Can anyone give me some feedback on this blog?

[SanTan Solar]

Hi everyone, I'm new to the solar world, but I'm really interested, especially in the DIY/RV side of solar panels. I'm working on some blogs for work (I work at a solar panel wholesaler) but I want the content to be really solid. I'll post a link to the actual blog underneath, but I don't want this to be seen as promotion, I'm really trying to get a better handle on the install side of solar panels so I can be better informed and help people who are also new. My goal is to help people who know nothing get an idea about solar and how it works.

Here's the blog:
What is a Solar Panel?
Solar panels are made up of silicon semiconductors that absorb light from the sun. The silicon used in solar panels is classified into two types, monocrystalline and polycrystalline. Monocrystalline solar panels, sometimes just called mono, are more efficient, but a little more expensive. Polycrystalline, or poly, are typically cheaper, but less efficient.
We won’t go too in depth into what that means here, but for a really informative deep dive check out Energy Sage’s article.
When light hits these silicon cells, the cells absorb the light and knock loose electrons. When these electrons are knocked loose, an electric field guides these electrons in a current which is directed to a designated point, metal contacts placed on the outsides of the cells. Those electrons are then transferred out of the solar panel and into other appliances through a junction box on the back of the solar panel.
So, in short, light hits the silicon cells in the solar panel, which frees electrons. The electrons are guided to a metal point at the end of the cells and extracted through a junction box. The junction box has two cables that come out of it, and those are what carry the electrical current to other devices.
How Stuff Works has a great article on these. You can check it out here!
Terms to Know Before Buying
Cost Per Watt
Cost per watt is a metric to determine how much you pay per watt gained from the solar panel. To determine the cost per watt, you divide the price of the whole solar panel by the listed wattage, for example here at SanTan Solar we have a SunPower P17 340W solar panel listed for $110. If we divide 110 by the wattage, 340, we get the price per watt, $0.32 per watt.
Ok now we have that number, but what does that mean? You can add context to that price by doing the same calculation for other solar panels and see if you’re getting a good deal. SanTan Solar has another solar panel, a 250W panel listed for $55.
This panel comes out at $0.22 per watt. So you’re paying less per watt, that could be a good deal. Some of our competitors offer a 335W solar panel for $215, which puts it at $0.64 per watt. This is one way you can determine if you’re paying too much.
Efficiency
Solar panel efficiency can be tricky if misunderstood. Another term that is synonymous with efficiency is conversion rate. What these two terms refer to are the solar panel’s ability to convert incoming solar energy into electrical power. Most solar panels are able to convert between 11-19% of solar energy into electricity.
One other number that gets thrown around is a percentage of the rated efficiency. This is usually in reference to how long a solar panel will be able to be efficient. For example, if a solar panel is five years old, it will still be between 11-19% efficient BUT might only be able to function at 95% of the rated efficiency. Solar panels do degrade slowly over time, and this means that they’ll be able to convert less and less energy, but don’t fret!
Solar panels are made to last between 10 and 25 years depending on the solar panel. All this means is that as your solar panel gets old you might see a slight dip in how much solar energy it’s able to convert into electricity.
Cell Count
Not all solar panels are created equal, in fact most are created quite different! Each manufacturer has a different theory in crafting their solar panels and maybe even a different goal for application. For that reason you might see variations in the number of cells each solar panel has.
Some are 60 cells, some 72 and as many as up to 144! There are several reasons behind these discrepancies. Monocrystalline, or mono solar panels usually only have 60 or so cells, but that’s because they don’t need more!
A 60 cell mono solar panel usually produces 300+ watts, while 72 cell solar panels are typically polycrystalline and usually stick in the 220 watt range.
Some companies, like QCell, will even cut their 72 cells in half making them 144 cell polycrystalline panels. The logic behind this actually has to do with shading. On a typical solar panel, if shade covers a corner of the solar cell, the whole cell is inhibited from producing electricity.
Cutting the 72 cells and making 144 means that if shade covers the corner of a solar cell, there are still many more cells that can produce, and are not inhibited from producing.
Temperature Coefficient (Real World Conditions)
Solar panels are built and tested in laboratories where scientists are able to create ideal conditions for their tests and production. These tests are used to determine the wattage output and in what conditions can the solar panel achieve the highest output possible. Most solar panels have a sweet spot, and the temperature of the solar panel can be a big factor in reaching optimum output.
The ideal temperature for most solar panels is between 43°C and 48°C (109.4°F to 118.4°F) which is pretty warm. If the temperature of the solar panel is outside of that range, it won’t be able to produce as much as it has the capability. These numbers are sometimes called optimal conditions vs real world conditions, and this is something to take into account when you buy your solar panels. You are going to produce less than the listed wattage in real world conditions most of the time.
How Many Solar Panels Do I Need?
When it comes to determining how many solar panels you need, there are a few factors to consider: Your electricity usage, sunlight hours your house receives and your budget.
First, you need to know how much electricity you use each month. On your electric bill this should be a pretty clearly labeled section that lists how many kilowatt hours you used this last month. Typical American kWh usage is about 950 kWh a month, and this number will vary greatly depending on where you live. That’s the first piece of the puzzle.
The second piece is knowing how many hours of direct sunlight your house (or other preferred location) gets a month. There are several websites that can give you an average, here's one on wikipedia.
The last piece is all about how much you want to spend. Do you want to stop paying your electric bill entirely, or just in part? Do you want to start with just a few solar panels and build it up? Or jump in headfirst?
You’ll also need to know what solar panel wattage is best. Usually it’s better bang for your buck to buy as high a wattage solar panel as you can afford to meet your kWh needs.
Lastly take all these numbers and put them into a solar panel calculator like the one we have here. The calculation we’re doing in this calculator is pretty simple:
First we convert your kWh into watt hours, the easy way to do this is just add three 0’s to the end, so if you use 1000 kWh a month, you’re using 1,000,000 watt hours a month. Now we take that number and divide it by your average monthly sunlight hours, here in Arizona its something like 270. Now we take that number and divide it by the wattage of the panel you like, let’s say a 340W solar panel.
This gives you 10.89. This is the number of solar panels you need at minimum and in optimal conditions. Obviously, you can’t have 10.8 solar panels, so round up to 11. It’s also a good idea to do some math for non-ideal conditions, or simply to get one or two more panels than you think you might need to make sure you stay where you need to.
Once again, all this math is done for you in the solar calculator found at www.santansolar.com/solar-calculator.
Which Solar Panels Are Best For Me?
The long winded answer above might have helped you get an idea on how to determine which solar panels are the best for you and your needs. To best determine which are best for you, you need to know how much electricity you want to create and how much space you have for the modules. Our general recommendation is to get as high a wattage of solar panel as available.
This saves on space because you’ll need less panels overall, it also saves on money because you’ll be buying less panels.
There are good reasons to buy lower wattage and lower priced panels though. Maybe space isn’t an issue for you, you just want to buy as many as you can within your budget. Maybe you just want to dip your toes in the solar panel pool.
Either way, there are lots of considerations to take into account before making a purchase: budget, spacing, desired panel wattage, kWh you use, other equipment you might have or be interested in, manufacturers or even country of origin.




https://www.santansolar.com/learn/everything-you-need-to-know-about-solar-panels/



I really appreciate any feedback! Thanks!

 

[gnubie]

That's pretty good really.

If you wanted to pad out Which Solar Panels Are Best for Me you could mention the difference between mono and poly when it comes to diffuse light conditions such as clouding and that mono and poly derate differently with temperature, but that ultimately if you have the space the deficiencies of either can be countered by adding more panels.

 

[SanTan Solar]

That's pretty good really.

If you wanted to pad out Which Solar Panels Are Best for Me you could mention the difference between mono and poly when it comes to diffuse light conditions such as clouding and that mono and poly derate differently with temperature, but that ultimately if you have the space the deficiencies of either can be countered by adding more panels.

That's a good note, I'll take a look at that! Thanks!

 

[svetz]

Hey SanTan! Welcome to the forums.

I really appreciate any feedback!

I sure hope you have a thick skin cause I'm about to be brutal. Not because I'm mean spirited, but because I want you to succeed; solar's import and the world needs bloggers talking about them.

Next, don't believe anything I say. Not because I'm saying anything to mislead you; but because your readers/customers will expect more accuracy than from some person on the internet you just met. Trust, but verify. I'll try not steer you wrong, if I do please let me know so I can learn.

What is a Solar Panel? Solar panels are made up of silicon semiconductors that absorb light from the sun. ... monocrystalline and polycrystalline. Monocrystalline solar panels, sometimes just called mono, are more efficient, but a little more expensive. Polycrystalline, or poly, are typically cheaper, but less efficient.

This section seems choppy to me. Part of that is glossing over some details and diving deep into others. For example an electric field guides these electrons in a current which is directed to a designated point, metal contacts placed on the outsides of the cells is very detailed compared to the rest. Solar panels are made up of solar cells, which are silicone semiconductors. Each solar cell produces about 1/2V, by putting them together in series the manufactures sets a panels voltage (more on this in a minute).

Efficiency Solar panel efficiency can be tricky if misunderstood. Another term that is synonymous with efficiency is conversion rate. What these two terms refer to are the solar panel’s ability to convert incoming solar energy into electrical power. Most solar panels are able to convert between 11-19% of solar energy into electricity.

Efficiency is a useless metric. Two 200 W panels produce the same power. What does efficiency tell you? Which one is a few square centimeters bigger/heavier. Most people don't care about that. See Comparing Solar Panels.

Cell Count Not all solar panels are created equal, in fact most are created quite different! Each manufacturer has a different theory in crafting their solar panels and maybe even a different goal for application. For that reason you might see variations in the number of cells each solar panel has. Some are 60 cells, some 72 and as many as up to 144! There are several reasons behind these discrepancies. Monocrystalline, or mono solar panels usually only have 60 or so cells, but that’s because they don’t need more! A 60 cell mono solar panel usually produces 300+ watts, while 72 cell solar panels are typically polycrystalline and usually stick in the 220 watt range. Some companies, like QCell, will even cut their 72 cells in half making them 144 cell polycrystalline panels. The logic behind this actually has to do with shading. On a typical solar panel, if shade covers a corner of the solar cell, the whole cell is inhibited from producing electricity. Cutting the 72 cells and making 144 means that if shade covers the corner of a solar cell, there are still many more cells that can produce, and are not inhibited from producing.

Not really an important item for the reasons listed below.... Sorry. The number of cells has to do with size, voltage, and weight. Shade is a factor but more cells doesn't necessarily mean better shade tolerance. Solar panels are built up of smaller sub-panels. You can tell how many by how many diodes there are or with the math knowing each cell is about 0.5V and knowing the panel voltage. So, let's talk about shade. A shaded panel in a string can bring the string voltage down. By having subpanels with multiple diodes a portion of the panel can be shaded and the voltage won't come down, only the power - so the overall string isn't affected. But the configuration within the panel is REALLY important. For example, the QCell you mention is divided into an upper and lower half, which means when the panel is half covered by snow it's not dragging down the rest of the string. Compare that to a traditional panel where they're all side-by-side, when partially covered by snow that panel will bring down the string.

Temperature Coefficient (Real World Conditions) Solar panels are built and tested in laboratories where scientists are able to create ideal conditions for their tests and production. These tests are used to determine the wattage output and in what conditions can the solar panel achieve the highest output possible. Most solar panels have a sweet spot, and the temperature of the solar panel can be a big factor in reaching optimum output. The ideal temperature for most solar panels is between 43°C and 48°C (109.4°F to 118.4°F) which is pretty warm. If the temperature of the solar panel is outside of that range, it won’t be able to produce as much as it has the capability. These numbers are sometimes called optimal conditions vs real world conditions, and this is something to take into account when you buy your solar panels. You are going to produce less than the listed wattage in real world conditions most of the time.

The ideal temperature for most solar panels is between 43°C and 48°C (109.4°F to 118.4°F) That's just wrong. Please check your sources. Panels put out more power when they're cold and less when they're hot. These numbers are sometimes called optimal conditions vs real world conditions, I think you're confusing STC with PTC; neither have anything to do with the temperature coefficient. Panels go from subzero in winter to blazing hot in the summer sun. The temperature coefficient is divided into 3 categories on a datasheet, one for power, one for voltage, and one for current.

How Many Solar Panels Do I Need? When it comes to determining how many solar panels you need, there are a few factors to consider: Your electricity usage, sunlight hours your house receives and your budget. First, you need to know how much electricity you use each month. On your electric bill this should be a pretty clearly labeled section that lists how many kilowatt hours you used this last month. Typical American kWh usage is about 950 kWh a month, and this number will vary greatly depending on where you live. That’s the first piece of the puzzle. The second piece is knowing how many hours of direct sunlight your house (or other preferred location) gets a month. There are several websites that can give you an average, here's one on wikipedia. The last piece is all about how much you want to spend. Do you want to stop paying your electric bill entirely, or just in part? Do you want to start with just a few solar panels and build it up? Or jump in headfirst? You’ll also need to know what solar panel wattage is best. Usually it’s better bang for your buck to buy as high a wattage solar panel as you can afford to meet your kWh needs. Lastly take all these numbers and put them into a solar panel calculator like the one we have here. The calculation we’re doing in this calculator is pretty simple: First we convert your kWh into watt hours, the easy way to do this is just add three 0’s to the end, so if you use 1000 kWh a month, you’re using 1,000,000 watt hours a month. Now we take that number and divide it by your average monthly sunlight hours, here in Arizona its something like 270. Now we take that number and divide it by the wattage of the panel you like, let’s say a 340W solar panel. This gives you 10.89. This is the number of solar panels you need at minimum and in optimal conditions. Obviously, you can’t have 10.8 solar panels, so round up to 11. It’s also a good idea to do some math for non-ideal conditions, or simply to get one or two more panels than you think you might need to make sure you stay where you need to. Once again, all this math is done for you in the solar calculator found at www.santansolar.com/solar-calculator.

Typical American kWh usage is about 950 kWh a month If I've learned anything, there is no typical American. The second piece is knowing how many hours of direct sunlight your house (or other preferred location) gets a month. You link to Wikipedia is completely incorrect for doing solar calculations. You want to use an insolation map. See this post.