solar&batteries - after some help\advice please

[nowty]

Hi there ,

Can that be true ?

Octopus Fixed tariff unit price per kWh.

27th January 2022 – 10.13p per kWh for a unit of gas and 37.29p per kWh for a unit of electricity.
21st January 2022 – 8.55p per kWh for a unit of gas and 34.63p per kWh for a unit of electricity.
15th December – 10.18p per kWh for a unit of gas and 37.08 per kWh for a unit of electricity.
9th December – 8.77p per kWh for a unit of gas and 33.65p per kWh for a unit of electricity.
2nd December – 8.11p per kWh for a unit gas and 31.23p per kWh for a unit of electricity.

https://www.octopusreferral.link/octopu ... y-tariffs/

Yes, because Octopus have to buy your energy up front (based on an average customer) a year in advance for a fixed tariff and that's how much it costs at the moment in the market, plus all the levies, etc.

Remember the OFGEM flexible rate capped values are effectively subsidised partly on a buy now pay later regime. That's why the capped prices are likely to stay high for some time after the market prices fall.

[billi]

Code: Select all

because Octopus have to buy your energy up front

ok thanks , so are they paying more than FIT export rates ? I hope so

[AE-NMidlands]

I'm thinking of installing some solar panels and batteries.
My house is E/W facing - however I could mount panels down the end of my garden (ground mount) which would be south facing (I have a large space to do this - non shadowed)
Mark

Me too! Remember that export prices are highest (or Agile pricing is most expensive) in the early evening, so a west-facing roof is ideal for maximising that harvest, or avoiding that import cost. I learnt from the solar thermal tubes that an east and a west-facing panel can be far more useful than worrying about not having one facing south.

I am at a similar stage on the pv journey... Of course I should have done it last year, but then there are other things which ought to be done first, like replacing the concrete roof tiles, which are nearing the end of their "design" life. And of course there is something else which needs doing before that roof gets replaced.
I have East, South and West facing roofs and am currently wondering whether to put up everything the roof will take and just accept it will be curtailed for a lot of the summer (but yield more in the winter and off-seasons when it will be most valuable.) I would particularly like to maximise what is on our west-facing roof, which is the biggest...

My solar thermal has a heat dump mechanism, I gather that if you have maximised your pv export, filled a battery and boiled your cylinder and have no other (electron) dump mechanism you can just let it stall if there is nowhere else to send it.
A

[ALAN/ALAN D]

I have had 20 tubes on the roof for many years. Took them down this week. Purley cause i am getting on a bit and had the odd leak from pumps / motorised valves through the plasterboard ceiling. Putting more panels where they used to be. With the P.V. You can use the Lecky for anything with no worries about it having a bad day. Tubes available if any one wants them.

[Ken]

Me too! Remember that export prices are highest (or Agile pricing is most expensive) in the early evening, so a west-facing roof is ideal for maximising that harvest, or avoiding that import cost. I learnt from the solar thermal tubes that an east and a west-facing panel can be far more useful than worrying about not having one facing south.

I am at a similar stage on the pv journey... Of course I should have done it last year, but then there are other things which ought to be done first, like replacing the concrete roof tiles, which are nearing the end of their "design" life. And of course there is something else which needs doing before that roof gets replaced.
I have East, South and West facing roofs and am currently wondering whether to put up everything the roof will take and just accept it will be curtailed for a lot of the summer (but yield more in the winter and off-seasons when it will be most valuable.) I would particularly like to maximise what is on our west-facing roof, which is the biggest...

My solar thermal has a heat dump mechanism, I gather that if you have maximised your pv export, filled a battery and boiled your cylinder and have no other (electron) dump mechanism you can just let it stall if there is nowhere else to send it.
A

Sorry i cannot agree with that.
The most valuable leccy is that produced in winter and in December and Jan the sun is very low and produces non outside the period 10.00 to 14.00. I would consider fiting south facing at a very steep angle or even vertical thus maximising Winter production and in effect reducing summer excess. One winter kwh is worth twice a summer kwh.

Also one has to consider charging EVs, HW and running HP.

When i fitted my PV 10yrs ago (south facing and 30deg) it produced annually roughly the same as my annual house usage which feels a sensible choice by accident. However times move on and i now have a EV (well actually 2 but i can only drive one at a time) and a HP and now out of choice i would be choosing one twice as big c10kwp. So think of the future.

[billi]

Well, , i experimented a bid , and came to my own situations conclusion that a split PV array , one S-E facing and other S-W facing (ground-mount) would suit the household habits best and as well for charging the battery , at an angle of about 60 degrees .... in the garden ground-mount

But , there cannot be a generalization , as all places have different conditions and habits
But i come from an off grid idea ....

I kind off agree , Ken

in December and Jan the sun is very low and produces non outside the period 10.00 to 14.00......One winter kwh is worth twice a summer kwh

on grid with battery and off grid seems to meet nowadays , but when the sun disappears so early from the panel in winter , then its worth while to think about battery size , and best harvest in the not so ideal PV times and a good performance in summer anyway , to avoid to much buying in, from the grid , and a bigger battery that can stretch the sunlight can avoid more el. import . (as far as i have now understod import from Octopus is costly , have to look into that more, as they are in Germany now too )

In this particular case , as it seems to be an ideal spot in the garden , i would mount them in an wide angled V withe the point of the V facing South in an angle of about 60 degrees, maybe two strings of 5-6 kW one via GTI , one via MPPT charge controller ... , but just thinking

[AE-NMidlands]

Me too! Remember that export prices are highest (or Agile pricing is most expensive) in the early evening, so a west-facing roof is ideal for maximising that harvest, or avoiding that import cost. I learnt from the solar thermal tubes that an east and a west-facing panel can be far more useful than worrying about not having one facing south.

I am at a similar stage on the pv journey... Of course I should have done it last year, but then there are other things which ought to be done first, like replacing the concrete roof tiles, which are nearing the end of their "design" life. And of course there is something else which needs doing before that roof gets replaced.
I have East, South and West facing roofs and am currently wondering whether to put up everything the roof will take and just accept it will be curtailed for a lot of the summer (but yield more in the winter and off-seasons when it will be most valuable.) I would particularly like to maximise what is on our west-facing roof, which is the biggest...

My solar thermal has a heat dump mechanism, I gather that if you have maximised your pv export, filled a battery and boiled your cylinder and have no other (electron) dump mechanism you can just let it stall if there is nowhere else to send it.
A

Sorry i cannot agree with that.
The most valuable leccy is that produced in winter and in December and Jan the sun is very low and produces non outside the period 10.00 to 14.00. I would consider fiting south facing at a very steep angle or even vertical thus maximising Winter production and in effect reducing summer excess. One winter kwh is worth twice a summer kwh.
Also one has to consider charging EVs, HW and running HP.

When i fitted my PV 10yrs ago (south facing and 30deg) it produced annually roughly the same as my annual house usage which feels a sensible choice by accident. However times move on and i now have a EV (well actually 2 but i can only drive one at a time) and a HP and now out of choice i would be choosing one twice as big c10kwp. So think of the future.

I don't really see which bit you disagree with, Ken.
I can see some people here putting panels wherever they can see the sun... surely there must be export/storage limits, and the more there are, the sooner it must be curtailed in early summer?
I take your point about maximising winter production though: if the neighbouring house didn't shade ours in mid-winter the south-facing wall would be a great idea, and the top half of it (with only a small bathroom window) might still be a goer. The sun reaches our ground floor windows over their roof again at the start of February, I haven't thought to look at the top half in mid-winter though. That might be the ideal place to relocate our thermal tubes to, making space for more pv on the roof It would cut the risk of summer overload too..
One potential complication we do have is that the other half of our semi get their electricity via the cable which goes on after feeding our fuse. (In that way it mirrors the water, which used to come to us after passing their stopcock on the party wall. We have our own water supply now, but I guess I can't force them to get their own electricity feed...)
I can't see energy ever being much cheaper again, so calculations of cost-effectiveness can only ever under-estimate the benefits - as long as you can export it.
(I have looked for a solar energy calculator which lets you put in aspect, angle and size but they don't seem to work that way.)
A

[Stan]

I use PVGIS a lot to play with geographical position, panel slope, azimuth and total power of array.

[AE-NMidlands]

I use PVGIS a lot to play with geographical position, panel slope, azimuth and total power of array.

That's good, thanks.

[billi]

I have East, South and West facing roofs and am currently wondering whether to put up everything the roof will take and just accept it will be curtailed for a lot of the summer

AE-NMidlands , go for it .

Makes sense to , while the scaffolding , or teleport-er or whatever help for getting on to the roof , is there .
But , but ,but think about shading , string length , and the resulting consequence of how to wire each panel and how to bring those wiring into the house to the battery and Inverter

Billi