Solar & Powerwall 2

Embattle

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So here are the totals for the last week, a week with a good deal of sunshine:

Home Usage - 128 kWh (46.4% From Solar, 48.6% From Powerwall, 5% From Grid)
Solar - 136 kWh (43.6% To Home, 51.2% To Powerwall, 5.2% To Grid)
Powerwall - From 62.5
Grid: From 6.5 kWh - To 7.3 kWh

Self-powered - 95% (46% Solar, 49% Powerwall)
 

Scouse

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Like it @Embattle - but for me it only makes sense if you include your gas spend too. Total energy cost is where it's at.
 

Embattle

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Average since we moved here is 1053 kWh of Gas per month, on our current provider that works out at an average of £51.40 per month but I intend to change provider soon.
 

Embattle

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So with this April being one of the sunniest on records the numbers are looking good:

Solar Total = 578 kWh
Solar Highest Day = 26.9 kWh (April 15th)
Home Usage = 577 kWh (Sources = Solar 47.7% - Powerwall 40.4% - Grid 11.9%)
Performance = 88% Self-Powered
Energy to Grid = 37.2 kWh (Free)
 

Embattle

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So a update:

1. Well our system just passed its previous record set yesterday for Solar of 29.2 kWh with a nice 31.4 kWh today, there was a small dip for about 20 minutes so excluding that it might be possible for our system to hit 34/35 kWh on the longer summer days.
2. Due to the preceding days figure the battery was at 100% again by early afternoon, this resulted in 10.2 kWh going to the grid.

Energy Supplier Change

We are currently with British Gas but we've initiated a change to Octopus Energy due to some of the following factors, firstly energy prices are considerably more with British Gas compared to Octopus Energy even taking into a newer British Gas tariff. I'll list some Gas figures below followed by electricity as well as the standing charges:

Gas / Standing Charge
  • Current British Gas - 4.274p per kWh / 22.137p per Day
  • Octopus Energy - 2.36p per kWh / 17.85p per Day
  • Newer British Gas - 3.503p per kWh / 24.874p per Day

Electricity / Standing Charge

  • Current British Gas - 18.953p per kWh / 19.643p per Day
  • Octopus Energy - 14.47p per kWh / 21.78p per Day
  • Newer British Gas - 18.213p per kWh / 22.380p per Day

The figures add up quite rapidly when you for example use over 13,000 kWh of gas and 4000 kWh of electricity in a year, in fact so much so that using similar usage figures we will save nearly £400 with Octopus over our current British Gas tariff. Also as a quick side note there are no exit fees with Octopus Energy compared to £30 for each for the Gas and Electricity tariffs.

Smart Meters

One strange thing about this new build house is for whatever reason only the electricity meter had the required smart meter transmitter on it, thus with our British Gas smart meter we could only send automatic figures for the electricity although recently this stopped as well.

Once up and running with Octopus our intention is to get a smart meter installed by them asap covornavirus willing, this opens up the possibility of two other tariffs.

Octopusgo

This tariff gives you a low electricity rate for 4 hours at night (00:30-04:30) which is charged at 5p per kWh, this is an advantage for people with electric cars and also people with battery systems. In essence using the Tesla software I can get it to download a full battery worth of energy during this period and then use that power the next day, this naturally isn't much good during the sunnier months but it should add additional savings during the winter. As an example here are some numbers of December 2019:

  • House Usage - 552 kWh
  • From Grid - 492 kWh
  • Solar - 81.1 kWh
  • Battery - 8.2 kWh

Solar is naturally so low during December that it only produced any excess for the battery to hold on 5 days of the 31 days which is where the 8.2 kWh on the battery came from but considering the battery can hold 13.5 kWh and a little over 12 kWh usable which is 372+ kWh for the month of December that isn't a great use of the battery. So some rough number work based on the idea of downloading the 12 kWh in those 4 hours each night:

  • Octopus Stardard Rate - 12 kWh x 14.47p per kWh = £1.73 x 31 = £53.63
  • Octopus Night Rate - 12 kWh x 5p per kWh = £0.6 x 31 = £18.60
So there is a saving of around £35.03 in using 12 kWh of the night download rate every night in December alone. The daily standing charge does increase a few pence compared to the standard Octopus tariff.

outgoingOctopus

This is an additional tariff that you can get with nearly any other tariff and it'll pay you 5p per kWh you export to the grid under Smart Export Guarantee (SEG), there is one exclusion currently from the other tariffs and that happens to be the Octopusgo tariff. I've done some rough numbers and bearing in mind our general usage along with having a battery this doesn't work out worth using since we can save more using Octopusgo:

  • Total output to grid so far (October 2019 - 12th May 2019) - 83.7 kWh
  • 83 kWh x 5p per kWh = £4.15

As you can see it doesn't make enough in our case to forgo using Octopusgo, even if you consider the sunnier months are still ahead to cover the savings in December alone using Octopusgo we would need to export over 700 kWh. Hopefully eventually they'll manage to get both working together.

 

Moriath

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So a update:

1. Well our system just passed its previous record set yesterday for Solar of 29.2 kWh with a nice 31.4 kWh today, there was a small dip for about 20 minutes so excluding that it might be possible for our system to hit 34/35 kWh on the longer summer days.
2. Due to the preceding days figure the battery was at 100% again by early afternoon, this resulted in 10.2 kWh going to the grid.

Energy Supplier Change

We are currently with British Gas but we've initiated a change to Octopus Energy due to some of the following factors, firstly energy prices are considerably more with British Gas compared to Octopus Energy even taking into a newer British Gas tariff. I'll list some Gas figures below followed by electricity as well as the standing charges:

Gas / Standing Charge
  • Current British Gas - 4.274p per kWh / 22.137p per Day
  • Octopus Energy - 2.36p per kWh / 17.85p per Day
  • Newer British Gas - 3.503p per kWh / 24.874p per Day

Electricity / Standing Charge

  • Current British Gas - 18.953p per kWh / 19.643p per Day
  • Octopus Energy - 14.47p per kWh / 21.78p per Day
  • Newer British Gas - 18.213p per kWh / 22.380p per Day

The figures add up quite rapidly when you for example use over 13,000 kWh of gas and 4000 kWh of electricity in a year, in fact so much so that using similar usage figures we will save nearly £400 with Octopus over our current British Gas tariff. Also as a quick side note there are no exit fees with Octopus Energy compared to £30 for each for the Gas and Electricity tariffs.

Smart Meters

One strange thing about this new build house is for whatever reason only the electricity meter had the required smart meter transmitter on it, thus with our British Gas smart meter we could only send automatic figures for the electricity although recently this stopped as well.

Once up and running with Octopus our intention is to get a smart meter installed by them asap covornavirus willing, this opens up the possibility of two other tariffs.

Octopusgo

This tariff gives you a low electricity rate for 4 hours at night (00:30-04:30) which is charged at 5p per kWh, this is an advantage for people with electric cars and also people with battery systems. In essence using the Tesla software I can get it to download a full battery worth of energy during this period and then use that power the next day, this naturally isn't much good during the sunnier months but it should add additional savings during the winter. As an example here are some numbers of December 2019:

  • House Usage - 552 kWh
  • From Grid - 492 kWh
  • Solar - 81.1 kWh
  • Battery - 8.2 kWh

Solar is naturally so low during December that it only produced any excess for the battery to hold on 5 days of the 31 days which is where the 8.2 kWh on the battery came from but considering the battery can hold 13.5 kWh and a little over 12 kWh usable which is 372+ kWh for the month of December that isn't a great use of the battery. So some rough number work based on the idea of downloading the 12 kWh in those 4 hours each night:

  • Octopus Stardard Rate - 12 kWh x 14.47p per kWh = £1.73 x 31 = £53.63
  • Octopus Night Rate - 12 kWh x 5p per kWh = £0.6 x 31 = £18.60
So there is a saving of around £35.03 in using 12 kWh of the night download rate every night in December alone. The daily standing charge does increase a few pence compared to the standard Octopus tariff.

outgoingOctopus

This is an additional tariff that you can get with nearly any other tariff and it'll pay you 5p per kWh you export to the grid under Smart Export Guarantee (SEG), there is one exclusion currently from the other tariffs and that happens to be the Octopusgo tariff. I've done some rough numbers and bearing in mind our general usage along with having a battery this doesn't work out worth using since we can save more using Octopusgo:

  • Total output to grid so far (October 2019 - 12th May 2019) - 83.7 kWh
  • 83 kWh x 5p per kWh = £4.15

As you can see it doesn't make enough in our case to forgo using Octopusgo, even if you consider the sunnier months are still ahead to cover the savings in December alone using Octopusgo we would need to export over 700 kWh. Hopefully eventually they'll manage to get both working together.
I thought everyone knew british gas was a rip for energy... even against the other big boys
 

Embattle

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So May 2020 is in the record books (May was sunniest UK month on record) lets have a look at the solar numbers for the sunny month of May:

Power Flow

Home Usage - 584 kWh
Solar Energy - 772 kWh (Energy Destinations - Home 42.1% - Powerwall 36.2% - Grid 21.7%)
From Powerwall - 242 kWh
From Grid - 17.6 kWh
To Grid - 167 kWh

Performance

97% Self Powered (Solar 56% & Powerwall 41%)

So using fag packet calculations if we didn't have the Powerwall another 242+ kWh would of gone to the grid for a total of 409 kWh, so if we take it that you can get 5.5p per kWh that would of bought in a total of around £22 however that 242+ kWh would be replaced by grid power at 14.47p so it would of been around £35.

Couple of Points

  • If you didn't have a battery you could optimise your usage to make better use of the solar power when it is avaliable.
  • There is a streak of bird shit on one of the panels and no rain to wash it off.
 

Embattle

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So in a couple more hours the Solar & Tesla Powerwall 2 setup will of been running for just under a year, lets look at the figures for this period:

Power Flow

Home Usage = 7344 kWh
Solar Energy = 4299 kWh
From Powerwall = 1445 kWh
From Grid = 3663 kWh
To Grid = 321 kWh

Performance

Self-powered = 50% (31% Solar - 19% Powerwall)
Solar Offset = 59% Energy Offset

Highest Monthly Figures

Home Usage = Aug 2020 (761 kWh)
Solar Energy = May 2020 (773 kWh)
From Powerwall = May 2020 (242 kWh)
From Grid = Dec 2019 (557 kWh)
To Grid = May 2020 (167 kWh)
Self-powered = May 2020 97% (Solar 56% - Powerwall 41%)
Solar Offset = May 2020 (132% Energy Offset)
 

Raven

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Ah OK.

This is my dilemma. You're using 'leccy for a lot of things, but I'd have to heat water and the house with a pure electric source. With the age of this place and the limitations for insulation it might simply be unrealistic for me to go down that route. :\
You would be surprised how cosy you can get old buildings. Ours is 400 years old and is very cheap to heat in the winter. The walls are thick, half a metre in places and we got the roof insulated. Most of the cold in old buildings is through the windows and doors. We couldn't change the external appearance of our house without a huge amount of red tape so I have done a lot of work draught proofing windows and doors, even internal doors are all draft proof.

Also, the way our house is designed is that the fireplace in the living room also heats the main bedroom, the chimney is internal and runs up the wall at the head of the bed so if you get a good fire going downstairs then part of the bedroom wall heats up.
 

Embattle

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How come august was the biggest usage then? Or is it just the amount you used from generated?
No idea, just imagine there was more cooker, dryer, etc usage for some reason Solar covered about 484 kWh of it but the rest 308 kWh was from the grid.
 

Scouse

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No idea, just imagine there was more cooker, dryer, etc usage for some reason Solar covered about 484 kWh of it but the rest 308 kWh was from the grid.
August was shit weather for most of it up here. But not cold ,:/
 

Embattle

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So here are the numbers for 2020:

Power Flow

Total Home Usage - 7355 kWh (Sources - Solar 31.4% - Powerwall 19.5% - Grid 49.1%)

Solar by Month

Jan - 81.1 kWh
Feb - 144 kWh
Mar - 373 kWh
Apr - 578 kWh
May - 773 kWh
Jun - 560 kWh
Jul - 590 kWh
Aug - 484 kWh
Sep - 369 kWh
Oct - 182 kWh
Nov - 114 kWh
Dec - 31 kWh (Predict maybe 50 kWh by end of month)

Total Solar Produced - 4283 kWh (Energy Destinations - Home 54% - Powerwall 38.7% - To Grid 7.4%)

From Powerwall - 1442 kWh
From Grid - 3670 kWh
To Grid - 322 kWh

Performance 2020

Self Powered - 31% Solar 19% Powerwall
Solar Offset - 7355 kWh Home - 4283 kWh Solar = 58% Energy Offset

Issues

No issues on the products but due to covid we still don't have a Smart meter, this would enable us to use cheap over night rates to fill the Powerwall and take more advantage of the Powerwall during the winter months, instead I just have it setup to keep 70% power in case of power cuts during winter months.

Payback

So if I exclude the Powerwall then the Solar going directly to the house would of been around 2309 kWh and basing it on about 0.17p a kWh that works out around £392 a year saving, you could probably do better with timing of high energy usage devices during peak solar times during summer. If we had a smart meter we could of possibly signed up to getting paid for every kWh we exported and that would be roughly 1764 kWh @ 0.05p per unit resulting in getting paid just over £88. So overall the saving and export means a saving of £480 a year bearing in mind the Solar alone with installation was £5500.

Developments


 

Embattle

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Attached a break down of the year and monthly data, can go to each day with every 15 minutes but that is a lot of work :p
 

Attachments

Scouse

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Hmmmm.

*strokes beard*

:)
 

Embattle

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Hmmmm.

*strokes beard*

:)
I suspect depending on a persons home you can reduce the costs a little further depending on setup, we've got 16 panels rated at 315w each with 8/8 split East and West for a combined total of 5.04 kWp. As stated earlier due to the split panels on our house and the inventor the generation will never go over the DNO limit of 3.68 kW thus if you had a south facing house or stuck all the panels on one side of the house you could do that with 12 panels rated at 315w.
 

Embattle

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Finally the first few days with some quality sun, already beaten last February solar energy generation with one day left.
 

Embattle

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Tesla Trouble

So for over a month now, since 24/02/2021, our Tesla Powerwall system has been detecting what could be best described as false power outages. In essence it kept clicking over to the backup supply even when there was seemingly no issue, in fact from the 24/02 to 30/03 it had 287 backup events with up to 35 in one day alone.

So to troubleshoot this I contacted Western Power Distribution who checked everything up to the meter, all was fine so I then ran a 46 hour test where the Tesla and Solar was turned off. The outcome showed at no time did we lose power or have any light flicker when we were on only the mains thus something was either wrong on the Tesla or the wiring. We contacted the installer who contacted Tesla and after a week it seems to of stopped doing it, in essence no false power outages for the last 3 days so I wait to hear back and hope to find out what the issue was with the system.

More Juice

The last 3 days have all returned above 20 kWh solar generation and yesterday was the first day of the calendar year where the house achieved a performance figure of 99% self-powered, this will be repeated today as well.
 

Moriath

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So hw much will that system cost today? And what savings did you make over the first year?
 

Embattle

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@Moriath This is for the last calendar year:

So here are the numbers for 2020:

Power Flow

Total Home Usage - 7355 kWh (Sources - Solar 31.4% - Powerwall 19.5% - Grid 49.1%)

Solar by Month

Jan - 81.1 kWh
Feb - 144 kWh
Mar - 373 kWh
Apr - 578 kWh
May - 773 kWh
Jun - 560 kWh
Jul - 590 kWh
Aug - 484 kWh
Sep - 369 kWh
Oct - 182 kWh
Nov - 114 kWh
Dec - 31 kWh (Predict maybe 50 kWh by end of month)

Total Solar Produced - 4283 kWh (Energy Destinations - Home 54% - Powerwall 38.7% - To Grid 7.4%)

From Powerwall - 1442 kWh
From Grid - 3670 kWh
To Grid - 322 kWh

Performance 2020

Self Powered - 31% Solar 19% Powerwall
Solar Offset - 7355 kWh Home - 4283 kWh Solar = 58% Energy Offset

Issues

No issues on the products but due to covid we still don't have a Smart meter, this would enable us to use cheap over night rates to fill the Powerwall and take more advantage of the Powerwall during the winter months, instead I just have it setup to keep 70% power in case of power cuts during winter months.

Payback

So if I exclude the Powerwall then the Solar going directly to the house would of been around 2309 kWh and basing it on about 0.17p a kWh that works out around £392 a year saving, you could probably do better with timing of high energy usage devices during peak solar times during summer. If we had a smart meter we could of possibly signed up to getting paid for every kWh we exported and that would be roughly 1764 kWh @ 0.05p per unit resulting in getting paid just over £88. So overall the saving and export means a saving of £480 a year bearing in mind the Solar alone with installation was £5500.

Developments

 

Embattle

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But what was the total cost with the batteries and all
I went through that in one of my previous posts with the solar side costing £5500 and the battery side was £8000, ultimately even with some changes in the future such as getting a smart meter so I can fill it up at night with cheaper electricity it'll probably never recoup its costs. In my opinion and using the figures it has produced the Solar side will cover its costs in 12 years, perhaps 13 when you factor in that the inverter will last 10 years so will need replacing.
 

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