Сheap solar power from metal mirrors. What's wrong
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I made a variety of
I made a variety of solar heaters from metal mirrors for the hot water supply of my summer cottage, for production of very cheap high-temperature thermal energy in order to generate cheap electricity, and for other purposes, and this video describes the problems you will face if you want to make your mirrors from stainless steel sheets.
We see that these stainless steel sheets focus the solar radiation into this spot where the radiation causes high temperature. Now I will measure the temperature, and here we see that it is almost 200 ⁰C, but the heating temperature will increase drastically if we cover the black surfaces with a transparent sheet and replace their black paint by a selective coating.
But it is obvious that this is not a place for bacon and sausages, but for a similar receiver which must convert the energy of solar radiation into thermal energy. So, let's look at the disadvantages of these mirror stainless steel sheets.
This white screen will help us better see the spot of solar radiation from my stainless steel sheets. We can notice that the height of the spot is less than 10 cm while all my stainless sheets have a total height of 170 cm. If we need a lower spot, we must use another method of fixation of the stainless sheets than these screws. For example, this blogger uses a different method, and now we will see the quality of the focus of his mirrors. It is realistic to set a goal to reach the height of a spot which is almost 100 times less than the total height of its mirrors.
Now I am again showing the spot of solar radiation from my mirrors, and pay attention to these areas. These light areas are created by solar radiation which was reflected off the top and bottom edges of my two stainless steel sheets, and the 1st cause of their presence is my method of fixing the edges of mirrors. At the same time, other bloggers use different methods of fixing the top and bottom edges.
The 2nd cause is manufacturing defects in the edges of my stainless steel sheets, but this is a low-quality Chinese product, and perhaps other manufacturers produce better quality sheets.
My research used stainless steel sheets of this grade with a thickness of 400 microns, and I bought these sheets for 12 $ / sq.m. But we can calculate that the wholesale prices of similar stainless sheets are less than 8 $ / sq.m, and therefore the cost of stainless mirrors is about the same as glass mirrors or thin anodized aluminum sheets. Due to the low price, our solar heaters with stainless mirrors can be the basis of such large solar power plants, which convert huge amounts of solar radiation into thermal energy for turbines not only during the day, but also at night through these heat storages.
My previous videos have often shown similar formulas which lead us to this cost of our solar electricity, 5 cents / kWh, and it is cheaper than electricity from thermal and nuclear power plants. This formula requires reaching this cost of our thermal energy from the sun, 0.5 cent / kWh, and it is about 10 times cheaper than the cost of heat from natural gas. The conditions for achieving this heat cost are described by this formula, and here we see that the total cost of manufacturing and installing our metal mirrors should be 15 $ / sq.m.
That is why stainless steel mirrors are not the only option, and therefore I started testing a few other options. For example, this is a very thin sheet of anodized aluminum on a sheet of cheap steel. This is another example, and it is a reflective film on a thin sheet of cheap steel, and I connected the film and the sheet with this very cheap glue.
It is interesting that similar devices also belong to our class of solar heaters, and for example, their metal surface can be covered with a reflective film. Unfortunately, such devices based on a satellite dish have little chance of matching our formula, but we can replace those expensive dishes with similar solar heaters from several dozen curved strips of mirrors.
My previous videos have often described how similar mirror dishes work. They must form long rows and focus solar radiation into receivers which have the ability to move from morning to evening.
A few years ago, I measured how much heat is produced by different types of mirrors. It was found that 1 sq.m of that grade stainless mirror produces 6 % less heat than 1 sq.m of this glass mirror and 9 % less than these anodized aluminum sheets.
These were measurements for new mirrors, but glass and aluminum mirrors can lose their reflection coefficient at a rate of up to a few percent per year. At the same time, it seemed to me that stainless mirrors lose their reflectivity more slowly, and now I am showing stainless mirrors that have already worked in the open sky for about 7 years. We can compare them with this situation of the same mirrors, but almost 7 years ago.
We see that these stainless steel sheets focus the solar radiation into this spot where the radiation causes high temperature. Now I will measure the temperature, and here we see that it is almost 200 ⁰C, but the heating temperature will increase drastically if we cover the black surfaces with a transparent sheet and replace their black paint by a selective coating.
But it is obvious that this is not a place for bacon and sausages, but for a similar receiver which must convert the energy of solar radiation into thermal energy. So, let's look at the disadvantages of these mirror stainless steel sheets.
This white screen will help us better see the spot of solar radiation from my stainless steel sheets. We can notice that the height of the spot is less than 10 cm while all my stainless sheets have a total height of 170 cm. If we need a lower spot, we must use another method of fixation of the stainless sheets than these screws. For example, this blogger uses a different method, and now we will see the quality of the focus of his mirrors. It is realistic to set a goal to reach the height of a spot which is almost 100 times less than the total height of its mirrors.
Now I am again showing the spot of solar radiation from my mirrors, and pay attention to these areas. These light areas are created by solar radiation which was reflected off the top and bottom edges of my two stainless steel sheets, and the 1st cause of their presence is my method of fixing the edges of mirrors. At the same time, other bloggers use different methods of fixing the top and bottom edges.
The 2nd cause is manufacturing defects in the edges of my stainless steel sheets, but this is a low-quality Chinese product, and perhaps other manufacturers produce better quality sheets.
My research used stainless steel sheets of this grade with a thickness of 400 microns, and I bought these sheets for 12 $ / sq.m. But we can calculate that the wholesale prices of similar stainless sheets are less than 8 $ / sq.m, and therefore the cost of stainless mirrors is about the same as glass mirrors or thin anodized aluminum sheets. Due to the low price, our solar heaters with stainless mirrors can be the basis of such large solar power plants, which convert huge amounts of solar radiation into thermal energy for turbines not only during the day, but also at night through these heat storages.
My previous videos have often shown similar formulas which lead us to this cost of our solar electricity, 5 cents / kWh, and it is cheaper than electricity from thermal and nuclear power plants. This formula requires reaching this cost of our thermal energy from the sun, 0.5 cent / kWh, and it is about 10 times cheaper than the cost of heat from natural gas. The conditions for achieving this heat cost are described by this formula, and here we see that the total cost of manufacturing and installing our metal mirrors should be 15 $ / sq.m.
That is why stainless steel mirrors are not the only option, and therefore I started testing a few other options. For example, this is a very thin sheet of anodized aluminum on a sheet of cheap steel. This is another example, and it is a reflective film on a thin sheet of cheap steel, and I connected the film and the sheet with this very cheap glue.
It is interesting that similar devices also belong to our class of solar heaters, and for example, their metal surface can be covered with a reflective film. Unfortunately, such devices based on a satellite dish have little chance of matching our formula, but we can replace those expensive dishes with similar solar heaters from several dozen curved strips of mirrors.
My previous videos have often described how similar mirror dishes work. They must form long rows and focus solar radiation into receivers which have the ability to move from morning to evening.
A few years ago, I measured how much heat is produced by different types of mirrors. It was found that 1 sq.m of that grade stainless mirror produces 6 % less heat than 1 sq.m of this glass mirror and 9 % less than these anodized aluminum sheets.
These were measurements for new mirrors, but glass and aluminum mirrors can lose their reflection coefficient at a rate of up to a few percent per year. At the same time, it seemed to me that stainless mirrors lose their reflectivity more slowly, and now I am showing stainless mirrors that have already worked in the open sky for about 7 years. We can compare them with this situation of the same mirrors, but almost 7 years ago.
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