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,...


23

There are a number of questions there. "Can LED light provide same amount of energy as sunlight?" In total, no, at least with humanity's available resources. The sun is kinda big. Per unit area? Sure, if you use enough LEDs and focus them tightly enough. "Can humanity get rid of the sun" Probably not, within our currently available technology ;-) ...


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 ...


16

It looks to me like you have three choices: Re-roof your property now, then buy solar panels and have them fitted. Buy and install your solar panels now, then in a few years remove all of the solar panels, re-roof your property and re-fit the panels. Wait until your property needs re-roofing, re-roof it and then buy and install solar panels. As such, you ...


14

TLDR; cadmium telluride panels have the highest EROI of the mentioned PV panels (around 34.2) EROI estimates vary widely. This is because of differences in the method of calculation, scope of the study, installation location, assumed lifespan of a panel, etc. This also makes it relatively easy to manipulate EROI calculations. Pessimistic The most ...


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

If your goal is to save money you'll need to do the calculations based on your exact location and costs. In Australia the main use of small battery-backed solar systems is for off-grid locations but people are increasingly looking at going off-grid as the cost of the grid keeps rising (mostly due to cheap air-conditioners) while the cost of PV systems drops. ...


12

Yes, if you want electricity, it's much cheaper and more efficient to just use the electricity directly from a solar panel, than to do any transformation of that electricity into any other form, then back to electricity. The only reasons that we'd use electricity to electrolyse water to create hydrogen, is if we had spare electricity now, and wanted to ...


11

This is built on, and directly quotes from, my answer and user26165's answer to a similar question over on Physics.SE. No, fresnel lenses are not widely used for solar power. Occasionally, but rarely. The issues are engineering and economics. Other solar competitors The big economic story is the amazing speed at which ordinary photovoltaics have reduced ...


9

In the purist sense of "the electricity I use was actually generated by a wind farm", your idea is broadly correct. However, unless you actually have solar panels or a wind turbine on your house, that's not how the system actually works. Broadly, all the electricity generators feed into the national grid (which in Australia covers only Qld-NSW-Vic-SA, but ...


9

There is no "best battery." There are different kinds of batteries for different applications. Here are some things to consider, What voltage do I want? (Most DIY projects pick 12V because they want to run 12V appliances built for RVs.) How much power do I need (instantaneous power)? Eg. do I want to run a Microwave (fairly high), just a couple of lights (...


9

It is not, necessarily The initial capital cost of a plant is not the same thing as its lifecycle costs. The best way to analyze the cost impact of an energy source is to look at the total expected costs over the lifetime of the plant, and compare to expected energy generation. This gives you a simple measure that you can use to compare systems. There are ...


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

Added: Based on the added comment that The purpose of the question is to determine whether solar panels can be made after fossil fuels are widely unavailable and long-distance supply chains are extremely expensive or unavailable. I won't address the assumptions made re unavailability of supply chain, and will just assume that it is true in this case. ...


8

You're being quite specific with regard to solar... but in principle, it is possible to move your electricity consumption to minimise its carbon footprint. Ecotricity (a UK "green" energy supplier) have a web page that shows the current carbon intensity of UK generation1, and gives a red/amber/green indication of whether you should turn stuff on now. If you ...


8

This counter-intuitive advice is actually the result of research. Unfortunately journalists are rarely qualified to cover any sort of science news, and this was no exception. I'll try to explain the result in more detail, and in a way people can understand. Most people know that dark colored objects absorb light and become warm in the sun. The darker the ...


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

Fthenakis has published more on the subject than anyone, to my knowledge. His LCA lists a whole bunch of factors, but it's roughly 1.5kg of silicon in the PV itself. But a module also has 16.1kg of tempered low-iron glass for a 210 Wp panel (p32). Glass is 60-80% silica, and silica is about half and half silicon and oxygen by weight. So there's 5kg - 6.5kg ...


8

Your first sentence is incorrect, as per the very chat discussion you've referenced: the sales price for panels is more than the cost of the panel's components. The second sentence is also incorrect: solar is viable as long as people are willing to pay for it. And so is your third sentence: panel prices have dropped a lot in the last six years. Take all ...


8

Summary No, that's way too little. I think "140 miles square" has got mangled into "140 square miles". Running the numbers Following on from one of Elon Musk's presentations, which showed an area of about 10,000 km2 as the area of PV panels needed to power the USA, the question came up on the Skeptics Stack Exchange. Taking the numbers ...


7

On the financing front: I don't know about the situation in the US, but some countries have schemes whereby grants or favourable loans are available for improving the energy efficiency of housing stock. For example, in the UK there is the "Green Deal". These schemes will vary in their usefulness versus the amount of bureaucracy involved, but are worth ...


7

As for federal tax credits, I believe they only apply to 'principal residence' so you must both own and live in it. However the landlord may be able to write it off as a cost if she pays the bill, for some relief. Check the energystar.gov site for details on what qualifies for tax credits: http://www.energystar.gov/index.cfm?c=tax_credits.tx_index . ...


7

I can think of one big advantage, in certain instances, to using PV to drive a resistance heating element: ease of transmission. I can run a cable up, down, sideways, etc. with little difficulty, provided that it is large enough for the anticipated current. To do the same thing with pipe can be tricky, especially where you have to deal with extreme ...


7

The line "All the DIY references I’ve found still require buying components that are dependent on fossil fuel-driven manufacturing and mining processes." makes it sound like you are hoping to build a solar cell with materials you pick up off the ground. Fortunately, there is such a cell. You can make Cuprous oxide solar cells using nothing but copper, heat, ...


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 ...


7

I was quite surprised by the number of upvotes the question got, and as I've now gone ahead and had the panels installed, I'll add a few more details of what I did, in case it is of use to anyone going forward. First stop was the MCS web site. (this is an absolute necessity, since as @EnergyNumbers says, to qualify for the feed-in tariff the installer has ...


7

Beware that chart - it is from 2004, and hence is very out of date! In particular, photovoltaics ("solar panels") have become cheaper much faster than anybody expected a decade ago, and wave and tidal power have proved more difficult and costly than some had projected. Here's some more up to date info on costs: http://www.eia.gov/forecasts/aeo/...


7

A common thing to do is use the cooler temperature of the ground to reduce the temperature of your home. If building a new home, you can simply build it into a hillside or completely underground. For Example, this house is built into the hillside and one of the key features is that it is covered with grass (vegetation) which will significantly reduce the ...


7

A simple short term test like the one you are thinking about will reveal little information. Many factors affect the output of photovoltaic cells. Results from a cloudy day will differ those for a sunny day. Also the angle of the sun relative to the horizontal changes throughout the year: low during winter and high during summer. The angle at which sunlight ...


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