Looking Into Solar but Afraid of the Upkeep? Let’s Talk Panel Maintenance!
So you’re looking at solar panels and you’re wondering about the upkeep – do you need to clean them? How often? Which products should you use?
Well, first of all – good news! You probably don’t need to clean them at all! Sure, your panels might be dusty or dirty and have some very slight productivity loss (about $20/year at most for an average home system if you don’t clean them), but the occasional rain will take care of it for you.
If your panels look a little dusty but they’re still performing the same, it’s probably better to just leave them alone – if it ain’t broke, don’t fix it!
“…you can clean your panel like a window…”
It’s worth checking with your solar providers to find out if they have any specific recommendations, or if any maintenance services come included with the initial purchase or installation price tag.
Of course, there are a number of situations that can get your panel dirty to the point you need actual maintenance. Let’s take a look at problems and solutions.
(Disclaimer: please keep in mind that if you have a rooftop solar installation, you may need to hire professionals for safety’s sake. Also, we don’t recommend doing this in the afternoon when it’s hot and sunny – the panels can burn your hands and dry too fast to clean well. Whatever you choose to do, please be safe!)
My panels are dusty and I live somewhere that doesn’t get a lot of rain.
This one’s easy – just hose off your panels. (Don’t power-wash them, you can damage the panels.)
My panels are still dirty after getting rained on/hosed off.
There might be lots of dirt, bird poop, or other debris on your panel. In that case, you can clean your panel like it’s a window. Mix warm water and mild soap (like dish soap – don’t use laundry detergent!), and wash the panels gently with a soft cloth or sponge. You may not even need soap – water typically works just fine. The most important thing here is not to scratch the panel. You don’t need to clean the cables.
My panels are covered in snow.
Since panels are typically slanted and facing the sun, the snow should melt off on its own and you’ll be good to go. If your panels are laid flat or if the snow’s not melting, consider getting a solar panel snow rake to softly slide snow off. Don’t use a normal broom or snow shovel to try to knock snow off, you might scratch your panels!
My panels are covered in leaves/debris that won’t blow off.
Like snow, you can get a roof brush (find one that’s recommended for solar panels) and just slide the leaves off.
“…there are self-cleaning solar systems you can buy…”
I want to wash my panels, but my water is hard water.
If your water is mineral-heavy, you made need to squeegee your panel hard to keep deposits or streaks from being left on the panel.
I can’t/don’t want to clean my panels.
There are self-cleaning solar systems you can buy for a bit more. Also, check with your solar providers or installers to find out if any periodic maintenance is included with your panels.
Ok. Anything else I should know?
If you do choose to clean your panels, check the productivity before and after. You may notice a difference, or you may not – something worth keeping in mind. It might not be worth all the trouble of regularly setting up a ladder, climbing up to the roof, and washing large panels under a hot sun for a barely noticeable increase in savings.
I can’t/don’t want to clean my panels.
There are self-cleaning solar systems you can buy for a bit more. Also, check with your solar providers or installers to find out if any periodic maintenance is included with your panels.
Wrapping Up
How much maintenance you put into your panels is up to you, but generally you don’t need to clean them at all. Install your panels, then sit back and enjoy producing your own clean, sustainable energy.
Recently there has been an increasing buzz about solar panels as more and more individuals and companies decide to adopt solar panels as their primary source of energy. Google Search Trends show an impressive increase of solar panel interest in the last five years. Between Apple installing them on their new headquarters and recent news of Walmart suing Tesla over potential negligent installation, the news has a new solar story every day!
But what are solar panels and how do they work?
Let’s start at the beginning.
What is a solar panel?
Solar panels, also known as photovoltaic cells, are tools used to capture heat from the sun and convert it into electricity.
Ok that seems pretty simple, but how does it work?
The simple explanation is that the panels are made up of smaller components called cells. These cells are made of silicon, and placed in rows on the panels. These cells are semiconductors that collect and convert solar energy (sunlight) into electricity.
The absorption of this solar energy knocks electrons out of place, allowing them to flow freely in a current. This current is directed to metal inside the panels, which can then be directed out of the panel and into another appliance.
This current is now electrical energy flowing in a Direct Current or DC. In your house you use AC or Alternating Current, so the DC energy needs to change to AC energy for you to be able to use it in your house. To convert DC to AC you’ll use an inverter. The inverter will change the energy, and then you can use it to power your home!
In conclusion: silicon cells absorb sun light, which is channeled and converted into usable AC energy through an inverter, then sent to your appliances or to a storage device like a battery for later use.
If you want to see a more in depth explanation check out this pdf from how stuff works! This is one of the documents we recommend to those new to solar! http://igs.nigc.ir/STANDS/ARTIC/SL-01.PDF
When you’re constantly out on the open road and enjoying nature, have you ever thought about going solar on your travels?
Make The Change To Solar
If you are frequently camping or RVing, are you always connecting to the grid? Isn’t it expensive and exhausting? If you’re out road tripping, you shouldn’t feel constrained to campgrounds or RV parks while making your journey. Luckily, switching to solar can change all of that. Go wherever your heart desires, be free and independent, and travel anywhere and everywhere. Going solar can change your life.
By switching to solar energy options, you can have access to the electricity you need no matter where you journey to. Traveling with solar provides you with a renewable energy source anywhere that has sunlight, without having to connect to any other sources. It’s easier than you think, eco-friendly, and it’s just what you need for your traveling necessities. Here’s how you can do it:
How to Travel with Solar
1.Calculating your Energy Needs
Know how much energy you need to power your appliances, so you know which system you’ll need to set up
There are a variety of ways to calculate your needs, but first you want to know how much power your appliances will be consuming. To calculate this consumption, find out how much wattage your appliances are using. ( e.g. A TV could be utilizing 80 watts- this could be found on the electrical label). Next, you take that number and multiply it by how many hours you’ll use it per day. So if you use the TV for 3 hours, you would be using 240W per day (3 hrs x 80 W). This process would be done for all your appliances. (If you have one 250W panel, that’ll produce 250 watts for every hour of direct sunlight, or more than three TVs worth of electricity every hour.)
Then, you need to know how much energy the panels are generating over time and how much energy your battery system will hold
You will have to decide where to put the panel: mounting it on the roof is common, but what if you want your panel to be mobile? Most of the time, people will store it in their camper or RV and take it out when necessary.
3. Setting It Up
Once you know where the placement of your panels is, you can begin the process of connecting all of the equipment necessary for your system. The system you use will determine the best way to set it up. Most systems use the same equipment (as seen in the picture below) such as a battery bank, an inverter or even a charge controller, depending on your voltage.
3. Enjoying Your Solar Life
Once everything is all set up and connected to everything you want/need, enjoy your sun-powered renewable energy!
Worth The Cost
We all know that going solar can be an expensive investment, however, in the long run the benefits of solar will prove to be worth the cost. It’s a well calculated risk that’s absolutely worth it, because with solar you’ll have the freedom to travel anywhere life takes you while still having the electricity to operate your appliances. Camping, hiking, RVing, or anything your imagination brings will become your freedom once you harness the power of the sun.
Exactly how much do solar panels wear out over time?
While solar panels degrade a little every year from exposure, they’ll last you decades and they’re an excellent investment, new or used.
Efficiency vs. Lifespan
If you’re shopping around for the best solar panels to buy, then you know that efficiency and lifespan are factors you should keep in mind.
First off, it’s important to know the distinction between efficiency and performance. Efficiency refers to how well the panel converts sunlight into energy – most of it is lost. Even with all the technological advances made in the last few decades, most panels range in efficiency from about 15-24%, depending on the manufacturer and kind of panel. Performance, on the other hand, refers to how much of the panel’s maximum power output you’re getting. New panels start out at almost 100% and after 20 years drop to around 80-90% performance, depending on the manufacturer and panel.
To sum it up: efficiency is about how good the solar cells are at converting light to electricity and that’s a low percentage, and performance is about how well a panel continues to generate power as it ages, and that’s a high percentage.
Keep in mind, efficiency ratings may sound impressive, but record-setting panels typically achieve those rates in specific laboratory situations. If you need a 250W panel, any well-made 250W panel will get you that power. Typically, efficiency matters when you want fewer, more powerful panels to fit on your limited roof space.
Degradation
Ok, now that you understand the difference between efficiency and performance and what those terms mean, let’s talk about degradation. Panels are built to withstand high and low temperatures, snow, hail, and other hazards, but they’ll still break down a little over time. Gradual decreases in your panel’s performance can be caused by UV exposure, bad weather, scratches, or other causes. A pretty standard rule of thumb is to expect a 3% decrease in the panel’s first year, and then about a 0.5% drop every year after that. This can vary depending on location – panels in a moderate climate might only have a 0.2% drop every year. Other conditions might worsen up that decrease – such as cracks in the glass or moisture in the cells.
Degradation
So now you might want to know what kind of output you can expect from your panels 25 years from now. We don’t quite know either – technology has improved rapidly enough that it’s tricky to predict how well panels made now will function in 20 or 30 years. Solar panels can be surprisingly durable – the world’s first modern solar panel still works, a panel made in 1979 actually outperformed its original factory specifications, and many other older panels still function well even after their warranty expired.
Alright, so panels are a good long-term investment. Which panels are the best though? Well, that’s up to you to decide depending on which factors are most important to you – whether you want top of the line panels or less expensive but still dependable panels.
We have a number of used, overstocked, and refurbished solar panels. Given how well panels continue to perform after a few years, you could save a lot of money and still find the high-quality, high-efficiency panels you need. All our panels are checked and tested to make sure they’ll still work well for you, and come at a much lower price than new panels. Learn more about the benefits of used panels here, see which panels we have in stock here, or contact us here if you have more questions
Planning on switching to solar energy? Take advantage of tax breaks and rebates available in your state!
Wondering which government financial incentives you’ll qualify for if you decide to go solar? Take a look below to see which tax breaks and bonuses you’ll get from the federal and state governments.
Federal Solar Tax Credit/Investment Tax Credit:
In 2005, the Energy Policy Act was enacted, giving people a 30% tax credit from the installation of their solar systems.This means that for the total cost of your solar project, you’ll get 30% back as a credit towards your taxes. For example, say you paid $10,000 for the whole installation – you’ll have $3,000 taken off your federal taxes. This means that if you owe $5000 on your taxes, that $3000 will be taken out of that cost, and therefore you’ll only be paying $2000 instead. That’s a pretty sweet deal, right? (It’s one of the reasons we recommend buying instead of leasing, as the legal owner of the panels gets the tax credit.)
Want to take the government up on that offer? Unfortunately, the tax credit will only stay at 30% this year, because next year in 2020 it starts dropping off. If you want to take advantage of the credit, build fast. The credit will only be 26% in 2020, 22% in 2021, and 0% in 2022 (10% for commercial projects).
To claim the credit, just make sure it’s on your annual federal tax refund. The form you’ll need to complete is the IRS 5695. You’ll get the credit amount for the year you completed the construction, so panels that you bought in 2020 but installed on your house on 2021 will only get you a 22% tax credit.
State
Most states offer a mountain of incentives, benefits, and rebates if you choose renewable energy, and there’s too many to fit them all here. Instead, check out the link below for resources to find out which perks you qualify for in your state or county.
Our team at RocketCity Solar often receives various questions regarding anything solar related. We often get asked what you need to install solar panels, the amount of panels you need to start your solar journey, what the right panel is for your solar project, etc. Our teams does their best at answering these questions and below you’ll see the most frequent questions we receive. Take a look at the questions below and see if we answered your doubts.
What do I need to install solar panels on my RV, van, trailer, etc?
You don’t need much to get started on your solar journey and RocketCity Solar makes it easier for you with our Solar Panel Kits. We provide the essentials to get started and make your life a bit easier. What you essentially would need is solar panels, charge controllers, MC4 parallel pigtails, MC4 inline fuse, circuit breaker, Z brackets, PV wire, and MC4 connectors.
Charge controller
Charge controllers prevent battery overcharge. They regulate the current traveling from the solar panel to the battery.
MC4 parallel pigtails
MC4 parallel pigtails are perfect for connecting multiple panels together in a solar field, and are typically used in parallel applications. These come in 2 to 1, 3 to 1, and 4 to 1.
MC4 inline fuse
An inline fuse provides protection for electrical equipment and the MC4 inline fuse is used to provide protection to solar panels wired in parallel.
Circuit breaker
Circuit breakers are designed to protect an electrical circuit from damage which is caused by excess current from an overload.
Z brackets
Z brackets are used to mount panels to flat surfaces. They’re ideal for RV, Marine, Boat, Car, and Home applications.
MC4 Connectors
MC4 connectors are simply used to connect solar panels together easily.
I need to charge 12V batteries, do you sell 12V panels?
Unfortunately, we don’t sell 12V panels but our panels can still be used with 12V systems with the use of a MPPT charge controller. We have many solar panels ranging from 250W to more than 400W!
How many watts do I need for my RV, van, trailer, etc?
The amount of watts you may need for your RV, van, trailer, etc. depends on your energy needs. Whether that be powering your fridge, microwave, blender, TV, etc. To calculate how many watts a certain appliance uses you need to do some calculations.
How many panels do I need to charge my battery bank? (Panels are measured in watts, battery banks in amp hours)?
The amount of panels you may need to charge your battery bank depends on the wattage of your panels and the voltage of your battery bank. Our solar calculator can help answer this too.
How many panels do I need to run my house?
The amount of panels you may need to run your house depends on your energy needs. Whether that be powering your fridge, microwave, blender, TV, etc. Some factors to consider are your electricity usage, sunlight hours your house receives and your budget. You can calculate how much energy you use by looking at your electricity bill. On there it will show you how many kilowatt hours you used this last month.
You also have to consider how many hours of direct sunlight your house gets a month and how much you want to spend. We have a informative article that will help you answer those questions.
When you decide to use solar energy, it’s important to choice the correct system to satisfy your needs. You face the decision of staying connected to the electrical grid, disconnecting from it or sticking to a combination of both. We’re here to help you decide what works best for you and to finally answer … What is the difference?
On-Grid
If you decide to stay on the grid, that means that your system will be directly connected to the electrical grid that powers the community. This give source of energy to compensate for any power loss if your solar system stops working for any reason. For the public services of the local grid, this connection would allow for any solar energy that your system generates to combine with that grid and then the members of the local community could use it.
Being connected to the local grid and returning the energy could qualify you for credits in compensations for the electricity your system generates depending on where you live.
Although the the solar systems connected to the grid don’t work when there’s a power outage because it can be dangerous for the electricians who work bringing the electricity back from the outage.
Anyways, if you’re connected to the grid, check in with your company of local services about how to proceed.
Off-Grid
Choosing an off-grid system means completely disassociating your system from the local power grid, which then means that your panels are independently producing energy for your electricity. Most people who use off-grid systems are those who travel, specifically in an RV or camper, people who don’t have access to the grids, or simply those who want to rely completely on their own system for power.
Choosing an off-grid system means completely dissociating your system from the local power grid, which then means that your panels are independently producing energy for your electricity. Which also means that this requires extra equipment because you need to assure yourself that this generates enough energy for your needs in all climate circumstances.
On the other side, if something is wrong with your system, you would find yourself without access to a backup energy source and might have to buy an energy generator.
Hybrid
A good half-point is a hybrid system like an electric car, a hybrid system combines the best of both systems and allows the owner of the property to be self-sufficient and at the same time have a strong backup source of energy.
Whatever your decision is, we can help you design your ideal system and provide you with all of the solar panels you could need to start.
Buying used solar panels is a lot like buying a used car, if you’re confident it was well cared for and the proper maintenance has been done, it can be a real bargain!
Buying used solar panels can be a tempting offer, but is it worth your investment?
Have you ever considered buying a used car? You might determine that buying used saves you enough money that you would deal with a used vehicle. Some of the things you would consider when inspecting a used car are the current condition, how well was it cared for, maintenance, seller, the current mileage, and its estimated lifespan.
If you can verify all those details, and they all come back positive, you’d call it a steal, right? You’d drive off into the sunset, pretty excited about the deal you just got.
Let’s apply that to solar panels, you would want to know the current condition of the panel, how well has it been cared for, has there been maintenance on the panel, is the seller reputable and how long will it keep working?
One of the benefits of buying a used solar panel is that the price is often lower. This gives you some wiggle room. Imagine a brand new solar panel (around 250 watts) sells new for $250 (this is actually still really cheap, the average price per watt for new panels is $2.67. This example new panel is $1 per watt).
If you can buy that same solar panel used for $90 (price per watt is $.36 here), you have some wiggle room to pay for 3 more panels before you reach the price of the new panel. Imagine this $90 panel ends up producing 215 watts instead of 250 for some reason. You can scrap that panel and buy a new one 2 times before hitting the cost of the new one. You could also just buy 4 panels and be generating between 1,100 – 1,200 watts. That makes sense but for how long will the panel produce?
Most manufacturer’s warranty their panels anywhere from 10-25 years. That means they expect the panel to be functioning as intended for that length of time. Imagine you get a panel that’s been used for 5 years. Depending on the panel quality, you could still have 20 years of power generation from that panel (most often when you buy used it doesn’t come with the manufacturer’s warranty, but that doesn’t mean the panel isn’t expected to work for the same amount of time!)
“…the solar industry is growing fast…”
All solar panels degrade over time, just like cars. You might get fewer miles per gallon as time goes on, and so it is with solar panels. The reason manufacturer’s offer their long warranty is because they expect the panel to degrade a certain rate (about 1% per year). This means that these manufacturers expect that when a panel is 20 years old, it will still be close to 80% effective! So, if you come across some used panels that aren’t very old, you can expect them to perform well!
One of the big factors that makes a panel unfit to be sold as “new” are the cosmetics. Maybe the frame has a small dent (doesn’t affect production), maybe the spacing on the panel is off (doesn’t affect production), or maybe there is a little line where the sealant is visible on the glass, aka a snail trail (doesn’t affect production). Panels with problems like these are where you make off like a bandit, because the production is unaffected, they just have minor cosmetic flaws.
Because the solar industry is growing so fast and the technology is improving so quickly, panels quickly become outdated, just like how when a new Jaguar comes out, the model from the year earlier is now “outdated”, but you’d still drive it if you could.
In conclusion, as long as you know that the used seller has done their due diligence and knows that the wiring and wattage of the panel are all in working order, it’s basically like buying new
When we talk about recharging batteries, two parts of the electric current are important: amps, and voltage.
If our battery bank runs at 12 volts, we want to recharge it with a current at or a little above that 12 volt rating.
Once we’ve reached our desired voltage in our charging current, additional amps result in a faster charge time.
EX: Our battery bank has a 400 amp/hour capacity and runs at 12 volts
A 12 volt 40 amp current will recharge our battery in around 10 hours.
A 12 volt 10 amp current will recharge our battery in around 40 hours.
You may look at this and think that maximizing your amperage is the way to go.
However, that has its own problems.
High amperage currents charge our batteries faster, but they also require much thicker wiring and specialized connectors.
As electricians will tell you, high amps means high heat.
We’d have to make sure our cables were low gauge(thick) to handle the increased heat.
High amperage current also doesn’t “play-nice.”
Expensive and bulky connections are necessary to deal with high amperage current.
Additionally, if our solar panels are far away from our battery bank, we can also run into problems of voltage loss, which occurs in low voltage current over long distances.
A 14 volt 40 amp current could drop to below usable levels if the current needs to travel over long distances.
So how do we reconcile these two facts?
If we try to charge our batteries with a high voltage current it will damage them.
High amps charge our batteries faster but make everything more complicated.
That’s where our Solar Charge Controllers can help.
Solar Charge Controllers limit the amount of voltage that reaches our battery bank.
They also limit the amount of energy lost during the night time by cutting the current off to our solar panels.
There are two kinds of solar charge controllers, MPPT and PNW.
PNW charge controllers limit the voltage coming into your battery by cutting off the voltage at the useful point.
If you have a 50 volt and 10 amp current coming from your solar panels but only want 15 volts, the PNW charge controller will send a 15 volt 10 amp current into your battery.
This is less than ideal due to the wasted energy.
On the other hand, MPPT charge controllers will convert the excess voltage into extra amperage to charge our batteries faster.
This is ideal because it allows us to wire our solar panels with the easy-to-work-with high voltage/low amperage current without wasting energy.
MPPT charge controllers are more expensive, though many find them to be worth the extra investment.
The Capacity of Your Batteries
Another way to know how many panels you need is to look at your battery bank.
Batteries come labeled with an amp/hour rating.
This rating tells you how much energy each one can store when it’s fully charged.
You’ll want to make sure your total amp/hour storage in your battery bank can handle this load each day (double the load if you’re using lead deep-cycle batteries).
Your batteries amp/hour will tell you how much energy you have available to be used in powering your appliances.
You can increase your available amp/hours by buying multiple batteries and wiring them in parallel.
As we said before, the current from your solar panels has two elements:
Voltage and Current.
These are measured by volts and amps.
If your battery bank consists of 12 volt batteries wired in parallel, your recharging current will have a voltage at or a little above 12 volts.
Once this voltage is achieved, we can calculate our recharge rate by looking at the amps of our recharging current.
If our batteries have 400 amp/hours of energy when fully charged, it would take a 40 amp current around 10 hours to recharge them fully.
It would take a 5 amp current 80 hours to recharge our battery bank.
So How Many Panels Should I Buy Then?
As we discussed in this article, there is not a one-size-fits-all answer.
To find a solution that works for you, you need to first get some idea of:
(1) What you’re hoping to power with your solar setup.
Solar energy can be used in a huge variety of applications, from home power to RV power to emergency situations.
You can use Calculatorto get some idea of how much energy you’ll need for your specific situation.
(2) The kind of battery bank you’re hoping to work with.
Lithium batteries have several advantages, but you’ll pay a premium for them.
Lead deep-cycle batteries are the cheaper solution in more ways than just price.
(Remember to keep those lead deep-cycle batteries above half charge!)
(3) Your Solar Charge Controller will help you convert current into usable voltages and amperages.
MPPT charge controllers give you more flexibility in wiring your solar panels but cost more than PNW charge controllers.
(4) Finally, we want to make sure our battery bank has the storage needed for each daily use.
Remember, we don’t want to damage lead deep-cycle batteries by allowing them to go below half charge, so be sure that your battery bank has more than double the capacity of your daily drain.
A common first step for most beginners is to look at a few key numbers when you start planning a new solar power project.
These numbers include projected wattage drain, projected number of sunlight hours, and total panel wattage.
You can calculate your potential power draw and sunlight hours through the calculator here.
After you get some idea of the power draw, it can be tempting to just go out and buy enough solar panels to cover your draw.
If you find that you typically use 2500 watt/hours each day, you may make the mistake of simply dividing that drain by the average number of sunlight hours to buy the appropriate number of panels.
If you get five hours of sunlight each day, you may think that a single 500-watt panel will be enough for your setup.
After all, 500 watts for 5 hours does equal 2500 watt/hours, your exact drain!
If you were to buy one 500 watt panel, you’d almost never generate enough power for your needs.
This is because a great number of inefficiencies nearly always accompany solar panels.
You must consider these inefficiencies when buying your solar panels, or run the risk of too little power.
We’ll be discussing some of the main inefficiencies that accompany all solar power in this article so you can be more confident in your solar design.
Panel Wattage in Lab Tests vs Real World (STC vs PTC vs Real World)
Most solar panels are rated in two ways, STC and PTC. STC stands for Standard Test Conditions, and are what you think of when you hear of unrealistic laboratory test conditions.
Every variable is perfect for solar panels to produce electricity.
They’re kept at an efficient temperature, they receive light that comes in at a perfect angle and with a uniform intensity across the entire panel.
Solar panel manufacturers measure their panels using STC.
Every panel that produces energy within a certain rating is then marked with that rating and sold.
Needless to say, STC does not represent real-world conditions.
In order to help installers get a better idea of actual solar panel performance, the PVUSA Test Conditions(PTC) rating was created.
A PTC rating is measured with a more realistic operating/ambient temperature and wind speed. On average PTC ratings reflect around 90% of the manufacturer’s STC rating.
This means that a panel rated for 500 watts will typically get a PTC rating of somewhere around 450 watts.
Every solar panel sold in California is required to receive a PTC rating, which means that almost every panel sold in the US has a PTC rating.
PTC is vastly more accurate than STC when representing real-world conditions, but it still doesn’t take into account degradation over time, off-angles, dirty panels, or other inefficiencies we’ll be covering later in this article.
Panel Degradation Over Time
We’ve covered how panels can produce less than their factory rating may imply.
Another concern to consider when buying panels is that they naturally lose efficiency as they age.
This fact can be especially important when designing solar setups with long projected lifespans.
It’s typical for solar panels to degrade by about 1% every year.
That means that in 10 years you’ll be generating about 90% of what you were when you first installed.
Let’s look at our example from earlier.
If we buy a 500-watt panel, we know it’ll likely have a PTC rating of around 450.
If we then use this panel for another ten years, it’ll drop down to around 400 watts even if we don’t take into account any other inefficiencies!
This degradation occurs for a variety of reasons.
Shortly after installation, solar panels are exposed to UV light which can rapidly lower the efficiency by a percent or two before leveling off.
Another way that degradation occurs involves thermal expansion and cooling.
As with most materials, solar panels expand slightly when warm and shrink slightly when cold.
This cycle of shrinking and growing can cause microfractures in the silicon.
You can see this degradation over time reflected in manufacturers’ performance warranties.
It’s typical to see a guarantee of 90% production for the first ten years and 80% for the first 25 years.
Voltage drop is usually considered acceptable when it’s less than 3-5% of your solar panel’s output.
Solar Charge Controllers PWM vs MPPT
Another key to increasing the efficiency of your solar panels is to buy the right kind of solar charge controller.
There are two main types of solar charge controllers.
PWM (Pulse Width Modulation) solar charge controllers limit the voltage coming into your batteries to prevent damage.
If you’ve got a 12-volt battery bank, a 60-volt current would cause serious damage to your batteries.
PWM charge controllers prevent this by limiting the amount of voltage.
All the excess current is lost with PWM charge controllers.
MPPT (Maximum Power Point Tracking) charge controllers are similar in that they limit the amount of current flowing into your batteries to prevent damage.
However, unlike PWM charge controllers, MPPT charge controllers convert the excess voltage back into the current to charge your batteries faster.
Depending on the voltage of your solar panels and battery bank, an MPPT charge controller could save you an incredible amount of efficiency.
MPPT charge controllers are more expensive than PWM charge controllers, but they could pay for themselves depending on your setup.
The last inefficiency we’ll be covering today is inefficiencies inherent in batteries.
Battery Inefficiencies
It’s not uncommon for charging and discharging your battery to be the single largest inefficiency in your solar setup.
We refer to the energy that batteries lose during the process of charging and discharging as their round trip efficiency.
There are two main types of batteries: lead deep-cycle batteries and Lithium-ion batteries.
Lead deep-cycle batteries have been used for decades and are cheap and reliable.
However, they usually have a round trip efficiency of somewhere in the 80% range.
Lithium-ion batteries have grown in popularity in recent years for their vast and varied advantages over lead deep-cycle batteries.
Lithium batteries typically have a round-trip rating in the high 90% range.
However, these batteries are far more expensive than lead deep-cycle batteries, sometimes costing up to ten times as much.
Conclusion
As you can see, the real world has a multitude of inefficiencies that can make planning your solar setup difficult.
STC ratings can be overly optimistic, panels degrade, and dirt and clouds can make everything even harder to account for.
On top of that, inefficiencies inherent to batteries and wiring can make the headache of planning even worse!
The main takeaway for your solar setup would be to buy far more power than you may think you’ll need.
You’ll never complain about having a battery bank that’s always full, or a solar panel setup that recharges them too quickly.
Remember, if it takes 10 solar panels to power an appliance, you can’t power the appliance with 9 solar panels, but you can with 10 or more.
