Energy saving measures around the house

12 V circuits are very common in cottages in Norway. The basic setup is solar panel + battery. You can also hook up a generator (diesel or gasoline). The bad side is that everything must be 12 V. Expensive/poor/small fridge, TV, freezer everything, and cabling drawing lots of power. In later years inverters is used more and more to get normal 220 V 50Hz, the setup is otherwise the same. Then you can use normal fridge etc. It’s all meant for “off grid” application though. It’s all off the shelves products.

A typical 220V setup looks like this (just remove the generator) Red lines are AC 220V, blue lines are 12, 24 or 48 V DC:

Hi Graham,
Live aboard boat owners usually relied on Shore-power connections to supplement but the newer solar panels are much more efficient.
A typical 2 person live aboard can run 4 batteries at 12v connected to 2 x 1.0mx1.5m solar panels with a charger/inverter unit.

In this configuration it’s possible to run a 240v fridge 24/7 12v TV and satelite dish at times, occasional 240v cappuccino machine, hair dryer, and general LED lighting almost without ever connecting to shore power. A 3rd panel may ensure that.
A 3000w Victron Phoenix inverter sits at the centre of this with a victron solar controller.

When the washing machine is used they usually have a genny running to supplement if not in a marina for shore-power.
That sort of set-up demonstrates that you could easily move all lighting and small power items to Solar without concern. I’d estmate £1800 to £2k to get all set up if doing it yourself. I’ve no idea how long the break-even would be.
On a boat that’s not considered because it’s borderline essential for off marina living.

I wouldn’t bother with DC wiring unless we are talking about a remote off-grid installation where every Wh counts and one can’t quickly run to the next store in town to buy a replacement LED bulb or a hair dryer anyway. There are all-in-one devices for solar installations available which combine an MPP tracker for solar panels a battery management system and an inverter. You can connect them to your existing AC wiring and they automatically store surplus electricity in a battery and feed it back when needed all while your house wiring is still connected to the grid. They are not cheap but you don’t need additional/parallel DC wiring which is also not cheap unless you do it yourself and you don’t need to buy expensive DC appliances. Only downside: If you order now you need to get lucky to get it within the next 12 months. And if you you don’t like integrated devices you can have it modular just like with avionics.

And no I don’t sell these kind of devices. I only started to read up a little bit on that topic and have recently bought two solar panels to tinker a little bit with solar technology and to get some experience for a planned larger installation. They now lay flat on my patio and are already producing a quarter of my daily consumption. The inverter plugs into a standard wall socket so not even an electrician needed.

But why not start to save energy without adding complicated technology? I have the lowest energy consumption among my friends and colleagues (only counting families with a house and at least one child to be fair). I do that by not owning a TV (no time for that crap) and not owning a tumble dryer.

Clipperstorch wrote:

I wouldn’t bother with DC wiring unless we are talking about a remote off-grid installation

Well, the major reason so many people are talking about installing those devices are the mounting energy prices but also the bombardment with news which indicate we may well end up with black outs and energy regimes next winter.

For many years I’ve tried to go the solar way but up to now my neighbours don’t want to hear of it and I need their consent for putting them on the roof. I am now thinking of a diesel generator which can feed my essentials and possibly non-install solar panels (up to 600 W are allowed to be plugged into a wall socket if I understand it right) to get a minimum off grid emergency supply.

The question I have about solar arrays which feed into the net is, what would happen if the net dies? Are there provisions that in such a case the house becomes off grid or can I manually switch my house to feed only of the solar array and battery?

It’s really appalling that in this day and age we need to fear for our electricity. Thanks to all the idiots who force us onto electric cars and shut down our NPP’s at the same time.

It is simpler to leave the house as it is and get a generator. We live in the countryside and have thus been very likely, at times, to get long power cuts.

So every piece of IT is on a UPS. We have UPSs coming out of our ears, both at home and at work, and some are powered by Concorde RG aircraft batteries which no longer quite pass the load test but they will run probably another 20 years driving a UPS You just need to find a UPS which uses 24V.

Then we have a Briggs & Stratton 3.5kW generator. That will power the whole house including the central heating water pump, but obviously not electric cooking and such. It will run for ~15 hours. Of course I have plenty of fuel for it. And enough diesel in cans to survive 2-3 months of petrol station unavailability (1 car tank lasts us 1 month). I have my super slick titanium 200 quid liquid fuel camping stove We would have to get a proper one of those…

If I had solar panels, or some big battery, it would still be easier to get an inverter and just plug that into a socket somewhere, having first turned off the house master switch, obviously Then you just need a “suicide cable”

There is a neater way to do this, with a generator changeover switch.

A proper automatic fallback is more complicated, plus you almost certainly need a big generator and those cost real money, not the 500+ quid for a little generator. You are looking at 5k+. Plus, if you want continuous power, a big UPS because it won’t start up instantly. Those systems of course exist but cost a lot.

If you have oil heating (the case in much of UK countryside) then a diesel generator, one which can burn heating oil, would be a good idea.

Forget solar if things turn difficult due to “Putin activity”. The sun doesn’t shine much in N Europe, and the PV panel area needed for a few kW is big.

Mooney_Driver wrote:

The question I have about solar arrays which feed into the net is, what would happen if the net dies? Are there provisions that in such a case the house becomes off grid or can I manually switch my house to feed only of the solar array and battery?

Depends on how much you pay. The better systems work similar to an online UPS with automatic switch over and you only notice that the house went off-grid because you constantly need to readjust the clock on the microwave oven because it derives the time from the normally very precise 50Hz mains frequency. But then, what would you do with power but no internet?

So is there any point in putting panels on my roof? Or just a massive waste of money?

For domestic hot water, none at all. The only hardware which had anything like a decent life were the vacuum tubes; everything else was junk. And just about everybody has problems with leaks where the pipes pass through the roof. Some awful stories… Think of the conmen and shysters in double glazing, insulation, roofing, you name it, and now imagine this is going up on your roof where you can’t get to stuff properly.

For a swimming pool, potentially it works, because that can use “low grade heat”.

I used to make and sell controllers for both above; the latter was a viable model because the panels (ground laid at an angle like the solar PV farms are done; almost never roof mounted) were very cheap. Just black plastic panels with channels inside. But for a pool there are nowadays better solutions: the electrically actuated “solar” covers (plastic slats, clear on top, black on the bottom) do a fantastic solar heating job and will easily take your pool to +35C (!) much of the summer. Then a cheap air-water heat pump will extend the usability season.

For PV (electricity generation) much depends on your local situation. One guy I know installed a huge PV surface area, and then his local electricity company changed the tariff and it became uneconomic! But he was happy because he would not have got planning permission to build the house without the “green” aspect. Too many factors for me to comment, except to say: beware of subsidies, because they can disappear, and don’t underestimate the cost of hardware failures.

I would not touch any of the above installations with a bargepole. The return on capital is finely balanced on so many factors.

With a totally purpose-built house, it is different, but almost nobody is doing that. It is expensive to do, and requires good and unusual workmanship. A friend in Germany (where this is supposedly mainstream) tells me the workmen are crap, the materials/products are crap, and he had to do a lot of it himself. But, yeah, if you start with very good insulation, everything becomes easier And you do underfloor heating, and then a heat pump becomes viable, and if it is ground-source, it will work in the winter also.

I see a new built house not far from here. Walk past it every day. Underfloor heating, ok, but a crappy little 6kW air source heat pump. They will freeze to death. The house is not specially efficient; you can’t get planning for a “moon base” architecture

Graham wrote:

So is there any point in putting panels on my roof? Or just a massive waste of money?

I don’t know how stuff works in the UK. In Norway we have these “smart systems”, mandatory from some years back. With this we can for instance turn of heating, stop charging the car and so on automatically when the price is high. The price can fluctuate a factor 10 or more through the day. This can be combined with for instance a Tesla house battery as a buffer. As things have turned here right now, I think a battery would be more useful than solar panels. Charge it when the price is low during the night, feed the house at peak prices during the day. I will essentially only pay for cheap energy and have no worries. Such a battery will of course work well with solar panels. But is it worth it? Solar panels gives a very limited amount of energy, and they cost a lot. They have to be compared with the lowest price, not the highest (if I already have a battery). Perhaps it would be better to have another battery, than to install a solar panel.

If the prices for electricity is steady and high, then this would make solar panels the better option.

You can also go off the grid completely. Then solar panels will be very beneficial, but a battery would be essential.