Solar panels and battery - any real world reccomendations?

Dunk05 said:
Morning,
Got my install at last yesterday. Nice neat install. Tidy as expected but I've had experience of some rough ( as in careless ) sparks recently. 5.3Kw PV and 9.9Kw battery. Started the morning with 100w at about half seven, an hour later we're on 2.4Kw which seems good for a February morning ( clear skies here, yesterday PM was ~300w with grey skies ) Free* power :D
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Yup wait until it's sunny, solar doesn't perform well in cloud, especially this time of year.
 
I have been thinking about the new Octopus Flux tariff again, obviously the export rates are nice, but I'm thinking that 3 hour cheap rate window is really going to be an issue. Initially I was just thinking it was pretty small to get a decent amount of charge, but I reckoned I could just about charge my 8.2 battery in the time available, assuming it started at 5%, though it is going to be very tight. However, I've realised the second issue then is that there is a longer period to get through between cheap periods, so pretty likely that the battery will not make it through on a bad solar day as there will be a much longer period that the battery will be exporting for.

Seems like a great tariff in the summer with plentiful solar and long days, but almost certainly going to end up using standard rate electricity during the winter months and not really much that could be done to avoid that, not much point in adding extra battery storage as will not be able to get any more charge into it, so that won't help (except for maybe if there happened to be a decent solar day, that allowed the battery to fully charge and that would allow the system to limp along a little longer before the battery was depleted). I think to really get the most from it will require both a large battery and battery\inverter with a high charge rate, guessing maybe it's aimed more at Powerwall owners, I guess as a replacement for the Powerwall specific tariff.

Quite possibly, the extra export return in the summer will outweigh the extra costs in the winter, though depends what happens with Agile Export prices this year, as last year they certainly seemed to rival (or beat) the flux prices quite often.
 
Tavis75 said:
I have been thinking about the new Octopus Flux tariff again, obviously the export rates are nice, but I'm thinking that 3 hour cheap rate window is really going to be an issue. Initially I was just thinking it was pretty small to get a decent amount of charge, but I reckoned I could just about charge my 8.2 battery in the time available, assuming it started at 5%, though it is going to be very tight. However, I've realised the second issue then is that there is a longer period to get through between cheap periods, so pretty likely that the battery will not make it through on a bad solar day as there will be a much longer period that the battery will be exporting for.

Seems like a great tariff in the summer with plentiful solar and long days, but almost certainly going to end up using standard rate electricity during the winter months and not really much that could be done to avoid that, not much point in adding extra battery storage as will not be able to get any more charge into it, so that won't help (except for maybe if there happened to be a decent solar day, that allowed the battery to fully charge and that would allow the system to limp along a little longer before the battery was depleted). I think to really get the most from it will require both a large battery and battery\inverter with a high charge rate, guessing maybe it's aimed more at Powerwall owners, I guess as a replacement for the Powerwall specific tariff.

Quite possibly, the extra export return in the summer will outweigh the extra costs in the winter, though depends what happens with Agile Export prices this year, as last year they certainly seemed to rival (or beat) the flux prices quite often.
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maybe....and i maybe wrong here, you could look at your high power usage, rather than the short charging window. Since the tariff was announced, ive looked at my usage during the expensive window of 4pm til 7pm and the most i have used so far in that 3hr window is 510whs...so half a kilowatt, so in essence 22.5P of electric. I am a low power user as people know and even lower with solar on the roof.

Rather than looking at what the tariffs or providers can do for you, just take a look at what you can do for yourself, by lowering your heavy power use.

Now you may already have looked ( to which i say look at my first line when i said a maybe wrong here)....
 
Welshman said:
maybe....and i maybe wrong here, you could look at your high power usage, rather than the short charging window. Since the tariff was announced, ive looked at my usage during the expensive window of 4pm til 7pm and the most i have used so far in that 3hr window is 510whs...so half a kilowatt, so in essence 22.5P of electric. I am a low power user as people know and even lower with solar on the roof.

Rather than looking at what the tariffs or providers can do for you, just take a look at what you can do for yourself, by lowering your heavy power use.

Now you may already have looked ( to which i say look at my first line when i said a maybe wrong here)....
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Do you have gas for cooking?
 
Welshman said:
maybe....and i maybe wrong here, you could look at your high power usage, rather than the short charging window. Since the tariff was announced, ive looked at my usage during the expensive window of 4pm til 7pm and the most i have used so far in that 3hr window is 510whs...so half a kilowatt, so in essence 22.5P of electric. I am a low power user as people know and even lower with solar on the roof.

Rather than looking at what the tariffs or providers can do for you, just take a look at what you can do for yourself, by lowering your heavy power use.

Now you may already have looked ( to which i say look at my first line when i said a maybe wrong here)....
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I'd probably be mostly fine during the highest rate period, it would be very unusual for me to not have charge for that period, so only usage is the general inverter balancing and occasionally a tiny amount of grid draw to cover shortfall due to the battery export limit if I'm running the oven (though bought an Air Fryer last year so rarely use the oven these days) and TBH I think the highest rate is similar to what I pay on my Eco 7 tariff at the moment anyway. My main concern is running out of power later at night, so having grid draw at the standard rate, especially as I will have to start drawing from the battery earlier in the day due to the shorter cheap period, rather than being able to use cheap rate through till 7:30 am.

My daily usage is usually in the 8-12KWh range, so a full battery charge and a bit of solar would generally get me through, but would definitely struggle on the bad days and obviously have very little export through the winter to counteract the extra costs.

It's a tough call, will probably keep an eye on the agile export prices and see how they go.
 
Tavis75 said:
I'd probably be mostly fine during the highest rate period, it would be very unusual for me to not have charge for that period, so only usage is the general inverter balancing and occasionally a tiny amount of grid draw to cover shortfall due to the battery export limit if I'm running the oven (though bought an Air Fryer last year so rarely use the oven these days) and TBH I think the highest rate is similar to what I pay on my Eco 7 tariff at the moment anyway. My main concern is running out of power later at night, so having grid draw at the standard rate, especially as I will have to start drawing from the battery earlier in the day due to the shorter cheap period, rather than being able to use cheap rate through till 7:30 am.

My daily usage is usually in the 8-12KWh range, so a full battery charge and a bit of solar would generally get me through, but would definitely struggle on the bad days and obviously have very little export through the winter to counteract the extra costs.

It's a tough call, will probably keep an eye on the agile export prices and see how they go.
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but surely grid draw late at night as you say, would be minimal anyway.....i mean, you would need to know your base power draw and work from there. I know at night from around 11pm until 6:15am i use less than half a kilowatt in energy ( some one will come along in a minute and comment about terminology, but I'm used to that now) so around 15p in current prices..

Yes, i dont have children or excess computers etc etc running like some do
 
I did a bit of theory crafting on go vs flux the other day
For me go still edges it, but not by much. Thats latest go pricing of 12/44 vs flux 20.5/34. I assumed no usage of the more expensive flux as assumed would ensure batteries covered that period.

Surprisingly even in the peak summer flux wasnt that mcuh better than go. On high output days yes, but on low output days go was decently better.

I also ran the same model for Mr Hippo and same result. Although closer again than mine was.

Its a reasonably detailed model to try to include the main factors but I didn't get into when the battery would not be fully discharged etc so assume to always charge a full charge even if real world its at say 40% and good solar the next day
Would need to do daily modelling really to include that level of variability. As it was I split each month into 3, and treated them as 50,100,150% of expected daily generation. Even tried with 20/100/180, still same result.

Flux is good for sure if you have batteries. But for now unless your a new exporter go seems to edge it.
 
Mercenary Keyboard Warrior said:
I did a bit of theory crafting on go vs flux the other day
For me go still edges it, but not by much. Thats latest go pricing of 12/44 vs flux 20.5/34. I assumed no usage of the more expensive flux as assumed would ensure batteries covered that period.

Surprisingly even in the peak summer flux wasnt that mcuh better than go. On high output days yes, but on low output days go was decently better.

I also ran the same model for Mr Hippo and same result. Although closer again than mine was.

Its a reasonably detailed model to try to include the main factors but I didn't get into when the battery would not be fully discharged etc so assume to always charge a full charge even if real world its at say 40% and good solar the next day
Would need to do daily modelling really to include that level of variability. As it was I split each month into 3, and treated them as 50,100,150% of expected daily generation. Even tried with 20/100/180, still same result.

Flux is good for sure if you have batteries. But for now unless your a new exporter go seems to edge it.
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i think the 23p export will be better for me, but i cant switch until November anyway as I'm on 12mth fixed export at 15p
 
Welshman said:
but surely grid draw late at night as you say, would be minimal anyway.....i mean, you would need to know your base power draw and work from there. I know at night from around 11pm until 6:15am i use less than half a kilowatt in energy ( some one will come along in a minute and comment about terminology, but I'm used to that now) so around 15p in current prices..

Yes, i dont have children or excess computers etc etc running like some do
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True, my base load overnight is about 0.25KW, so 11pm to 6am would be about 1.75KWh, knock out the 3 hours cheap rate and that's 1KWh at the standard rate, with a relative cost of about 17p (34p minus the 17p I'd currently pay on Eco 7). On the worst days I could potentially run out of power mid evening, so that would add a bit more, though I guess that could happen now (less likely due to the later finish of the cheap rate) but the cost would currently be higher as it would be at the 44p Eco7 rate rather than the 34p Flux rate.

Though obviously counteracted quite a bit if I'm exporting 20 units a day in the summer at 22p rather than say 15p on Agile (though on the other hand I've quite often had export rates of 30-40p in the middle of sunny summer afternoons before).

I think Flux may be the better option, but it's a tough call.
 
Mercenary Keyboard Warrior said:
I did a bit of theory crafting on go vs flux the other day
For me go still edges it, but not by much. Thats latest go pricing of 12/44 vs flux 20.5/34. I assumed no usage of the more expensive flux as assumed would ensure batteries covered that period.

Surprisingly even in the peak summer flux wasnt that mcuh better than go. On high output days yes, but on low output days go was decently better.

I also ran the same model for Mr Hippo and same result. Although closer again than mine was.

Its a reasonably detailed model to try to include the main factors but I didn't get into when the battery would not be fully discharged etc so assume to always charge a full charge even if real world its at say 40% and good solar the next day
Would need to do daily modelling really to include that level of variability. As it was I split each month into 3, and treated them as 50,100,150% of expected daily generation. Even tried with 20/100/180, still same result.

Flux is good for sure if you have batteries. But for now unless your a new exporter go seems to edge it.
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I've done some sums (very roughly), for me Flux will better than my current tariff as I don't have an EV and I think I will generate enough to make it worth my while over the year - and my battery is large enough (and if I get another it'll make it even more worthwhile).
 
Freefaller said:
I've done some sums (very roughly), for me Flux will better than my current tariff as I don't have an EV and I think I will generate enough to make it worth my while over the year - and my battery is large enough (and if I get another it'll make it even more worthwhile).
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i think its the export is where people like you and me will win....because its another 8p extra per kw

I mean i have exported 77kwhs this month at 15p...so circa £11.55
on flux it would be £17.71...so an extra 6 bucks in export
 
Welshman said:
i think its the export is where people like you and me will win....because its another 8p extra per kw

I mean i have exported 77kwhs this month at 15p...so circa £11.55
on flux it would be £17.71...so an extra 6 bucks in export
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I think even in winter topping up the batteries during the cheap rate would be pretty significant help for me.

Ultimately, I'm comparing it to not having solar - it's win:win for me. I don't REALLY need to move to flux, but the little benefits for me are useful - looking at my historical usage from now back till October, topping up the batteries during the evening on a cheaper rate would have netted me at least 50kWh of savings per month over the winter months which is not insignificant. I have enough panels that unless they're covered with snow, I generate enough to reduce my draw from the grid even on a gloomy day.

I've moved from spending £7 per day to some days paying just the standing charge or a max of £4-5 per day on really bad solar days. Had I been able to charge my batteries, that would lower to £3-4 per day. Yes the peak rate is higher, but with some careful management and accepting that some days I will take a hit at a higher rate, overall, for at least 8 months of the year I should be saving around £20 per month - which is really interesting.

In terms of export even in January considering we had awful weather I exported 35kWh to date in Feb I'm on 55kWh - less than you but I have batteries that are charged and a water diverter too.

If let's say I average 70kWh over the whole year (no idea how much I'll export in the summer) that will easily cancel out any high rate spend.

As @Mercenary Keyboard Warrior suggested it's sort of a balance and depending on your usage and export and storage, for those of us not on Go and likely to export even after batteries are charged, I think flux is probably more sensible for my large family home.
 
Welshman said:
nope......i cook on electric and in the months of march to november i cook outside.

I also work from home fulltime...so can have my evening meal anytime after 3pm when i finish and my partners is retired through ill health from the nhs
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How do you use so little electric to cook? Even if i'm using the oven for 40 minutes it'll still pull close to a kwh on it's own. Thats on a 3 year old Neff.

@Freefaller we know you're soft though :D
 
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SoliD said:
How do you use so little electric to cook? Even if i'm using the oven for 40 minutes it'll still pull close to a kwh on it's own. Thats on a 3 year old Neff.
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i use an induction hob....1.2kws per ring. If i cook ( a pasta meal ) as i did last night, it took 12mins to cook. thats a 1/5 of 1.2kws, so around 8p of electric ( if the ring is constantly pulling 1.2kws, but it doesnt as it pulses) so may use a little less.
 
Welshman said:
my garden is 25mtrs long by 18mtrs wide.......after the decking and its two tiered, so two completely flat sections, taking out the slope. March isnt winter lol....
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Winter lasts until 20th March - so yes March is Winter :p

Joking aside, it just seems a faff to me - though good on your for it :)

SoliD said:
How do you use so little electric to cook? Even if i'm using the oven for 40 minutes it'll still pull close to a kwh on it's own. Thats on a 3 year old Neff.

@Freefaller we know you're soft though :D
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Yes my wife says the same... I mean er...

We have a relatively efficient oven, as you say once it's on it draws a lot of power, but once up to temp it's actually not to bad.

The worse offender in our home is in one of our bathrooms we have a 10.5kw electric shower - I'm looking at replacing it completely as it's just not efficient and now we have a hotwater diverter it makes less sense.
 
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