Episode #125 of the Stack Overflow podcast is here. We talk Tilde Club and mechanical keyboards. Listen now
23

I use PVGIS calculator to estimate photovoltaics energy gain to my satisfaction. It contains realistic Europe and Africa weather data. Although this would be only a far estimate, let's assume you face south and you're based in Rome, Italy (instead of Chicago, IL), and we get: a maximum of 1260 kWh a year with an optimal inclination of 34° and almost south ...


22

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 ;-) ...


21

It's quite a hard question to answer objectively, because you don't know how much these panels will be used. They may be left out in bright sunshine all day in which case they will likely generate more energy than was used to manufacture them over their lifespan, or they may stay locked in a cupboard on all but a couple of days a year. Their efficiency will ...


17

Although there is a definite allure to generating your own energy on-site, if you do not have good solar access then it is hard to get around that reality. Instead, there are other ways to have renewable energy captured on your behalf: If you have a choice of energy suppliers, buy 100% wind or solar generated energy. Look into group solar. Perhaps you ...


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 ...


15

You have to get several numbers: payments how much will you pay to obtain the PV system how much will you pay on taxes, recycling fees from the PV system etc. returns how much will you get back from produced power how much will you save on your electricity bill (price of electricity is rising) how much will you be payed from incentives (if any) ...


15

If you are in the U.S. in particular, I would recommend the National Renewable Energy Laboratory's PVWatts calculator, which will provide both likely solar gain (the defaults are reasonable, but you can tweak them to your situation) and potential savings on electricity. For installation costs, again for a US case, LBNL has a great report on installed costs (...


14

If your want to calculate your own Insolation figures then I would highly recommend having a look at the gaisma website, which provides sunrise, sunset, dusk and dawn times for thousands of locations all over the world. For our purposes though, it also provides details of average Insolation (kWh/m²/day), along with Clearness, Temperature, Wind speed, ...


13

A specific answer to your very narrow question wouldn't be much use to anyone else; and you haven't given us enough information to give you a specific answer anyway. But what we can do, is give you the types of information you'd need to make a decision. And I'll restrict it just to PV and wind, as that's what you've asked about; others reading this might ...


13

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 ...


13

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 ...


12

Exergy PV is generally superior to solar thermal because it produces a higher-quality energy: electricity rather than low-grade heat: 1kWh of electricity has more exergy than 1kWh of low-grade heat. As you say, PV's efficiency tends to be significantly lower than solar thermal, in straight watt-for-watt terms, which means less power per unit roof area. ...


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 ...


10

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. ...


9

I will answer your question from a different approach, which is practicality rather than raw efficiency. You asked if there are advantages to heating water using solar PV instead of direct solar hot water. The first potential advantage is how the variation throughout the year can be handled. In a modern grid-tied solar PV system, you can bank electrical ...


9

For estimating the solar power system requirement it depends on mainly following factor Your power consumption. Sun light peak value. Your power storing device. How much energy can a Solar panel generate over a period of time? there are many walls solar panel is available lets take one example The power generation rating of a Solar panel is also given in ...


9

If you compare a MC (monocrystalline) and PC (polycrystalline ) PV (photovoltaic) panel with the same full-sun efficiency in each case, there is very little difference in efficiency as light level falls, between the MC & PC panel. For the same full-sun efficiency monocrystalline are slightly better in low light conditions but the difference is liable ...


9

Photovoltaic system's performance parameters belong to two categories: energy generation (electricity units like Volts, Amperes, Watts and Watthours) and supplemental (some other units). Although you don't mention it, to make the answer complete, I add energy storage category (if you had a battery storage attached). A PVE system can be in one of these ...


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

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 ...


8

One option which may well become more popular in the future is photo-voltaic double glazing - a form of Building-integrated photovoltaics (BIPV). Although low cost thin film PV generally has a lower efficiency than crystalline silicon cells - since they are layered on top of transparent glass, any light not converted into electricity passes through the ...


8

I only have one anecdote and avague idea: An agrarian schooling center (Haus Düsse) in Germany clean their PV System once a year, and clean/dirty means a difference of 10% effectiveness. However, as this is basically a small farm with lifestock, different grain treatments, lots of diesel vehicles etc. you would expect far more dust there than at a lot of ...


8

Generally, no they're not. For a combination of several reasons the tracking system itself has a high capital cost. static PV systems are extremely low maintenance. Tracking PV systems are not. adding a tracker means bigger spacing between groups of panels, so that they don't shadow each other The net additional energy yield isn't that high: for PV, ...


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

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 (...


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

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 from this fact-...


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