Hot answers tagged

31

It could be that the system will spend such little time providing above 5 kW, once shading and losses are taken into account, that it's not worth the cost of getting the next-largest inverter. It could be a restriction of your electricity network operator: often, they have bandings based on the maximum power that a PV system will deliver to the network,...


20

Take a look at a passive solar heat collector. They work on the principle of thermosiphoning. The design in the link and the picture below has an additional top vent exposed to the outside so you can close the top interior vent and draw air out of the building during the summer. I've seen more advanced designs that include doors that automatically close at ...


20

Standard Test Conditions vs Real life Photovoltaic panels are rated at "Standard Test Conditions" (STC): Irradiance = 1000 W/m² Cell temperature = 25°C Air Mass = 1.5 Those conditions are achieved in testing laboratories, and basically never happen in real life. Modules need to be cooled down in order for them to stay at 25°C. 1000W/m² is a lot of ...


18

Thermal storage Surprisingly to many, conversion of electrical energy from PV (photovoltaic) panels to heat energy and storage in hot water is a potentially excellent use of the energy - provided that you have a use for the hot water. Water stores energy at the rate of about 1 Watt hour per litre degree or 1 kWh per 1000 litre degrees*. So eg a 100 litres ...


14

Try the simple answer before looking for more complicated solutions. Apply a white coating. They should be much more durable than a simple white paint, and a good quality coating will return nearly 90% of solar energy to the atmosphere. This should make a big difference. Alternately, cover your roof with solar panels. Since they transform energy rather ...


14

Solar systems are rated at peak power. It's normal for inverters to be rated less since you will very rarely have ideal conditions to reach peak power. For example, my inverter is rated at 80% of peak power and I live in a sunny area. Only during the best days in the summer does my inverter get maxed out for a few hours at a time. Regarding your edit, there ...


12

@techjerk I too live in India and have the same problem. I don't want to use aircon because it consumes too much energy by local standards. I have so far considered the following: Painting the concrete roof white Adding a layer of roof tiles (placed directly on floor of roof) which allow air to circulate under and over, but keep convectional heating ...


12

If you're currently in Western Europe, then Eastern European countries may be very interesting for you to look at, because compared to Western Europe: The cost of living tends to be lower, so you could invest more of your savings into alternative technologies such as solar energy Cost of property tends to be lower (both housing and land) There's generally ...


12

Just about anything you would normally do with rags, but these ones are already in tube and bag form: Use for washing, polishing and cleaning - just put your hand inside Use to keep stuff in - small items like wingnuts, earrings... Use fancy socks for wrapping presents - tie a ribbon round the top Put stones inside and use to hold down bird nets or apple ...


11

I have heard that disposables use less energy than reusables if you also use hot water and they dryer. But it seems that many experts disagree. Most of the energy that goes into reusable diapers is in heating the water and the dryer. So, the colder the water you're using and less often you dry them the better off you are. Using rain water and/or solar ...


11

Yes, limonene is a terpene and terpenes react with ozone to form formaldehyde and other micro-particle pollutants. Limonene itself isn’t toxic and hasn’t been found to be harmful, but some people are sensitive to it’s various oxidation products causing skin irriation or respiratory problems. Research has shown that: when people use the [terpene-based ...


11

Throw a bunch of large potted plants up there - maybe even something edible. They'll shade the roof and help feed you.


11

Ironically, the better you are at reducing your waste, the less likely you are to succeed at replacing plastic bags for the irreducible portion. My mother throws out actual garbage twice a year - one small plastic bag such as the ones you get from grocery stores, every 6 months. While she always has a reusable shopping bag in her purse, she finds that ...


11

I live off-grid, so I did a lot of study on this topic. All used coffee grounds make good fertilizer. Drip machines seem to use a lot of energy, and they seem to use it for a lot of time. They also use disposable filters. Drip machines are kind of on the off-grid "blacklist". Percolators waste a lot of energy because they have to keep the water boiling ...


9

If you really want to do it yourself: Shred them. Fireproof them. Insulate. It is extremely important to treat newsprint with fire-retardants before using them as insulation. Without treatment, newsprint stuffed into wall cavities or attics is a serious fire hazard. A better option is to simply purchase cellulose insulation. It's made from recycled ...


9

If you have the property, and resources, make sure your house is tight. Then, dig a four foot trench that zigzags across a suitable part of your yard, taking care to call Mis Dig for location of underwater electrical, water, and gas lines. Lay PVC pipe into the trench, making sure it's water tight. Bring one end up from the ground, above the maximum snow ...


9

Your most sustainable choice is an old straight razor, but there's a reason the replacement is called a "safety razor"... you're much less likely to kill yourself with a safety razor. But these last a long time and you can shave using a small amount of water and a soap stick. You can buy one second hand, that's how long they last. Much safer is an old style ...


9

Thermal lined curtains would make a big difference especially if the windows are single glazed. Draught proofing using self-adhesive strip is both subtle and removable. Topping up loft insulation, as it's out of sight, is something that might be permitted quite easily, but could be expensive. Other options are things like shower flow reducers and toilet ...


9

Planting a large garden and covering other areas with gravel and/or stepping stones is one approach. Maybe look into rain gardens; water retention is a key concern here and why you want something water can go into (as opposed to concrete etc.). I've also seen folks use square flat stones to create a large playable chessboard to accomplish this goal (but it ...


9

Building on the garden answer : Turn your lawn into a native plant garden. Six or Seven years ago I turned the front lawn of my house (roughly 30' x 50') into a (mostly) native plant garden. The trick is to pick plants that will thrive in the conditions of your yard as well as maintain a manageable size and shape. Be very wary of invasive and/or spreading ...


9

I think you're right that building your own is likely to be necessary (we're in the same position). What I've discovered in Australia is broadly applicable in the global north, so: An earthship can't be sustainable, and is not designed to be sustainable - they are about being self-contained within a very narrow definition of the term. They rely on free ...


9

Original answer (which had a long explanation): I proposed using degree days information to determine a baseload value for consumption of electricity and natural gas by region, and assume anything above this baseload was used for heating and cooling. This assumed that all seasonal changes in energy consumption were for heating and cooling only (so no change ...


9

A related question was asked on SE Skeptics - Is this tealight-flowerpot heater more efficient than just tealights? In the third answer, it is claimed the heat produced by one tea light candle is 0.75 MJ per candle. Where I live, one of the domestic gas suppliers sells gas for 2.78 cents per MJ. The energy value of the gas is 38.713 MJ per cubic metre of ...


9

There already are some answers addressing the fact that you probably will not reach or will rarely reach the rated power of your panels. That explains why you don't need a higher rated inverter. Now, you could want a higher rated inverter just in case, assuming it doesn't hurt either. But that assumption is often wrong. Inverters are not perfect; they have ...


8

Ok, let's break this down. I will assume photovoltaic solar panels (as the question implies alternatives to batteries) and therefore skip all kinds of solar thermal collectors. Starting from electric energy coming from this PV panels we can convert to various forms of energy. For the purpose of storage this boils typically down to a few used forms only: ...


8

Electronically they're the same and will waste as much energy as a conventional adaptor. Depending on your electrical regulations they may be forced to be at the good end of adaptor efficiency, or they may be at the very cheap end. This will be a matter of safety regulations, but the cheapest designs fall down on safety and efficiency. I hunted for one ...


8

The outside relative humidity may be almost as high but the absolute amount of water held in the air is lower. So removing the most humid air is effective. That's the principle behind shower extractor fans and cooker hoods. Replacing a lot of lower humidity air with outside air lets a lot of heat out. A dehumidifier uses a couple of hundred Watts when it's ...


8

I suggest that you question some of your assumptions. Difficulties of off-grid. Off-grid is HARD, and generally isn't worth it unless you are a long ways from the power lines. If you are looking at one acre, you probably aren't that far away. Let's look at what goes into off grid: Electricity Grid connected solar means you size your PV to provide about ...


7

You will probably lose less energy from a very short burst of high-rate ventilation, than slow ventilation over a long period. That's because you'll probably lose more hot air in a long, slow ventilation: it will take some time to notice that the air really is fresh now, whereas with all the windows open for a few seconds, you'll notice the fresher air ...


7

The Energy Saving Trust (EST) is an organisation that has no vested interest in selling you things (although their mission is certainly to encourage takeup of renewables). They have a lot of good advice on their website - I suggest having a read from this starting page. Make sure you're looking at the page relevant to the right part of the UK, as the rules ...


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