Deleted

zeupater

Hi

<cough>

"In which case, total running cost in 24hrs =  267 wh + (24 * 6.2w) = 415.8kwh" ... ?

Would that rather be 0.4158kWh ... or ... 415.8Wh ?? ... ~400kWh is around our average imported electricity over 4 months .... 

HTH - Z

zeupater

Martyn1981 said:

70sbudgie said:

This post has been highly addictive. 😂

It has also prompted me to have a look at my blank south facing wall to see whether the winter shading (from next door) is too much to make it worthwhile installing vertical panels for increased winter generation. I will also be visiting PVGIS to see how my location impacts.

My idea will suffer a lot of shading, but still viable I believe. Crucially I'm chasing winter generation, so the poor performance in the summer doesn't concern me, so that may be the trade off you need to consider.

At the bottom (ESE) end of our garden is a large and ancient Magnolia, so it will shade ground mounted PV to its SE, and at the upper end of the graden is the house (of course), shading the SW, so I need to pick a sweet spot along the northern fence. Originally I was planning a 3 panel south facing ground mount, probably 70d, specifically to target winter sun in the SE to SW which should be unshaded.

3 panels to avoid planning permission which is required if you exceed 9m2, but also no more than 3m on any one side. I even have some tower scaffolding for the face, and a SB1700 inverter, all donated by a lovely bod from another forum. However, I've now been seduced by the thought of doubling my winter gen, requiring ~2kWp of PV, so 4 or 5 panels of the oversized (2m(ish)) variety. So now plan a wooden frame, which I'll panel off to the lower front and sides, making it a ladder store, on which PV can be mounted without PP.

I mention all of this to point out that it's far from ideal on an annual basis, which is of course a valid concern when first considering PV, but this would be aimed solely as a top up measure for poor generation periods. And not just the winter, but also a boost during low gen in the shoulder months, such as cloudy weather, when I need about 1kW of PV generation, to allow the use of the a 3.5kW heat pump (roughly 700W draw) for 'free'.

And lastly, to give all the lucky 'southers' a giggle, in the worst 2 or 3 months, my gen actually dips during mid day - the ESE sees a bit of sun in the morning, and the WNW a bit later on, but mid day when the sun is really low in the south, it can't hit the E/W panels, so actually drops from poor to carp generation. It's a hard life! 



Ohhh, lastly (again) all of this is due to the fact that PV panels themselves are now so cheap, so that part of the ponderings is of less/little concern. My troubles are instead one of a DNO nature as I'm at max, and hinge on getting a zero export home battery approved by the DNO. Whilst this would be an AC side battery, I'm looking at ones with hybrid inverters and an additional DC PV feed. So the PV would piggyback off the battery certification, with no direct mains connection with the battery managing everything, and when the battery is full, the inverter/charge controller would simply shut down the DC side PV.

Returning to the thread purpose, is this cost effective, I think so, but only based on getting a battery anyway. Will the additional PV be best placed - not if maximising generation, but yes if maximising my needs, as summer gen is already more than enough, even with BEV's.

Hi

On a similar theme, some years ago I modelled the winter shading effect of a line of large conifers in the front garden as they grew larger ... pretty simple to get an idea using the PVGIS horizon modelling, although the granularity isn't really designed for tall thin objects it's proved to be pretty accurate so far - mind though, I've recently been eyeing the thermal energy stored in them and weighing it against the effort involved in conversion ...

Regarding the battery/inverter setup you mention, I'd guess you'd be looking at a Victron unit to provide the flexibility regarding future connectivity, integrating with the current setup & providing failover on mains interruption ? ... if it's not been a consideration yet, it's probably worth having a delve ...

Z

    

Martyn1981

zeupater said:

Martyn1981 said:

70sbudgie said:

This post has been highly addictive. 😂

It has also prompted me to have a look at my blank south facing wall to see whether the winter shading (from next door) is too much to make it worthwhile installing vertical panels for increased winter generation. I will also be visiting PVGIS to see how my location impacts.

My idea will suffer a lot of shading, but still viable I believe. Crucially I'm chasing winter generation, so the poor performance in the summer doesn't concern me, so that may be the trade off you need to consider.

At the bottom (ESE) end of our garden is a large and ancient Magnolia, so it will shade ground mounted PV to its SE, and at the upper end of the graden is the house (of course), shading the SW, so I need to pick a sweet spot along the northern fence. Originally I was planning a 3 panel south facing ground mount, probably 70d, specifically to target winter sun in the SE to SW which should be unshaded.

3 panels to avoid planning permission which is required if you exceed 9m2, but also no more than 3m on any one side. I even have some tower scaffolding for the face, and a SB1700 inverter, all donated by a lovely bod from another forum. However, I've now been seduced by the thought of doubling my winter gen, requiring ~2kWp of PV, so 4 or 5 panels of the oversized (2m(ish)) variety. So now plan a wooden frame, which I'll panel off to the lower front and sides, making it a ladder store, on which PV can be mounted without PP.

I mention all of this to point out that it's far from ideal on an annual basis, which is of course a valid concern when first considering PV, but this would be aimed solely as a top up measure for poor generation periods. And not just the winter, but also a boost during low gen in the shoulder months, such as cloudy weather, when I need about 1kW of PV generation, to allow the use of the a 3.5kW heat pump (roughly 700W draw) for 'free'.

And lastly, to give all the lucky 'southers' a giggle, in the worst 2 or 3 months, my gen actually dips during mid day - the ESE sees a bit of sun in the morning, and the WNW a bit later on, but mid day when the sun is really low in the south, it can't hit the E/W panels, so actually drops from poor to carp generation. It's a hard life! 



Ohhh, lastly (again) all of this is due to the fact that PV panels themselves are now so cheap, so that part of the ponderings is of less/little concern. My troubles are instead one of a DNO nature as I'm at max, and hinge on getting a zero export home battery approved by the DNO. Whilst this would be an AC side battery, I'm looking at ones with hybrid inverters and an additional DC PV feed. So the PV would piggyback off the battery certification, with no direct mains connection with the battery managing everything, and when the battery is full, the inverter/charge controller would simply shut down the DC side PV.

Returning to the thread purpose, is this cost effective, I think so, but only based on getting a battery anyway. Will the additional PV be best placed - not if maximising generation, but yes if maximising my needs, as summer gen is already more than enough, even with BEV's.

Hi

On a similar theme, some years ago I modelled the winter shading effect of a line of large conifers in the front garden as they grew larger ... pretty simple to get an idea using the PVGIS horizon modelling, although the granularity isn't really designed for tall thin objects it's proved to be pretty accurate so far - mind though, I've recently been eyeing the thermal energy stored in them and weighing it against the effort involved in conversion ...

Regarding the battery/inverter setup you mention, I'd guess you'd be looking at a Victron unit to provide the flexibility regarding future connectivity, integrating with the current setup & providing failover on mains interruption ? ... if it's not been a consideration yet, it's probably worth having a delve ...

Z

    

Yep, I have looked at the Victron kit on and off over the years, but recently had an e-mail chat with Givenergy, following thoughts and figures with some others (elsewhere).

I'm not worrying about powercuts, maybe I should, but for now, just thinking about their AC side kit, which now uses a hybrid inverter. So I asked them if they are certified by the DNO's for a zero export application to get their kit installed, and they are. Then the crucial follow up question (and discussions with others) - does anything change if the DC input is used also / at a later date.

Hopefully I'm not doing anything naughty, nor even trying to be clever, it's just that the battery/inverter if certified as zero export compliant, effectively acts as a blocker against any PV export. So the additional PV is not a concern for the DNO, as it can't add to export, it's all handled behind the Givenergy kit approval. [Other makes are I'm sure available.]

I'm having to look for a convuluted route as the DNO expressed concern regarding my 5.9kW export permission I was granted in 2012, when I asked for V2G permission in 2020. They say I shouldn't have been given it, but they are not minded to review the permission. Hence I need to tread very carefully when considering my next step, as rocking the boat isn't ideal. I'm hoping a zero export battery application won't trigger a removal of my current permission. In fact a battery would reduce my actual export, but they have to work to extreme and hypotheticals, unfortunately.

Martyn1981

Also Z, it was interesting you mentioned Bluetti a while back, as another thought I've had is a totally separate system, like their's, with PV and a battery stack. That sounds really messy and I'd then have to plug something into it, and it wouldn't be backing up the existing PV I have. However, with the BEV's, I could use it as a dedicated store that is discharged to them each day, or so, but ..... let's be honest ...... that's a really messy and somewhat desperate solution, but it did cross my mind.

There are a few products like Bluetti that look ideal for off-grid solutions, like sheds etc, where you connect up PV, batts, lights, and can plug in AC devices too. But I'm not sure it's a sensible, and certainly not an economic choice for me.

zeupater

Martyn1981 said:

zeupater said:

Martyn1981 said:

70sbudgie said:

This post has been highly addictive. 😂

It has also prompted me to have a look at my blank south facing wall to see whether the winter shading (from next door) is too much to make it worthwhile installing vertical panels for increased winter generation. I will also be visiting PVGIS to see how my location impacts.

My idea will suffer a lot of shading, but still viable I believe. Crucially I'm chasing winter generation, so the poor performance in the summer doesn't concern me, so that may be the trade off you need to consider.

At the bottom (ESE) end of our garden is a large and ancient Magnolia, so it will shade ground mounted PV to its SE, and at the upper end of the graden is the house (of course), shading the SW, so I need to pick a sweet spot along the northern fence. Originally I was planning a 3 panel south facing ground mount, probably 70d, specifically to target winter sun in the SE to SW which should be unshaded.

3 panels to avoid planning permission which is required if you exceed 9m2, but also no more than 3m on any one side. I even have some tower scaffolding for the face, and a SB1700 inverter, all donated by a lovely bod from another forum. However, I've now been seduced by the thought of doubling my winter gen, requiring ~2kWp of PV, so 4 or 5 panels of the oversized (2m(ish)) variety. So now plan a wooden frame, which I'll panel off to the lower front and sides, making it a ladder store, on which PV can be mounted without PP.

I mention all of this to point out that it's far from ideal on an annual basis, which is of course a valid concern when first considering PV, but this would be aimed solely as a top up measure for poor generation periods. And not just the winter, but also a boost during low gen in the shoulder months, such as cloudy weather, when I need about 1kW of PV generation, to allow the use of the a 3.5kW heat pump (roughly 700W draw) for 'free'.

And lastly, to give all the lucky 'southers' a giggle, in the worst 2 or 3 months, my gen actually dips during mid day - the ESE sees a bit of sun in the morning, and the WNW a bit later on, but mid day when the sun is really low in the south, it can't hit the E/W panels, so actually drops from poor to carp generation. It's a hard life! 



Ohhh, lastly (again) all of this is due to the fact that PV panels themselves are now so cheap, so that part of the ponderings is of less/little concern. My troubles are instead one of a DNO nature as I'm at max, and hinge on getting a zero export home battery approved by the DNO. Whilst this would be an AC side battery, I'm looking at ones with hybrid inverters and an additional DC PV feed. So the PV would piggyback off the battery certification, with no direct mains connection with the battery managing everything, and when the battery is full, the inverter/charge controller would simply shut down the DC side PV.

Returning to the thread purpose, is this cost effective, I think so, but only based on getting a battery anyway. Will the additional PV be best placed - not if maximising generation, but yes if maximising my needs, as summer gen is already more than enough, even with BEV's.

Hi

On a similar theme, some years ago I modelled the winter shading effect of a line of large conifers in the front garden as they grew larger ... pretty simple to get an idea using the PVGIS horizon modelling, although the granularity isn't really designed for tall thin objects it's proved to be pretty accurate so far - mind though, I've recently been eyeing the thermal energy stored in them and weighing it against the effort involved in conversion ...

Regarding the battery/inverter setup you mention, I'd guess you'd be looking at a Victron unit to provide the flexibility regarding future connectivity, integrating with the current setup & providing failover on mains interruption ? ... if it's not been a consideration yet, it's probably worth having a delve ...

Z

    

Yep, I have looked at the Victron kit on and off over the years, but recently had an e-mail chat with Givenergy, following thoughts and figures with some others (elsewhere).

I'm not worrying about powercuts, maybe I should, but for now, just thinking about their AC side kit, which now uses a hybrid inverter. So I asked them if they are certified by the DNO's for a zero export application to get their kit installed, and they are. Then the crucial follow up question (and discussions with others) - does anything change if the DC input is used also / at a later date.

Hopefully I'm not doing anything naughty, nor even trying to be clever, it's just that the battery/inverter if certified as zero export compliant, effectively acts as a blocker against any PV export. So the additional PV is not a concern for the DNO, as it can't add to export, it's all handled behind the Givenergy kit approval. [Other makes are I'm sure available.]

I'm having to look for a convuluted route as the DNO expressed concern regarding my 5.9kW export permission I was granted in 2012, when I asked for V2G permission in 2020. They say I shouldn't have been given it, but they are not minded to review the permission. Hence I need to tread very carefully when considering my next step, as rocking the boat isn't ideal. I'm hoping a zero export battery application won't trigger a removal of my current permission. In fact a battery would reduce my actual export, but they have to work to extreme and hypotheticals, unfortunately.

Hi

Similar thought to mine then ... I looked at the possibility of putting our current grid connect PV setup & most domestic loads behind an export denied Victron inverter on a pass through setup so that it would effectively island the PV generation in case of power outages thus continuing to charge a Victron connected battery bank ... at the time it seemed an elegant solution to future proofing battery technology & brand independence whilst leveraging the value of existing kit ... as it is, it's on the 'back-burner' with many other things ...

HTH - Z   

Solarchaser

Assuming your batteries are 12v, could you not just connect the fridge straight to the battery, that saves any inverter losses

zeupater

Solarchaser said:

Assuming your batteries are 12v, could you not just connect the fridge straight to the battery, that saves any inverter losses

Hi

I think that was the OPs plan ... the Bluetti units have pretty good connectivity, including a 12V car port socket.

We have a 12V cooling/warming box (about the size of a worktop fridge) which has been useful on picnics, parties etc & I'm sure we've slow cooked fish in it once ... anyway, it plugs into the normal car port socket, but it's also been run from a 12V carport based solar setup down the garden that we've had far longer than the main PV ... still worked last time I checked, but thinking about it, I should really plug it in & find out!

HTH - Z

70sbudgie

There's something been bothering me about the summated efficiency calculations. I can't decide if it is me that has missed something.

If the solar panels generate 100whrs and DC charge batteries with a round trip efficiency of 95%, and then output through an inverter with 88% efficiency and through cables with 3% losses (97% efficiency) isn't the output 81.1whrs?

100 x 0.95 = 95
95 x 0.88 = 83.6
83.6 x 0.97 = 81.09

So the total efficiency of the system is 81%. I don't know if that 1% really makes enough difference, just the maths was bothering me.

70sbudgie

Oh, and the issue with using peak sunshine hours is because as well as there being fewer hours of sunshine in winter, at a lower angle, there are fewer photons (they have more atmosphere to travel through, I think). Which is why newer calculations use irradiance, which takes into account how energetic the sunshine is at different times of the year.

PS. I don't really understand irradiance, but it is why Blackpool really is more sunny! If you don't believe me, check out how many solar farms there are on the west coast.

chris_n

'Also, how do you know how efficient your panels are? Is this published data? What figure should I be looking out for? My panels are Renogy'
From the specifications tab
Module efficiency, 19.2% on the 200W panel 
Module efficiency, 19.8% on the 175W panel
Cell efficiency, 22% on the 100W panel.