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gaz1
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what the hell are you running
A normal, well small, house, and a workshop, with compressor, 3 de-humidifiers (for 6 months of the year) and electric heating in my office. Just 2 people.
No doubt the de-humidifiers are the killer. I could get rid of, or massivly reduce their use, if i insulate the roof, but, frankly, thats not remotely affordable.
Heating in the house is oil, so not included in the above electricity consumption.
dyno-tron
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We have solar + battery. Solar doesn’t do much dec/jan/feb but some days can be very good.
We just switched to octopus “cosy”, 3 periods (totalling 8 hours) in 24 hours where the price is 13.3p per kWh. So the battery is set to charge at those times and dish it out in between. Now all our consumption is at 13.3p, and if we have a sunny day the solar gets exported at 15p. Some days have worked out completely free or better
. For reference, solar panelage is about 7kw max output, battery is 10kwh capacity, daily consumption is about 17kwh on average
We just switched to octopus “cosy”, 3 periods (totalling 8 hours) in 24 hours where the price is 13.3p per kWh. So the battery is set to charge at those times and dish it out in between. Now all our consumption is at 13.3p, and if we have a sunny day the solar gets exported at 15p. Some days have worked out completely free or better
. For reference, solar panelage is about 7kw max output, battery is 10kwh capacity, daily consumption is about 17kwh on averageWe have solar + battery. Solar doesn’t do much dec/jan/feb but some days can be very good.
We just switched to octopus “cosy”, 3 periods (totalling 8 hours) in 24 hours where the price is 13.3p per kWh. So the battery is set to charge at those times and dish it out in between. Now all our consumption is at 13.3p, and if we have a sunny day the solar gets exported at 15p. Some days have worked out completely free or better
How big is the battery, and what does your pay bacl look like if you dont mind me asking?
I'd be guessing leccy costs less than half "normal" costs, plus some income from summer generation? £1500 to £2k a year?
Battery and 7kW of solar, maybe £12k? 6 to 8 yr payback, just a guess.
7kW of solar needs permission from the DNO though, they might limit your export (peak).
Worth thinking about...
gaz1
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agree
3 de-humidifiers dont help but work better in a sealed enviroment
roll is cheaper insulate board is quicker but also dear
edf reference night charge
Super Cheap Off-Peak Rates Of Just 9p Per Kwh To Power Your Electric Car And Home
Gareth J
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Won't be saving you anything on a pallet! I'd get that up as a priority, especially if it's all bought and paid for.
See what excess generation you end up with. And see what you can defer to sunny times to maximise savings.
If it's MCS certified, you can get paid to export. Currently in the range of 12-15p. Apparently Octopus will let you do it without certification but check whether that's reality yet or not.
I doubt the differential between day and night tarrifs alone will be enough to make batteries financially stack up.
I've not looked into it, but I used to be involved with off-grid systems (generator & battery pack & inverter combinations. We didn't do solar but you could add solar, wind or water turbine either as direct supplementary charging to the battery pack, or with the right inverter - as AC grid-tie system).
I'd say the pay-back is always the biggie. With off-grid you got a lot if added benefits of continuous seamless power with batts & inverters... as well as more efficient generator usage, less hours, service cost and wear & tear on the genny all offsetting investment. You get none of those with mains.
Also, you need to factor in depreciation in the form of the degradation & need to replace battery cells. OK, I was working with lead-acid traction cells not Lithium (even then the charging regimes and peak load cut-offs were all set up to maximise pack life, & 10-12 years was achieved) ... but you need to consider and allow for possible inverter failure (dunno, £3k??) and/or battery pack replacement (dunno, several £k??).
IMO it's always better to minimise consumption than it is to spend finding ways to make that consumption cheaper (as that's harder to do in reality than a lot of the sales patter implies).
I'd be looking at insulation, and maybe at a more direct heating source like kerosene/diesel heaters before I'd be investing in power storage myself. Insulation is passive and tech-free, and mtce-free compared to these systems.
(Arguably solar is better for water heating than electricity production? Years ago there was a firm in Wales building water heating solar - but I think the market direction went the other way, so they went the way of the Betamax).
I'd say the pay-back is always the biggie. With off-grid you got a lot if added benefits of continuous seamless power with batts & inverters... as well as more efficient generator usage, less hours, service cost and wear & tear on the genny all offsetting investment. You get none of those with mains.
Also, you need to factor in depreciation in the form of the degradation & need to replace battery cells. OK, I was working with lead-acid traction cells not Lithium (even then the charging regimes and peak load cut-offs were all set up to maximise pack life, & 10-12 years was achieved) ... but you need to consider and allow for possible inverter failure (dunno, £3k??) and/or battery pack replacement (dunno, several £k??).
IMO it's always better to minimise consumption than it is to spend finding ways to make that consumption cheaper (as that's harder to do in reality than a lot of the sales patter implies).
I'd be looking at insulation, and maybe at a more direct heating source like kerosene/diesel heaters before I'd be investing in power storage myself. Insulation is passive and tech-free, and mtce-free compared to these systems.
(Arguably solar is better for water heating than electricity production? Years ago there was a firm in Wales building water heating solar - but I think the market direction went the other way, so they went the way of the Betamax).
I do it without a battery, I only have 3Kw array up at the moment split across two inverters/locations and if we feed anything back to the grid instead of consuming it, we get nothing for the privilege. But we have some smart switches on the heavy consumers and get realtime output stats from our inverters and some automation switches on progressively heavier loads automatically to keep that figure of electricity given away as close to zero at all times. So the water heater, small blow heaters dotted about just to top off the energy from the wood furnace, charge the mrs's little EV etc.
Winter we mechanically changed the angle of the panels for the season as they are on easily accessible ground stands and the mounts have a series of holes in them, and I have a app on my smartphone that you lay it on the panel and it tells you when the angle is best for the season & longitude/lattitude and then it depends on the day, if its dull and misty there's not much solar radiation, but if its cold but clear we're seeing 1.5-2Kw out of the panels at peak, sure its not 3Kw like spring/summer/autumn, but its all stuff we're not paying for. Also as the sun is lower in the sky, the hours it generates well is shorter and some tree's shrouded some of the panels early morning and later on as a result of that change too so we're seeing much better winter results out of one array than the other. I might move the underperforming ones when I get chance, but that means new power and data leads and prepping the area so its easy to maintain so its a rainy day idea for now.
Also if it was roof mounted, it would be more difficult to change the angle with season for optimum yield unless it had some kind of powered system which would be prone to wear and breakage in high winds, and it would be more prone to wind and harder to clean, so as we have a big garden, having it on the ground has maintenance advantages. I've steered clear of tracking systems for the maintenance aspect too. I'd rather just move the panel angles with a spanner 3-4 times a year and have more of them to get the same yield with less complexity/things to go wrong.
I have another 3kw to go up sat on a pallet and two more micro inverters that I got in a deal during late autumn as the initial experiment is going well, I have to move a load of rubble and junk for the area that's going to be optimal for them and I've been snowed under with other stuff.
As currently we're consuming all of our 3Kw peak during the day, and during the night time we're consuming a lot less electricity as a result I dont see the economics of getting battery storage working out yet.
Looking at our bills I estimate its going to pay for itself in about 4 years.
Initially I wanted them on the roof but its a mess of planning for me and permits to connect the stuff to the electricity grid. If I navigated all that, its possible to get a tarrif where I get paid for what I feed back, but I have enough on right now as it is and the only easy way to do that is to pay a company to install & certify it all, which makes it a expensive job. I should add we're on 3phase supply and part of the load balancing element is the smart meter see's returned power on one phase, and diverts it in terms of billing to a phase seeing power being consumed on the other, so the smart meter bills us for total energy consumed even if we're heavily loading one phase but returning power on another. This means also we can use single phase micro inverters (much cheaper...) and arrays in different places easier as its just a single phase supply out to the area. And if the inverter ever goes bad, your not having to replace all the inverter capacity, just that one small one.
The other thing when you start getting monitoring on energy consumption, you notice your own bad habits and load usage patterns, and change them and can get even more savings.
So, tl,dr; the array is working well, happy with the return on investment so far but also putting in monitoring to load shed, means I'm much more aware of energy consumption and I'm saving even more by doing small changes.
One thing I am slightly interested in when I get the above working, I've noticed low yield days are often miserable blowy days. And good solar yield is rarely combined with wind. So maybe one of those vertical axis wind turbines might go to filling in some gaps, and they have appeared at a reasonable price recently with some sellers in Poland. If I mount them so they are easy to get to ground level for maintenance and repair it could help fill some gaps and make it even more efficient.
When I was in suffolk about 20 years back, we did wind calculations on a house using local wind records for the area and for a small wind turbine, and it would have to be up on the roof for 20 years, and require no maintenance or repairs at all to even break even, maybe that equation has changed enough to be worth doing too.
Winter we mechanically changed the angle of the panels for the season as they are on easily accessible ground stands and the mounts have a series of holes in them, and I have a app on my smartphone that you lay it on the panel and it tells you when the angle is best for the season & longitude/lattitude and then it depends on the day, if its dull and misty there's not much solar radiation, but if its cold but clear we're seeing 1.5-2Kw out of the panels at peak, sure its not 3Kw like spring/summer/autumn, but its all stuff we're not paying for. Also as the sun is lower in the sky, the hours it generates well is shorter and some tree's shrouded some of the panels early morning and later on as a result of that change too so we're seeing much better winter results out of one array than the other. I might move the underperforming ones when I get chance, but that means new power and data leads and prepping the area so its easy to maintain so its a rainy day idea for now.
Also if it was roof mounted, it would be more difficult to change the angle with season for optimum yield unless it had some kind of powered system which would be prone to wear and breakage in high winds, and it would be more prone to wind and harder to clean, so as we have a big garden, having it on the ground has maintenance advantages. I've steered clear of tracking systems for the maintenance aspect too. I'd rather just move the panel angles with a spanner 3-4 times a year and have more of them to get the same yield with less complexity/things to go wrong.
I have another 3kw to go up sat on a pallet and two more micro inverters that I got in a deal during late autumn as the initial experiment is going well, I have to move a load of rubble and junk for the area that's going to be optimal for them and I've been snowed under with other stuff.
As currently we're consuming all of our 3Kw peak during the day, and during the night time we're consuming a lot less electricity as a result I dont see the economics of getting battery storage working out yet.
Looking at our bills I estimate its going to pay for itself in about 4 years.
Initially I wanted them on the roof but its a mess of planning for me and permits to connect the stuff to the electricity grid. If I navigated all that, its possible to get a tarrif where I get paid for what I feed back, but I have enough on right now as it is and the only easy way to do that is to pay a company to install & certify it all, which makes it a expensive job. I should add we're on 3phase supply and part of the load balancing element is the smart meter see's returned power on one phase, and diverts it in terms of billing to a phase seeing power being consumed on the other, so the smart meter bills us for total energy consumed even if we're heavily loading one phase but returning power on another. This means also we can use single phase micro inverters (much cheaper...) and arrays in different places easier as its just a single phase supply out to the area. And if the inverter ever goes bad, your not having to replace all the inverter capacity, just that one small one.
The other thing when you start getting monitoring on energy consumption, you notice your own bad habits and load usage patterns, and change them and can get even more savings.
So, tl,dr; the array is working well, happy with the return on investment so far but also putting in monitoring to load shed, means I'm much more aware of energy consumption and I'm saving even more by doing small changes.
One thing I am slightly interested in when I get the above working, I've noticed low yield days are often miserable blowy days. And good solar yield is rarely combined with wind. So maybe one of those vertical axis wind turbines might go to filling in some gaps, and they have appeared at a reasonable price recently with some sellers in Poland. If I mount them so they are easy to get to ground level for maintenance and repair it could help fill some gaps and make it even more efficient.
When I was in suffolk about 20 years back, we did wind calculations on a house using local wind records for the area and for a small wind turbine, and it would have to be up on the roof for 20 years, and require no maintenance or repairs at all to even break even, maybe that equation has changed enough to be worth doing too.
iNf
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How big is your workshop, what type of construction and what do you do in there that requires 3 dehumidifiers? Why is paying £3.5k/Yr affordable but insulation isn't? More info required. For instance if it's a large building could you make a well insulated room within the space?
cheb
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Do you know of this? It looks similar to the scheme in Scotland. I don't know much about it but friends who had it done out here seem happy with it.
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Gareth J
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Don't buy any wind turbine that doesn't provide an output chart of annual average windspeed Vs kWh production ideally produced or verified with real world data.
Spoiler alert, vertical axis wind turbines are generally pretty poor performers and these charts are, unsurprisingly, rarely provided
dyno-tron
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Thanks minimutly, saved me the brain cells:-). Yep, that’s about right.
In summer we are mainly self sufficient. When the battery is full, any production over the DNO limit is lost, however this year I’ll be experimenting with with Predbat (on GitHub) to try and get more intelligent charging eg exporting more earlier in the day and only charging from the clipped energy but still making sure the battery is filled up.
gaz1
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a chinese diesel heater can be bought as well seen as you already buy oil
3000sq/ft. 5.5m high. Cavity block walls, but fibre cement roof.
Its pretty well sealed up now, but its the middle of wales, so humidity is high for 6 months of the year plus. So i run them to avoid rust forming. Im just about keeping it at 65 - 70%, which im happy with.
The roof is a challenge. Like most fibre cement roofs it has weeps and suffers damp patches in heavy rain as a result of small cracks etc. So putting insulation against it isnt going to end well. I have had quotes to replace the whole roof with insulated composte steel panels, but its close to £50k. And its not a DIYable job. There are some other options ive considered, but either way we are deep into 5 figure territory. Im going to need to live a very long time to make it pay. The total cost includes the house. Though thats clearly the minor part of it.
I have built a room, and am doing another. From a heating perspective, great, but the bulk of the building, where everything is stored will remain as it is, so the dehumidifier issue doesnt go away.
These rooms, plus the office, ill eventually fit an oil fired heating system, so the office heater load will go. But thats only 7 hours 3 days a week.
As i see it currently, whilst i can tinker at the margins, the electricity use is only likely to increase not decrease, hence the question on reducing electricity cost, rather than use.
Thanks for the detailed reply.
Im assuming from this, you self installed? I have no interest in paying for an "MCS certified" installation, mainly on cost grounds, and because ive no intention of lining the pockets of said organisation (probably for another thread!).
Ive done most of my own electrics over the years, indeed was qualified way back in the early 90's, but i really struggle to understand how to wire and connect it all up. It seems hard to get clarity on what exactly i would need to do. Invertors seems to be an unfathomable minefield.
My intention, like you was ground mount. Workshop roof, whilst large is shaded from early afternoon onwards. I do have a decent sized field with a clear view of the sky in the south, so intended to put it there.
Whilst id love not have batteries, the reality most of my annual usage takes place in the winter, inclusing use of the compressor etc. And batteries is where the big costs are.
charlysays
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I'd love to kit out my future house with solar panels and a generator to charge batteries. Off grid potentially. Use solar as much as possible but run the generator as needed off recycled chip fat (probably twin tanked and water injected). Run a heat exchanger on the generators cooling system to heat the hot water too. Would cost so little to run and yield full use of mod cons.
