down to 80/90% without a problem. I've also bought a 48v solar charge controller to handle some more
panels which will be going up shortly to help keep the battery bank charged up
With everything I've spent so far, including the Solic, the above batteries, the & BMS & the stuff I'm no longer using, it stands me
in around £2800, but will probably pay for itself within 18 months to 2 years, it's been quite a bit of work & a HUGE learning curve, but
I've enjoyed doing it & gives me great pleasure to be able to stick 2 fingers up to the energy industry as they will be ripping millions of
peeps off, but I won't be amongst them!
If you're installing yourself, I'd recommend keeping the install under the 3.6kW limit, that way you can do a straightforward g98
application which requires only a sign off from a sparky, you need to get a tame sparky under your wing b4 you start & discuss it with him to make
sure you meet the necessary requirement. Once installed (I find this next bit absolutely barmy!) you commission the system & only then, within a
month, send the G98 application in, you are already generating power by this point!
If you want a larger system with battery backup & get paid on a feed back to the grid, you are talking a full MCS install on a G99 application
& probably £8k spend as an absolute minimum, going up substantially if you want a decent size battery, even with the daft energy prices after NEXT
April that's gonna be a loooong payback period
However, if you just do the 3.^kW self install as suggested above, if you DIY & use SH panels you're looking at substantially less than £2k
assuming you don't pay the sparky more than a couple of hundred or so
You can then add whatever you want whenever you want as long as it stays off grid, a 3,6kW grid tie inverter & a 4kW off grid inverter cost less
together than a hybrid inverter does.
Good luck & hope you enjoy your system whatever you do with it!
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.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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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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mark chandler
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| posted on 17/11/22 at 11:42 AM |
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I had this dilemma earlier this year, we had a company quote to allow us to go self sufficient - £28,000 for a 16k array with 10kw battery….. wow
put the brakes on that, was not even top of the range kit.
So I purchase a second hand Growatt SPH hybrid inverter with 3kw battery backup - £2,500
16 x 180w new panels and associated wiring £950
It was going on my barn roof so did not bother with an expensive tracked system to attach as this would have added another £1,000, so made 64 1”
standoff’s from a few meters of 1” aluminium bar and tapped out for M10 bolts, on tiles I guess you have little choice?
So for £3,500 I immediately saw 75% saving on the electric bill, we then started running machines during the day and it went to maybe 85% - the
electric company amended our direct debit.
My payback will be a couple of years.
Drawbacks - as I installed it my self no feedback tariff possible unless I pay to have it certified.
My hybrid inverter supports 5kw so sunny times it’s great, the battery can probably only flow 1kw so once it’s dark it runs down quickly, it will also
not support any high usage machines on its own.
Next year I plan to buy a 10kw battery, also thinking about a small wind generator to charge the battery when the sun is not shining, the inverter
will then turn the 48v into 240v
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russbost
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| posted on 17/11/22 at 01:16 PM |
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"16 x 180w new panels and associated wiring £950" !!! Is that a typo? Where on earth can you get new 180W panels for £60???
As you installed yourself, did you inform the DNO or not, anything over 3.6kW or with battery needs a G99 application, which is a little more onerous
than a G98, if you put in an application to the DNO what did you put down for accreditation & qualification on the application, or was it all
signed off by a sparky?
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.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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mark chandler
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| posted on 18/11/22 at 10:57 PM |
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Panels were over ordered for a solar farm so they were just clearing them, not particularly high wattage by todays standards however I have plenty of
space on my barn roof so high density did not bother me.
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hobbsy
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| posted on 19/11/22 at 05:09 AM |
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I've got zero PV on the current house as planning to move plus the roof really doesn't lend itself to it
I do however have a home battery with a 3kW charger / inverter which load matches (current clamp on one of the meter tails)
Battery is currently 5kWh and is LiFePO4 and awesome
Due to upgrade to 14kWh shortly but might keep the 5kWh (under 100 cycles of 80Pc DoD). But may expand
Occasionally I pull more than 3kW of an evening so considering an 8kW hybrid inverter which when we move I can then add up to 2x 4kW of solar to. Roof
is better but still not ideal but may use the garage or make a garden office and use that.
I may have a "spare" 14kWh brand new LiFePO4 battery in the next month or two (as decided to over order on the cells to lower total cost) in
a rack mountable case, LCD display, 200amp continuous max draw (so will put out around 10kW so enough to power the 8kW inverter to it's max)
If anyone is interested shoot me a message 
Edited to add if not obvious I am using off peak elec which lucky me is 5.5p/kWh til May next year as Octopus messed up notifying me of the tariff
change in May. Get 5hrs of this so can charge the battery at a nice low 1kW for 5hrs (so 0.2C). Unless someone knows better octopus is where it is
at, Go Faster is what I'm using. Interested to know about this new tariff someone mentioned above where it's longer duration but octopus
choose the timings. That said my current off peak starts 2030hrs and runs for 5hrs so is ideal for eg putting the dishwasher or washing machine or
tumble drier (especially) on whilst we are still awake.
If anyone reading this isn't on octopus then below is the link. I do have an EV again currently but I had over a year without one and Octopus
don't seem to care or stop you having Go / Go Faster even though it's designed for RV owners...
Use this link to sign up for octopus and we both get £50... Not long ago it used to take 2 or 3 weeks, nowadays it's 48hrs to switch!
https://share.octopus.energy/sage-queen-253
[Edited on 19/11/22 by hobbsy]
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mark chandler
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| posted on 19/11/22 at 08:05 PM |
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The chap who sold me my hybrid inverter and battery recommended I change to Octopus.
My system with 3kw battery was removed to be replaced by a 10kw system - without any PV provided!
The logic was very simple, charge the battery on cheap EV rates and use this to run the house at high rates, it’s then a case of running all your
greedy machines, washing, drying stuff also at the low rate, a decent sized battery is the future.
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hobbsy
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| posted on 19/11/22 at 11:17 PM |
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Yes couldn't agree more. Plus if you move house you can take it with you very easily.
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craig1410
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| posted on 21/2/23 at 12:32 PM |
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Hi,
I installed an "ESS" (Energy Storage System) a few months back with the intention of taking advantage of cheap overnight electricity to
charge them up and then releasing that energy during the day when prices are high.
So, basically I have installed two 4.8kWh Pylontech US5000 batteries for a total of 9.6kWh. These are charged (and inverted) by a Victron Multiplus-II
48/5000/70-50 inverter-charger which can charge the batteries at a rate of 70A DC and can generate a continuous power output of 4.4kW and up to 9kW
peak for 15 mins or so.
It can also provide battery backup for my house in the event of a grid outage. To enable this I split up the loads in my house onto two new 18th
edition consumer units. The primary CU takes the main meter tails in through a surge protection device and then has RCBOs for the Cooker (40A), Shower
(40A), Garage/EV (40A MCB) and the Inverter (50A MCB). The output from the Inverter then feeds the secondary CU and it has all other house RCBOs
including 3 ring final circuits, 3 lighting circuits, smoke alarms and boiler. I also have a transfer switch to allow me to bypass the inverter for
maintenance or if it failed. The inverter also has its own TT earth rod because the regs don't allow you to rely on the DNO earth in the event of
grid failure.
I have an EV (2017 BMW i3) and have been on the Octopus Go Faster tariff for a few years. That allows us a 5 hour window (21:30hrs to 02:30hrs) each
day when grid power is 8.25p/kWh (inc VAT) whereas it is just over 40p/kWh for the other 19 hours a day. So we charge up the EV and Pylontech
batteries at the same time and then discharge the Pylontech batteries during the rest of the day so that we effectively pay 8.25p/kWh for all our
electricity.
We've been running this for about 6 months so far and it's been great. We use something like 9600kWh per year, 2800 of which goes into the
EV. We've reduced that a bit through generally economy savings but probably still use 5000kWh/year in the house alone. That's about 13-14kWh
per day which obviously is more than the 9.6kWh of battery we have. However, we have also been running the dishwasher, washing machine and drier
during the 21:30hrs+ window. Also, the battery only has to last 19 of 24 hours each day. My electricity bill for last month showed that 97% of our
electricity was consumed at 8.25p/kWh and the other 3% was at 40.13p/kWh. The previous month was 95% so this wasn't a one-off.
Bottom line is that we are finding the 9.6kWh lasts all day most days and that's keeping 10% charge in reserve. It won't last all day if we
are running all the appliances during the day and maybe baking stuff in the range oven etc. But that's unusual.
I did a lot of work on the spreadsheet before committing to buy the battery system and I worked it out as a 4-5 year payback period. That involves a
number of assumptions, not least is what the price of electricity will be in the coming years, but I did the calculations very conservatively rather
than as an exercise in justifying a new "toy" if you know what I mean.
The other thing is that Solar PV can be added to this system really easily by just connecting up strings of panels via MPPT charge controllers. MPPT
stands for Maximum Power Point Tracking which basically means the voltage and current being output from the solar panels are kept within the most
efficient window and can yield 99% efficiency since it's a DC to DC conversion rather than the usual DC-AC-DC conversion you get with a normal
inverter.
My plan is to buy 16-20 400w+ panels, probably Trina brand and fit them in time for spring. That should allow me to charge my batteries entirely from
solar depending on time of year and then just use Octopus Go to top them up as needed. The payback period with the solar doesn't actually change
because the extra capital costs are offset by the lower running costs almost exactly. But it gives further insulation from energy costs in future and
a degree of self sufficiency. I might also buy a third battery if I find that I run out of storage during the summer months because I can always dump
some energy into the EV.
The Pylontech batteries have a 6000 cycle/ 15 year projected lifetime and I think they have something like a 7 year warranty which is extendable to 10
years or something. I forget the details.
I bought my kit from here ( https://essandsolarsolutions.co.uk/products/multiplus-ii-gx-48v-3-5kva-230v-ess-bundle.html ) and would highly recommend
the company. It's a small business owned by a guy called Etienne and I've had nothing but great support from him all along. His mission is
to supply the DIY market because he really dislikes the whole "MCS approved" racket that has also been commented on.
There is a great Victron community forum at http://community.victronenergy.com/ if you want to get a feel for things. The Multiplus-II is a solid
piece of kit but it does make a bit of noise when running at full power so I'd advise choosing location carefully. The batteries don't work
below 0C and prefer room temperature for efficiency so again choose location wisely. I can go into this more if interested.
Anyway, that's my story for now. Happy to answer any questions.
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tegwin
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| posted on 21/2/23 at 01:47 PM |
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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?
------------------------------------------------------------------------------------------------------------------------
Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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JoelP
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| posted on 21/2/23 at 06:36 PM |
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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.
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