Discussion
Our house roof is ok, in fact had the lead work and pointing redone earlier this year.
The garage roof however could do with a refresh but, I’d make material changes to it at the same time which I’m not quite ready to do (as in knock it down and start again). I am sure it’ll be fine for a decade.
16.5 seems fair though doesn’t it ince the roof work. Is that including scaffold?
The garage roof however could do with a refresh but, I’d make material changes to it at the same time which I’m not quite ready to do (as in knock it down and start again). I am sure it’ll be fine for a decade.
16.5 seems fair though doesn’t it ince the roof work. Is that including scaffold?
Tyndall said:
Hi all
I'm being tasked with looking at potentially fitting solar panels to a block of flats that we own 1 of 16 of. Aside from the complications of how we actually fairly distribute what's generated (13 are holiday homes, only 3 are full time residents so use a lot more power than the rest - thoughts welcome on how to overcome that one!) it's the actual fixing that I'd love your input on.
We're about to have a new 800sqm flat roof installed, the block faces south with no obstacles until you hit France so seems ideal for solar. I had expected as part of the new roof to fit a series of upright 'stubs' that we could then in the future essentially scaffold off for the solar, however the roofing contractors are all telling me that the usual way to do solar on a flat roof like this is with ballast.
Is that correct? It feels slightly unnerving as it's bang on the south coast so gets some pretty serious weather at times!
Just bumping this in case anyone has any experience of large flat roofs like this?I'm being tasked with looking at potentially fitting solar panels to a block of flats that we own 1 of 16 of. Aside from the complications of how we actually fairly distribute what's generated (13 are holiday homes, only 3 are full time residents so use a lot more power than the rest - thoughts welcome on how to overcome that one!) it's the actual fixing that I'd love your input on.
We're about to have a new 800sqm flat roof installed, the block faces south with no obstacles until you hit France so seems ideal for solar. I had expected as part of the new roof to fit a series of upright 'stubs' that we could then in the future essentially scaffold off for the solar, however the roofing contractors are all telling me that the usual way to do solar on a flat roof like this is with ballast.
Is that correct? It feels slightly unnerving as it's bang on the south coast so gets some pretty serious weather at times!
sammyb349 said:
Perhaps easier if I post the two quotes for more specific help
First is from Feb. Second is from last week. There has been some movement (inverter is 1k more), bigger battery as mentioned etc. but the biggest movements are loss of discount and panel cost significantly higher.
Feels egregious to me - but keen for others views, as it could have been the Feb quote was amazing…
I wouldn't want to buy anything from people who quote for batteries in 'kW'.First is from Feb. Second is from last week. There has been some movement (inverter is 1k more), bigger battery as mentioned etc. but the biggest movements are loss of discount and panel cost significantly higher.
Feels egregious to me - but keen for others views, as it could have been the Feb quote was amazing…
Either they know jack s
t about batteries, or they're lazy people who are careless about detail.Either way, doesn't inspire confidence in their work.
MaxFromage said:
Same markup on the panels. No-one can blame them cashing in at the moment, but personally they'd be better not itemising the bill. Easier to hide £8K labour and profit then.
I think it'd be easy to work out anyway. there's no issue paying mark up on listed prices, even if it was 20% over retail. however they're just taking the piss. just sit it out, prices will come down. especially with the caps.You remind me. Just on the kw thing, I was wondering how much power these very expensive batteries really have compared to, say, a big leisure battery from Tayna such as this: https://www.tayna.co.uk/leisure-batteries/enduroli...
Using the C100 (ie more gentle) rating for that battery it's 200 Ah
200x12/1000=2.4kwh I think?
So to match capacities, I'd want 4 of them to match the givenergy 9.5 jobbie. Which while twice the weight (I think this would be about a quarter of a tonne of batteries!), it'd also only be 800 quid and provide a 48V output.
Why do I think about this? a. it's just the way I think and b. I wonder if there's a market for "old tech" batteries to be used much more extensively - not just for the off grid crowd, but in the modern inverter setups on grid too.
800 quid of batteries and at the end of life, a lead acid battery, being much more "mechanical" in it's design is quite easy to break down into bits, recycle, or sometimes even rebuild with new plates. And nothing exotic in it either.
Using the C100 (ie more gentle) rating for that battery it's 200 Ah
200x12/1000=2.4kwh I think?
So to match capacities, I'd want 4 of them to match the givenergy 9.5 jobbie. Which while twice the weight (I think this would be about a quarter of a tonne of batteries!), it'd also only be 800 quid and provide a 48V output.
Why do I think about this? a. it's just the way I think and b. I wonder if there's a market for "old tech" batteries to be used much more extensively - not just for the off grid crowd, but in the modern inverter setups on grid too.
800 quid of batteries and at the end of life, a lead acid battery, being much more "mechanical" in it's design is quite easy to break down into bits, recycle, or sometimes even rebuild with new plates. And nothing exotic in it either.
Capacity is half that stated as typically you don't want to discharge them below 50%
How many cycles can it do ?
How many cycles can it do ?
Arnold Cunningham said:
You remind me. Just on the kw thing, I was wondering how much power these very expensive batteries really have compared to, say, a big leisure battery from Tayna such as this: https://www.tayna.co.uk/leisure-batteries/enduroli...
Good points. I selected a leisure battery as it's a bit more resilient to discharging.
But even so - I guess we're saying if it can do half the cycles and has half the usuable capacity (or at least it has a 5 year warranty vs the givenergy 10), then perhaps this makes the total lifetime value of the "modern" batteries a lot more interesting.
But even so - I guess we're saying if it can do half the cycles and has half the usuable capacity (or at least it has a 5 year warranty vs the givenergy 10), then perhaps this makes the total lifetime value of the "modern" batteries a lot more interesting.
Based on Max's comments above, I've been doing some analysis of our usage, in Kilowatts, during any half hour period. Now, it is still average over a half hour period since this is the max grain I can download from octopus. But it'll give a good indicator hopefully.
Of the 3184 hours I've had a smart meter installed, we've been above the battery max power (3.6kW) for 115 hours.
And only above the inverter max capacity (5kW) for 5 hours.
All of these times were when I was heating the kids pool for a play date, so inevitably the weather was very sunny
X Axis is bucket of Kilowatts load
Y Axis is number of times (half hour slots) we were within that range
So, ignoring momentary peak loads, we are generally well under the 3.6kW battery limit, let alone the combined 5kW limit
As long as manage when I put the pool heat on (for transparancy it's a cheapy intex above ground jobbie, so who knows if it will survive the winter)
But as long I only put it on when the sun's out or we're on off-peak grid power, (if on octopus go) - then I think we're good and 5kW is a decent fit.
Of the 3184 hours I've had a smart meter installed, we've been above the battery max power (3.6kW) for 115 hours.
And only above the inverter max capacity (5kW) for 5 hours.
All of these times were when I was heating the kids pool for a play date, so inevitably the weather was very sunny
X Axis is bucket of Kilowatts load
Y Axis is number of times (half hour slots) we were within that range
So, ignoring momentary peak loads, we are generally well under the 3.6kW battery limit, let alone the combined 5kW limit
As long as manage when I put the pool heat on (for transparancy it's a cheapy intex above ground jobbie, so who knows if it will survive the winter)
But as long I only put it on when the sun's out or we're on off-peak grid power, (if on octopus go) - then I think we're good and 5kW is a decent fit.
Edited by Arnold Cunningham on Friday 16th September 14:28
Had 10 panels installed on Tuesday, so 4.05kW. We've hit 3.65kW today, but the sunny spells is certainly playing havoc with any kind of ability to generate anything consistent.
Back of a fag packet sums show us saving about 600 quid a year (if based on this week).
No battery yet, waiting for prices to continue to tumble.
Back of a fag packet sums show us saving about 600 quid a year (if based on this week).
No battery yet, waiting for prices to continue to tumble.
I am doing more sums - I'm wondering about pushing the boat out and adding some more battery capacity - so that when it's less favourable weather for a day, we have more in reserve in the battery.
So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
Arnold Cunningham said:
I am doing more sums - I'm wondering about pushing the boat out and adding some more battery capacity - so that when it's less favourable weather for a day, we have more in reserve in the battery.
So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
If It is the GivEnergy 9.5kwh battery, then they can be daisy chained at a later date. You don't even need an electrician to do it. They are pretty much plug and play (almost). So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
Puggit said:
Had 10 panels installed on Tuesday, so 4.05kW. We've hit 3.65kW today, but the sunny spells is certainly playing havoc with any kind of ability to generate anything consistent.
Back of a fag packet sums show us saving about 600 quid a year (if based on this week).
No battery yet, waiting for prices to continue to tumble.
Have battery prices started to tumble?Back of a fag packet sums show us saving about 600 quid a year (if based on this week).
No battery yet, waiting for prices to continue to tumble.
I thought they were still at a peak (to date....)?
Arnold Cunningham said:
I am doing more sums - I'm wondering about pushing the boat out and adding some more battery capacity - so that when it's less favourable weather for a day, we have more in reserve in the battery.
So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
If it’s easy to add a 2nd battery later my thought would be to wait and see how you get on. You’ll get the best payback by maximising “the area under the curve”, not by chasing the transients.So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
Tyndall said:
Just bumping this in case anyone has any experience of large flat roofs like this?
I am building one now and suspect we will not put solar on. The issue is loading. It is approx 100kg of ballast per panel and most roofs were not designed with this load in mind. Before you go any further get a structural engineer involved.
You could piece the roof covering and bolt it down but personally I don’t want to do that on a new roof.
Arnold Cunningham said:
I am doing more sums - I'm wondering about pushing the boat out and adding some more battery capacity - so that when it's less favourable weather for a day, we have more in reserve in the battery.
So at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
Just note that for many inverters the grid charge rate is lower than the max production. I think the smaller Givenergy stuff has a max 3 kW charge rateSo at the moment looking at a single 9.5kWh battery - but according to my sums, in the octopus go overnight tariff, we should be able to consume 3.6kW x 4 hours, which would also mean during the winter months I could run the house 100% off the battery for 24 hours even with no solar production during the day.
Is this worth the extra? Or shall I just shut up and get it built "as is" to see how we go?
I'd be wary of making a significant investment like a second battery solely based on the availability of a super cheap overnight tariff like Octopus Go. Thay could easily bebwithdrawn and normal economy7 rates are not so attractive.
gazapc said:
Just note that for many inverters the grid charge rate is lower than the max production. I think the smaller Givenergy stuff has a max 3 kW charge rate
I'd be wary of making a significant investment like a second battery solely based on the availability of a super cheap overnight tariff like Octopus Go. Thay could easily bebwithdrawn and normal economy7 rates are not so attractive.
Indeed - my single victron 5000 can only charge at 70amps - so can just about fill 13kwh of batteries in the four hour window. But you can put units in parallel and scale out horizontally.I'd be wary of making a significant investment like a second battery solely based on the availability of a super cheap overnight tariff like Octopus Go. Thay could easily bebwithdrawn and normal economy7 rates are not so attractive.
Eloit & Gaz. Agreed.
I'm trying to ensure the systems is robust - so if the cheap overnight tariff is not possible, it doesn't undermine the usefulness of the system
On a rolling 12 month basis we use an average ot 16kwh per day (including the kids pool, which I only keep calling out since it its an energy hog, and also optional - so if anyone else uses any of my sums to look at their own setup, the numbers are not unfairly biased. I mean, I'm looking back at the middle of june 2021 use and we burnt an average of 115kWh per day. Those days are long gone - hence I'm using rolling 12 months).
So I'm pretty much ignoring feed in tariffs and also want to make sure that during the summer period, if there's a cloudy day we have enough to carry us through withouth consuming much from grid. And during the winter, we have enough battery capacity to ensure that all solar production can be stored for us to use. but with enough grid charging going on during any off peak periods to make sure that gives us enough capacity if solar is doing nothing that day.
The givenergy gen 2 inverter handles 3.6kW of charging - so 3.6kw x 4 tells me we can consume up to 14.4 kWh from the grid in a 4 hour period.
So I'd like to make sure that we can charge the battery up enough to give us 24 hours of battery power with no solar, and then if we get to the next charging window, if the battery is still over the daily average, we consume 0 from the grid. Even factoring in my 2022 heating strategy for the pool, I think it should be possible to stay virtually off grid for 6 months of the year. I would love that. Lots to think about.
I'm trying to ensure the systems is robust - so if the cheap overnight tariff is not possible, it doesn't undermine the usefulness of the system
On a rolling 12 month basis we use an average ot 16kwh per day (including the kids pool, which I only keep calling out since it its an energy hog, and also optional - so if anyone else uses any of my sums to look at their own setup, the numbers are not unfairly biased. I mean, I'm looking back at the middle of june 2021 use and we burnt an average of 115kWh per day. Those days are long gone - hence I'm using rolling 12 months).
So I'm pretty much ignoring feed in tariffs and also want to make sure that during the summer period, if there's a cloudy day we have enough to carry us through withouth consuming much from grid. And during the winter, we have enough battery capacity to ensure that all solar production can be stored for us to use. but with enough grid charging going on during any off peak periods to make sure that gives us enough capacity if solar is doing nothing that day.
The givenergy gen 2 inverter handles 3.6kW of charging - so 3.6kw x 4 tells me we can consume up to 14.4 kWh from the grid in a 4 hour period.
So I'd like to make sure that we can charge the battery up enough to give us 24 hours of battery power with no solar, and then if we get to the next charging window, if the battery is still over the daily average, we consume 0 from the grid. Even factoring in my 2022 heating strategy for the pool, I think it should be possible to stay virtually off grid for 6 months of the year. I would love that. Lots to think about.
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