Solar panels and battery - any real world recommendations?

[b0rn2sk8]

Maximum panels. As many as will fit on the roof. Adding more later is disproportionately expensive.

You get paid 15/16p to export at the moment and the vast majority of the benefit from the panels will come from exporting to the grid during the summer to build up credit for the winter.

Likewise, 12 panels will generate a material amount of energy all year. 6 panels will not produce much in winter.

Even if energy rates drop and corresponding export rates drop, they’ll not collapse and there are ways to manage your consumption and export to gain the most benefit from the system depending on the price signals at the time.

Edit: Everything is going electric at the end of the day whether you like it or not. The more panels you have, the cheaper and easier that transition becomes for you as an individual. Best to make hay while the sun shines, literally.

The 12 panel system will have a shorter pay back period based on current prices and any future prices in the near term.

 

[tamzzy]

1. £6,000: 6 panels (on the South-facing roof) + inverter + 5 kW battery
2. £7,500: 12 panels + inverter + 5 kW battery

1 is well overpriced, taking the literal mick
2 is last year's prices, that should be around £6500-6800 nowadays

If in manchester get Spectra Solar to quote, they're based in Wigan and I can personally recommend (I've used them for my install, and several others here have since used them too)

 

[Mercenary Keyboard Warrior]

Hi all,

A friend in Manchester is planning to install solar panels on his roof and could use some advice. His roof has North- and South-facing sides, and he’s received two quotes for solar systems:

1. £6,000: 6 panels (on the South-facing roof) + inverter + 5 kW battery
2. £7,500: 12 panels (6 South, 6 North) + inverter + 5 kW battery

His electricity usage is fairly low since he has a gas boiler, gas cooker, and shower powered by the gas boiler. Given his low consumption, which option makes more financial sense? Any insights on how the number of panels and roof orientation might affect performance? Thanks!

You really want to see the detailed breakdown so what type of panels, what inverter etc

 

[SkyTerran]

Thanks for your help guys. I'll tell him to give Spectra Solar a call and ask for 12 panels.

The panels quoted are Aiko Neostar 2S 455W, not sure about the inverter.

 

[Ron-ski]

Get him to ask for as many that will fit.

6 perfect south at 35 degree pitch would give 2355 kWh a year
6 perfect north at 35 degree pitch would give 1329kWh a year

Edited as PVGIS was playing up

 

[reef]

Get him to ask for as many that will fit.

6 perfect south at 35 degree pitch would give 2355 kWh a year
6 perfect north at 35 degree pitch would give 1970 kWh a year

I'm surprised its only 385 kWh less - I put -180 as the azimuth in PV GIS

That sounds a bit off. I get 2350kWh-ish for the south-facing and 1329kWh for the north-facing on there for 2.73kW arrays in Manchester.

 

[Ron-ski]

It certainly seems off, but it what PVGIS comes up with.

Just tried it again, not sure if its a bug, but if I tick the optimize slope, then it comes up with 1970 kWh and shows the pitch as 1 degree, with optimise slope unticked, set at 35 degrees and nothing else changed I get 1329 kWh, which seems more likely.

 

[SkyTerran]

Wonder if my Powerwall 3 and Zappi EV charger are set up correctly.

I'm on Octopus Intelligent Go tariff and Octopus is controlling the charger (my car is not directly supported by Octopus). If I plug the car into the charger during the day, it says "Waiting for surplus". Usually a couple minutes later Octopus app sends a notification that a schedule was created and eventually the car starts charging. But the power comes from the Powerwall. A few minutes later the Netzero app picks up on the Octopus schedule and sets the backup power setting on the Powerwall to 100%, at which point both the car and the home battery start getting power from the grid.

Is there a way to make it so that the EV charger never uses Powerwall energy?

 

[1pudding1]

Sounds like its a few minutes worth of battery usage into the car before it changes. Is it that bad? Only way is for you to intervene if you don't want to wait for Netzero to change the Powerwall settings, or set something else up that can do it quicker?

 

[b0rn2sk8]

Wonder if my Powerwall 3 and Zappi EV charger are set up correctly.

I'm on Octopus Intelligent Go tariff and Octopus is controlling the charger (my car is not directly supported by Octopus). If I plug the car into the charger during the day, it says "Waiting for surplus". Usually a couple minutes later Octopus app sends a notification that a schedule was created and eventually the car starts charging. But the power comes from the Powerwall. A few minutes later the Netzero app picks up on the Octopus schedule and sets the backup power setting on the Powerwall to 100%, at which point both the car and the home battery start getting power from the grid.

Is there a way to make it so that the EV charger never uses Powerwall energy?

Yes. It involves an electrician though.

Basically you need your EV charger wired into your electrical system between the Tesla gateway and your electric meter so the Tesla system can’t measure the energy being used by it. If it can’t measure it, it can never fill that demand.

The downside of doing this is the graphs etc in the Tesla app will not show the energy usage of the car charger.

[Engage rant mode]
This sort of ill thought out installation grinds my gears. This situation is not unique, in fact it’s very common.

For most people, the car charger pulling energy from the battery completely undesirable behaviour but most pay zero attention to other products when installing their own and how the two may interact with each other.

The customer is not an electrician, the whole point of paying someone thousands to install this stuff is that they are meant to know these basic fundamentals of how this kind of hot works.

This really grinds my gears, can you tell?

[/Rant mode disengaged]

Part of the issue is far too many installers don’t understand how a lot of the products they are installing actually work because they have never used them outside of the initial commissioning process. The customer ultimately ends up paying the price.

Edit: if you went down the home assistant route, it would be instant as you have local control over some of the items in the chain but it’s far far far far far more complex to set up and is basically for nerds.

 

[Freefaller]

Hi all,

A friend in Manchester is planning to install solar panels on his roof and could use some advice. His roof has North- and South-facing sides, and he’s received two quotes for solar systems:

1. £6,000: 6 panels (on the South-facing roof) + inverter + 5 kW battery
2. £7,500: 12 panels (6 South, 6 North) + inverter + 5 kW battery

His electricity usage is fairly low since he has a gas boiler, gas cooker, and shower powered by the gas boiler. Given his low consumption, which option makes more financial sense? Any insights on how the number of panels and roof orientation might affect performance? Thanks!

Max panels always, once the scaffolding is up the installation costs become neglibile. I wish I had added them to my north pitch. Even in the winter it would have added enough power to offset energy usage in winter.

 

[john_smith]

Wonder if my Powerwall 3 and Zappi EV charger are set up correctly.

I'm on Octopus Intelligent Go tariff and Octopus is controlling the charger (my car is not directly supported by Octopus). If I plug the car into the charger during the day, it says "Waiting for surplus". Usually a couple minutes later Octopus app sends a notification that a schedule was created and eventually the car starts charging. But the power comes from the Powerwall. A few minutes later the Netzero app picks up on the Octopus schedule and sets the backup power setting on the Powerwall to 100%, at which point both the car and the home battery start getting power from the grid.

Is there a way to make it so that the EV charger never uses Powerwall energy?

I have the same setup and the same issue. I resolved it using home assistant to control everything. The zappi is off unless it's after 23:30 at night or the powerwall battery falls below 5%.

 

[SkyTerran]

OK, thanks I'll look into Home Assistant when I have some free time. I have a spare Mac mini M1, that should be able to run HA.

 

[Ron-ski]

Mine is also all automated using Bottle Cap Dave's Home Assistant plug in which then lets the Victron system know when there is a cheap period outside the normal off peak hours, so my code on there controls what's happening.

Only thing I do which is a pain is plug the car in before I go to bed, otherwise Octopus see I'm exporting and start a charging session to try and steal my exports, which doesn't happen as the house batteries start charging.

 

[b0rn2sk8]

M1 Mac mini is completely overkill for home assistant but it will very much work.

It will run in a Pi or better, an N100 based mini PC.

 

[Ron-ski]

Mines running on an old Intel Nuc, total over kill, but it was sat there doing nothing, and it doesn't use much power, more than a Pi though.

 

[Freefaller]

Pi 5 with a NVMe drive is what I have and it's more than powerful enough.

 

[Mercenary Keyboard Warrior]

Yes. It involves an electrician though.

Basically you need your EV charger wired into your electrical system between the Tesla gateway and your electric meter so the Tesla system can’t measure the energy being used by it. If it can’t measure it, it can never fill that demand.

The downside of doing this is the graphs etc in the Tesla app will not show the energy usage of the car charger.

[Engage rant mode]
This sort of ill thought out installation grinds my gears. This situation is not unique, in fact it’s very common.

For most people, the car charger pulling energy from the battery completely undesirable behaviour but most pay zero attention to other products when installing their own and how the two may interact with each other.

The customer is not an electrician, the whole point of paying someone thousands to install this stuff is that they are meant to know these basic fundamentals of how this kind of hot works.

This really grinds my gears, can you tell?

[/Rant mode disengaged]

Part of the issue is far too many installers don’t understand how a lot of the products they are installing actually work because they have never used them outside of the initial commissioning process. The customer ultimately ends up paying the price.

Edit: if you went down the home assistant route, it would be instant as you have local control over some of the items in the chain but it’s far far far far far more complex to set up and is basically for nerds.

I know we have caution in regards Artisan round here but they did a video a few days ago that epitomises this.

Complete mess of an install between batteries, car charger etc and they were even on the same ecosys!

(Not an artisan install but they went in to investigate initial issue of house batteries not charging fast enough) you could pretty mush predict the main issues with a couple of mins but it was worth watching the whole thing to see the total picture.
As ever Jordan doesn't come across super well, very fast to criticise others, but it really did get to the jist of what your rant was about.

I think people forget that most sparks really aren't that bright. It may change over time as trades aren't seen as negatively as they were years ago, but even so many still aren't that capable once you deviate from "guideline says this"

 

[Ron-ski]

In this video the electrician actually shows how to wire in the batteries so that the Zappi doesn't drain them.

It's that mega expensive heatable install.

 

[94JDH]

In this video the electrician actually shows how to wire in the batteries so that the Zappi doesn't drain them.

It's that mega expensive heatable install.

Yes, this house was costing him something like £30 per day because of electric radiators.
Also his explanation of the available PV power and his "paralleled system" wasn't great as there was no mention of the ability to to improve each 5 kW hybrid inverter's throughput by charging at the same time as his max use/export maximising the potential of the oversized array.

I know we have caution in regards Artisan round here but they did a video a few days ago that epitomises this.

Complete mess of an install between batteries, car charger etc and they were even on the same ecosys!

(Not an artisan install but they went in to investigate initial issue of house batteries not charging fast enough) you could pretty mush predict the main issues with a couple of mins but it was worth watching the whole thing to see the total picture.
As ever Jordan doesn't come across super well, very fast to criticise others, but it really did get to the jist of what your rant was about.

I think people forget that most sparks really aren't that bright. It may change over time as trades aren't seen as negatively as they were years ago, but even so many still aren't that capable once you deviate from "guideline says this"

Jordan always critical, expensive & made a dog's ear of the large install on an unused tennis court blaming the over and under voltage on the DNO. Another YouTuber who's an electrician amusingly ripped him apart.
Fortunately for Jordan, probably due to his visibility, the DNO have got him out of the situation by upgrading the local transformer (also after criticising them I must add!).