Solar & Powerwall 2

[Embattle]

Well instead of overloading the Nerdy thread with more Solar stuff I thought a separate thread would be a bit better, so below is the previous information with some minor changes:

Parts Information

Solar Panels - 16x Q Cells 315 Q Peak Duo All Black Module
Inverter - SolaX X1 Boost 3.6T Inverter
Battery - Tesla Powerwall 2
Assorted mounts, electrical, etc parts

Cost

The solar panels, inverter, installation, etc. is about £5,500 and the battery, backup gateway, installation, etc will be nearly £8,000. Any additional power over the battery/usage will naturally feed back into the grid eventually under the SEG next year, although I'm not expecting much even during summer highs. The solar panels will make a saving over their lifetime but the battery is a bit of an unknown which the rep was honest about, a way that was suggested to use the battery better is you would use a Economy 7 tariff and during winter you get the battery to fill from the grid at night.

Survey (Sungift Energy)

Our house is East/West and after he did his survey it worked out best to have 8 panels on the East side and then 8 on the West side of the roof, I guess this also means the Inverter can be a little lower at 3.6Kw. The surveyor also stated that we really didn't need the most expensive panels as we weren't short on roof space, if we had been then it might be worth paying the considerable additional cost to get the higher efficiency.

Installation (Sungift Energy)

So install day (25-09-2019) is here and there are 4-5 guys doing the work, after a walk around there are some changes to the original plan.

The Tesla Powerwall was going to be installed on an outside wall but after some discussion the installer stated it wouldn't be a good location. The unit can go outside but the location was going to be exposed to full sun for most of the day, so the unit is now going to come inside the study against the wall with the gateway going to the left of it.

So with day 2 complete the equipment is all in place as is the cabling, it all worked initially but during the power loss test something went wrong.

In essence it looks like there was a mix up in two of the neutral cable numbers and during this test it seems to of damaged the Tesla Gateway thus leaving it utterly dead. So until the replacement Gateway arrives the Powerwall is unusable, so for the moment we have a working PV system and mains power.

They sent a engineer with a new Tesla Gateway today, so after 3 hours or so we now have a fully operational system.



It is a bit of a shame that you get some sleek looking Tesla units that are surrounded by ubiquitous trunking

Also I find it odd that I keep feeling the need to watch the energy flow in the Tesla App.

Warranties

Solar Panels - 25 Year Warranty.
Inverters - Normally last 10 years.
Powerwall - 10 year unlimited cycle warranty with guaranteed 80% power retention.

Initial Results

28-09-2019

House Used: 18.9kWh
Sources: Solar 30.9%, Powerwall 14.3%, Grid 54.8%.

First Week Breakdown (30-09 to 06-10)

Home Usage = 122kWh
Solar Energy = 47.8kWh
Powerwall = 14.3 kWh
Grid = 81.1kWh

There is an easy performance figure provided in the app, in the case of the above week it showed as 34% self-powered with the lowest day on 30th Sep at 15% and the highest being 2nd Oct at 66%. Graph below:



Solar Generation Monthly Figures (kWh)

Oct (2019) - 205
Nov (2019) - 90.9
Dec (2019) - 72.5
Jan (2020) - 81.1
Feb (2020) - 144

Powerwall Adjustments/Changes

During winter the lower generation will never manage to fill the battery so it is worth increasing the power reserve for any power outages. Tesla also activate the Storm Watch feature on UK Powerwalls:

Storm Watch

Severe weather is the leading cause of power outages. Storm Watch mode allows you to maximize savings by keeping a low reserve percentage in Self-Powered or Time-Based Control mode, while still having peace of mind that Powerwall will protect you during a severe weather event.

Powerwall communicates with the National Weather Service to know when severe weather is on the horizon and automatically triggers Storm Watch. This mode pushes the limits and charges Powerwall to maximum capacity so it can provide backup power.

When activated, the Tesla app will notify you that you are now in Storm Watch mode. This remains active until the weather event ends. After, the system returns to its previously selected mode. Although you cannot turn on Storm Watch or adjust it, you can disable this mode altogether by going to the Tesla app, selecting 'Customize' and adjusting the slider next to 'Storm Watch'.

Note that Storm Watch only activates during severe storms that are likely to knock down power lines and cause outages, like hurricanes and ice storms. To best protect yourself from everyday weather events, keep a high reserve percentage or choose Backup-Only. As your Powerwall learns more about the type of storms that typically cause outages, events that trigger Storm Watch will be adjusted.

Sunny Day Boob Graph

A sunny spring Sunday (22-03-2020) with dawn to dusk sunshine, followed by what looks like a sunny week:



So with the following day (23-03-2020) we were able to achieve:



22-03-2020

Home - 14.3 kWh
Solar - 20.4 kWh
Powerwall - From 5.5 kWh - To 13.7 kWh
Grid - From 2.7 kWh - To 0.6 kWh

23-03-2020

Home - 18.9 kWh
Solar - 18.7 kWh
Powerwall - From 10.6 kWh - To 10 kWh
Grid - From 0.4 kWh - To 0.7 kWh

In essence the Powerwall on the 22-03 was full before the sun went down and the solar panels stopped providing energy, most the energy requirements after this period such as the cookers, dishwasher, etc were supplied by the Powerwall. On the 23-03 as people got up the Powerwall still had 45% and as we move in towards summer the solar panels were already starting to provide energy at 6:35 thus at 6:40 the Powerwall was starting to charge again.

As stated earlier the Grid usage is the result of Grid limitations of how much power can be supplied by the Powerwall at any one time so if turn on two ovens at the same time as the kettle you'll need the grid to cover anything over the 3.7 kWh.

 

[~Yuckfou~]

Our house was completely off grid until a few years ago. So independent water supply and solar + wind turbine. The wind turbine was borked and judging by the 2 other borked turbines left in the garage it wasn't a good idea. They were burning out in the high winds coming up the valley here in the winter. The solar needed servicing but appeared to be working. It's not a pretty system, 4 (old) panels on the garage roof, inverter shenanigans, and 24 x 24v lead acid batteries. All put together in a very Heath Robinson manner.
I've been pleasantly surprised how well it works though. We have to switch manually between solar and mains. Can be a pain if the solar packs in at night, scrabbling in the dark to find a torch or phone to switch to mains. If fully charged by midday we go solar, usually it will keep us going until the following morning. The panels are only generating 550w in perfect conditions but there's only 2 of us and usually we spend most of our time outdoors anyway.
The plan is to get a couple more modern panels to give us another 500w and that should do us. Lockdown has made that difficult at the moment.
I do get a buzz (no pun intended) out of running the house on free electricity. Would I have spent the money on a system had it not been here? No. Too much expense and a long time to get the money back. Having it already here though is a huge bonus.

 

[Scouse]

As stated earlier the Grid usage is the result of Grid limitations of how much power can be supplied by the Powerwall at any one time so if turn on two ovens at the same time as the kettle you'll need the grid to cover anything over the 3.7 kWh.

Didn't know that was a thing. I figured you'd just run your powerwall down faster. 3.7kWh ain't that much really (lights + PC + TV + underfloor heating + ovens + kettle) shouldn't be that uncommon in the big scheme of things.

If this place was remotely energy efficient I'd be seriously considering it. Wanted to get a heating engineer out but I think that's going to not be a thing for quite some time. Neither is fixing the hole in the roof.

 

[dysfunction]

I don't see why you couldn't get the roof fixed. They wouldn't need to come indoors would they?

 

[Moriath]

Didn't know that was a thing. I figured you'd just run your powerwall down faster. 3.7kWh ain't that much really (lights + PC + TV + underfloor heating + ovens + kettle) shouldn't be that uncommon in the big scheme of things.

If this place was remotely energy efficient I'd be seriously considering it. Wanted to get a heating engineer out but I think that's going to not be a thing for quite some time. Neither is fixing the hole in the roof.

So this your only home ? Or you one of those second home dudes moving into the countryside away from everyone stretching the limited resources of the pretty regions?

 

[Scouse]

I don't see why you couldn't get the roof fixed. They wouldn't need to come indoors would they?

Damp ingress has been so long that there's evidence of rot on one of the rafters and purlins so they'll need to be replaced along with the rest of the roofing work. There's probably about £1500 worth of work to make it watertight.

So this your only home ? Or you one of those second home dudes moving into the countryside away from everyone stretching the limited resources of the pretty regions?

Nope. We've got the house in Nottingham - but this place is far from long-term liveable in at the moment. There's at least £15k's worth of work to necessary externals and heating systems before we even think of groundworks and renovations (internal and external - I'll post a pic of the porch later), and another £10ks worth of work for septic tank systems. - so £25k is just a starter really.

It's going to be 18 months before it's liveable, presuming I can stay in work for that long.

After that - plan is to move here permanently. Don't know whether we'll sell or rent our house in Nottingham. That needs some refurb too.

 

[Embattle]

Didn't know that was a thing. I figured you'd just run your powerwall down faster. 3.7kWh ain't that much really (lights + PC + TV + underfloor heating + ovens + kettle) shouldn't be that uncommon in the big scheme of things.

If this place was remotely energy efficient I'd be seriously considering it. Wanted to get a heating engineer out but I think that's going to not be a thing for quite some time. Neither is fixing the hole in the roof.

Tesla Powerwall 2 Specs - https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall 2_AC_Datasheet_en_GB.pdf

So the important parts:

Grid Standards (UK) - G83 / G59
Real Power, max continuous - 3.68 kW / 5 kW (charge and discharge)
Apparent Power, max continuous - 3.68 kW / 5 kW (charge and discharge)

You'll by default be on the G83 standard at a house which is for small scale embedded generators such as roof solar. The G83 standard has a 3.68 kW limit but beyond notifying the local Distribution Network Operator (DNO) 28 days before completing work you don't have any thing else to do and there are no charges from the DNO.

Even if you can go for the G59 standard, which allows up to 5 kW, you would not only have any additional local costs to pay for but any the DNO decides are needed and there is a lot more paperwork involved.

You can put a lot of stuff on at the same time but putting anything that heats does draw a lot of power, so our kettle will pull 3 kW but over a short period and if you start heating two ovens at the same time the initial heating phase to get them to temperature will spike to 2 kW+. Right now our house is drawing 0.5 kW with the following running:

1. Desktop Computer
2. Laptop
3. NAS
4. 1-2 TVs On.
5. American Style Fridge Freezer
6. Assorted other items such as tablets on charge, phones, etc.
7. Assorted other standby items.

The solar is still pulling in 1.3 kW and since the battery is full the 0.8 kW is going to the grid.

The thing to understand is the Tesla Powerwall is not a off grid device because firstly it isn't designed to be and secondly it requires a network connection.

 

[Scouse]

I'm really annoyed that the Tories have killed the FIT. Makes it hella expensive in todays environment.

 

[Embattle]

FIT did offer a better return although starting this year they introduced SEG but it is designed around competition for your excess energy and even the best offer on the market is only 5p per kWh. Our supplier is British Gas and they pay 1.5p per kWh and you might have to change tariff and would have to fill out this dumbass form -- https://www.britishgas.co.uk/aem6/content/dam/britishgas/downloads/SEG_Application_Form.pdf - and then if you keep in mind that since our system start running in Oct 2019 we've only exported 13.3 kWh so it really isn't worth the hassle for 20p.

 

[Scouse]

Still. 6k for solar plus 8k for powerwall.

Eight thousand pounds! I think it's about 5 grand equivalent in the states.

 

[Embattle]

Solar has come down in price compared to where it used to be so the total for that was £5,566.57 (Inc 5% VAT).

Parts Included:

16x Q Cells 315 Q Peak Duo All BLack Module
1x Solax X1 Boost 3.6T Inverter
16x K2 Systems Tile Mounting System
1x Electrical Items including total generation meter, AC and DC isolation
1x Full Scaffolding
1x MCS registration
1x Insurance Backed Workmanship Warranty

 

[Moriath]

The powerwall was tesla stuff right? I guess there are other cheaper battery solutions? So you dont lose whats generated.

 

[Embattle]

Yes the Powerwall 2 is the Tesla stuff and it cost £7,949.55 with a breakdown of costs is below:

1x Tesla Powerwall 2 - 13.5 kWh Battery
1x Tesla Backup Gateway 2
1x Assorted electrical items such as isolators, meter, cable
1x setup and handover training
1x DNO Application
1x Installation of backup gateway to supply house in powercut

There are a number of other manufacturers which also offer a variety of different capacities as well, see here - Solar Battery Storage: The Best Solar Batteries [2020]

 

[Moriath]

Yes the Powerwall 2 is the Tesla stuff and it cost £7,949.55 with a breakdown of costs is below:

1x Tesla Powerwall 2 - 13.5 kWh Battery
1x Tesla Backup Gateway 2
1x Assorted electrical items such as isolators, meter, cable
1x setup and handover training
1x DNO Application
1x Installation of backup gateway to supply house in powercut

There are a number of other manufacturers which also offer a variety of different capacities as well, see here - Solar Battery Storage: The Best Solar Batteries [2020]

Did you get tesla because you have a car and want it to interface? Or just because your research showed that it was the best solution?

 

[Embattle]

Did you get tesla because you have a car and want it to interface? Or just because your research showed that it was the best solution?

We don't have a Tesla car but the other factors all played a part in the decision, plus for it capacity it isn't really any more expensive than some of the other options out there.

Although as we were told there was no guarantee of any kind on the monetary return of the battery, just the solar aspect.

 

[Embattle]

We were given the following conservative figures for our PV system:

£114.75 Export Income
£335.49 Savings on electricity bill (year 1)
£450.24 Annual financial benefit from your PV system

 

[Moriath]

We were given the following conservative figures for our PV system:

£114.75 Export Income
£335.49 Savings on electricity bill (year 1)
£450.24 Annual financial benefit from your PV system

But your not getting the export income right ?

 

[Embattle]

But your not getting the export income right ?

No since with the battery there isn't a great deal going out, thus not signed up to it under British Gas and the figures given for the export income are based around a SEG price offered by a company like Octopus energy which is 5.5p per kWh.

 

[Embattle]

I've noticed we get higher power peaks on sunny days such as today where there are some clouds in the sky, I suspect this is due to the setup being split between East & West. In essence the sun is fully hitting the East panels and we are getting sun reflections off the cloud hitting the West panels.

Peaks

Sunny Day (27th March) - 2.6 kW
Sunny Intervals (28th March) - 3.2+ kW

 

[Scouse]

Nice hypothesis

If your roof was south facing what do you reckon you'd be getting?

 

[Embattle]

I would get a higher peak and overall but the system would require assorted changes such as a more powerful inverter, lower power solar panels to keep within the maximums for home generation without extra work.

Comparison of East-West arrays – Sheffield Solar

There is a lot of talk that depending on your use, setup, etc. then each one has benefits.

The figures provided by the supplier/installer for our yearly generation using two different calculators came out as:

MCS Sap =3,906.00 kWh
PV Sol = 4,379.76 kWh

 

[Scouse]

Gawd damnit. All sources of energy are looking dayum expensive tbh.

I could put gas in for about 8k (boiler, ground works, tank, replumbing etc) but I don't want to because: environment. Whereas solar + battery works out hella expensive and I'm not sure I could run cooker / water heating / underfloor heating / computers / etc without having to draw from the bloody grid anyway.

BTW @Embattle - how's your water heating? Tank size / time to heat to supply baths / showers / heats.

I'm interested in a wholistic view of your house makeup, how it works, pros n cons as you see 'em.

If you have the time / can be arsed with all that detail, ofc. Pretty please

 

[Embattle]

Well firstly it is a modern timber framed home with lots of insulation and here are some of the other bits:

• Bedrooms - 4 bedrooms with en-suite showers, sinks and toilets in 2 of them plus 2 TVs and 3 Sonos speakers.
• Bathroom - Bath, sink and toilet.
• Kitchen Dining Room - Integrated dishwasher, induction hob, double undercounter oven, extractor, american style fridge freezer, toaster, kettle, coffee machine, microwave, TV, Laptop.
• Lounge - TV, PS4, BT TV, NAS, Orbi, Sonos.
• Study - PC, Printer, Tesla Powerwall and Tesla gateway.
• Cloakroom - Toilet and Sink.
• Utility Room - Washing machine, tumble dryer and boiler.
• Airing Cupboard - Megaflo Eco Unvented Indirect Cyclinder 210i + Pressure vessel
• Garage - Lights and sockets for powering and recharging stuff.
• Loft - Massive insulation, inverter, aerial cables and solar panel cables.
• Additional - Phones, tablets, etc on charge.

There is a radiator in every room and in the hallways, the upstairs radiators are controlled by the panel in the master bedroom and the downstairs radiators are controlled by the one in the hallway. We only have they setup to heat for a couple of hours in the morning and evening, even then they are turned off quite often as the house holds its heat well due to the insulation.

Below is some of the EPC stuff:

Energy Efficiency Rating

Current 85 (B)
Potential 108 (A)

Actions you can take to save money and make your home more efficeint

Recommended measures - Indicative cost - Typical savings over 3 years - Rating improvement
1. Solar water heating - £4000-6000 - £141 - B86
2. Solar photovoltaic panels, 2.5 kWp - £5000-£8000 - £936 - A93
3. Wind turbine - £15000-£25000 - £1,728 - A108

Summary of this home's energy performance related features

Element - Description - Energy Efficiency (Stars)
Walls - Average thermal transmittance 0.27 W/m²K - 5
Roof - Average thermal transmittance 0.10 W/m²K - 5
Floor - Average thermal transmittance 0.15 W/m²K - 5
Windows - High perfomance glazing - 5
Main Heating - Boiler and radiators, mains gas - 4
Main Heating controls - Time and temperature zone control - 5
Secondary heating - None - NA
Hot water - From main system - 4
Lighting - Low energy lighting in all fixed outlets - 5
Air tightness - Air permeability 4.7 m³/h.m² (as tested) - 4

Current primary Energy use per square metre of floor area: 77 kWh/m² per year.

Heat demand

Space heating (kWh per year) - 4,161
Water heating (kWh per year - 2,211


Our current EPC rating due to solar panels would now be A(93+).

 

[MYstIC G]

Gawd damnit. All sources of energy are looking dayum expensive tbh.

I could put gas in for about 8k (boiler, ground works, tank, replumbing etc) but I don't want to because: environment. Whereas solar + battery works out hella expensive and I'm not sure I could run cooker / water heating / underfloor heating / computers / etc without having to draw from the bloody grid anyway.

BTW @Embattle - how's your water heating? Tank size / time to heat to supply baths / showers / heats.

I'm interested in a wholistic view of your house makeup, how it works, pros n cons as you see 'em.

If you have the time / can be arsed with all that detail, ofc. Pretty please

Future energy policy is going to be heavily anti-boiler as I understand it, so it might be an idea to factor that in as well.

 

[Scouse]

Future energy policy is going to be heavily anti-boiler as I understand it, so it might be an idea to factor that in as well.

Trying to.

@Embattle - you got any info on your electric boiler and water storage tank that I can go away and delve into.

I think one of our first jobs will be removing the concrete slab floor, drilling down and getting some proper underfloor insulation in there. I can feel the heat seeping through the fur and plastic sole layers of my slippers into the carpet.

 

[Embattle]

@Scouse We are on gas for heat, the parts are:

Boiler: Ideal Logic Heat 18
Tank: Megaflo Eco Unvented Indirect Cyclinder 210i + Pressure vessel
Controllers: Honeywell

The idea of getting off gas is great but there are issues with doing so in houses that are already use gas boilers.

 

[Scouse]

@Scouse We are on gas for heat, the parts are:

Boiler: Ideal Logic Heat 18
Tank: Megaflo Eco Unvented Indirect Cyclinder 210i + Pressure vessel
Controllers: Honeywell

The idea of getting off gas is great but there are issues with doing so in houses that are already use gas boilers.

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. :\

 

[Embattle]

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. :\

Honestly with what you've seemingly bought, no you can't although all is not totally lost if you read around - How to Insulate a Period House - Build It

We nearly moved to another place in Devon in a place called Chulmleigh which had no gas, it used air source heat pump system but this requires a well insulated house with under floor heating on the ground floor and radiators on the first floor.

 

[Moriath]

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. :\

Cant use the solar heating. Pipes heating water on the roof?

 

[Embattle]

Again there are limitations to solar heating, like solar panels they are a help not a complete substitute - Solar water heating

I may well turn on the immersion element for the hot water tank if thee is too much excess energy going back to the grid during the peak months.