Not using solder paste?

I made the mistake of ordering a board and not ordering the solder paste stencil.

So what to do - well, not a complex board, I tinned the pads and applied some flux as it is a bit sticky...

Then I applied the components. Now this is where I wish I had applied less solder to make it flatter as they did not stay put very well.

Getting flux on the tweezers was also an issue, so lots of cleaning.

Then I cooked in the oven the same as if I had solder paste.

To my utter amazement, it worked perfectly. I did put in a sonic cleaner, which did not help much in cleaning it up...

But the damn board works!

So there you have it - an option when you have no stencil!



First off, an apology! FireBrick and A&A have been pioneers in making IPv6 work in practice in the UK. The current FireBrick operating system has been designed with IPv6 from the start, and not as an afterthought. This means that at every stage the notion of an IP address comes with the notion of "which sort of IP address". We are proud of that. But we have been lax in one notable area - DHCPv6. Sorry.

The problem is that IPv6 has a mechanism, SLAAC, which assigns an IP address on Ethernet. It is very simple, and works. The router sends out some details (which can include DNS servers, etc, as well), and allows devices to pick an address. With 64 bits of local address, this is easy to do in a way that avoids any collisions. Indeed, devices often pick lots of addresses, cycling them quickly, to hide how many devices you have on a subnet, etc. (privacy addressing). It works well, and in the UK it was pretty much the only thing being used.

DHCPv6 is a "stateful" way to manage addresses, and like DHCP (for IPv4) it has a lot of options. Thankfully IPv4 DCHP has been around a long time, and the sane options to implement are clear. The FireBrick IPv4 DHCP server is actually pretty flexible and powerful and works well.

But DHPCv6 is newer, and has a lot of options. One of the big ones is "prefix delegation" - telling a device it has one or more blocks of IP addresses to use on its interfaces to give out to devices it has connected. This is just one of the complications for a DHCPv6 server on Ethernet - it has to consider not only allocating and tracking an IP address, but a block of IP addresses and routing. As a client we also have to consider if we want to ask for a block of IP addresses and what interfaces we can use to assign those IP addresses.

We do this already, but we only do it for the LNS/PPPoE (broadband) side of things. We work as a server when operating as an LNS, linking to RADIUS and routing. We work as a client when PPPoE, allocating a dynamic block of prefix delegated IPs to the LAN interface. So we have a lot of the tools already.

Until now we did have an option on our router announcements on IPv6 over Ethernet to allow a DHCPv6 server, and even an option for that to be the FireBrick itself. The idea was the FireBrick would issue an address the same as SLAAC. This was specifically to allow for devices that only worked using DHCPv6. But we really did not find any such devices. Devices (like the FireBrick itself) that only handle SLAAC are actually more common from what we can see.

But the time has come for DHCPv6. And there will be several alpha releases around this. We need to take careful steps to integrate the code which currently only works for LNS and PPPoE to be used for Ethernet. We need to decide on the config for this, and the options we offer. This will not be simple.

So, watch this space. It will take a while as we are working hard on the new 10G FB9000 router right now, but we are starting. We already have an alpha which does a consistent simple IPv6 address allocation over DHCPv6 on Ethernet (a hash based address to avoid giving out the MAC). We hope next to have DHCPv6 client over Ethernet and then DHCPv6 client prefix delegation. The server side will be a lot more work considering the config, and how much we link with IPv4 config, so bear with us.


The latest crazy law

The latest crazy law imposed, today, with no notice, is The Russia (Sanctions) (EU Exit) (Amendment) (No. 9) Regulations 2022. My good friend, and lawyer, Neil, has blogged on it already...

This is one of those rare cases I am blogging as director of AAISP rather than purely personally.  See here for A&A news post on this.

The main issue is we, as an ISP, have to "take reasonable steps to prevent a user of the service in the United Kingdom from accessing, by means of that service, an internet service provided by a designated person."

I do wonder why - I mean this is asking anyone providing internet access, whether for their family at home, or via free wifi, or anything, to do this? Why not ask the handful of transit providers to do this instead - much simpler, surely? But OK...

My first issue as an ISP is what are those services? I mean these are not services offered by some corporate entity that happens to have a "designated person" as shareholder, officer, or even employee, but services actually provided by a "designated person", over the internet. This list of such persons is not simple or small, and working out which provide what services over the internet will not be a simple task.

So we plan to ask, maybe, OFCOM, as they have specific enforcement requirements in that legislation, for a list of such services.

But when we get that, what then? LOL, like we will get a sane answer, ha... But, well, then we have to try and block access somehow, if reasonable.

We do not have means to block access or filter anything by IP, or DNS name, in our network!

I can't stress this enough, we have never had any order to block anything or any previous legal requirement to do so, really. It is, in my opinion, not "reasonable" to expect us (for no payment at all, or otherwise) to magically implement such a measure, especially to do so between Laid before Parliament at 5.00 p.m. on 27th April 2022 and coming into force 29th April 2022, really. Or even (as it will cost a lot) later.

Update: As some people say, we have BGP routers that could have a black hole route added, and customer facing DNS servers that could have a bogus entry added. But this is the tip of the iceberg in terms of a "system" for blocking. There needs to be the management systems to maintain the blocked IPs and domains. Systems for who can add and remove entries. Systems to ensure they are applied correctly to the various config files. Procedures for handling mistakes. Procedures for handling support queries from customers relating to blocks (and mistakes in blocks, over-blocking, etc). Systems for getting the sanctions lists, processing it, researching the services provided by those Russian companies, and making changes over time. Yes, some ISPs have (most of) these systems and procedures in place for other reasons. We don't! On top of which, actual URL blocking is a completely different matter and simply impossible when considering the current use of https.

Update: That said, for a couple of domains, it is not impossible to add a DNS entry manually, but it is far from a scaleable solution.

What could we do?

At a push we could refuse to answer DNS for some domains on our customer facing DNS servers, but customer do not have to use them, so that would not be effective in meeting the requirement. And weirdly the providers of public DNS, like and are not subject to this order - why?

Indeed, if we had some way to block some routing to some IPs (and remembering we must not "over block" to meet net neutrality laws), customers are allowed to, and often do, use VPNs, so again, it would not actually be effective.

I am not sure we could "reasonably" take any technical measures. The closest we could get is not answering some DNS.

So what do we do?

Well, step one is we ask OFCOM for the list of services, and see what we get. That is it for now. I expect no list, to be honest, which sort of solves the problem.

Then we consider what next.

The other consideration is that we might "ask customers nicely" not to access such services. That sounds like a reasonable step to me. We might do that once we have a list of such services.

Update: The sanctions list has been updated - two "designated persons" have been listed: TV-Novosti and Rossiya Segodnya, with the web site rossiyasegodnya.com specifically listed. What is odd is that OFCOM have seen the list and decided that the sites rt.com and sputniknews.com should be "blocked" somehow. So which is it? What is the process for finding the "services" offered by the designated persons and how did OFCOM come up with those two domains? Is every coffee shop offering WiFi to somehow research some Russian companies to find what services they offer?

In practice, it looks like our (free) customer facing DNS servers may have to fib about a couple of domains for now. Not a scalable system, but hopefully "reasonable steps".

And just to be clear, I want the war to stop. But I am not sure how these sanctions help or are in any way effective. They are, however, a break from any notion of "mere conduit" for Internet Access. If they are needed, they are in the wrong place (surely transit providers, or DNS providers like and, are more appropriate than every coffee shop offering WiFi). So we are doing what may be the only "reasonable steps" we can do.



Back on the Mammoth, having re-installed Mastodon.

You don't have to set up your own instance. You can simply join any of the bigger mastodon servers. If you want to make your own, it is still a pain to set up, but the instructions do work if you follow them carefully. Here.

The larger servers are struggling a little right now, after the Musk take-over of twitter has been announced. Seems a lot of people think Mastodon is viable alternative. It may be, but it is different.

It is much more of a "social" network in that you have to socialise, and talk to people, to get followers and find who to follow. But no adverts and no "algorithms".

But I am here, on Mastodon, again, toot.me.uk/@revk so do follow me if you like any of the stuff I do/say.

P.S. As this is a new server, some servers have the old stuff cached in some way, so I may have to follow you first to get it to sort itself out. Let me know if you have problems following me.


Solar install, part 4 (export)

Read part 1 for more background.

I'm really pleased with the install, and we are making 40 to 50kWh a day at the moment. So now for some paperwork...

One bit is a micro generation certificate, this confirms it is all installed by approved installers, etc, and has the details. I need that for and export tariff.

I have been discussing with the installers - we have a 12.09kW system (i.e. 31 x 390W panels), but they are east / west split so never all get direct sunlight. With the split and roof angle they have determined that maximum is going to be around 9kW, so a 10kW inverter is more than adequate. It will be interesting to see in the height of summer - but interestingly, even though only April, the generation in June won't necessarily be as good as you expect just by sun angle, because it is hotter. Being hotter makes the panels less efficient, so may cancel out the extra sun angle.

I heard there is some trick with some panels with water cooling, i.e. using the waste heat as a heat pump and keeping the panels cool for maximum PV. But we don't have that :-)

So, I may be making 9kW some days, yay. But what do I do with that?

As you will have read, the primary target for this my own usage, and then the excess power goes to a battery, so I can then use the power later when the sun is not shining as much - maybe covering my whole 24 hour day's usage for most if the summer, which is mental.

The bad news!

The battery is likely to be August. So 4 months of no battery. So, I'll export to the power grid, simples!

Well, yes, but that needs paperwork to. The Distribution Network Operator have to give permission to connect, which they have. The DNO decide what they consider the limit for export, if everyone was exporting, before it would cause damage to transformers, etc.

It varies, it can be as low as 3kW. Thankfully, in our cause though, it is 6kW. So we cannot export more than 6kW, legitimately.

Well 9-6 is still 3kW, and whilst I have the hot tub heating during the day, normally, a daytime idle power (when hot tub not heating), is a bit more than 1kW.

The result is, on a really sunny day, we could be exporting 2kW too much. Ooops.

Well, not quite, the inverter is set up to limit to the agreed amount, 6kW. It adjusts the panel optimisers to ensure that overall they are not quite as efficient, if we go over 6kW. So on a sunny day I should see a flat top on my export stats at 6kW. It means I will be literally throwing away some sunshine, up until I get my battery.


However, there is another snag - the final handover paperwork is normally done when the install is complete. The permission covers the solar and the battery - but we have no battery for 4 months - so I have no paperwork. So I cannot get on an export tariff.

The installers are trying to work out with Western Power Distribution how the handle an interim paperwork handover for the solar only without losing the permission to install the battery later. Hopefully something we have sorted shortly.


So the next step is a tariff for the next 4 months. It looks like I can get 5p/kWh from so.energy, less from Octopus unless I move to them for import as well. Octopus also do an agile tariff, but not being able to control when I export (yet, no battery), just relying on sunshine, I am not convinced that makes sense (a variable tariff for every half hour noticed a day in advance).

So my plan for now is probably the 5p/kWh from so.energy for 4 months, if I can confirm how the 12 month minimum works penalty wise. Once I have a battery I will need to revisit tariffs as there are interesting options.


Solar install, part 3 (performance)

Read part 1 for more background.

I have now had one cloudy day, and one much more sunny day. This is April 14th and 15th. Bearing in mind that the forecast from the installer was an average of 24.28kWh/day over the year. I expect winter to be much lower, obviously.

Cloudy April day

The cloudy day had a total of 17.9kWh, usage was 47kWh.

Sunny April day

The sunny day had a total of 48.5kWh, usage was 45.4kWh. Yes, we made more than we used!

P.S. After a few days I can see we are typically doing 40kWh to 50kWh most days, the low cloudy day seems to be very much the exception.

What does that mean?

It looks very much like the forecast is, as expected, somewhat pessimistic and I can expect much higher. The 40 and 50kWh days in April suggests we will easily exceed the forecast for the year.

The sunny day is interesting - we made more from solar than we used, even in April. I can't be sure how usage will go over the summer - I expect it to drop noticeably as the heated kitchen floor used a lot in the winter, but also we now have air-con. The air-con is quite low usage at present, but when it is really hot and sunny it will be using more. The good news is those days will have more solar.

It really does highlight the need for the battery (which is on order). With a battery I could have had all of yesterday's power from solar and imported none. That is, quite frankly, amazing.

I have also changed the hot tub, as one of the really high users of power, to heat during the daytime when we have spare solar rather than maintaining temperature all day and night. Especially without the battery - that alone will save £'s a day.


Solar install, part 2 (tasmota/shelly EM)

Read part 1 for more background. See my blog on power monitoring.

I installed monitoring for power usage a few months ago. This is using Shelly EM power monitoring modules with current clamps, reflashed with tasmota code. It works well, I have some nice graphing stuff (all on GitHub).

Now I have the solar panels I have to allow for "negative" power flow, i.e. exporting to the grid.

Sadly it did not work, and my googling did not help. I raised a question, and apparently this has come up before #15315#12861, and a merge #12874, great. So the current code should handle the ADE7953 sign bits and do negative power.

The problem was that I was not seeing negative values at all, so my graphing is all messed up as all export shows as import. Very frustrating. I even went to building tasmota code myself, and no joy.

However, I found a clue, in the later source code (after that merge), it has a model flag to indicate if Shelly 2.5 or Shelly EM, and it only does the negative power on the Shelly EM. This has to be a clue.

I tried the config template from the code, and nothing happened. Still not working. After a lot more reading of the code I worked out the issue.

It is subtle, but the "2" next to the ADE7953_IRQ, rather than "1" seems to be the trick here. Of course, changing to "2" did not fix it - because I was exporting AND I had the clamp backwards so still seeing +ve (import) figures only. Fixing the clamp as well, and now it looks good.

Now I have graphs that show negative (export) power, at last. I have to tweak my graphing code to allow for that next...

And yes, the sun is shining a bit now...


Solar install, part 1

I finally have a solar install, and a battery on order. So this blog is the first one on this - I don't have a lot of data yet as it just went in, and I don't have a battery yet as they are like hen's teeth, so more on both of those later.

Solar panels waiting to be installed

The basics on a solar install

Firstly, it is not a simple/quick "free electricity" solution for the current price rises. There is more to it in terms of whether it is worthwhile, and over what period, and so on. I hope I can explain some of the factors here. There are several factors.

When the sun actually came out yesterday

How much power do we use anyway?

In my case we use a lot of power. Over the winter, since I have started monitoring in more detail, we have been using around 60kWh a day. One kWh (kilowatt hour) is one "unit" of electricity, and currently that is costing me over 28p - but tariffs are a key factor here. 60kWh is a lot, and a typical household is more likely to be 10kWh/day. Bear in mind that will depend on the time of year and the type of heating and so on.

One of the first things I did was install some monitoring. This is way more useful that simply having a smart meter as it tells me much more accurately where the power usage is happening. This meant some Shelly EM modules with tasmota and current clamps - not that expensive, but did mean messing with current clamps on lots of circuits. It means I can graph usage per circuit.

It immediately highlights the key uses of power here are the hot tub (yeh, it came with the house), and the heated kitchen floor (also came with the house). Other users like tumble drier come in when used, obviously, and now we have air-con that too is a noticeable factor. Some adjustments to temperature made a noticeable difference, and I really want to find something nicer for the kitchen floor (it is also a living room). The rest of the house is gas central heating. I would say that summer is expected to be lower, but the air-con will make a difference.

So yes, we are a very high user. This is, however, a factor in terms of solar - if you make more than you need you are "selling" it as export - but getting a good tariff for that is not so simple. You make/save most with solar if you are using it yourself, as that will save you money at that huge 28p/unit rate. Exporting it may only get you 5p/unit. Oddly you can have a different company for "exported" power payment than for your "imported" power - crazy, but apparently the best deals on export are when both are the same.

The other issue here is that our usage is in bursts - we have a base of around 1kW a lot of the day, but hot tub uses an extra 3kW in short bursts, and the kitchen floor is even more, but again in short bursts and often in the morning before the sun rise in winter. So we have these high bursts of usage that will often not be covered by solar. This is where the battery comes in - being able to store the extra solar when only using 1kW and power things when they burst. (more on power monitoring)

Hot tub

The good news is the air-con is not quite so bursty the way I have it set up now, and this can more easily be covered by the solar before I even have a battery.


So why solar anyway?

One obvious factor is saving money - but this is where there is a catch - if I simply put the money in a savings account and used it to reduce my electricity bill every month, that would probably be better for the next decade - well, maybe, but certainly for a few years.

This is all a bit of a "Vimes's boots" scenario - i.e. the poor have to keep buying cheap boots, but the rich can afford to spend a fortune on boots once and they last so much longer than they end up spending way less overall. The same is true here - if you can afford a solar install you can have decades of spending way less on electricity - something from which that those who cannot afford the install would greatly benefit.

So what other factors are there?

Well, one factor for me is the stability of this (or perhaps "energy security" is a better phrase) - electricity prices are silly now and could get extra silly soon (next rise is October). If I can produce a noticeable chunk of my electricity, and have a means to reduce a lot of the rest (shut down the hot tub, etc), I can protect myself from those silly prices. It is, of course, hard to pin a figure on what this means in advance, especially if trying to plan for the next decade.

Another factor comes in with the (expensive) battery (Tesla power wall). It is able to power the house, so a short power cut (of which we have only had one so far) can be covered. Again, there are risks - the way the country is being run, and factors like Russian oil/gas, etc, could mean power cuts - who knows? This is a small risk, but it would be very nice to manage small power cuts - whether deliberate ones, or simply storm related (as last time).

Finally, it is investment in the house. We expect to be here some time - maybe "forever" from our point of view, but the solar install should improve the house value. This may be useful if ever we do want to sell, or if we raise funds on the house, or even when it comes to our kids selling it. The installation is not just throwing money away - it increases the house value some (yes, this itself is complicated as some older solar "roof rental" deals are more of a burden and can reduce value).

Of course it is also an environmental aspect - it helps reduce the burning of fossil fuels. Indeed, I seem to have earned a gold star already!

Solar and/or battery?

There are two distinct aspects - solar panels and battery. These are distinct but do help each other, so you may want solar, battery, or both, depending on your circumstances.


The Solar aspect is pretty simple - the panels make power - more in summer than winter - only during the day - more when the sun is shining than in cloud. The installer can predict how much in the year. That will allow you to work out the cost vs payback. The installer should do proper forecasts.

For us, based on 22p/unit starting point, we are looking at a little over 10 years to cover the cost of the solar system install. Over the following 10 years we are looking to save a further twice the cost of the install. This assumes some inflation on electricity prices as well as some degradation on performance.

On this basis you can see solar cost per unit over 20 years is good, better than you would get from any electricity supplier even now. On a long term plan it makes sense. It may even make sense for some people on a "loan to install" basis, but that is a risk over future interest rates.


This is where the options and costs get even more complex. It seems there are some battery systems which basically help "level out" the solar some (those 3kW spikes for hot tub, etc), and are not a lot of good as a "backup" for a power cut. These are probably a no brainer in terms of managing the solar supply from any install as the usage and the solar can vary during the day - something even a small battery can level out nicely.

There are, however, some that can back up the house, and the tesla power wall is one of those. Such systems cost a lot.

For a start, the battery helps make the most of the solar. It means you are not exporting. Without this, any time in the day we are making more than we use, we are sending that electricity to the grid. It you are lucky, and have sorted the paperwork (I have not yet, just installed), you may get 5p/unit for that. It is much better for that to go in to a battery and then get used later saving you 28p/unit.

For example, right now, on a very cloudy April morning, I am making over 2kW but only using 1.43kW. As I don't yet have all the paperwork to be on any "export tariff", I am just wasting that 0.61kW going to the grid.

A cloudy morning

In an ideal world with solar and battery, when you have enough solar in a day to cover a day's usage, you want a battery that can store enough to cover the night time, and hence never import any electricity on those days (typically in the summer). If you have usage figures then that can be quite easy to work out. Even so, you may also be able to move usage around - especially if anything (e.g. a car) needs charging as well.

But a battery has other advantages - apart from the possibility of covering a short power cut, it can also work with agile tariffs - charging from the power grid when electricity is very cheap in the middle of the night, etc. You then use that power during the day.

Indeed, just having a battery, and no solar, can end up making your electricity very cheap. We may even want a second battery at some point for this very reason.

In this case you want a battery that can charge in the short periods of cheap power (middle of the night), at the same time as perhaps charging your car, and hold enough (allowing for any solar contribution) to power your house for the rest of the day until the next cheap charging point. Again, not too hard to work out, and to decide if you want to cover winter (less solar) and summer (less battery needed).

So for some people a battery is an option - but a good battery system like the tesla power wall can end up costing a lot more than the solar install.

There are some power companies (Octopus, for example) with special tariffs where you give them control of your battery (if a Tesla battery) allowing them to feed in power when they need, and they end up charging you only for net power usage at a much lower rate. Such a tariff is extra "simple" as you don't have to do anything - it just works and you have power at a low rate. They even keep some in reserve for power cuts.


In my case, I have gone for both - though that does make it harder to work out what each separately may be saving me. It also means I need to sort some suitable tariffs. That special tariff that need control of the battery also only works if you also have a solar install and a tesla battery. Even then, there are some limits per battery on solar capacity and daytime usage, with which I may have a challenge on only one battery. This could be fun, and I am sure another blog post eventually.


The forecast payback, as I said, was a round a decade, for the solar alone, based on 22p/unit starting point.

That said, if I was to take a simple calculation of 60kWh/day usage at 28p/unit, that is £6132 a year. If I make an average of only 25kWh/day from solar, and get on a 10p/unit "they control the battery" tariff, that gets to £1277/year, saving around £4855k/year. That makes a payback of a £22k solar and battery system under 5 years. If I can make use of the battery to charge at 5p/unit middle of the night, top up with solar, and use battery for my usage, then payback would be 4 years. There is even a saving on standing charge to add to that. Now allow for inflation, or maybe an October rise to 35p/unit, and well, things get very interesting - there is a very real prospect of the whole system payback in only a few years - even Vimes would be impressed.

Of course, it could be we get a sane government, and sensible power pricing, and the payback is way longer - but I am, none the less, buying stability.

More specifics...

The supplier I have used is Green Park Power, based in Abergavenny (a short walking distance from my house). They have been very professional. I'm impressed.

The system is 31 panels, each 390W, so 12.09kW total. It is using solar edge - with per panel optimisers and an inverter in the loft. The per panel optimisers are DC/DC convertors allowing the mix of panels that have high and low light levels to all work together, even allowing for some in shade. Traditionally panels in shade can bring down the overall performance, but not so in this system.

It also allows monitoring of power per panel, and whilst there system is cloud based (which I dislike), it is very good. (I thought solar panels did not like "clouds"). I may set up some MODBUS stuff to provide some local monitoring in the long run, obviously. The inverter does connect to WiFi or, as in my case, Ethernet.

The figures in my case are roughly £12k for solar and £10 for battery, but it will very much depend on circumstances.

It really is simple

It is just working, the solar power cancels a chunk of the usage and creates some export. I mean, yes, once I have a battery, I may want to fine tune to make the best of some tariff, but in general I don't have to actually "do" anything - it just works. For now (before I get a battery) I have tweaked the settings on my hot tub, as one of the main power uses in the house, to be when the sun is shining.

But ultimately if someone bought the house they would not have to "do" anything, it would just lower their bills!

More to follow...

The solar edge monitoring if very comprehensive, and in a few days I should have some more useful data to share. Later this year I'll also have a battery to play with.

The first day, yesterday, was very gloomy, wet, and cloudy, but in the afternoon we were seeing a consistent 5kW, and at one point in the morning when the sun came out, well over 8kW. In our case, even though the system is rated to 12kW, it is 12 panels facing west and 19 facing east, so not expected to have full capacity, making 8kW rather impressive. I am going to love seeing a proper sunny day on this. But only starting stats some time yesterday, I don't even have a full (cloudy) day's stats yet.

A quick update: First whole day (all cloudy) 18kWh, second day (more sun) 43kWh so far (4:30pm). Remember the forecast was only 10kWh/day over the year, and at this rate I'll exceed that just in the summer.


Power line signalling thoughts (demand power management)

There are ways that things can communicate over power lines, notably Ethernet over power, which, IMHO, is crap. I am sure it has its place, but I would avoid like the plague.

However, I can see one area where some simple signalling would be very cool, and ideally in a really standardised way. Indeed, the idea that this could even signal incoming on your mains feed is not at all daft.

It actually sort of exists, it is frequency - when under 50Hz (UK) the power grid is struggling to meet demand, and when over 50Hz it has extra capacity. At present, few, if any, devices can detect or use that. Just using that could be useful, but I am thinking only a simple signal of 5 possible values.

What I am talking about is some signal that can tell a device :-

  • Right now power is effectively negative, please consume some power now even if it is going to waste
  • Power is cheap now, if you have a choice, now is the time to use it
  • Normal - use power as needed
  • Power is expensive now, if you have a choice, now is the time not to use it
  • Please shut down usage if at all possible right now

Not suggesting a complex set of signals by any means.

Now, if this was inherent in the mains supply, that could be useful of a lot of devices in the home. Ideally you need some signally (i.e. not frequency, really) so that you can isolate and run your own in the house. So for a house with solar and not a sane feed in rate, you can set this based on your solar/battery status in the home. But for most people not having this, the grid can set it.

I guess, it could be a standard that is frequency as the primary key and a secondary power signally for home override, maybe.

The point is that lots of kit really has a choice. At the simplest level, things like electric emersion heater, but in my case things like my hot tub. At present my hot tub heats based solely on temperature. With a very slight bias it could target that heating when we have spare solar. Just adjust target temp by say 0.5C depending on the signal on cost of power right now. Same for water heater. Same for heating or cooling a home, e.g. even aircon. Especially true for charging anything from a mobile phone, right up to a car.

It would need to be a simple standard and somehow in the chipsets for power supplies on any and every device. A world wide standard for this would be great.


New air-con, part 4

As you know, I got air-con last year, and it had to be taken out. That was a Mitsubishi system. It did not manage to heat or cool even the smallest room sensibly, and had a show stoppers in terms of temperature control of the rooms. So yes, removed. We did keep the lossnay for fresh air though.

I have now got 4 Seasons Solutions to put in new air-con. It works. A lot of this blog is comparing the Mitsubishi with my new Daikin system.

Outside unit

The Mitsubishi system was set up with two outside units on the back wall. Each drove an inside unit. The Daikin is done with one outside unit. It is ironic that the old system seemed to really lack power to actually heat or cool even with more units of a similar size.

A single unit is better, not just for appearance but if there are any issues with planning permission. A heating only single outside unit is actually a permitted development. Yes this unit cools, but you then get in to interesting debates about what happens if you change a heating only (permitted development) to a heating and cooling (non permitted development) and how such a change "does not change the external appliance of the property" so is outside the scope of planning permission. One hopes we don't get in to that debate. In our case I have pictures of the place from just before we moved in with two large outside air-con units that had been there for years, so at best this is about the fact that the air-con location is slightly different. I doubt there will be issues, and retrospective planning permission is not usually an issue. If it was two units, it would be a different matter. It was quite handy as the second power cable and RCBO can be used for the solar install now.

Inside units

The Mitsubishi system had two inside units, each covering two rooms. I should have decided against this, in hindsight. The plan was that we would have motorised vents to allow each to work one room, the other room, or both. That actually worked. We also had relays to switch the controller from one room to the other (it oddly only handles one controller!). That too worked. What did not work is using the controller for temperature, so we could never control temperature in the second room on each unit (assuming the air-con worked properly in the first place, which it did not). So that was a show stopper.

The new system has 4 separate inside units. Even so, it is cheaper. It is cheaper than the rest of the original bill after paying for the lossnay to stay, even.

Like the Mitsubishi, these inside units are ducted. This is nice as it means no big wall mount unit - which frankly would have been difficult to find space to mount in some rooms.

However, one of the rooms has no loft. With the Mitsubishi system, we managed to run the air flow duct behind plaster board (there was a surprising gap) and behind wardrobes in a room above. It was a lot of work (which we did, not the installers). We decided that trying to run two more ducts, at 4 times the size each, would really not be practical. So we went with one of the 4 rooms having a wall mount unit. The pipework for this was somewhat easier.

We kept the original duct for the lossnay, so we still have fresh air.


The ducts were different. The new system had ducts that are 4 times the size of the Mitsubishi system. This is where we changed one to the new ducts.

The vent/covers are nicer too.

What is more fun is the original Mitsubishi installation had ducts that were half the size of this, i.e. 1/8th of the size we now have, and they were adamant they should have been enough!

Wired controls

The Mitsubishi system had a separate control for the lossnay and air-con, which was annoying in itself for an integrated system. It allowed one air-con control for each inside unit. It could not use the controller as temperature reference - crazy.

The new system has wired wall mount remotes. They are not bad. (yes, some holes to fill).

The system can use the controller for temperature - yay, and all 4 rooms have separate control (the wall mount uses an IR control though). The system, as a whole, is only heat or cool at once, but each room is separately controlled at separate temperatures at the same time. As we have central heating (also controlled by Shelly modules) if we ever need mixed heat and cool we can do that easily enough.

The new controllers also have bluetooth and an app. This means the controller itself is pretty simple, and all the admin or installer menu stuff is on the app. Not a bad compromise.

Computer integration

This is where the Mitsubishi was really limited. There was no WiFi or bluetooth. The unit did have some connections that allowed for external control, so as fan speed, but not something simple like heat/cool mode. I was expecting to connect to this, and maybe even reverse engineer the wired remote. I stopped doing that when it seemed clear that the whole thing was not going to work well.

The Daikin system, however, has bluetooth on the wired controllers, and wifi modules. OK, yes, I have reverse engineered and replaced the WiF modules, but even so, that was not too hard. What they provided did actually work (if you are happy with a cloud based system).

The fact I now have fine control using my own WiFi modules is a real win. At present it is heating my room over night (see image on right).

Some limitations of ducted systems

Having now tried two ducted systems, they are a little different than the wall mount I have been used to, and some things still hold true for that.

Both systems had few fan settings. The Mitsubishi had 4 levels, but only the top two actually ran the compressor, the first two just blow air, so very limited. The Daikin has 3 levels. The wall mount Daikin has 5 levels and "auto" and a "night" mode. I'd love a "night" mode on the ducted systems to be honest, but looking in to noise attenuators possible, or just getting used to it.

Another caveat is that a ducted system, having vents in the ceiling, it can take a while to heat as the heat fills from the top of the room - this creates a noticeable lag in heating at bed level. The wall mounted unit is much better at this as it able to direct the airflow down and create more circulation.

The proof of the system

The real proof will be in the summer, and we will see. Tests so far suggests it just works, and works really well.


Almost forgot, as people will ask: It cost around £10k and took a week to install.