Sweet Home 3D Forum - Print Thread

Sweet Home 3D Forum » List all forums » » Forum: Sweet Home 3D bar » » » Thread: Off grid solutions
Print at Dec 17, 2025, 9:41:42 AM

Posted by okh at Apr 9, 2015, 1:01:59 PM

Off grid solutions
Follow-up from thread 5778 and moving here: Challenge is a small cabin > 5km from grid and no motorised access (too steep, wild). It works well already with wood, candles and water from a stream (if not exactly family friendly). To increase modern comforts, planning is now:

Small photovoltaic system, 50w panel, 100 Ah battery capacity.
(for 8 LED lamps + radio + charging mobile/gps)
Small power generator for topping battery and use of tools/water pump.
Additional self contained solar lamps for exterior lights.
Solar thermal collector (air) to raise base indoor temperature, improve ventilation and reduce humidity/condensation. Will reverse in summer and draw cool air from vent on North wall (shade).
Hot water coil in wood-burner to provide for hot showers. (Possibly with 12V pump. Or maybe just air pressure camping shower filled from 25ltr tank on top of wood stove. Solar Camp Showers, the black bags, did not work: too flimsy and hard to keep clean.)
Cooking on gas (minimal consumption)/wood stove in winter.

The modest capacity is just a result of every component having to be carried several km in steep and rugged terrain. For now, a few ideas have been abandoned that could be good elsewhere:

Wind turbines (too noisy, relatively low output, vibrations, turbulence, too many moving parts and bad for bats/birds).
Pico hydro systems (stream too far away, components too heavy, too much maintenance, frost proofing). Yet, some very attractive systems are being developed.
Water tank heating from solar collector in combination with wood stoves even if there are some very good maritime and residential solutions available (too complicated, requires frost proofing, constant electricity for pumps).
Roof water collection (requires frost proof tank, filtering system and a new roof...).
A mobile phone (gsm) remote controlled gas/paraffin stove to pre-heat the cabin before arrival (feel uneasy about starting a flame without knowing whether a bird has snuck in the chimney and built a nest on top of the stove, and I dislike carrying gas/paraffin).
Gas/12V fridge (too heavy, energy consumption too high, using snow or cold stream water in a cold box in the shade is usually sufficient).
Heat pump, also for refrigeration (too complicated/heavy).
A modern wood burning stove to install in open fireplace. Would increase heating efficiency enormously, but they are just too heavy.
TV/Computer deliberately left out, not worth disturbing the silence and a lot more weight electric capacity needed.

The main challenge is actually sewerage/septic. Solutions exist, but I would prefer a flushing toilet (e.g. marine style), but environmental requirements makes it almost impossible to create a legal, composting septic system. Even so, the bottom line is that, yes, it is possible to create a comfortable living environment with pretty simple technologies.
So, if anyone has any experience with such or other alternative technologies, please share. SH3D is a brilliant canvas, but ideas for optimal solutions would be welcome.

Challenge

Much, much steeper than it looks, beyond snowmobiles

SH3D planning, early overview rendering

ok

Posted by Raysab at Apr 10, 2015, 12:47:55 AM

Re: Off grid solutions
Here we are in the core of the subject !
I’ll be giving a good thinking about all items you listed and share my experience here. I just need a few days for it as I’m busy finalising my container-bio-farm-off-grid project :)
For now, I’ll point out one important aspect of the off-grid concept: it's very hard and complicated to adapt or transform a pre-existing “traditional” house into a self sustained unit. Full efficiency from alternative energy can only be achieved when starting from scratch inclusive of rethinking home design and raw structural material in use.
The key word in this field is: Insulation !... before any other consideration.
Thanks again for opening this thread.

Posted by Raysab at Apr 10, 2015, 1:10:57 AM

Re: Off grid solutions
Oops, I made a double command here... BTW, can we delete or edit a post after it has been posted ?

Back to our subject, here’s some links to start with: https://youtu.be/qAJIandP5c0

I like the animation of this one: https://youtu.be/YylmeMilok8

Posted by okh at Apr 10, 2015, 1:58:49 PM

Re: Off grid solutions
Yes, insulation and material use come first. Useful videos (note that one is Australian, so when the video says North, that would mean South in the Northern hemisphere). There are really two different issues here. Neither is black magic. Pretty basic considerations (before starting your SH3D design) run like this:

For anyone designing a new home, net zero (or zero energy or passive house) should/must be considered (legal requirements are getting stricter). That has - as the videos show - profound effects on construction. Thicker walls, floors and roofs. E.g. traditional houses here are built with outside walls in wood some 15+ cm thick. To satisfy modern energy requirements, the same building technique now implies walls twice as thick. Also, orientation of the house, roof angles etc. must be calculated. BTW: What I dislike most about these buildings is that they need to be more or less airtight, which again implies a (mechanical heat exchange) ventilation system to get a half decent indoor climate (and there is still a feeling of being a canned sardine).
For existing buildings, as you say, it is in practice impossible to achieve the perfect: a zero energy building. But, there is still very much you can do with an existing building to reduce energy consumption (and/or switch to renewable). To take our own (on-grid) example: We put new panelling on the house, added extra insulation/wind-proofing, changed a couple of windows and sealed a few cracks (infrared camera useful). Switching to LED lights and letting two new efficient wood-stoves provide most of the heating was revealing: hot water (long showers) now account for most of the electricity bill. That means we are considering pre-heating hot water via solar thermal collector (water) and/or the use of heat pumps. The long and short of it is a considerable reduction in carbon footprint and considerably lower energy bills (admittedly in part thanks to cheap access to firewood). And all this before we have sacrificed any comforts. If we could kick a teenager out of the shower at half time, the saving would be in the order of € 500 annually. While it will take some time to recover the cost of the investments, it has increased house value, improved environmental conscience, made us more flexible in changing energy sources, reduced our grid drain by half (so far) and we are less vulnerable to power shortages.

All this clearly quite simplified. What is exciting though, is the development of new techniques related to energy and housing. And for planning with SH3D, there are implications to consider: ranging from thicker walls/floors to making room for energy storage (batteries/thermal). Point is, keep such issues in mind before getting distracted by the details of the plan.

ok

Posted by okh at Apr 10, 2015, 7:31:17 PM

Re: Off grid solutions
A relevant post turned up in thread 5829 - house made with straw - seems that house has many of the qualities of the houses in the videos. See also the previous posts in thread 5643 which give more background on location and a couple of links to relevant videos. ok

Posted by Raysab at Apr 10, 2015, 11:02:15 PM

Re: Off grid solutions
Awesome ! There’s definitely people interested in the off-Grid field. I suggest that we funnel all these posts to the present thread to avoid the scattering of dedicated members in the myriad of this Forum threads. hugs

Here’s also interesting sources for infos: http://naturalhomes.org

http://endeavourcentre.org/2014/10/air-tightness-details-for-straw-bale-walls/

https://www.facebook.com/buildnaturally?fref=photo

http://earthship.com

http://simondale.net

http://www.theyearofmud.com/2009/06/17/finish...t-1-materials-and-recipe/

Next time would be “Energy”, then later “Farming” but all from the BUILDING perspective. angel

Posted by Raysab at Apr 10, 2015, 11:25:07 PM

Re: Off grid solutions
Actually that’s the link I wanted to share: Calculate your environment situation !

http://solargis.info

Posted by Raysab at Apr 11, 2015, 5:03:38 PM

Re: Off grid solutions
Here’s another interesting one:
http://earthhandsandhouses.org/various-workshops-poland/

Posted by homerbask at Apr 13, 2015, 1:57:46 AM

Re: Off grid solutions
nice house-cottage. Where is it located?

I read some of the post though not quite understand because I do not speak English and I'm reading and writing using google translate.

the bathroom the best solution is a dry bath. It is economical, easy to do and also you get your own compost for vegetation.

I leave a video is in Spanish but I think you understand its operation:
https://www.youtube.com/watch?v=Cta6xaE2tKg

on the thermal and sound insulation straw is a great even better than the isolates used in building insulation. the bad thing is you need certain requirements for straw does not degenerate over time, humidity etc

in Germany was tested fire resistance of a wall of straw. The test consisted in raising the temperature inside the wall slowly up to 1000 degrees Celsius to watch the wall behaves.
I spent 30 minutes inside wall is 800 degrees Celsius when the outer wall is at a temperature between 35 ° c

There are also other systems to heat your home with the energy of the sun or the earth such as a Trombe wall or a Canadian well tapping geothermal energy.
http://www.sitiosolar.com/wp-content/uploads/...ncionamiento-invierno.png

on a simple hot water solar heater can help you in summer but seeing those snowfall I do not think it is very hot there ...

I feel the translation. I used google translate if you do not understand something explained dimelo and try to explain otherwise, or in other words.

A greeting

Posted by homerbask at Apr 13, 2015, 2:53:00 AM

Re: Off grid solutions
More information on the houses of straw

http://www.greenhomebuilding.com/videos/strawbalevideos.htm

this documentary is very good and interesting I saw on youtube in Spanish , try to look for in your language . here comes the test of fire resistance as commented in the previous post

http://oekofilm.de/houses-of-straw.phtml

Posted by Raysab at Apr 13, 2015, 3:07:11 AM

Re: Off grid solutions
Thank you Homerbask for your contribution.

No worry about languages, we all here share IDEAS smile

Your first YT exemple is fine in terms of recycling but it lacks one very important element in the process: Methane gas produced should not be released in the air as it participates to the greenhouse effect. In many off-grid endeavours this highly flammable gas is redirected into a flexible chamber (or container) then redistributed through gas pipeline to feed household cooking, or else, as alternative source of burned energy. This has been implemented in many countries of Africa and Asia.

I’d try to provide some visual exemples of it, later on.

Let’s keep going in this field !

Best, Ray

Posted by homerbask at Apr 13, 2015, 3:08:39 AM

Re: Off grid solutions
Here I have some photos of the construction process , there are several methods , each appropriate to use here more than anything to SH3D and sketchup programs that were used although it was the first time you use sketchup . as you can see the front ranks of strawbales are well placed but according taking height will I begin to put on each other , that was because he was tired

http://imgur.com/a/eYOAp

Posted by Raysab at Apr 13, 2015, 3:12:06 AM

Re: Off grid solutions
... dig deeper, I would say :D

Posted by homerbask at Apr 13, 2015, 3:20:18 AM

Re: Off grid solutions
I think the methane gas produced by your excrements is not a problem . imagine the droppings of animals also produce methane gas imagine an elephant or a horse ... thing to do is try to pollute as little as possible and thus at least you avoid your excrements end up in water such as a river and you make sure you end up being food for other living creatures such as worms and plants and trees because after making your excrements is made to the toilet a little sawdust wood dregs of coffee, a mixture of wood chips .. . that helps your droppings decompose and serve as food for earthworms and plants

Posted by okh at Apr 13, 2015, 1:01:16 PM

Re: Off grid solutions

nice house-cottage. Where is it located?

Norway (Noruega) - 60,5°N, 900 metres altitude.

.. a dry bath. It is economical, easy to do and also you get your own compost for vegetation...

Thanks for this. Yes, it is a good idea and the method is similar to the traditional way of building toilets. The problem is that the compost process is slow at high altitude, especially in the winter months = risk of smell. For me, a separate house is difficult to use (imagine a snow-storm) and almost impossible to build.

..hot water solar heater can help you in summer but seeing those snowfall I do not think it is very hot there...

Warm in summer, cold in winter. Actually, a solar thermal collector (colector solar) should work well with cold/snow because of the high altitude and reflection from the snow. The collector would be mounted almost horizontally on the South wall to catch the low winter sun and avoid being covered by snow. Tests indicate an indoor temperature rise of 10°C or more with dry air. Additional heating will be necessary in winter, but it seems even a small solar collector could make a big difference. A water based system would not be a good idea in cold temperatures, though. Also, the air based systems are simple, easy to install, light weight and inexpensive. One manufacturer's pictures * seem to illustrate the point smile

.

ok

Posted by homerbask at Apr 13, 2015, 1:35:14 PM

Re: Off grid solutions

nice house-cottage. Where is it located?

Norway (Noruega) - 60,5°N, 900 metres altitude.

.. a dry bath. It is economical, easy to do and also you get your own compost for vegetation...

..hot water solar heater can help you in summer but seeing those snowfall I do not think it is very hot there...

.

ok

so you see a solar collector is very similar to a Trombe wall just to spend more money and giving publicity to a company. I think you should to look at it because it is easy to make economical and can increase the temperature a few degrees
http://en.wikipedia.org/wiki/Trombe_wall

according to information in English I see the walls trombes see using a hole in the wall. say that the system is even easier because with putting a window "glued" to the south wall is sufficient. I mean a window mounted on the wall without opening the window. not if I explain but it's just a window without opening the interior of the house more than 2 small one at the bottom round holes for the cold air out the house Trombe wall and upper to allow air to be a warmed in the Trombe wall between your home.

something like that
http://2.bp.blogspot.com/_VmmpqwOIK0w/SAdAujD...para+calefacci%C3%B3n.jpg

http://0grados.com/home/wp-content/uploads/2013/07/Ilustracion-Oli-Chatre.jpg

on dry bath is true that in winter will be difficult composting. but it is also true that you can build indoors and simple windows with mosquito nets and a small ventilation system not think it smells. besides being indoors I do not think they're that low temperatures.

Posted by okh at Apr 13, 2015, 3:47:44 PM

Re: Off grid solutions

..publicity to a company...

Just for the record, the link was not intended as a recommendation of a company. I have no opinion of manufacturers. In many cases, I also agree that a Trombe wall could be a better solution. The principle is the same. I could build both myself. In my case, however, I will opt for a dedicated solar air collector with all components in one package for several reasons: transportation (< 10kg), thermostat included, quicker installation and predictable output. Especially the reversible thermostat driven fan, appeals to me. I need the ventilation to reverse on hot summer days. ok

Posted by Raysab at Apr 23, 2015, 6:30:51 PM

Re: Off grid solutions

There are also other systems to heat your home with the energy of the sun or the earth such as a Trombe wall or a Canadian well tapping geothermal energy.
http://www.sitiosolar.com/wp-content/uploads/...ncionamiento-invierno.png

on a simple hot water solar heater can help you in summer but seeing those snowfall I do not think it is very hot there ...

Geothermal systems are a bit complicated in Canada, only the southern part of the country can implement it properly while the Northern (and coldest) part soil is frozen all year long, even in summer (permafrost ) down to 3 meters deep.

Apart from downtown cities, almost all individual housing is built out of timber old England style. Fortunately for Canadians, the country has a very low inhabitants ratio compared to its vast land surface. But we have a serious problem with big login corporations harvesting forests like crazy.

Posted by okh at May 19, 2015, 5:56:20 PM

Re: Off grid solutions

Geothermal systems are a bit complicated in Canada,

I have been wondering about this. Shouldn't a decent borehole still give good conditions for a ground source heat-pump? If you drill beneath the permafrost and then some, isn't the temperature also pretty stable - at least out of the deep Arctic? Scandinavia doesn't do permafrost, even if further north than Canada, thanks to the Atlantic currents. But it gets cold. Very cold. Easily with a metre of frozen soil. And ground source heat pumps are enormously popular.

..big login corporations harvesting forests like crazy...

Interesting. Here the problem is opposite. Houses are built in wood and firewood consumption in areas averages on 500 kg/capita/year. Apparently Norway uses equivalent to a wood pile 60 cm wide, a metre high and 7200 km long every year for heating. Yet this constitutes only some 12% of forest growth and the total forest volume is increasing dramatically.

In terms of SH3D, what is important though, is that whoever wants to use firewood needs to consider stove/chimney location and wood storage space. A kg of pure wood gives 5,3 kWh. So normal firewood (<20% moisture) in a good stove (80% efficient) should provide 3,3 kWh/kg worth of heating. Nice heating. But some storage space is needed for your SH3D construction smile

.

ok

Posted by ElfenM at Sep 14, 2015, 8:30:53 PM

Re: Off grid solutions
For heating using a fireplace, are you considering pipes in your fireplace? These draw in cold air from the bottom and shoots out hot air as the log burns within the recess area of the pipes. Though expensive here, you could probably make one for a lot less cheaper with the right tools:
http://www.woodlanddirect.com/Fireplace-Acces...earance-Fireplace-4-Tubes

There are fences one can use on "wind mill" generator if it is a vertical spinning turbine. If you use a Globe Style Turbine with external bracing (a few seen here: http://www.ebay.com/itm/like/321857326306 ) you can wrap thin chicken wire fencing around it with no wind loss. I've seen these (but as exhaust vents) all over NYC, with some buildings having as many as 10 on a roof, most used by restaurants for their kitchen exhaust. I've never heard of an animal crawling or crashing into one. Adding a shaft to a generator (some are built for that) is easy.

The Wind generator noise comes from the gearing from the shaft of the wind blade to the generators. Direct drive units are practically noiseless. I forget the company name but there is a firm in Massachusetts that has an old style windmill connected directly to a car's alternator for its generator and has a braking system in case the RPMs get too high. It is noiseless and though it looks like an old style windmill, its about 1/2 to 1/4 the size; their small unit as a blade span of 4ft across. But their larger units which are gear driven are not noiseless but it low noise as it in a sealed transmission box.

One thing I have not seen, maybe I skipped it, is have you figured out how much power you are going to need? Because no matter how much power you need, you need to generate twice as much. With Solar - 1/2 of it to run your daily needs and the other 1/2 to charge you batteries at the same time for night use. For wind for 24 hour usage, the same thing if not 4X as much as the wind is not always there for you when you need it. If you have a nearby stream, then you can go for Hyrdo-electric power with an old fashion water wheel, but you still need to make double of what you need.

And don't forget the batteries.

Last thing - upkeep and replacements! Ugh, a touchy subject here. With Wind and Water, they are basically maintenance free and last a life time if taken care of right. Just shut them down and clean and lube them up every 6 months or so - no more than an hour per unit. But solar? You need to wash them down every month, daily if it snows, and solar cells only last 10 - 15 years and then you need to replace them all! Over time their power output will drop and continue to drop to zero. Also one bad solar panel can screw up the others as they would try to run at the level of the damaged one, which I find strange but seen it demonstrated. Not saying that Solar is bad, it is great! But it is not as maintenance free as some people make it out to be. And batteries - they need to be replaced every 1 to 3 years, depending on the battery. The best solution is to mix all of these up and get a balanced output, and always have that gas generator back up.

1400W sounds like a lot, but I know hair dryers that use that much power! LOL!

Posted by okh at Sep 16, 2015, 11:05:04 AM

Re: Off grid solutions
Thanks for this. Interesting.

For heating using a fireplace, are you considering pipes in your fireplace?

Did not know they existed as standalone units. But I have seen the principle used in some older fireplaces with copper pipes embedded in the fireplace walls. However, I am looking at some new clean-burning, closed fireplace inserts. Had one fitted at home last year, and the increase in efficiency was remarkable. We went from maybe 10-15% to some 85%. That means from some 1/2 kWh/kg of firewood, to almost 4 kWh/kg. (Completely dry wood = 5,3 kWh/kg, with actual normal moisture <20% somewhere around 4,5 kWh/kg). Biggest problem with the open fireplace though, was that the flue/damper had to be left open when we went to bed to get rid of CO. Meaning that the net effect was probably negative on a cold night.

One thing I have not seen, maybe I skipped it, is have you figured out how much power you are going to need? Because no matter how much power you need, you need to generate twice as much.

True. And at 60°N solar is rather limited in the winter. But for LED lights, phone-charging and radio, requirements will be minimal. For fridge (45W) or other appliances it would be a totally different story. Still, I suspect I shall have to rely on a portable power generator for power tools and topping the batteries. All heating/hot water will come from firewood.

And don't forget the batteries.

This is a bit of a headache at the moment. Currently almost all off-grid solutions come with lead-acid (agm), thick plated batteries. But here I suspect things will change over the next couple of years. New types of batteries with clever controllers should dramatically improve lifespan and weight/efficiency ratio.

With Wind and Water, they are basically maintenance free and last a life time if taken care of right.

I suppose you are right in theory, but in harsh climates moving parts are difficult. I have more faith in a solar system for now (but also because of distance to creek and strong turbulence around the building). I have used wind-turbines on sailing boats, and I was not impressed with output. To generate 50W, a pretty strong wind was needed.

1400W sounds like a lot, but I know hair dryers that use that much power! LOL!

Yes, well, hairdryers are out of the question. Not a great concern smile

Posted by ickle_bea at Jan 2, 2016, 2:50:50 PM

Re: Off grid solutions
Hi guys, I am following this thread from the original thread 5778.

I am looking to purchase a property in Spain which will be my home but also a yoga/dance and eco-arts centre with accommodation for up to 15 workshop attendees.

I am looking at renovating a very old building but the outhouses and barns are also in need of complete renovation or possibly just full rebuild in which case I would aim for a sustainable build using elements of permaculture design.

This is not going to be a small property though so I need to look at what type of energy sources will work best for a bigger property as well as what the best building materials to use in a Mediterranean climate.

I am completely new to this and would appreciate any advice. It seems there are so many options for off the grid design and I just don't know where to begin.

Posted by okh at Jan 2, 2016, 5:34:48 PM

Re: Off grid solutions
How wonderful. Spain offers a lot of possibilities in terms of renewable energies, in addition to being a lovely country.

First question is, approximately where in Spain? There are differences in average sun-hours and not least average/winter temperatures. Then the property / house(s). Does the property have a lot of sun in general? South facing façade / roof with no shade from trees? What are the current building materials (degree of insulation)?

It will also depend on whether you want to be completely off-grid or just use renewables as supplement.

All that said, there are some pretty interesting developments in sustainable energy supply. And installation prices are coming down. My current favourite would be a combination of solar thermal collector, wood burning stove (or pellets). Even if you want to go very low cost, a solar thermal collector (air) should give considerable effect.

Also, Spain was quite early in using heat-pumps for water heating (came across it for the first time in Malaga early nineties - and that was an old installation).

Please keep posting what you find out. Sounds like an exciting project.

ok

Posted by okh at Jan 14, 2016, 7:22:58 PM

Re: Off grid solutions
Just to elaborate, in addition to the above. Just read an article today (in Danish, I am afraid and promoting one brand, so I will not link), but it explained modern mass heaters, like the Finnish variety. The one I read about came with water heating for floor and hot water, and it could be combined with a solar thermal collector. A really interesting solution provided you have reasonable access to firewood. The beauty of this system is the heat retention so you will not get all the heat at once like with most firewood stoves (in other words, it should be good for winter in Costa del Sol).

But for full autonomy you need to consider using alternative sources as well. Photovoltaic for light etc. But also possibly gas for cooking and supplement (you will not use much, so it is justifiable even in an eco environment). And then there is a fuel cell, like this one in one of the most beautiful spots on earth, Savoie ...

Still, I would have gas / generator back-up. Unless, of course, you are a total purist...

ok

Posted by okh at Jan 15, 2016, 11:21:20 AM

Re: Off grid solutions
A crisp -18°C outside and time to reassess some energy investements.

Extra house insulation a while back, brought heating costs down by some 20%.
New electric floor heating in basement (up to 120W/m³) keeps house relatively temperature stable. (An old house in a cold climate could require as much as 200W/m³, modern houses should be able to manage with 1/4th or less).

Firewood is blazing of in a relatively new stove (installation cost around €4000) delivering 2500-11000 W. No reliance on the grid, except for frost protection. Cost is interesting, and it is well worth comparing firewood quality and prices. Dry firewood will deliver approximately the same kWh pr kg regardless of whether it is heavy or light wood. The variables are the cost, moisture content and not least, stove efficiency.

The long and short of it is that a good stove with good firewood will deliver up to 4 kWh pr kg of firewood. But a quick test revealed that the actual cost pr kWh here ranged from €0,1 to €0,2 depending on the firewood quality and price. Seemingly similar sacks of firewood vary greatly in sack weight, dampness and price. So much so that the price/kWh more than doubles from one retailer to another. That was surprising.

ok


                                Stove efficiency
                                Open fireplace    Modern stove
Wood moisture        kWh/kg      15%    50%    80%    85%    90%
0% (does not exist)     5,3     (0,8)  (2,7)  (4,3)  (4,5)  (4,8)
Very dry wood 10%       4,7      0,7    2,4    3,8    4,0    4,2
Dry wood 15%            4,4      0,7    2,2    3,5    3,8    4,0
Relatively dry 20%      4,1      0,6    2,1    3,3    3,5    3,7
Damp firewood 25%       3,8      0,6    1,9    3,1    3,2    3,4

Normal firewood will have a moisture content between 10% and 20%. Moisture over 20% is not acceptable. Getting good efficiency from a stove (85%), requires a modern construction and knowing how to use it.

Posted by okh at Jan 24, 2016, 12:59:26 PM

Re: Off grid solutions
Some reflections on sun energy. The sun provides roughly a kW pr m³ at earth surface. Manufacturers of thermal sun collectors claim to be able to exploit up to 70% of that - which can either provide some hot air ventilation (air collectors) or quite a lot of hot water.

For electricity (photovoltaic), solar has a lower output - in the range of 15% although newer systems may yield more. In practice, however, a lot of variables come into play. So looking at empirical data, it seems that manufacturers of photovoltaic panels estimate between 100 and 200 kWh/m³/year in Europe.

Problem is that output is lower in the winter (when days are shorter and weather less forthcoming), which means that the installation needs to be dimensioned based on winter electricity needs. Still, thanks to low-energy lamps, you will get quite a lot of light from a relatively small, correctly angled installation.

Realistically, it seems many rely on a fossil supplement to charge (top-up) batteries in the winter. Downside is that although it may only be needed in short periods, the cost per kWh is high. The small generators supplied locally give from 1,5 to 2,5 kWh per litre of petrol. Which means they exploit only a fraction of the energy contained in the fuel.

The good news is that modern installations, good insulation and some clever solutions, makes self-sufficiency possible. But more important, it certainly opens up for reducing both carbon footprint and grid reliance considerably even in traditional on-grid houses.

ok

Current timezone is GMT
Dec 17, 2025, 9:41:42 AM