Jeremy Harris

My wife has always wanted cars with a sunroof. I hate them with a passion. She's compromised with a "panoramic" roof in the Yaris she drives at the moment, and hasn't mentioned not having an opening roof for some time. I'm not even a fan of "panoramic " roofs, TBH. I put up with the all glass roof on my car just because there was no other choice. Thankfully it's tinted and so isn't too much like being inside a greenhouse.

I've been looking at various battery storage solutions for a few years. None are perfect, and some are a bit bizarre in the way they work. Until recently, getting backup power from a battery system wasn't that easy, but there are a few systems around that offer a separate, always on, supply via the battery. This can be connected to a separate circuit in the house to power essentials that are needed in the event of a power cut. Tesla offer a changeover relay option with their latest Gateway, too, but of all the battery system the Tesla Powerwall seems the least flexible. Users have little control over the way that the Powerwall works, so it will charge and discharge according to what its systems believe to be appropriate, rather than what the user actually wants. Sometimes this is OK, sometimes it results in the system charging from peak rate electricity. A good example was this weekend, where Powerwalls went into "Storm Mode" automatically, and fully charged from the grid, on the assumption that there would be power cuts. I suspect that those not in an affected area, who had to pay for peak rate electricity used to charge their Powerwall because of this behaviour may not have been best pleased. Of all the other systems available, it looks as if the Pylontech batteries may well be the best overall value, plus they use a battery chemistry that is well suited to the high cycle life required for home battery storage. When it comes to inverter/charger units, then there are several that are compatible with the Pylontech batteries, and the choice really comes down to the peak power needed, price plus how much control you would like to have over the system. For example, SMA make a pretty good inverter/charger, but it suffers a bit from the same sort of behaviour as the Powerwall. The Sofar and GroWatt inverter/chargers are more flexible, but the most flexible seems to be the Lux Power range. These seem to be more easily programmed to do exactly what the user wants, rather than what the manufacturer expects the user to want. For me, having control of when the unit charges and discharges is key; the very last thing I want is a system that charges because some bit of remote code in another country has signalled the thing to charge because it believes that's the best option. I want to be sure that the battery only ever charges when there is an excess of PV generation, and then, as a secondary charge source, during the E7 off peak period.

That was my view, too. The first three contracts we placed were for the groundworks, the borehole and the house foundations, frame supply and erection. All were firm price, and I suspect we paid over the odds for the ground works contract, but at the time I was insufficiently confident to feel able to manage any other sort of contract. By contrast, I believe that the firm price contract for the foundations and frame supply and erection was a pretty good deal, and I doubt I'd have been able to do better by choosing another option.

The only reason I emphasised exchange rates was because we purchased our house from Ireland, and it was shipped from there in large prefabricated panels, so having a contract that was firm and priced in pounds, rather than Euros was reassuring. A fair few people here buy fairly expensive stuff from Europe, too. We bought our MVHR from Denmark, and it seems as if the UK installers for this make also buy units in from Denmark to order, so there may be an exchange rate risk there.

The good news is that the unit is one of the newer ones, with the redesigned fill valve. The original fill valve fitted to the earlier models looks quite different. The resin is probably fine, it's pretty robust and will tolerate a fair bit of abuse. About the only thing that will kill it is if someone has decided to flush something nasty through it, like neat bleach.

No idea, but you've given me something else to check next time we're anywhere near one!

The fill valve is the pipe thing mounted on the side, between the two tanks. It's a type of float valve, that sets the level of brine in the outer tank. If the resin needs changing then it's not that difficult to do, it's just a bit fiddly. There are resin fill ports on the tanks, at the top. Hardest bit may be flushing the old resin out of each tank. The challenging bit is if the water meter develops problems, or the O seals on the valves it controls need replacing, as it's a night mare to reassemble. When you connect the thing up, with salt in, do two manual regenerations once the salt has had time to form brine in the tank. To do a manual regen, fit a screwdriver in the white slot on the top of the water meter, push down against a spring and rotate the white bit clockwise through 360 degrees, until it pops back up. You will hear it start to regen one of the tanks, a process that takes ten minutes or so to complete. Once it has finished regenerating one tank, repeat this process to regen the other tank. The need to do this is largely because you don't know the state the unit is in, and this ensures that both tanks are fully regenerated at the start. The unit is then set up and ready to go.

Firm price contracts are always going to contain a fair bit of risk contingency, they have to in order to allow for unforeseen problems. Fixed price contracts (which, as above, are not really fixed at all) will also have some risk contingency built in, but this can be less, as a fixed price contract allows price variation for some aspects outside the contractors control (like exchange rate variation hitting materials pricing). It seems that people often confuse firm price and fixed price contracts. Worth remembering that a fixed price contract does not define the exact price that will be paid, whereas a firm price contract does.

This will not work well with the Model 3, because Tesla have failed to implement charge control from a smart charge point. It will work with most EVs, though, as the majority do implement the spec correctly. It will work OK with other Tesla models, it's only the Model 3 that refuses to wake up and accept charge from a controlled charge point. There are a few smart charge points that can control EV charging like this, although the range of charge current is limited by the specification to a minimum of 6 A, about 1.4 kW. The Zappi is probably the best known that allows this sort of control. DC charging isn't easy at home, as I don't think anyone makes the required DC connection units. DC charging is normally reserved for rapid charging (50 kW and above usually). The only practical option for home charging from PV at the moment is AC charging with a charge point like the Zappi, that has some form of PV charging capability (I say some form, as it's not 100% PV because of the 6 A lowest current limitation). It may be that Tesla get around to fixing the Model 3 scheduled charging problem, although they have been aware of it for well over a year now and there's been no indication that they will fix it any time soon.

The display in my car has an image of the car (the exact model, including colour and wheel type) on the right hand side of the screen, the bit that displays traffic, people, obstacles etc all around the car, as well as the road markings. On this image there are projected reflections on the top, that use the current weather data for the car's location. If it's sunny there's a reflection of the sun on the roof, if it's cloudy there are moving clouds reflected on the roof, and on a clear, dark night there are reflections of stars on the roof. . .

One of the problems if smart metering gets used for load shedding (every smart meter is capable of doing this - your supply can be remotely turned off if you have a smart meter) is that they need to sequence the way loads are brought back on line after a load shedding event. At the moment, there are no published plans to use domestic load shedding, it only applies to commercial users. However, the remote disconnection provision was included in the smart meter spec, for two reasons, to allow customers to be cut off if they fail to pay their bills (this primarily applies to those with credit meter type tariffs at the moment) and to allow load disconnection in the event of a major network problem (much the same as the LFDD system that applies to commercial users). One of the problems with load shedding by turning the supply off to customers is that when the supply is turned back on the grid may see a large step increase in load. Managing big step changes is challenging, so, where possible, they like to be able to sequence reconnection so that users with large connected loads aren't all switched on at the same time. This used to be a potential problem when night storage heaters were popular, and teleswitch controls were common, and its pretty common now to find that the time clock in an off-peak meter with switch control is slightly out. Having all the meter clocks on a very different time means that the off-peak loads don't all switch on at the same instant. My guess is that they want to know about any heavy loads in order to assess the impact of any reconnection event.

Just checked. We're currently paying over £50/month, plus the cost of calls. We can get a package from Plusnet that gives us free calls for £32.99, or £9/month less if we don't want free calls. Methinks we're being well and truly ripped off. . . It really pisses me off the way these companies just increase prices for existing customers. I'm sure that we started out with a contract that cost around £30/month.

We've been with Plusnet (which is really BT I believe) for around three years now. I suspect we're being ripped off just because I've not bothered to look around for a better deal.

Same for us. Our non-food bills are (roughly): Council tax £2,076.31 Broadband and phone £640.44 Electricity £582.24 House Insurance £210.18 TV licence £154.50 We receive about £1,000 a year in FiT and export payments, which more than offsets the electricity bill. I think I need to do something about the 'phone and broadband bill, though, as it seems daft paying more for that than we do for electricity.

This one, I think: https://www.ebay.co.uk/itm/Prefab-House-Building-Office-Timber-A-Frame-Home-Lumber-House-58-5-sqm/264406305835?hash=item3d8fd80c2b:g:VE4AAOSwdSRaDwHv

It doesn't look like I'm "most people" either, at ~ 4,500 kWh for household electricity (including heating and hot water) and ~ 2,000 kWh for car electricity use. Quite a contrast to @SteamyTea, though, with his ~5,000 kWh for household electricity (including heating and hot water) and ~ 20,000 kWh for car energy use.

So similar household energy consumption (although there are two of us here), but a massive difference for personal transport energy use. I'd guess that, for most people, personal transport uses significantly more primary energy than anything else. Really need to turn both the house and personal transport numbers into primary energy to make a fair comparison, though.

What's the ratio of transport energy use to house energy use here, then, in terms of probable CO2 impact? Our house uses around 4,500 kWh/year from the grid, my car uses around 2,000 kWh/year from the grid. We probably also use around another 3,000 kWh of potentially zero carbon self-generated electricity.

If that were its electricity consumption, then that would cost me about £1,630 in off peak electricity. Interestingly, it's equivalent to roughly 80,000 miles a year in my car.

There are three basic forms of contract pricing, fixed price, firm price and cost plus. Fixed price isn't fixed, variation is allowed for things outside the contractors control, like exchange rate variations etc. Firm price is fixed, in that it is the actual price that should be paid at the completion of the contract. Cost plus is basically what it costs the contractor to do the job, plus a specified profit element. For example, it could be actual costs plus 20% profit. The snag with cost plus is that there is no incentive for the contractor to get a good price for materials, as the cost will be passed on in full. There's also not much incentive with cost plus to finish by an agreed date, unless this is specified in the contract.

Welcome. There are loads of threads here discussing it: There are probably several more as well, so a further search should throw up more results.

I believe you do, as a part of this deal. That was certainly the case last time this came up. It depends on how the battery system is connected, I believe. If it's AC coupled and doesn't take your max export over the agreed figure with the DNO then I think all is OK, but there is the possibility of there being an issue if the battery system either takes you over the agreed export limit, or if the battery system is DC coupled to the PV system.

That's the snag! At the moment, around 65% or so of our electricity is at the cheap rate, 8.148p/kWh. Our total electricity bill for the year is under £600, but we receive about £1,000 a year in FIT and export payments. Losing the FiT would be have a big impact. We get paid a bit over 5p/kWh for the deemed export (roughly £150/year) and we also get paid another ~£850 as FiT payments.

The main problem for us is that, because we don't use much grid electricity (around 4,000 to 4,500 kWh/year), any saving from being on a slightly lower tariff is too small to warrant doing much by way of an investment in something to reduce it. The numbers for battery storage just don't stack up for us at all well, especially not the Tesla Powerwall, with its oddball controls that mean you cannot directly and easily set the thing to charge and discharge when you want it to. I was very seriously looking at other, cheaper, and more easily controlled, home battery systems, but even then the cost would never have been recovered through life. I was working on the basis that having a backup power supply, in the event of a power cut, would be worth paying for, but since our local network had a load of cables replaced last year, it seems to be far more reliable. It used to be that we'd get a power cut in any sort of a blow, but yesterday and last nights storm was the worst we've experienced here, and the power didn't as much as flicker.

Bear in mind that you can only put around 28 kWh of charge into any EV during the 4 hour Octopus Go off peak window. That's around 100 miles or so, depending on the weather, which may or may not be enough. I quite often need to put close to double that amount of charge into my car overnight.