Jeremy Harris

My view is that the whole concept of FIT/RHI is/was deeply flawed right from the start. Looking at the very basics, the government (and everyone else) recognised that the initial barrier to entry for micro generation systems was the high capital investment needed. It would have been relatively simple to apply a subsidy to PV panel and inverter costs, on a per watt basis, as a one-off subsidy for the capital investment, with that subsidy level being subject to review every few months.based on the volume of units sold. It would have had the same impact - reducing the price of PV (or other systems) so that people would be inclined to buy them, but would have removed part of the "wealth barrier", because the scheme they did introduce only applied to those who had enough savings to buy the relatively expensive systems and be willing to accept their investment being paid back over 25 years by a subsidy. Investing the same amount of money as they did with FIT (ignoring the fact that they did this via a roundabout way by getting suppliers to actually make the payments, who then get relief from tax on those payments anyway) would, I'm sure, have had a more beneficial impact. Those who wanted to make a relatively small investment, in return for reduced energy bills plus a small income from the sale of exported energy could have done so with a much lower capital outlay, which would have resulted in a broader range of people fitting systems. It would also have removed all the rent-a-roof scammers, and the regulations could have been arranged to avoid the heavy overhead of MCS certification, by just allowing any SE to do the structural calcs and any qualified electrician to certify the wiring. Another benefit would be to remove the ongoing overhead of running the FIT scheme for well in excess of 25 years (I hate to think what that costs).

No it isn't, and never was, and I don't quite know how you reached the conclusion that the subsidy had any effect on our decision making process (it didn't at all - I wanted to DIY the install, but couldn't for warranty reasons). It's not like we get much of a subsidy anyway - the premium we had to pay for the PV system outweighed any small subsidy that we get, and we still get paid less for energy generated than we do for energy imported, even with the combination of the FIT and export payment. Read my blog and you will find I opted not to fit an MCS approved ASHP installation, so don't get RHI. With PV I had no choice - I needed a warrantly, as the in-roof PV is an integral part of the roof covering, so had to have an MCS install whether I wanted it or not. Generalising about people's motives causes offence, so it's best to check out the readily available facts before doing so. High FIT rates are long gone. We don't get them and neither will anyone else now. What does remain is the high premium payable for an MCS approved installation, as that is very definitely now an obstacle to people having systems installed. A DIY system can be installed for around half, or less, than the cost of an MCS system, including the cost of a Part P qualified sparky to wire things up.

Not their smartest ever move, IMHO. It seems that every time the government decide to introduce incentivisation schemes associated with renewables or energy reduction they screw up, often very badly indeed. It really annoys me that every scheme they introduce ends up being abused by installers who increase their charges in order to either collect the subsidy for themselves as extra profit, or to increase the price to consumers because the government have created a rigged market.

I was interested in the solar tiles too, which was one of the main reasons for looking closely at NuLok. We don't have any shading problems, but I did find the price of the PV tiles to be high, around three times the price of an in-roof PV installation. Whether you can fit microinverters to the PV tiles to get around the shading issues I don't know, I'd guess it depends whether there is enough room behind the tiles to accommodate them.

Over the whole year we export about 30% more than we import, so in winter we are a net importer. It's not uncommon at this time of the year for us to export four or five times more energy than we consume each day. Our net export over the year is around 60% of our generated power, but we only get paid for 50% of it. I don't really have a problem with that, other than the fact that it would be very, very easy to just use the exported energy reading from the meter to pay us, rather than assuming a deemed 50% export, but the supplier can't be arsed to ever issue meter readers with an IrDA reader, even though the standard has been around for 20 years or more. We don't have enough PV, that's for sure. If we had more we would not have to rely on the grid so much during the winter. Given that winter is the period when the grid is more heavily loaded, it would make sense if we were better able to support it, but we fitted as many panels as could physically fit on the roof - we have no more space. Our PV array is 6.25 kWp, but I've been thinking of trying to add around another 1 to 1.5 kWp on the wall at the rear of the garden.

We export well over 50% of our generation, so it's us being scammed, rather than the supplier or generation company. Our meter is an old one, by current standards, but records export internally (as virtually all digital meters do, and have done for years as an anti-fraud measure). It's dead easy to read out the export register via the IrDA port, I do it all the time on our secondary (unofficial) house meter, as it's the easiest way to obtain good data on house consumption and generation. The fact that the suppliers can't be arsed to use the standard IrDA port to read meters is their problem. The meters were designed specifically to allow this many years ago, and at the same time the export register was added internally to allow better accuracy in cases of meter fraud, so the suppliers could make accurate claims in the courts for those that defraud meters using the very common reverse phase trick (I won't go into details, but suffice to say it's a very cheap and easy way to stop any meter recording imported energy).

In our old house we had a right angled worktop very like this, and the problem was the proximity of the joint to the sink. I made a new worktop using two layers of 18mm high density MDF, cut and glued to form the L shape with no joint on the upper surface in the corner. I had the MDF cut to size in the local DIY shed, and the corner is just overlapping glued together sheets. I then tiled the top with large format floor tiles (got them cheap as they were a couple of boxes that were the end of a line) and then finished it off with a thin varnished wood trim along the front, to cover the edge of the tiles and the MDF. It lasted very well and turned out to be both durable and reasonably good looking. It also needed no real skills to put together, just lots of glue and screws plus a bit of tile laying. The hardest part was cutting the mitres on the wood trim around the edge.

I disagree strongly. Our house has no access to the gas grid and for obvious reasons I didn't want to burn oil, coal or wood, plus we had no where we could safely fit an LPG tank if we'd wanted one. That left is having to use electricity, and so it makes perfect sense to divert self-generated electricity to the Sunamp PV and use it for our primary hot water system. By doing that we massively reduce our demand on the electricity grid, and, in summer, reduce the level to which the local grid shuts our inverter down (it's a rural area and the grid voltage regularly hits the 253 VAC upper bound on sunny days). The same goes for the diverter that feeds my car charger. It seems far better to use excess locally renewably generated power to charge my car on an ad hoc basis, than it does to charge the car from the grid, perhaps at a time when the grid load is already high. Smart meters are primarily a means to introduce variable spot pricing, and that will be the number one priority as soon as the adoption rate is high enough. The whole concept of smart meters was, and is being, driven by the need to reduce the high risk that suppliers currently have to hedge, which is setting their supply tariffs based on their best estimate of the mean 30 minute unit wholesale cost that they buy in at. Smart meters are not aimed at reducing emissions, improving efficiency or anything else that is claimed, they are primarily a means to allow consumers to be charged a flexible tariff, that aligns better with the wholesale cost per 30 mins + profit. Nothing wrong with that from a business perspective, but I do wish that the people "selling" this programme to the public would be honest. The truth is that once there is widespread rollout of smart meters the first thing consumers will see is a variation of the variable tariff scheme that companies like EDF already use in parts of France. We have one supplier already offering such a variable tariff scheme, albeit in a crude way, with peak time unit prices at close to 30p and off peak unit prices down to just a few pence. Right now we know that the off-peak wholesale cost drops below zero at time, and the peak wholesale costs approaches double the average retail price. This is something that the smaller electricity supplier find hard to manage, as they just don't have the volume of sales an financial security to ride out periods of high peak wholesale cost. I suspect there may well be some interference in the process by the large energy suppliers, using market forces (nothing dodgy) to make sure that wholesale prices stay high during peak times, in order to put the squeeze on the smaller suppliers. The sad thing is that smart metering has the potential to be a force for positive change, but I doubt very much that will ever happen, as the temptation to just use it to reduce supplier risk and raise profit levels has to be very high indeed.

That's a difficult question to answer accurately, but I can have a stab based on our experience. We have a 6.25 kWp array facing South at 45 deg inclination. This is pretty good for midday, especially in winter, because of the steep roof pitch. However, we come no where near to generating enough electricity in winter, and struggle to even generate enough to cover our base load. We rarely ever export any power for around 3 or four months, and often import power for days on end. Arguably our 6.25 kWp array is too small, and would need to be around three to four times larger to meet all our daytime loads, all year around. The flip side is that in summer we generate massively more energy than we can use. Most days recently We've been exporting a few kW, having charged up the Sunamp PV, charged the car, run the dishwasher etc. We export around 1/3rd of our total annual generation, and all that export happens in around 6 months. I don't think you can ever avoid exporting to the grid, even with battery storage. The dynamic range between a good generation day and a bad generation day is just too great.

Getting back to basics, nine times out of ten there are external things over which you have no, or limited, control over, so best to start with the framework within which you can consider options, before going down into rabbit holes about detail. The core external constraints are: 1 - What is the maximum power that the DNO will allow to be connected to the grid where you are? Everyone is allowed to installed up to 3.68 kWp of PV (16 A per phase) without consent from the DNO, but often the DNO will grant consent for more than this (our DNO was happy for us to go up to 10 kWp, for example). You can only find this out by asking the DNO, as it depends on the local network capacity. 2 - Are you able to roof mount and array, or will it have to be ground mounted? The answer to this leads to follow on questions: a) If you can fit roof mounted array, or arrays, what inclination and direction would they be able to face, and how much roof area will you have available? b) If you cannot fit roof mounted arrays, then, without planning permission, you are only permitted to install a ground mounted array of 9m², which isn't a lot, around 1.4 kWp. If you can gain planning permission you can fit a larger ground mounted array, and have the space, then you have more options. 3.- How much money are you prepared to invest in a PV system, and what sort of a return or benefit would you hope to get from it? I appreciate these questions are not instantly answerable, but there's little merit in planning a way forward until you have a feel for the limiting conditions that will post some constraints on what you would like to do. Once these are cleared out of the way, the it will be easier to come up with a range of options that you might be able to consider, and with a bit of luck match one as closely as possible to your needs.

Glad to hear you got a good result, that's better than I would have thought likely, and bodes well for the future in terms of support. The best bit is that it looks like you get to be able to play around with the old one and find out why it's not working and whether it can be fixed easily (and I strongly suspect it can). Good news all around.

I think the best approach is really to just fit as much PV as you can afford/have room for. I've never heard anyone complain that they have too much PV, and, providing you can afford it/have room for it there are no problems with having more than you need in summer, as that then gives you a bit more in winter. No need to switch anything on and off, the inverter does all that already, in effect, and will maximise the energy delivered from the amount of sun shining.

@newhome is spot on, and I speak from experience, having become obsessed with dealing with a neighbours problem tom cat. Getting that thing to stop crapping on our drive drove me to distraction, and was out of all proportion to the level of nuisance it caused. Neighbours don't have any legal responsibility to control cats, unlike dogs, and my experience has been that cats can't be made to do anything, they will behave as they see fit. The garden of our first ever home was a good example. I decided to create a vegetable plot and spent hours digging and sieving the soil to get a really nice seed bed. Needless to say it was used as a cat toilet as soon as I planted the seeds, both making a foul mess and digging out the seeds. I ended up covering the plot with chicken wire on a frame, just to keep the cats out. We have got wound up with a neighbour once, but quickly realised that the most sensible option was to just move house, as it didn't take long to realise that there was no way the neighbour was going to change at all. A bit drastic, but the good thing was that we moved to a lovely village over the other side of the Rhins, Portpatrick, where we had really wonderful neighbours. There are some people who delight in being able to wind up, or take advantage of, others. You're not likely to change them, so all you can really do is come up with a strategy to stop them getting to you. I know that's easier said than done, but staying quiet and ignoring provocation, whilst putting in place the best measures you can to secure your boundaries and reduce the nuisance caused by cats, is the best course of action, I'm sure. Back in the early-1970's, I worked with, and became close friends with, a chap from Antigua. He found me my first bedsit when I was kicked out of home. He had a car, when I didn't, and we'd often go out for a drink together, along with a fair bit of partying at weekends. It was great fun, as he saw it as his job to turn me into an honorary West Indian, educating my on the delights of West Indian music and food. What shocked me was the discrimination he faced everyday. Back then few garages were self-serve, and attendants would invariably refuse to serve him because he was black. The same happened in the bank one lunchtime - the clerk openly refused to serve him and told him to go somewhere else. If this had happened to me, I'd have flipped, but his way of dealing with prejudice and ill feeling was to be extremely polite and thank the person, with a massive smile on his face. He explained to me that he'd found it was pointless trying to change people's behaviour, as doing so would just get him angry. By letting their prejudice and rudeness wash over him, and just smiling and being polite, he managed to cope with it and just get on with life. He shouldn't have had to, but he'd learned the hard way that some people just won't ever change.

That sounds like a massive heating requirement to me, way, way more than I think is realistic, even for a house that is only built to "just" comply with building regs. Our house very worst case (house empty, no appliances etc running, maintained at 21 deg C) only needs 1.6 kW to maintain that internal temperature when it's -10 deg C outside. In reality, with two occupants plus the odd appliance, PC etc running, it rarely, if ever, needs as much as 1 kW of heating. Most of the time in winter it only needs a few hundred watts, if that, and we often have winter days when the heating doesn't come on at all. To specify the requirement, you first need to define the heat loss, for the worst likely case. There are several ways to do this, but I wrote a fairly simple spreadsheet that works OK, although it was only intended to be a "what if?" tool, to allow the quick comparison of changing design elements, when looking at the cost/complexity/benefit. The spreadsheet is here, if you want to play around with it: http://www.mayfly.eu/wp-content/uploads/2017/01/Fabric-and-ventilation-heat-loss-calculator-Master.xls

Ours is tucked around the back of the house, about a 18" from the rear wall, and about 4 ft from the back door. The area is very quiet, no traffic noise and really just wildlife (and the sound of the occasional mower). It's inaudible from the back door, and there's no way of knowing from inside the house as to whether it's running or not, other than by looking at the command unit on the wall. It can't be heard in the garden, or by the neighbours, either.

If anyone wants the Si version then they can have it for free, as it's no use to me, as it needs resetting. Just PM me and I'll stick it in the post.

Warning! Do NOT buy a timer with a Service Interval feature as in the post by @Alexphd1 above. I made this mistake and bought the Si version, and it becomes a useless brick after a year and shuts down. You can only reset it with the very expensive service interval resetting tool, which costs a lot more than the programmer. You also need to reset it every year when it shuts the system down. The "Si" models are intended for rented properties where landlords have a responsibility to ensure boilers are annually serviced. Unless you intend to use a service engineer who has got the proper resetting tool and make sure that you always get the system serviced and the programmer reset, you will end up with the system just shutting down. I found this out the hard way - anyone want a free single channel Si programmer that's bricked?

Where we are it's very quiet, yet the gentle noise from the air intake for our MVHR is louder than the ASHP below. I think it very much depends on the type of ASHP and how heavily it's being loaded. For a new build, even one that's just built to the bare minimum required by building regs, the heating requirement isn't going to be massive, so there shouldn't really be an issue with ASHP noise.

Yes, Touchwood do, as I mentioned earlier in this thread. I've seen one of the builds but not one with oak framing internally. When I got a quote they were expensive, though.

Yes, no problem at all. I pulled about 20m or so of 3 core 25mm² SWA through a 50mm duct, including a reasonably tight bend where it came up through the slab. Not sure why some topic areas are greyed out - I'll have a look and see if I can see if there's a problem. I've just looked and cant see a problem. Which sub-section were you trying to access, Power Circuits?

The curves change for different refrigerants, but remain much the same sort of shape, so the general principle still applies I think.

It makes no sense at all to have a CO detector in a house that has no combustion devices, as that's the only source of CO in a house. Makes more sense to have a CO2 sensor, as that's a pretty good indicator of general air quality indoors, I've found. When I measured CO2 levels in our old house I found an explanation as to why our bedroom always seemed to feel stuffy, despite a small window always being open. The CO2 level was increasing to around 1,600 ppm in the early hours of the morning, only dropping when we got up and opened the bedroom door. Opening the door quickly dropped the CO2 concentration, as it allowed through ventilation. I've no doubt that window ventilators would be just as useless as leaving a small window open, as long as the door is closed. It probably explains why houses with MVHR always seem to feel much fresher.

The experience and experiments that I've done with ours suggests that over sizing an inverter drive (and that's important) ASHP has two benefits. It makes the unit less likely to defrost, because the external heat exchanger is larger than needed for the heat output, and so the COP will generally be better, and the fan and compressor only need to run relatively slowly in order to deliver the required output. This makes the unit run very quietly, but having said that, when ours is running flat out it really doesn't make much noise, either. When it turns on it takes around 30 seconds to ramp up to full speed, and this tends to make it far less noticeable ( there's no big "whoosh" as it turns on). It then runs at full power for around a minute, whilst it reaches the set flow temperature, and then it ramps back down to whatever power it needs to maintain the set flow temperature.

Ours is about four feet from our back door. Standing at the back door I can't tell whether it's running or not, and invariably have to go and look at it to see if the fan is turning. One or two from here have been over and seen it, including @SteamyTea, and they may be able to give their own view on the noise level.

I doubt that you will never get the money back for such an expensive GSHP installation. At best a GSHP may cost a few percent a year less in electricity cost over an ASHP, if you ignore the ongoing maintenance cost, like replacing the (expensive) brine every few years. You need to work out the energy saving over the 10 to 15 year likely life of the system, and then see if it makes economic sense. I costed up installing a Kensa GSHP (and, FWIW, I though the Kensa was about the best option) and it came to around £8k, for a largely DIY install. I ended up fitting an ASHP that cost around £2k installed (again a DIY install). I get a real-world COP of around 3.5 on average and a GSHP might possibly have given an average COP of up to perhaps 4. Our ASHP uses around 2000 kWh per year, so if we had a GSHP that would reduce to about 1700 kWh, or an annual saving, at current electricity prices, of around 300 kWh, or £45 p.a. at most. Over the estimated life of the kit, of perhaps 15 years, then the GSHP would save around £675. So, had we opted to fit the GSHP, then we'd have saved £645 in energy cost through life, for an increased capital cost initially of around £6,000. In addition, the GSHP would need two or three brine replacements, at a few hundred pounds a time, through life. The efficiency difference for an ASHP with air temperature changes is tiny. Air at 10 deg C only has about five or so percent more heat energy than air at -5 deg C, not enough to make a significant difference.