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Questions about Solar Panels - EEVblog

Author: GE

Jul. 28, 2025

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Questions about Solar Panels - EEVblog

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SH@RK

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Questions about Solar Panels
« on: November 16, , 05:11:04 pm » Hi

I want to start using solar panels to power some small things as start in my home (mainly to learn)

And if it works fine I will get bigger ones so I can power more and more

So first I want to learn about them and find how much I can use them

I already read a lot of topics and watched a lot on youtube about them and how to make them

So I decided to get one and try it

1:- How about these ?

Grade A , poly crystalline ,  6' x 6'  , 4.1 W for each piece

http://www.ebay.com/itm/18-Best-solar-cells-Grade-Multi-Solar-Cell-6x6-High-efficiency-4-1W-each-cell-/?pt=LH_DefaultDomain_0&hash=item3f1d7d2c7d

Or

Grade B ,  6' x 6'  , 3.6 W for each piece (with small minor cosmetic defect)

http://www.ebay.com/itm/20pc6-6-3-6W-solar-cells-solar-panel-DIY-high-efficiency-free-shipping-/?pt=LH_DefaultDomain_0&hash=item3f1ea

Or

2:- Should I go with the full packages (panels + flux + diodes + tabbing wire + bus wire)

http://www.ebay.com/itm/6x6-High-efficiency-solar-cells-3-6W-piece-cell-kit-DIY-panel-fountain-toy-/?pt=LH_DefaultDomain_0&var=&hash=iteme5d8bc

http://www.ebay.com/itm/80-3x6-POLY-CELLS-2-WT-EA-TAB-BUSS-WIRE-FLUX-PEN-J-BOX-SOLAR-PANEL-DIY-KIT-/?pt=LH_DefaultDomain_0&hash=item27caa

I am interested in the last link (free shipping to KSA)

I found in eBay they say  "B Grade with small minor cosmetic defect"

3:- What do they mean by "small minor cosmetic defect" ?
The products in the pictures looks good for me

4:- And for the front face for the ending frame is glass the best thing to use ?

5:- So any suggestions where to start and buy ?

6:- Should I buy the best or start with B grade ?

7:- Do u think buying the pieces and making my solar panel by my self is cheaper ?

8:- Do I have to use battery bank or I can use solar power directly (small appliances ) ?

9:- what about using solar energy at home , the idea itself , Is it good or wasting money ?

Thanks « Last Edit: November 16, , 05:16:15 pm by SH@RK »

Lightages

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Re: Questions about Solar Panels
« Reply #1 on: November 16, , 05:28:06 pm » First, forget everything before question 7. Making your own panels might be a nice hobby, but it does not pay off in the long run. Manufactured panels can be purchased for under $1USD per watt now. You can buy a good quality 240W panel for $221USD. It will be weather proof, guaranteed, and more durable than almost anything you can build yourself at anywhere near the same price.

You can use the solar panel to charge directly, but you need to use a charge controller in any case. It is better to have some battery capacity for stability in the power output and for being able to have power to do other things, and to store the power from the panels when you are not charging a device directly.

If you are in a very sunny area and electricity is unreliable or very expensive, then solar power is a viable alternative. If you have normal not too expensive electrical power from the grid available, solar power is never cheaper.

poptones

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Re: Questions about Solar Panels
« Reply #2 on: November 16, , 10:29:46 pm » This is why many people hate China...

Can I offer this mode of thinking? "Solar panels" can be just about anything. People think of "solar energy" as those black roof panels that make electricity, but when you consider most of the energy use in a home for several months will be for heating, it's amazing how many still don't think of "solar heating" as something that's usable. My own home is solar heated for much of the year - right now it is, for example, because the sun is out and it's closed up. What I want to do is add a collector and closet on one side so I can store heat to be released at night over the winter. That's active solar but doesn't entail electricity. Look at the stuff nick pine is doing with solar closets. PV cells can take decades to pay off, a solar closet can pay itself off in two.

http://www.ece.villanova.edu/~nick/solar/solar.html
https://sites.google.com/a/southsidecomfort.com/natural-comfort-by-design/solar-closet-by

Cosmetic imperfections can lead to inefficiencies in PV cells. So can heat, which is trapped by glass and especially by glass that is not UV rated. So if you get glass that is not UV transparent then it can help heat the cells through radiation AND trap the heat. I don't know that cheap solar panels are going to be made with quality glass, or with utmost efficiency in mind.

Also, you might think about concentrated solar. Regular PV panels don't do particularly well with efficiency. With concentrated solar you can get over 30% efficiency.

G7PSK

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Re: Questions about Solar Panels
« Reply #3 on: November 16, , 11:11:54 pm » I wondered what you meant by solar closet for a moment then I realized you were talking about conservatory's. Some thing that has been around since Victorian times.

poptones

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Re: Questions about Solar Panels
« Reply #4 on: November 16, , 11:27:30 pm » No, it isn't. Conservatories are big open spaces. Solar closets are just what they sound like - closed, small areas designed for one thing: to hold heat. Conservatories are lousy at keeping heat because they're covered with glass. They're too hot in the summer and too cold in the winter. Solar closets are made to be heat reserves. That's all they do. They're not living spaces, they're not greenhouses.

G7PSK

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Re: Questions about Solar Panels
« Reply #5 on: November 19, , 06:12:33 pm » I googled solar closet and found this. It looks like a conservatory to me. also I don't know what standards are used in the US but here in the UK conservatory's are double or triple glazed with heat retaining glass and even in winter get hot in the sun.

M. András

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Re: Questions about Solar Panels
« Reply #6 on: November 19, , 06:43:43 pm »
First, forget everything before question 7. Making your own panels might be a nice hobby, but it does not pay off in the long run. Manufactured panels can be purchased for under $1USD per watt now. You can buy a good quality 240W panel for $221USD. It will be weather proof, guaranteed, and more durable than almost anything you can build yourself at anywhere near the same price.

You can use the solar panel to charge directly, but you need to use a charge controller in any case. It is better to have some battery capacity for stability in the power output and for being able to have power to do other things, and to store the power from the panels when you are not charging a device directly.

If you are in a very sunny area and electricity is unreliable or very expensive, then solar power is a viable alternative. If you have normal not too expensive electrical power from the grid available, solar power is never cheaper.
hmm i would be glad to get 1 for that price here in hungary. checked a few sites for solar panels and they go minimum the double of that price you mentioned, calculated back from our currency to usd

poptones

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Re: Questions about Solar Panels
« Reply #7 on: November 19, , 06:47:17 pm » conservatory's are double or triple glazed with heat retaining glass and even in winter get hot in the sun

Uh huh. And shed it all night long because your thermal mass has terrible insulation around it. It's hard to control temp during the day AND at night and it costs a fortune because of all that expensive glass.
 
That's NOT a solar closet, it's a conservatory or greenhouse or atrium or whatever you want to call it OTHER than a solar closet. How did you manage to google solar closet, find this image, and not find the 100 other images that DO show what a solar closet is? This is the first image that comes up in the search.



As you can clearly see it is NOT an atrium or even a livable space. It is designed to do one thing: collect and store heat. It's not a place for your plants or a place to entertain, it's a mass attached to your house that is designed to store heat year around and (most important) to release it back into your living space in controlled fashion. « Last Edit: November 19, , 06:49:45 pm by poptones »

Zero999

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Re: Questions about Solar Panels
« Reply #8 on: November 20, , 01:20:22 pm » I don't think any one has noted the original poster's location is Saudi Arabia where it's very sunny so very little energy will be used for heating and lots will be used for cooling.

SH@RK

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Re: Questions about Solar Panels
« Reply #9 on: November 20, , 03:05:59 pm »
First, forget everything before question 7. Making your own panels might be a nice hobby, but it does not pay off in the long run. Manufactured panels can be purchased for under $1USD per watt now. You can buy a good quality 240W panel for $221USD. It will be weather proof, guaranteed, and more durable than almost anything you can build yourself at anywhere near the same price.

You can use the solar panel to charge directly, but you need to use a charge controller in any case. It is better to have some battery capacity for stability in the power output and for being able to have power to do other things, and to store the power from the panels when you are not charging a device directly.

If you are in a very sunny area and electricity is unreliable or very expensive, then solar power is a viable alternative. If you have normal not too expensive electrical power from the grid available, solar power is never cheaper.

Thank you

For my home monthly electricity usage ---
Each month almost KWh

KWh  costs == 800 SR =~ 213 $

This is how it is calculated (calculate each level separately then sum the total)



So do u think the solar energy will be good thing to make this cost (almost ) disappear

I will start looking for manufactured panels and see the prices if I can get something cheap and working good

I don't think any one has noted the original poster's location is Saudi Arabia where it's very sunny so very little energy will be used for heating and lots will be used for cooling.

Yeah we  do not  use heating systems (I do not have one) . Mainly cooling systems (day and night)

In summer, temperature reaches 51C' at noon (most of the time between 41 - 46 C' )

Thanks « Last Edit: November 20, , 03:12:05 pm by SH@RK »

Lightages

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Re: Questions about Solar Panels
« Reply #10 on: November 20, , 05:23:23 pm »
For my home monthly electricity usage ---
Each month almost KWh

Really? that much? Wow! I use 20KWh per day, not 250KWh per day!

KWh  costs == 800 SR =~ 213 $
So do u think the solar energy will be good thing to make this cost (almost ) disappear

I think you miscalculated here. From your chart and consumption I see the cost in SR as 2,100. And the current conversion as I see it on the web is more like $560USD per month.

So, to answer your question I need to know; what is your peak draw or consumption? what is land area you have for panels? is your main consumption only during the day or is it all day and night? If the main consumption is day only, what is your night time consumption.

With my 20KWh daily consumption, I have a system with around W of panels and 750AH at 48V worth of batteries. My system cost around $25,000 USD. If you need a system 12 times bigger.......

I am really finding it hard to believe your monthly consumption is KWh.

ejeffrey

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Re: Questions about Solar Panels
« Reply #11 on: November 20, , 05:37:58 pm »
I think you miscalculated here. From your chart and consumption I see the cost in SR as 2,100. And the current conversion as I see it on the web is more like $560USD per month.

That is a progressive rate.  So he pays .05/kWhr for the first , 0.10 for the next kWhr and so forth.  That works out to about the 800 he quotes.  I get 980

In any case, kWhr/month is huge for a residential use -- that is 10 kilowatt 24/7.  Do you have a manufacturing plant or data center running in your home, or run heavy farm equipment?  If that is your average, what is your peak load?  That will affect what type of inverters/batteries you need.

Lightages

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Re: Questions about Solar Panels
« Reply #12 on: November 20, , 05:44:12 pm »

That is a progressive rate.  So he pays .05/kWhr for the first , 0.10 for the next kWhr and so forth.  That works out to about the 800 he quotes.  I get 980


DOH! Of course!

poptones

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Re: Questions about Solar Panels
« Reply #13 on: November 20, , 06:35:43 pm » It sounds lie what you really need is to get kw/h off your bill, not necessarily ALL of it (which I think is impractical). If you reduce your usage by kwh you would cut your bill nearly in half because of your progressive billing method. That's about 20% of your power usage.

So now I understand you are in Saudi Arabia. So how expensive is water there? I live in Tucson AZ which has similar weather at least a large part of the year. Summer temps here routinely exceed 110 degrees, often it gets to about 120, and I almost never use my air conditioner because I have a swamp cooler. Have you considered that? Last summer my heat and water combined never went over 100 bucks a month. It doesn't seem impractical at all to consider reducing your power bill 20% through the use of a swamp cooler, but of course that depends on cheap water.
 

Lightages

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Re: Questions about Solar Panels
« Reply #14 on: November 20, , 06:45:26 pm » Yes, reduction is always the best alternative. I just still can't understand using 250KWh per day. 

SeanB

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Re: Questions about Solar Panels
« Reply #15 on: November 21, , 04:27:46 am » Aircons on in all rooms 24/7 will do that, especially in a poorly insulated building and with windows/doors left open for significant periods and with them turned down to as cold as possible so the compressors run 24/7. 6 BTU units will do that easily. Each draws around 15A when running, so 3kW.

14 Interesting Solar Energy Facts You Need to Know | Earth.Org

Solar energy is a renewable energy source in which it can generate clean and sustainable electricity without producing planet-warming greenhouse gas emission or toxic pollution in the process. As time is ticking before the world crosses the tipping point to limit global temperature increase under 1.5C, switching to renewable energy such as solar is now more crucial than ever. Here are 12 solar energy facts to help make the argument. 

While solar energy can be dated all the way back in 700BC, it was not widely commercialised until about 40 years ago and accepted as a clean and effective alternative to fossil fuels. Though developing countries enjoy the advantage of being located in regions where they have optimal access to the sun’s rays, the lack of investment and climate debt means solar energy has been slow to grow in the region. Meanwhile, developed countries such as America, Australia, and more recently, China, have become the leaders in solar power generation.

Interesting Solar Energy Facts

1. Solar is the Most Abundant Energy Source on Earth

Solar energy refers to light and heat radiation from the sun that is harnessed to generate electricity. While we scale up technologies across the globe to capture and convert solar energy, the Earth already receives it in spades. An hour and half’s worth of solar energy that reaches to the surface of the planet has enough power to meet all of humanity’s energy consumption for an entire year. Since the sun is not going away anytime soon, we have the ability and technology to depend on solar energy entirely and end the global use and consumption of fossil fuels. 

2. Solar is the Fastest and Most Popular Form of New Electricity Generation

In , solar energy represented only 0.06% of the global energy mix. Within nine years, solar rose up to 1.11%. Solar also makes up the largest proportion of growth in the renewable energy mix, where it grew from 0.8% in to 10.3% in . Solar power capacity is rapidly growing at the same time, meaning the amount of electricity it can generate from energy it captures. Global solar power rose by 22% in as installations have experienced a boom. Together with wind power, renewable output has more than doubled since .

3. Minimal Greenhouse Gas Emissions are Generated in a Solar Life Cycle

While the process of solar power generation does not emit any greenhouse gases, other stages of the life cycle do produce some, but minimal, emissions. This include the manufacture of solar cell and panel materials – primarily made of monocrystalline, polycrystalline, or thin film (“amorphous”) silicon – transportation, installation, maintenance, and decommissioning and dismantlement. Most estimates of life-cycle emissions for photovoltaic (PV) solar cell systems are between 0.07 and 0.18 pounds of carbon dioxide equivalent per kilowatt-hour.

4. Solar PV Accounts for 3% of Global Electricity Generation

Power generation from solar PV in grew by a record 156 TWh to reach 921 TWh, marking 23% growth from , and accounts for 3.1% of global electricity generation. China, one of the world’s top greenhouse gas emitters, alone was responsible for 75% of the increase in annual solar PV installations from to . 

5. Solar Power Plants Can Last 40 Years or More

Aside from solar PV cell systems, energy can be generated with solar power plants where panels within an infrastructure can last at least 40 years. Panels can be easily replaced and updated with new and more efficient modules at relatively low costs, ensuring a long lifespan of these power plants. 

If you like these solar energy facts, you might also like: What the Future of Renewable Energy Looks Like

6. Solar Power Plants Does Have Some Environmental Impacts

According to the National Renewable Energy Laboratory (NREL), for a solar power plant to provide electricity for 1,000 homes, the facility would require 32 acres of land. In other words, to meet the energy consumption needs of the US, the plant would require 18,734,500 acres to be used for solar plants, which is equivalent to 0.8% of the entire country. Aside from land use, solar thermal power plants require water use and hazardous materials can be dangerous if not disposed of correctly.

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7. Solar Will Become 35% Cheaper By

One of the most notable solar energy facts is that solar costs will drop significantly within the next few years. Industry experts have predicted that the US will double its solar installations to four million by while global uptake is projected to soar as more countries turn to solar to help meet their climate goals. In , Australia installed a record more than 3,000MW of rooftop solar panels, where almost one-third of Australian households have solar panels – the highest rate in the world. A positive uptake trend will allow solar costs to drop thanks to its accessibility. Some expect it decline by 15% to 35% by , spurring further growth over the second half of the decade.

8. Solar Power in was the Cheapest Electricity in History 

According to a report by the International Renewable Energy Agency (IRENA), solar power is now the cheapest electricity in history. In most major countries, solar technology is also cheaper than coal and gas.

You might also like: Can We Build Solar Power Systems in Space?

9. The Biggest Solar Farm in the World is in Morocco

The Noor Complex solar power farm is the world’s largest concentrated solar power (CSP) plant located in the Sahara Desert in Morocco. Its geographical location allows for optimal access to sunlight and is said to have a 580-megawatt capacity and can provide electricity to more than one million people. 

10. China’s Solar Power Capacity is the Fastest Growing in the World

China installed the most new renewable energy capacity in and is expected to reach 1,200GW of wind and solar capacity in , four years earlier than its target. By , China will also likely register the largest installed residential solar capacity in the world. This growing trend contributes to China’s pledge to carbon peak by and to reach carbon neutrality by . Unfortunately, the nation has also been increasing its coal use at the same time due to a recent energy crisis. 

11. India Aims to be a Global Leader in Solar Energy

As part of the country’s net zero emissions strategy, the Prime Minister of India Narendra Modi pledged to increase its energy from renewable sources up to 50% by the end of . One aim is to install 100GW of grid-connected solar power plants by . Another overarching goal is to decentralise solar power and to widely distribute to meet the country’s cooking, lighting and other energy needs. However, pandemic lockdowns and supply chain issues have disrupted many project constructions, resulting in only less than 4GW of solar PV capacity being installed in , almost 60% less than in .

12. Recent Supply Chain Issues Could Hinder Solar Energy Growth

The COVID-19 pandemic has severely impacted the global economy in many ways, and the solar energy industry is expected to experience decline in growth due to rising costs in raw materials such as steel and aluminium, global supply chain bottlenecks, and elevated shipping costs from travel restrictions worldwide. Should this trend persists, this could deal a blow for countries to scale up solar energy production and capacity, forcing many to remain relying on fossil fuels such as coal and natural gas. 

13. Solar Technologies Are Getting More Efficient

According to Rhone Resch, President of the Solar Energy Industries Association (SEIA), the global PV sector has been growing at an average of over 40% in the last eight years and major advances in automation, manufacturing, and throughput have considerably improved this technology. Most panels today are between 15% and 20% efficient, meaning that they are able to convert 15% to 20% of the amount of sunlight they absorb into electricity. Panels’ efficiency has improved consistently over the past decade, a promising factor and one that contributes to continued cost reduction. Furthermore, their resistance to extreme weather has been drastically improved, bringing their average durability to about three decades with little to no loss in efficiency.

You might also like: What Are the Advantages and Disadvantages of Solar Energy?

14. Scientists Are Exploring the Idea of Building Solar Power Stations in Space

Last on our list of solar energy facts is the futuristic, yet very likely possibility to build solar power stations in space. In European Space Agency (ESA) launched a campaign to collect new innovative ideas for technologies to increase the feasibility of space-based solar power to support the provision of clean energy and is now looking to fund some of these projects. Meanwhile, some prototypes are already underway in some countries. 

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