[UK] Help me achieve an Open Source home solar energy installation

[solartist]

I am a homeowner at the design phase of renovating my 1930s terraced house in England, and I want to incorporate solar energy into the plans.

I would appreciate your help at this early stage. It's "cheaper to make mistakes on paper" (cf. Sofie Pelsmakers), and I might need a few design iterations to get this right!

After wrestling with some questions for weeks, I decided to summarise my situation and post here. I hope with your help I can achieve a plan that is affordable, safe, legal, and efficient.

Questions:

1. Which makes/models of inverter/micro-inverter/optimiser/charge-controller/gateway/battery/AIO/BMS/etc should I be looking at, to meet the desiderata below? (Tesla Powerwall 2 + Tesla Gateway combo seems to meet most of the desiderata - but can it be used without proprietary apps/cloud? If it can't be, then where else should I be looking? Victron? Something else?)
2. Are smart sockets reliable enough that I wouldn't need to run extra wires to each room for essential vs non-essential loads? (See discussion in "Desiderata" below.)
3. In the desiderata list below, I flagged some points where I am unclear on the terminology/jargon. Have I used the right terms?

Background:

• Grid is single-phase 230V AC nominal @ 50Hz. I would upgrade to a 3-phase supply if that would reduce overall cost.
• House is 4.6m wide, 6m deep, with a pitched roof. It has a 30m long back garden. The front of the house faces west-north-west.
• Skylights will occupy approx 2m² of front pitch, and 1m² of rear pitch.
• Neighbour has a tall, narrow chimney whose shadow moves across roof during day. String inverters are therefore probably not ideal.
• I want to do as much planning as possible before I contact a licensed electrician/installer. This way, I'll know if any suggestions they make are constructive.
• Retrofit will hopefully include:
  • insulation/airtightness to Passivhaus enerPHit standard, or close.
  • MVHR.
  • air-source heat pump (mini-split) for space heating/cooling.
  • replacing the gas boiler with a fossil-free alternative for hot water.
• Loads will include:
  • domestic needs of 2 adult residents (with high laundry requirements for medical reasons) + occasional guests.
  • HVAC as above (MVHR/space-heating/water-heating).
  • servers & networking equipment consuming ~1kW on average.
• Predicted essential loads (lighting, computing, fridge/freezer, microwave): 2kW peak, 16kWh/day mean.
• Predicted non-essential loads (including electric car, if I get one): 12kW peak, 26kWh/day mean.

Desiderata:

• Meets Permitted Development rules.
• Once commissioned, can be controlled & monitored using free as in freedom (aka Open Source, aka FOSS) software only.
  • OK: emonPi, iotaWatt, Home Assistant, and similar control/monitoring systems; physical control panels on the wall (if not "cloud"-connected).
  • NOT OK: proprietary smartphone or cloud apps.
• Grid-tied, so:
  • excess daytime solar (if any) can go to grid instead of being wasted
  • cheap night-time grid energy can be used to charge the batteries for daytime use (crucial on cloudy winter days)
• Grid-supported (is that the right term?), so when loads exceed solar & battery capacity combined, grid will supply the shortfall.
• Automatic UPS functionality, so essential loads are seamlessly switched to solar and/or battery power if grid goes down (power outage). (Is "hybrid" the term for this?)
• Automatic anti-islanding: disconnects from the grid if grid goes down (power outage).
• Automatic recovery from anti-islanding when grid comes back up. (Is "automatic reclosing" the term for this?)
• Capable of gradual installation (in stages/phases) e.g.:
  1. Home rewiring first (during interior renovations) to:
     1. Put consumer unit in sensible location.
     2. Install additional mains wiring/sockets circuits so essential loads can be automatically separated from other loads (see earlier) - each room would have some "essential load" sockets and some "inessential loads" sockets. (Alternatively, are there smart sockets that are trustworthy enough for this task, so that separate circuits would not be necessary?)
     3. Lay conduit in walls/floors/roof for additional cabling (48V DC?) that might be needed later.
  2. Install inverter(s) & anti-islanding device(s) when funds allow.
  3. Install panels on roof when funds allow.
  4. Install 1st battery bank when funds allow.
  5. Install panels (or solar brise-soleils) on rear wall of house when funds allow.
  6. Install 2nd battery bank when funds allow.
  7. Install panels on outbuilding when funds allow.
  8. Install 3rd battery bank when funds allow.
  9. Install panels on garden wall when funds allow.
• When complete (see above), can power essential loads for 24h in case of power outages.
• Sourced from UK retailers.
• Long parts/systems design-lives/warranties preferred (≥10yrs, ideally), even if this means only charging at 0.5C.
• Batteries should be capable of being safely charged at 0.5C irrespective of ambient temperatures, even if this means adding heating/cooling/insulation to keep them at ~25°C or whatever is optimal for their chemistry. (Ambient temperatures fluctuate from about -10°C in winter to almost 40°C in summer.)
• As inexpensive as possible, even if that means e.g.:
  • DIY such as assembling batteries using prismatic LiFePO4 cells from Fogstar/similar.
  • AC-coupled panels & batteries, if that would cost less than running 48V DC wiring.
• Edit: carbon neutral once renovations & solar complete.

Sub-threads:

• [UK] Are there any G98/G99-compliant "cloud"-free microinverters?
• [UK] Consumer units with affordable SPDs, AFDDs, and Type B RCDs/RCBOs?
• KNX home automation: is there a FOSS (Free and Open-Source Software) alternative to ETS?

I know this is a lot to digest. I'm grateful to anyone who reads this far and offers constructive suggestions! Thank you!

If I think of any more desiderata/questions/clarifications, I'll update this post.

 

[Quattrohead]

Keep your gas appliances at any cost whilst you still can.
What has been your previous electricity consumption per month for the past year.
Then we can start advising you some stuff.

 

[Sean Very North]

• I want to do as much planning as possible before I contact a licensed electrician/installer.
  • Install inverter(s) & anti-islanding device(s) when funds allow.
  • Install panels on roof when funds allow.
  • Install 1st battery bank when funds allow.
  • Install panels (or solar brise-soleils) on rear wall of house when funds allow.
  • Install 2nd battery bank when funds allow.
  • Install panels on outbuilding when funds allow.
  • Install 3rd battery bank when funds allow.
  • Install panels on garden wall when funds allow

How do you think the installer when be pricing the installation giving how many (when funds allow) visits are likely to be required ?

What you have outlined could easily be in a typical UK Victorian terrace within 2/3 contiguous days.

Forget 3ph

 

[solartist]

Keep your gas appliances at any cost whilst you still can.

I'm puzzled by this advice.

After the insulation/airtightness work is done, the gas boiler should no longer be needed for space heating, because the energy consumption within the thermal envelope (people, appliances, cooking) should be sufficient to maintain adequate heat year-round.

And I don't see how I can achieve carbon neutrality unless I replace the gas boiler with a different way to heat water for hot water taps (faucets) and showers.

What has been your previous electricity consumption per month for the past year.

The existing energy consumption is not representative of the anticipated usage after the renovation, because the usage patterns will be so different. The predicted post-renovation energy consumption figures are at the bottom of the "Background" section, in the first post in this thread.

Thank you!

 

[dmsims]

"servers & networking equipment consuming ~1kW on average."

This jumped out, what on earth have you got that uses that much? (and why)

(coming from an IT guy with lots of kit)

 

[solartist]

How do you think the installer when be pricing the installation giving how many (when funds allow) visits are likely to be required ?

What you have outlined could easily be in a typical UK Victorian terrace within 2/3 contiguous days.

I was expecting to do as much of each stage's work myself as is lawful (I am not an electrician), such as sourcing components, fishing wires, and mounting components in place (leaving the terminals disconnected from the wiring, with insulating caps over all bare ends).

Having done that work for any given stage, I expected to pay a licensed professional to inspect the work, rectify if needed (hopefully not!), connect the equipment to the wiring, and commission/certify the installation. (Edit: a bit like @Paul Smith described here.)

I figured this would let me proceed in stages, economically (I wouldn't be paying any unnecessary labour costs), and would get me some solar power sooner rather than later.

If I instead waited until funds were available for the entire system, that could add an extra couple of years' delay, during which I wouldn't be realising any of the financial or environmental savings of having solar or batteries.

Forget 3ph

The two reasons I was considering 3-phase AC are:

• 3-phase micro-inverters are apparently cheaper and simpler than single-phase ones
• if we ever get an electric car, it would be nice to have a 22kW fast-charger instead of just a 7.4kW charger

The latter isn't crucial, though, and if the cost savings of 3-phase inverters doesn't balance out the cost of upgrading to 3-phase from the kerb, then I'm happy to forget 3-phase.

Thank you!

 

[Sean Very North]

Given the tiny footprint of your house, you might want do an analysis on exactly how much space the measures required to achieve PH or near will take up, you might be surprised and somewhat disappointed by how much your living space has been reduced due to insulation, MHVR etc.

 

[solartist]

"servers & networking equipment consuming ~1kW on average." This jumped out, what on earth have you got that uses that much?

Once it's up and running, there should be web, mail, DB, media, home automation/monitoring, CCTV, time, backup, and home-lab servers, plus firewall, PoE switches, and some redundancy. I thought 1kW was quite modest for all that.

 

[solartist]

Given the tiny footprint of your house, you might want do an analysis on exactly how much space the measures required to achieve PH or near will take up, you might be surprised and somewhat disappointed by how much your living space has been reduced due to insulation, MHVR etc.

Already analysed, thanks! For exterior walls, will use cavity insulation plus EWI - not IWI. Will also improve insulation/airtightness in roof and under ground floor. Those measures will not lose us any living space.

Roof has room for MVHR unit and most of the ductwork. The rest of the ducting will run in wall/floor voids. So, negligible living space loss on that front.

We will lose a few cm depth inside the party walls due to acoustic/thermal IWI (thin walls, noisy neighbours...) but can live with that.

 

[solartist]

Which makes/models of inverter/micro-inverter/optimiser/charge-controller/gateway/battery/AIO/BMS/etc should I be looking at, to meet the desiderata below? (Tesla Powerwall 2 + Tesla Gateway combo seems to meet most of the desiderata - but can it be used without proprietary apps/cloud? If it can't be, then where else should I be looking? Victron? Something else?)
...
Desiderata:

• ...
• Once commissioned, can be controlled & monitored using free as in freedom (aka Open Source, aka FOSS) software only.

I just stumbled across this thread, which in turn led me to https://www.victronenergy.com/live/venus-os:start

This looks promising!

 

[Quattrohead]

I'm puzzled by this advice.

Gas is great for heavy heating like home and hot water as they hit hard on electric current so you need a bigger inverter.
Carbon neutral is a government fantasy to keep the tree huggers quiet. F1 and Amazon say they are carbon neutral, such bollocks.

 

[Quattrohead]

Gas was the cleanest and most efficient way to generate electric they said as they were phasing out coal, now it is the devil's work.
New gas appliances are being banned across the world, keep them as long as you can because electric will be in short supply soon.

Honestly, just do what you can to lower your bills by spending the least amount of money you can and FFS don't borrow to do it.

 

[solartist]

Gas is great for heavy heating like home and hot water as they hit hard on electric current so you need a bigger inverter.

If climate change, and the pollution and geopolitical corruption associated with fossil fuel extraction and consumption, were non-problems, then yes, gas would be great for heating.

But all those things are serious obstacles to human wellbeing, so gas is not great.

Carbon neutral is a government fantasy to keep the tree huggers quiet.

First of all, "treehuggers" - people interested in sustainability - helped pioneer the craft of DIY solar power. It's a bit rich for you to come onto a forum named for that craft and to disparage a group that helped pioneer it!

Secondly, a combination of carbon-neutrality, carbon-negativity, plus maybe carbon capture-and-storage and geoengineering, is likely to be the only way to stop catastrophic climate change making life on Earth massively more challenging and unpleasant. The lowest-risk approach within that combination, and the most achievable for individuals at home, is carbon-neutrality.

Gas was the cleanest and most efficient way to generate electric they said as they were phasing out coal, now it is the devil's work.

In may cases, "they" were fossil-fuel lobbyists trying to keep fossil fuels in use as long as possible. The lobbyists realised coal was largely a lost cause - it's just too obviously harmful. But gas wasn't as bad as coal, and the same lobbyists had succeeded in delaying investment in grid-scale solar and wind. So, those lobbyists had a chance to sell gas to politicians and the public, and unfortunately many politicians and members of the public were duped into accepting it - despite the fact that it's still a huge source of carbon emissions, and gives dictators massive international economic leverage.

New gas appliances are being banned across the world

Good!

electric will be in short supply soon.

Not in areas (or homes) where adequate renewable energy capture and storage infrastructure is up and running.

 

[Quattrohead]

Not in areas (or homes) where adequate renewable energy capture and storage infrastructure is up and running.

There is no adequate renewable energy around, especially if everyone jumps on electric cars and heating at the same time over the next few years.
I am actually on your side, I love solar and am building a LEED rated home here in Florida. It will be entirely off grid and as such, I have looked closely at using propane for cooking and clothes dryer. But I came to the conclusion I did not want the extra cost of a tank etc and rely on someone else to supply it. I therefore committed 100% to solar. I think it will work out for us....well it has to now lol

My family is still in the UK and I see Mum's bills, gas is still way cheaper than electric for heating.

Oh also, very few if any professionals will install equipment you buy yourself.

 

[houseofancients]

If climate change, and the pollution and geopolitical corruption associated with fossil fuel extraction and consumption, were non-problems, then yes, gas would be great for heating.

But all those things are serious obstacles to human wellbeing, so gas is not great.


First of all, "treehuggers" - people interested in sustainability - helped pioneer the craft of DIY solar power. It's a bit rich for you to come onto a forum named for that craft and to disparage a group that helped pioneer it!

Secondly, a combination of carbon-neutrality, carbon-negativity, plus maybe carbon capture-and-storage and geoengineering, is likely to be the only way to stop catastrophic climate change making life on Earth massively more challenging and unpleasant. The lowest-risk approach within that combination, and the most achievable for individuals at home, is carbon-neutrality.


In may cases, "they" were fossil-fuel lobbyists trying to keep fossil fuels in use as long as possible. The lobbyists realised coal was largely a lost cause - it's just too obviously harmful. But gas wasn't as bad as coal, and the same lobbyists had succeeded in delaying investment in grid-scale solar and wind. So, those lobbyists had a chance to sell gas to politicians and the public, and unfortunately many politicians and members of the public were duped into accepting it - despite the fact that it's still a huge source of carbon emissions, and gives dictators massive international economic leverage.


Good!


Not in areas (or homes) where adequate renewable energy capture and storage infrastructure is up and running.

i believe we share goals, however, you are looking at some serious electrical usage regardsless of insulation of your home .
I use a heatpump for my domestic water and heating ( and a mini split where i can't get my infloor heating ).
you would be using a minimum of 30 Kwh in winter ( i also leave in Europe, rather just across the sea from you ) and about 7 Kwh of daily use in summer.

you do need to be looking at what is allowed and certified in the UK, or you will not pass inspection, nor be insurred .

my system :
12k Sunsynk 3 phase inverters ( you may be able to use a smaller model, will depend on you peak load when running off grid ), controlled by Solar Assistant, controlled by Home Assistant , both sharing a pi..
given the IT infra structure you're running i highly suggest over provisioning you inverter and batteries so they survive boot ups/down plus heatpump will put a generous load on it
about 60 KWh of batteries , also monitored by before mentioned Solar Assistant
a considerable amount (31) of Jinko 545 watt panels
while inverter is closed source ( the are litterally -0- proper inverters open source and within regulations ), control and monitoring is done by FOSS stuff

 

[solartist]

There is no adequate renewable energy around, especially if everyone jumps on electric cars and heating at the same time over the next few years.

This argument is unconvincing and off-topic, sorry. enerPHit houses don't really need heating, except for faucets & showers, and the house's solar array & storage when finished should cover most of its electricity needs including charging a car if we get one.

My family is still in the UK and I see Mum's bills, gas is still way cheaper than electric for heating.

Not cheaper than insulating to a high standard. Not in the long run.

I am actually on your side, I love solar and am building a LEED rated home here in Florida. It will be entirely off grid and as such, I have looked closely at using propane for cooking and clothes dryer. But I came to the conclusion I did not want the extra cost of a tank etc and rely on someone else to supply it. I therefore committed 100% to solar. I think it will work out for us....well it has to now lol

Not sure how LEED compares to enerPHit.

For people who really like gas but hate suppliers, a home biogas reactor is possible - kit or DIY. I won't be doing that.

Anyway, glad you're on my side here. Thanks, and good luck with your build!

Oh also, very few if any professionals will install equipment you buy yourself.

OK then, time for me to find professionals who will do that.

 

[solartist]

I use a heatpump for my domestic water and heating ( and a mini split where i can't get my infloor heating ).

you do need to be looking at what is allowed and certified in the UK, or you will not pass inspection, nor be [insured].

Exactly.

One of the reasons I started this thread was so people could advise me which makes/models of inverter/AIO/etc are both legal/certified for UK use and capable of being controlled/monitored with FOSS and capable of handling the loads for my application.

So far in this thread, you are the first person to do that. Thank you!

my system :
12k Sunsynk 3 phase inverters ( you may be able to use a smaller model, will depend on you peak load when running off grid ), controlled by Solar Assistant, controlled by Home Assistant , both sharing a pi..
given the IT infra structure you're running i highly suggest over provisioning you inverter and batteries so they survive boot ups/down plus heatpump will put a generous load on it
about 60 KWh of batteries , also monitored by before mentioned Solar Assistant
a considerable amount (31) of Jinko 545 watt panels
while inverter is closed source ( the are litterally -0- proper inverters open source and within regulations ), control and monitoring is done by FOSS stuff

This is super-helpful. Thank you again!

I did not previously know about Sunsynk. They seem to be based in the UK, so ought to know UK certification requirements/etc. This pointer alone is enough to make me glad I started the thread ?

 

[houseofancients]

Exactly.

One of the reasons I started this thread was so people could advise me which makes/models of inverter/AIO/etc are both legal/certified for UK use and capable of being controlled/monitored with FOSS and capable of handling the loads for my application.

So far in this thread, you are the first person to do that. Thank you!


This is super-helpful. Thank you again!

I did not previously know about Sunsynk. They seem to be based in the UK, so ought to know UK certification requirements/etc. This pointer alone is enough to make me glad I started the thread ?

they are the same in hardware as Deye ( or in the us sol-ark )
here you'll find their certifications : https://www.sunsynk.org/certifications

Keith ( CEO and member here ) also has a YT channel where he posts quite a lot of video's, but amongst those are complete installer courses :

https://www.youtube.com/@sunsynk5885

 

[solartist]

they are the same in hardware as Deye ( or in the us sol-ark )

Yeah, I just spotted that they're actually Chinese. The "Part of the Global Tech China Group" link in their website footer was one of the clues, and their main address seems to be in Hong Kong. I came back here to correct my earlier comment about them being in the UK, but you got there first ?

here you'll find their certifications : https://www.sunsynk.org/certifications

Keith ( CEO and member here ) also has a YT channel where he posts quite a lot of video's, but amongst those are complete installer courses :

https://www.youtube.com/@sunsynk5885

Cheers. I'll check those out

 

[solartist]

my system :
12k Sunsynk 3 phase inverters ( you may be able to use a smaller model, will depend on you peak load when running off grid ), controlled by Solar Assistant, controlled by Home Assistant , both sharing a pi.. ...
while inverter is closed source ( the are litterally -0- proper inverters open source and within regulations ), control and monitoring is done by FOSS stuff

One of the reasons I started this thread was so people could advise me which makes/models of inverter/AIO/etc are both legal/certified for UK use and capable of being controlled/monitored with FOSS and capable of handling the loads for my application.

So far in this thread, you are the first person to do that. Thank you!

I spoke too soon

I looked into SolarAssistant just now. Unfortunately, it is proprietary software. It is not free-as-in-freedom ("open source") So, it won't be an option for me.

I would have to find other ways to monitor/control the inverter.