PV Solar & Battery Installation - UK

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TeeDee

Full Member
Nov 6, 2008
8,490
2,109
47
Exeter
Has anyone UK based looked seriously into a Solar PV array with Battery storage for maximising usage and storage. ?

Its at times like these that i'm happy to hear from anyone that has better suggestions of waiting if a better technology is predicated to break through.

Had a Quote for a 8.3 kWp system with a 10 kWH Solar Edge Powerbank.

TIA
 

Robson Valley

Full Member
Nov 24, 2014
9,547
2,265
McBride, BC
They're the same, the world over. I have a small system because we are subjected to power failures at a weekly rate, more or less. The driver is the power that I need for home heating in -20C weather (like last night and the week to come). I've used it every year for the past 15+.

So, the first thing to do is estimate your power consumption if I were to pull your plug. Then double that. Most electric motors with universal windings act like a dead short on start. The inrush current is about 2X the running draw.

I believe that 12VDC will be the system standard for decades. There's so much of that stuff out there already.

Inverters come in 3 flavors: square wave (for lights, etc), modified sine wave (lights and a few motors) and pure sine wave which can run any motors and all lights. I have all three of them. The pure sine wave is the main unit of house power generation.

The inverters use some electricity to power their own electronics. They can only suck so hard on the batteries. My system quits at 11.6 VDC (down from the storage peak of 13.6VDC). There isn't enough juice left to drive the inverter.

Batteries store the juice, day and night. Day and night, your inverter will be looking at the batteries for supply, not the PV panels. Big battery budget is the best thinking.
= = =
If you got this far, here's some free advice from hindsight:
If it's your intention to use this system for essential services at home in a power outage, skip the PV panels and buy more deep cycle batteries. Buy a big, fat smart battery charger that runs off your mains. You can reload your batteries even at night when the power comes back on. I am happy that I did this.
 

Broch

Full Member
Jan 18, 2009
5,600
4,970
Mid Wales
They're the same, the world over. I have a small system because we are subjected to power failures at a weekly rate, more or less. The driver is the power that I need for home heating in -20C weather (like last night and the week to come). I've used it every year for the past 15+.

So, the first thing to do is estimate your power consumption if I were to pull your plug. Then double that. Most electric motors with universal windings act like a dead short on start. The inrush current is about 2X the running draw.

I believe that 12VDC will be the system standard for decades. There's so much of that stuff out there already.

Inverters come in 3 flavors: square wave (for lights, etc), modified sine wave (lights and a few motors) and pure sine wave which can run any motors and all lights. I have all three of them. The pure sine wave is the main unit of house power generation.

The inverters use some electricity to power their own electronics. They can only suck so hard on the batteries. My system quits at 11.6 VDC (down from the storage peak of 13.6VDC). There isn't enough juice left to drive the inverter.

Batteries store the juice, day and night. Day and night, your inverter will be looking at the batteries for supply, not the PV panels. Big battery budget is the best thinking.
= = =
If you got this far, here's some free advice from hindsight:
If it's your intention to use this system for essential services at home in a power outage, skip the PV panels and buy more deep cycle batteries. Buy a big, fat smart battery charger that runs off your mains. You can reload your batteries even at night when the power comes back on. I am happy that I did this.

Some good points! :) I found that the 1kw generator I had bought, hoping to run the water pump, wasn't man enough because of the pump start current! Also worth pointing out that some small generators use inverter technology and won't run some motors :)

I have an 8.5kw inverter/battery charger waiting for me to install it. I am planning a) to be able to survive 2 days of total blackout and b) under normal conditions to charge a hybrid car so my local travel is free (to the nearest town and back is only 26 miles). However, I am rethinking how many batteries and panels I need to achieve that in a British winter!

I'm getting £250 from the electricity supply company as compensation for our recent power outage - I'll put it towards a couple of batteries :)
 
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Robson Valley

Full Member
Nov 24, 2014
9,547
2,265
McBride, BC
You have to see a graph of the different inverter wave forms.
The square wave and the "modified" sine wave go positive then come down to zero before going negative in each AC cycle.

However, the wave hangs at zero just long enough for a motor to believe that the power has been turned off. So you're back at the "dead short" start with the 2X inrush current to get rolling again but you're on it all the time. Every half AC cycle in fact. Hard on the inverter, too.

The pure sine wave inverter wave form whips straight across zero and goes negative without a pause. As if the power is "ON" all the time. So you have a bump to get the motor rolling and that's all.

I could install the square wave inverter in my GMC Suburban and decorate the pig with Christmas lights. It would all run just fine. At 60cps, you would not be able to detect any flicker at all.
 
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Paul_B

Bushcrafter through and through
Jul 14, 2008
5,276
1,025
Cumbria
Moved into a house with pv cells. 2014 install when the sweet feed in tariff scheme was still generous. Last summer free electricity until 930 in the evening and 50% of the potential generation I think back from our electricity supplier. Got £400+back from British gas in October or November for just 6 months. Factoring in how much it reduces our bill during the sunnier months it's a good deal I think.
 
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demographic

Bushcrafter (boy, I've got a lot to say!)
Apr 15, 2005
4,483
496
-------------
Got a few mates who have moved into an off grid house last year
They have a few solar panels and a mass of scrap truck batteries.
The batteries don't last due to being deep discharged but they only paid scrap prices for em so it seems its not that much of an issue.

I imagine they'll have a rethink come spring when they know just how much work it is but they're bright people and resourceful so will manage.
 
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TeeDee

Full Member
Nov 6, 2008
8,490
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47
Exeter
I had a recent quote for a large solar array and modern day batteries to potentially go off grid as much as possible - or to at least reduce the draw down from the Grid to minimal levels.

Cost of the total Install was circa £20k.

I think if Solar is going to be relied upon at the direct level to help alleviate the burden on the Grid more FITS or funding schemes are going to be required. Payback on £20K certainly takes some time.
 

Paul_B

Bushcrafter through and through
Jul 14, 2008
5,276
1,025
Cumbria
I think it's batteries that must bump up that cost. Our pv array i think cost little over £7k in 2014 for the previous owner according to the paperwork we were given. No storage though I think probably reduced the cost but it was some time ago so a similar system should be cheaper than back then because of scale. Some places it's very common to see the cells on roofs.
 

swyn

Full Member
Nov 24, 2004
874
15
Eastwards!
Now this is a personal thing. Take my opinion as you wish. I would love to hear otherwise.
I looked into PV fifteen years ago and thirty years ago. I never went down this route, simples.
For running lights it is ok. For a small yurt/scandi type of building it will certtainly work. For a house, unless you have a large back-up generator or a very large battery bank with wind-power in the equation as well, being totally off-grid in the UK is a seriously expensive investment. It may work in Oz but I have not managed to persuade my brother in the 40 years he's lived there that this is a way forward.
My parents lived a nomadic life afloat in and around Europe..... with a stand-by genny and when visiting there was always the 'don't-do-this' unless the genny was working.
Living a slightly hippy lifestyle this is fine with constant awareness of the limitations and possible pit-falls. If you simply want to use 3Kw say to boil a kettle or get your solar hot water immersion to heat the water to 60+ degrees thus reducing the risk of legionella infection these limitations have to be taken into consideration. After a day at the pit-face does one really want the 'faff'? Perhaps when one is retired but personally when working I did not.
When building my own house I opted to keep with mains electricity and spend my money on insulation. As most folks know a 2.4 x 1.2 sheet of Kingspan/Ecotherm 100mm or 75mm is not cheap. Multiply this by 'lots'!
I have left a power control point in case things change and I could run a 25mm SWA cable a short distance and connect up a PV/battery/wind system. Basically where all the cables join up at a centralised point and where they could be made to switch away from the incoming mains power. I have oversised (6mm as opposed to 2.5 twin & earth) cables running to my immersion and UFH systems to compensate for voltage drop so these two important players are future-profed.
LED lighting is now very cheap and relatively so is electric under-floor heathing if you have dug deep into your £'s and fitted good insulation. I shied away from a wet system for now apart from a solar hot water array and hot water tank which is the best £3.5k I ever spent.
LED lighting in a shed running from a PV panel, charge controller and a few batteries is also cheap but for every-day living and to work properly, keeping an average three bed house on 'a-flick-of-a-switch', without access to the mains supply, is very costly, hence not many people have this set-up without a large stand-buy genny.
S
 
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TeeDee

Full Member
Nov 6, 2008
8,490
2,109
47
Exeter
Now this is a personal thing. Take my opinion as you wish. I would love to hear otherwise.
I looked into PV fifteen years ago and thirty years ago. I never went down this route, simples.
For running lights it is ok. For a small yurt/scandi type of building it will certtainly work. For a house, unless you have a large back-up generator or a very large battery bank with wind-power in the equation as well, being totally off-grid in the UK is a seriously expensive investment. It may work in Oz but I have not managed to persuade my brother in the 40 years he's lived there that this is a way forward.
My parents lived a nomadic life afloat in and around Europe..... with a stand-by genny and when visiting there was always the 'don't-do-this' unless the genny was working.
Living a slightly hippy lifestyle this is fine with constant awareness of the limitations and possible pit-falls. If you simply want to use 3Kw say to boil a kettle or get your solar hot water immersion to heat the water to 60+ degrees thus reducing the risk of legionella infection these limitations have to be taken into consideration. After a day at the pit-face does one really want the 'faff'? Perhaps when one is retired but personally when working I did not.
When building my own house I opted to keep with mains electricity and spend my money on insulation. As most folks know a 2.4 x 1.2 sheet of Kingspan/Ecotherm 100mm or 75mm is not cheap. Multiply this by 'lots'!
I have left a power control point in case things change and I could run a 25mm SWA cable a short distance and connect up a PV/battery/wind system. Basically where all the cables join up at a centralised point and where they could be made to switch away from the incoming mains power. I have oversised (6mm as opposed to 2.5 twin & earth) cables running to my immersion and UFH systems to compensate for voltage drop so these two important players are future-profed.
LED lighting is now very cheap and relatively so is electric under-floor heathing if you have dug deep into your £'s and fitted good insulation. I shied away from a wet system for now apart from a solar hot water array and hot water tank which is the best £3.5k I ever spent.
LED lighting in a shed running from a PV panel, charge controller and a few batteries is also cheap but for every-day living and to work properly, keeping an average three bed house on 'a-flick-of-a-switch', without access to the mains supply, is very costly, hence not many people have this set-up without a large stand-buy genny.
S

I actually ( now ) work for a UFH / Renewable energy ( ASHP/GSHP/SOLAR ) company and tend to echo your thoughts on most things especially regarding the minimizing the electrical draw of items whilst increasing the thermal insulation factor.

The Insulation 'push' is what I think the next big thing will be in the UK and it won't be achievable for all houses but there is also a desire to raise the level of EPC across the board.
I'm predicting a lot more unsightly external cladding unless its government led and well organised ( an oxymoron, I realise ) across the generic older housing stock.

You comment ref the benefit of solar hot water is interesting but unfortunately Thermal solar isn't much use in winter - but still if it can offset summer/spring costs it can't be bad thing.

As electricity costs seem predicated to be only heading in a upwards orientation and the slightly strange 2025 deadline to have no new houses built with cheaper to run Gas Boilers on the near horizon its certainly going to make how we heat our beloved homes a 'hot' topic of conversation and policy.
 
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Paul_B

Bushcrafter through and through
Jul 14, 2008
5,276
1,025
Cumbria
Bought a house last year and looking at energy efficiency ratings of houses it seems 60 or 62 is the national average that's a D! It always seemed to me that whilst there has been government schemes to push insulation of houses they all seem patchy and variable across the country. I heard about people on better money than me getting access to support insulating their private property in one part of the country but whenever I looked I needed to be unemployed or near minimum wage to get any subsidy or assistance.

I always thought it's one thing going down renewable power route but without improving the insulation of housing stock across the country you'll not get anywhere near where we need to be to minimise climate change.

Recent schemes got over subscribed and with contractor rules I believe you couldn't get the work done in time for the cutoff.

I don't mean to sound political because I don't think this is, as a nation we need to change our housing stock as much as we need to change our car stock. That's not strictly political because it's down to us being unwilling to pay up to get insulated.

I watched a house buying programme and they interviewed the boss of a SE England House retrofitting company. Apparently tthats the new fashion among people with enough spare cash to completely pay for a whole house renovation by professionals. It costs a lot more but these retrofitting specialist builders go around the house sealing gaps and insulating it as much as possible. The goal is to get it as close to passive house levels as old housing stock can get.

BTW when we looked at houses there was a 2 bedroom house up for sale at over twice what our 3 bed house we ended up buying cost. The only reason was it had an A rating which included the leakage rate iirc which was just below passive house status. The people who got it built were probably gutted and pi$$ed at that.

Sorry for the digression. Insulate then look to alternative energy sources is my main point.
 
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swyn

Full Member
Nov 24, 2004
874
15
Eastwards!
I actually ( now ) work for a UFH / Renewable energy ( ASHP/GSHP/SOLAR ) company and tend to echo your thoughts on most things especially regarding the minimizing the electrical draw of items whilst increasing the thermal insulation factor.

The Insulation 'push' is what I think the next big thing will be in the UK and it won't be achievable for all houses but there is also a desire to raise the level of EPC across the board.
I'm predicting a lot more unsightly external cladding unless its government led and well organised ( an oxymoron, I realise ) across the generic older housing stock.

You comment ref the benefit of solar hot water is interesting but unfortunately Thermal solar isn't much use in winter - but still if it can offset summer/spring costs it can't be bad thing.

As electricity costs seem predicated to be only heading in a upwards orientation and the slightly strange 2025 deadline to have no new houses built with cheaper to run Gas Boilers on the near horizon its certainly going to make how we heat our beloved homes a 'hot' topic of conversation and policy.
In the 1859 part which is not a bad looker in its Victorian way I have stripped out everything and by that I mean both floors and am building a house within a house. 100mm filled cavity and then 100mm ‘Celcon’ block for load-bearing walls and 75mm for the non bearers saving a whole 25mm. This also is what Building Regs requires a proper refurbishment to comply with.
For the original structure this means no more 162 year old rotten and wood-worm infested structural timber, door and window lintels or nogs for that matter. All loads brought down to a 200mm double layer 10mm reo mesh concrete slab and ss ties where necessary. This is ongoing work.
Looking at my hot water today. We had a gloriously sunny day after a minus four night. My solar array produced enough hot water for two showers. Maybe we’ll have similar tomorrow and if so it will be a repeat and nearly cost free eh!
I have lit the wood burner tonight just coz its going to be another minus four or so night but my three temperature gages all say similar readings; 20, 21.6 & 22.2 degrees respectively the biggest drop today was to 18.6 degrees….not exactly cold but a flat curve and that’s what I like to see.
Interestingly the worst cold-bridging is through the Eurolocks on the entrance doors. No doubt this will become another requirement as the regs for insulation get higher but for now this is the most obvious failing.
Condensation on the toilet cistern is another one to watch out for and also if like me you live in the woop-woops have low mains pressure and in consequence a cold water header tank. Mine lives in its own heavily insulated compartment which is keeping it cool! All cold feed pipes are lagged. This pretty much stops condensation which becomes more of a problem in a well insulated home.
There y-go!
S
 
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Robson Valley

Full Member
Nov 24, 2014
9,547
2,265
McBride, BC
The thermal economy of a pellet stove over an oil-fired furnace gave me the savings to build up a small PV system. The real driver out here were the frequent total grid power failures with unknown times for repairs. Just the simple act of finding the break in winter mountains is a serious chore with high avalanche risk.

You all are correct. The mass of the battery bank is the source of the juice, day and night, for your home. That's the big investment.

Now, I can't lift the 19kg pellet bags so I sold the stove. Doing the stairs to load the stove is nearly more than my legs can manage, even with a bulk pellet hopper on the stove. Furnace fuel will set me back at least $4,500 this winter. Luckily, I can just afford to do that.

In the city, I might have experienced a power failure once every decade. In that case, grid is cheap. I thought PV was clever but not worth the capital investment at all.
 

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