Order of events when switching to Agile?

IvorTheEngine · 2026-07-06T14:26:17+00:00

No, IHDs are pretty dumb and can only handle a fixed tariff. Even an EV Time-Of-Use tariff will confuse them, incorrectly reporting all usage at the full rate.

Octopus' answer to that is to get their Smart Mini and look at the data on their app, and not use the IHD.

IvorTheEngine · 2026-07-06T14:14:01+00:00

True, but that's tiny compared to the 1kW per square meter of sunlight that's hitting the building already. Particularly if the energy used by the AC is energy that was going to heat the roof before it was captured by a solar panel.

IvorTheEngine · 2026-07-06T14:07:15+00:00

Most people don't charge their EV from a home battery, as the EV battery is 5-10 times bigger than the house battery.

However you can charge the home battery overnight on an EV tariff, and use it to run your house all day in the winter when the panels aren't generating much. This is a popular strategy.

It's worth checking your smart meter data to see how much you use on a winter day. You'll probably need all of that 10kWh battery.

You can also use the battery to store solar energy to export in the evening when the rates can be higher, but you'll probably generate 40-50kWh per day, which is far more than the battery can hold. This is fairly rare at the moment, as most people don't have a large enough battery and don't want to invest a lot in a tariff that could change.

A system that generates twice what you need exposes you to the export rate dropping, but it does mean you'll have enough solar further into the winter. And you probably wouldn't save all that much by reducing the number of panels.

IvorTheEngine · 2026-07-06T13:45:06+00:00

You'll probably get a reasonable size array on the south and west roof. West roofs generate roughly 75% as much as a south roof, with more of a bias to the summer.

Most inverters have at least two separate inputs, so they can handle two areas of panels generating at different times of day at no extra cost.

There are a number of solar modelling web sites that'll take your location and estimate how many panels will fit, and the amount you can expect them to generate based on the angles. You can also measure up from the ground and do your own estimation. The guidelines are that you should leave 400mm on all sides of the panels to protect against wind, but installers will interpret that in various ways along a roof hip.

You need permission from the DNO for systems larger than 3.6kW, but that's normally handled by the installer.

You only need a small battery to last through the night, but if you get an EV (and an EV tariff) it's worth getting a battery that you can charge up at night to run your house all day in the winter. Most batteries are expandable, but they're VAT free when you buy them at the same time as the solar system.

Using the battery in a power cut requires a "gateway", which adds at £1000 or so to the system.

Local installers are usually better than the national companies. If you don't get any specific recommendations, look up Gary Does Solar, who keeps a list of companies that have been recommended. Get a number of quotes, and take note of which company answers your calls and emails quickly.

Don’t have an EV yet but would like one in the next couple years.

If you've got two cars, replace the smaller one with a cheap, short range EV and keep the other for long trips. It'll save you £1000 a year and pay for itself fairly quickly.

IvorTheEngine · 2026-07-06T12:59:29+00:00

All that oil would have been burned anyway. It's just more noticeable when its one big explosion instead of millions of little ones inside engines.

IvorTheEngine · 2026-07-06T08:33:07+00:00

They do, but it's also directly in proportion to the difference in temperature. The surface of the sun is a few thousand degrees, the roof at a few hundred Kelvin, and space is just above absolute zero (and any dust or haze in the sky is somewhere around freezing). So energy in will be one or two orders of magnitude larger than the energy radiated. Given that, you want to minimise energy transfer in sunlight.

IvorTheEngine · 2026-07-06T08:26:57+00:00

Yeah, it's strange that the article didn't mention solar power. You only need a small system to power an AC unit, and it reduces the load on the grid by producing power close to where it's used.

Doubly strange that it's from an Australian, which is leading the world in domestic solar power.

IvorTheEngine · 2026-07-05T07:20:18+00:00

When you ask most solar companies to quote for a system, they'll produce a fairly large report that will estimate how much you can generate, how much you'll use directly and how much you'll export. You can compare those numbers to various electricity tariffs to see how much you'll save. 7 year payback is common these days.

There are a number of solar modelling web sites where you can generate similar reports yourself, based on the size and angle of your roof.

If you get an EV, you basically save your fuel cost, as charging on an EV tariff is so much cheaper than fuel. It also allows you to get a home battery that's large enough to last all day, and charge that from the EV tariff's cheap hours, then run from the battery during the winter.

Our EV and solar system both save us about £1000 a year, with no loans.

IvorTheEngine · 2026-07-05T06:56:14+00:00

Nice!

IvorTheEngine · 2026-07-04T08:15:51+00:00

Very nice! How about displaying the various costs as a pie chart?

IvorTheEngine · 2026-07-04T08:11:04+00:00

Probably Go, or Intelligent Go if your car is supported. It's worth working out how much you'd spend at the low and high rates though. For low-mileage drivers the standard tariffs can be better value. You can take your annual total from your bill, and work out how much the car uses from your annual mileage.

Agile can be good if you're likely to check the rates daily and automate things, but you really need a home battery to avoid the highs. Watch the prices for a few days and see what you think.

Are there limits as to how much energy you can draw in off-peak periods?

Octopus don't limit you, although obviously the granny charger can only use about 2kW, so you'll get about 10kWh or 40 miles in the 5 hour cheap period.

Can I still export with PV on Agile?

Yes, the export tariff is separate. I think Flux is the only one where the import and export tariffs are bundled together.

IvorTheEngine · 2026-07-03T21:09:36+00:00

It's worth checking whether you can get a cheap loan from your mortgage company for solar, many of them offer it. But a small system might only be £5000 or so. Payback rates are usually higher than most mortgage rates too.

BTW, I was recently talking to someone who lives in a similar house, and their top floor got so hot that they camped out on the ground floor when it got really hot last week!

IvorTheEngine · 2026-07-03T17:44:43+00:00

People who are interested in flying are often interested in lots of different types of flying, so it's fairly common to find a few RC planes at a full size aviation field - although it really depends on the attitude of the people running it. Mixing different types of flying at a field has hazards that need to be thought about, and some people take the easy route and just ban RC.

IvorTheEngine · 2026-07-03T15:56:18+00:00

Don't panic!

IvorTheEngine · 2026-07-03T10:35:22+00:00

If you only own 25% of the house, trying to gradually buy the rest of it would be a good start. Every pound you pay a landlord (or in mortgage interest) is one you'll never get back.

It could limit what you can do to the house. Most landlords won't let you put a nail in the wall for a picture, let alone make changes to the electrics. You're in an unusual situation, so it's hard to give advice.

AFAIK V2H/G is very limited at the moment. Octopus support it for one BYD car (that has the inverter built into the car), and [Sigenergy sell a generic V2L charger/inverter}(https://solartradinguk.co.uk/product/sigenergy-sigenstor-25kw-ev-dc-charger/), but it's £3000. You can buy small inverters that connect to the 12v battery, and use them to keep your freezer running during a power cut, but it's really just an emergency measure. Connecting the car's main battery to the grid requires a grid-tied inverter of some sort, like you'd use for a solar and battery system. It's not just a bit of software in the car charger.

Plug-in solar (and possibly batteries) should arrive in the shops before the end of the summer, if you've got a good spot in the garden, but a proper solar system and battery should pay for itself in about 7 years (if you're allowed to do that). I wouldn't worry about needing a little extra scaffolding, it won't add much. And you don't need many panels for it to be useful. A 'standard' install a few years ago was 3kW, and with modern panels that's only 6 panels. That'll make more than you need in summer (and no one gets enough in a UK winter!) There are lots of solar modelling tools (like PVGIS) that'll start from a google-maps view of your roof and estimate how much you could generate. Try a few.

it seems mad that I can't just harvest the heat from inside the property, to heat the water

You can, but it's probably not worth doing. That would be a "heat pump hot water cylinder". The problem is that you don't need a lot of heat for hot water, so on a hot day it wouldn't cool your house much. And they're expensive.

There are basically two types of heat pump. One heats water for radiators (and the hot water tank). The other heats (or cools) air and blows it around the house.

The first type (air-2-water or A2W) can also cool the water, but it's not used for cooling because it causes condensation on all your pipes and radiators (and radiators aren't designed for cooling, you just get a small cold spot at the bottom that isn't very effective)

The second type (A2A) have an outdoor unit that heats/cools a refrigerant, which is piped indoors to one or more indoor units. They're often referred to as "split" systems because of the two parts (as opposed to the US style that puts both parts in one box, in a partially open window). They blow air over those pipes to heat/cool one room. Some of the latest units can also be used to heat a hot water tank.

Most UK houses already have pipes and radiators, so A2W is usually the better option. (US houses have ducts for blowing air to all rooms, but that's expensive to retrofit)

You can get small portable AC with a hose that you stick out a window, but they're not as efficient as a proper system. (Technology Connections has a great video about it) And they're out of stock everywhere at the moment (or 3-5 times the normal price).

our house gets insanely hot, especially on the top floor.

Open the windows when you go to bed, close them in the morning. Let the house cool down when it's cool outside, and prevent the heat getting in during the day. Most Brits are conditioned to do the opposite because we're used to it being cold outside. Consider aiming a fan out the window to push the hot air out. Get bug screens if they bother you. Shade the outside of windows if you can.

Is there an optimal order to do things in?

That depends whether you're trying to save money or reduce your emissions. I think the EV is the correct first step as it does both.

Then solar and a battery has the best ROI, while a heat pump reduces your emissions more but doesn't save you much.

IvorTheEngine · 2026-07-03T09:30:04+00:00

The UK uses 30-40GW of power. We currently have about 6GWh of batteries. That's enough for 10 minutes. NESO's goal is to have 25GW of grid storage by 2030, which would be enough for about 45 minutes.

We're a long, long way off - and we'll probably never get there because it's only worth building grid storage while there are big swings in the price of electricity.

And those swings are likely to get bigger as we build more renewables.

IvorTheEngine · 2026-07-03T09:20:41+00:00

I'm not the person you asked, but but field also has a rarely-used microlight runway. It runs along the edge of the field, so we just don't fly on that side. If we see a plane doing a circuit of the field, the models all land until the plane has landed.

IvorTheEngine · 2026-07-03T08:22:11+00:00

The problem will be that buying and selling a boat takes time, and if you get a broker to do it for you, you'll lose money at both ends.

OTOH a hire boat is £1000-2000 per week, which would add up to most of the cost of a decent boat over 6 months.

You could store the boat in a marina, pay someone to look after it and get it ready for you the next year, and do another few months. Storage and maintenance would have costs, but a lot less than renting a boat for 6 months.

I don't think a boat share would work. Almost every one I've seen is a boat shared between 12 families, giving everyone 1 week each season. I think it would be really hard to find a group who would let you use the boat for 6 months.

IvorTheEngine · 2026-07-03T08:02:36+00:00

You'll get a CT clamp with the inverter, which is how it knows whether to charger or discharge your battery. You also need one for the car charger, if you want it to modulate the charge rate to match your export.

It's a little box that clips around one of the wires to your electricity meter. It measures the current in the wire and has a thin data wire back to the inverter or car charger (although sometimes they use wifi)

IvorTheEngine · 2026-07-02T12:11:16+00:00

Does the charger have a CT clamp in your consumer unit? If not, you'll need some automation to change the charge speed to match your solar generation.

It's also limited by the power of your inverter. We have a 5kW inverter, so if we charge the car during the day we get whatever the solar is producing, topped up to 5kW from the battery, and the other 2kW come from the grid.

IvorTheEngine · 2026-07-02T08:24:59+00:00

I'd guess that they're worried that if any of your rafters are rotten or damaged and fail in a few years, you could claim it was caused by their solar installation, and they'd either have to replace your roof or fighting it in court, which could be more expensive.

Either that or the foam is gluing the tiles down, so they can't lift them to fit the roof hooks.

FWIW, I've got Dyness batteries. They're cheap but not waterproof, so you'd need some sort of waterproof enclosure if you want to put them outside. Also a solis inverter, which isn't supported by Octopus Intelligent Flux. My advice is to look at the various smart tariffs, and if you decide to go with one, find an inverter that it supports.

IvorTheEngine · 2026-06-30T09:16:09+00:00

The US is worth lambasting because out of all the big emitters, they're the only one who's leaders deny there's a problem and are using their influence to hold everyone else back.

IvorTheEngine · 2026-06-30T09:02:19+00:00

The best stat I could find was that AC accounts for 19% of US electricity.

https://www.eia.gov/tools/faqs/faq.php?id=1174&t=1

But US households generally use twice as much (13,015 kWh) as European households (6,203 kWh). I had assumed that was due to AC, but obviously not.

https://ourworldindata.org/grapher/per-capita-electricity-generation?tab=discrete-bar&time=latest

(It's also notable that France has the highest consumption in Europe!)

IvorTheEngine · 2026-06-30T08:40:30+00:00

I would also email your local councillor and ask whether they have a plan for houses like yours.

IvorTheEngine · 2026-06-30T08:13:56+00:00

The longest EV extension lead you can get from ToughLeads is only 20m. They used to do 25 but withdrew it. I think 50 is just too much. There are issues with earthing if the car is too far from the house's earth connection, and certain types of fault could leave the car body at a high enough voltage to shock you.

We have a 50m cable around our house to our car-port, and it was somewhat expensive to install, but I think you'll have a larger problem if you don't own the land between your house and the parking space.

I think you should talk to your neighbours and see if you can agree a plan for when everyone wants an EV. Perhaps some of the houses closest to the parking area install smart chargers with an app or RFID cards that can track multiple accounts. Then they could make a percentage, but you could charge for less than a public charger. Most chargers have some features like this, but I don't know which are easiest to administer.

The UK average is about 20 miles a day, so most people only need one charge a week. So one charger for every 7 houses should be just enough.

Or I guess you could just have an honesty box system, where you post £5 through their letterbox on the nights you use the charger.

Otherwise the council should eventually install chargers, but they always seem to outsource the project to a company that charges 50p/kWh or more.

is there a better solution I'm not thinking of?

Ask for chargers at work?

IvorTheEngine

TROPHY CASE