So How Many Solar Panels Do I Need
Different properties will have a varying number of solar panels based on a number of factors:
- Property size
- Energy demands
- Power output of the solar panels
Using your property’s annual energy usage, we can work out how many solar panels you will need to meet your demands.
Let’s take the average UK annual energy usage as an example 3,800 kWh.
If we refer back to the table at the beginning of the article, a 4kW solar system is the best suited to meet this demand. This means having enough solar panels as part of the solar system to reach 4,000W .
It’s worth remembering that the energy usage in the table above is an average and may well differ depending on your energy habits if you live alone you might only use 1kW of electricity each year. For that reason, it’s important to take a look at how much electricity is used by your home in a year on a recent energy bill.
While a solar PV system might appear to be large enough to meet the energy demands of your home at first, the solar inverter needs to be factored in too.
Your Solar Panel Size
The solar power available at full sun is 1000 watts per square meter. So in Boston in December you’ll get the equivalent of that power for 2.9 hours, or 2,900 watt-hours per square meter per day. In Albuquerque in July you’ll get 6,900 watt-hours per square meter per day. If you assume your solar panel is 10 percent efficient, that means that each square meter would provide you with 290 watt-hours in Boston in winter and 690 watt-hours in Albuquerque in July. You need 1600 watts to light your bulb for three nights, so you’d need 1,600/290 = 5.5 square meters in Massachusetts in December or 1,600/690 = 2.3 square meters in New Mexico in July.
If you do that same calculation for an efficient light bulb — say a 14-watt compact fluorescent — you’ll see why conservation is so important. You’d need less than 1 square meter of solar panel in the New England winter, and less than a third of a square meter in the Southwest summer.
Can You Connect A 100w Solar Panel To A Solar Generator
A solar panel can be connected to a solar generator and used to recharge the unit. However, PV modules are not always required for solar generators though they are compatible.
A portable solar generator or solar power station is basically a battery. You charge it via an AC wall outlet, DC or solar panel and it runs whatever device you connect to it. Generators have multiple inputs and outputs and capacity ranges from a few hundred watts to some large enough to power a house .
Because solar generators can be charged by AC power, a solar panel is not required. Many power stations dont have solar panels built in but you can hook up one easily. Most people charge their generator with AC and use the system while camping. If the power runs low thats when you can use a solar panel to recharge the unit.
There are many types of solar generators, some with more features than others. Check first if it is compatible with your 100W solar panel or if there is already one built in. You may also need more than 100W to recharge the generator, depending on its capacity.
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How Long Will 50 Amps Last
It would be great if a 50 amp battery lasts for 50 hours right? 1 amp = 1 hour seems logical. Unfortunately, battery capacity and charging does not work that way.
Battery rating is 5 amps per 20 hours, meaning if the load is consistently 5 amps an hour, it will last 20 hours. But that rarely happens because appliance amp draws vary, sometimes more than 5, sometimes less. In the real world, a 50 amp battery may last 10 to 15 hours.
The heavier the load, the faster the battery gets depleted. 5 amps per 20 hours does not necessarily mean drawing 10 amps = 10 hours. It depends on the battery type, age, discharge rate, capacity and operating temperature among other factors.
You cannot use the full capacity of lead acid batteries because it results in deterioration. The recharge point is 50%, so if you have a 50ah battery, only 25ah is available.
Lithium batteries can be drained to 0% and still be recharged. While manufacturers claim this is safe, it is not a good idea to do this regularly. Discharging at the 35% level is the lowest most lithium battery owners allow.
In other words, you will rarely ever have full use of the battery power. At most you can get 75% to 80% with lithium, but you pay a premium for the price. You just have to adjust your calculations according to the battery discharge rate.
Not Fully Charged
How Long Will A 100w Solar Panel Take To Charge A 100ah Battery
Everything is driven by the load, that is, how far is the battery discharged? You need to know this to work out how much energy to put back in.
Assuming a lead-acid battery, I can imagine 3 common situations:
All calculations use a 100 watt solar panel in full sunshine i.e. 1000kWh/m2. Panel output current is 5 amps and an MPPT charge controller is used.
Case 1 Calculation:
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How Many Amps Does A 100w Solar Panel Produce Per Hour
This is not normally measured, as it can changed a lot. The best way is to convert the energy produced in watt-hours to amp-hours, which will give is some idea of the average current delivered per hour.
First of all, how much energy in watt-hours does a 100 watt solar panel generate in an hour?
- Daily energy 595 watt-hours / 12 hours = 50 watt-hours .
Next, convert an hours energy output into amp-hours:
- Using Vmp of 17.5 volts, 50 watt-hours equates to 2.86 amp-hours.
So on average throughout the day, a 100 watt solar panel will push out an average of 2.86 amps per hour.
Keep in mind this value will be much higher in the hours around mid-day, up to 5.75 amps, while much lower early morning and late evening maybe not even 1 amp.
What If Your 100 Watt Solar Panel Kit For Rv Is Not Running In Excellent Conditions
The truth is your solar panels will use most of their lifetime operating in sub-optimal conditions. For beginners, keep in mind that most of the day is not peak sunshine hours.
You have to consider that morning and late afternoon hours acquire less direct sunlight compared to the hours around noon. Likewise, all locations have overcast days, so you need to be well aware of that.
There are also winter months that come with less daylight than summer seasons. Fundamentally, what all this implies is that your 100W solar panel would generate different amounts of energy depending on where and when it is being utilized.
Even so, it is essential to note that a solar panel that is not running at its maximum power potential could still produce usable energy.
Check whether your panel, inverter, battery, and charge controller are sized correctly. Solar panels also lose efficiency as time passes, so if your system is too old & cant satisfy most of your energy needs, consider upgrading it.
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Few Things About Solar Panel Output Efficiency
Solar panel type and quality make a significant difference in terms of solar output and efficiency. Not all solar panels are the same.
For instance, monocrystalline photovoltaic solar panels are known to be the most efficient solar panels on the market, but also the most expensive.
Their two main advantages over the other types of solar panels such as polycrystalline or thin film panels is that 1) they absorb more sunlight than conventional cells and their output efficiency is not affected that much by temperature and 2) they occupy less space. These are an ideal option if you do not have enough roof space for standard panels.
On the other hand, polycrystalline panels are cheaper, they are less efficient and therefore occupy more space, but offer a better return on investment than monocrystalline panels.
Because of these wide differences in quality and efficiency, its up to you to decide which solar panels are right for your home.
The main takeaway is that, the more efficient the panels are, the more power they can produce, and the fewer photovoltaic panels you will need on your roof to get the same energy output as you would get with polycrystalline or thin film solar panels.
Overall, if money is not an issue, monocrystalline panels are the best option.
Drain From Appliances And Amount Of Sunlight
Perhaps the single most important bit of information you need to know to buy the correct number of solar panels is what youll be using them for.
Different users have wildly different builds and appliances.
This makes guessing at your number of solar panels very difficult.
You could be hoping to install solar panels on the roof of your RV to help power a TV or recharge a laptop.
You could be looking for a small solar panel to bring with you on a backpacking trip to recharge your phone.
Alternatively, you could be planning a roof installation with the hope of powering your entire home with solar to become entirely energy independent.
Different parts of the country vary in how much sunlight they receive.
This is influenced by your latitude and how cloudy your region is, amongst other factors.
Its also important to consider that youll be receiving far more sunlight in summer than the winter.
Because generalizing with this is impossible, weve created a calculator that can guess at your average drain and sunlight hours based on your zip code.
There are several different kinds of batteries you can use for your solar setup.
A common and cheap solution is lead deep cycle batteries.
A more expensive but higher quality battery would be a lithium battery.
Many RVs find that a few lead deep-cycle batteries more than suffice for their application.
On the other hand, Tesla solar setups use a massive lithium battery to store energy.
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What Will A 100 Watt Solar Panel Run
A 100W solar panel that acquires 8 hours of sun exposure each day will generate nearly 1 kWh per day. That means a 100 watts solar panel output can reach 365 kWh per year.
If youre going to look into different scenarios, there are plenty of home devices and appliances that could operate efficiently using 100W solar panels. A single 100W solar panel is capable of running several small devices such as ceiling fans, mobile phones, Wi-Fi or router, lamps, etc.
On the other hand, home devices or appliances like air conditioners, televisions, heaters, etc., will need more than one 100-watt solar panel. To acquire a precise computation of what you can and cannot run with one 100-watt solar panel, you need to analyze the output per day or month.
For instance: compare 1 kilowatt per hour for the solar panel with the requirements of a home appliance. Lets say a fridge requires 3.8 kilowatts per hour, so this shows that a 100W solar panel will not be adequate to run the fridge.
Meanwhile, a laptop uses roughly 60 watts per hour hence, a 100W solar panel will be appropriate to satisfy those requirements.
So, what can 100 watts power? To get further details, it is also helpful to check the following list of devices with their wattage:
- Toaster Oven 1200 watts
- Campervan, RV: 400-600 watts
Should you wish to uncover more about the devices running on the power 100 watt solar panel produce, watch the following video:
Solar Panels For Commercial Businesses
For businesses, solar panels might represent an environmental good or a financial strategy.
Whatever the reason could be, solar panels are a great move for all sizes of businesses.
Just as in residential cases, the size dimension of your system will be determined by the same factors listed in the how much power do I need section. And the size of solar panels for commercial businesses are just the same as the ones we mentioned above.
Nonetheless, since businesses require on average more power than homes, the typically used solar panel size in businesses is 72-cells size or more, like that of 96-cells.
The difference lies in the size of the solar panel array, given that the power demand for commercial businesses is higher than for residential use.
The figure below illustrates an approximation of that comparison.
An average home fits its energy needs with systems of around 6 kW or 7 kW. Businesses will require larger systems. In this case, expect to occupy a larger rooftop surface to cover your companys energy needs.
If you install a 6 kW system with, say, 20 average-sized solar panels, expect to occupy a surface of 27 ft. wide by 13 ft. long on your rooftop.
The table below shows a rough idea of the common size of solar panels for commercial businesses and the expected price range
Common system sizes for commercial businesses and expected price range.
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What Can You Run With A 100
The answer to this question can be a bit tricky. The general response seems to be, it depends.
The wattage of your solar panel wont directly define what you can run or not on your installation. Its your inverter. Since you cant directly use the electricity generated by your solar panel , your inverter will be your main limiter to your electricity consumption.
For example, if you have a 3000W inverter hooked to a 100Ah lithium battery that you charged with your 100watts solar panel , then your limit is 3000 watts and not your 100-watt solar panel
But as a general rule of thumb, a 100-watt solar panel can power a few small devices with a suitable solar controller and battery setup. For example, youll be able to charge your laptop , phone, and other small appliances.
How Much Do Solar Panels Weigh
If youre planning on installing a rooftop solar system, understanding the weight of your solar panels is another key factor to consider. Knowing a solar panels weight is the best way to be certain that your roof can support a full installation.
While panel weights vary from brand to brand, most panels weigh about 40 pounds.
SunPower panels are the lightest of all major brands*, with some of our panels weighing as little as 33 pounds. For comparison, at the top end of the range some conventional panels weigh as much as 50 pounds.
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Figure Out How Much Power You Use Per Day
Before we can figure out how many solar panels you need, we need to figure out how much power you actually consume at your cabin.
The best way to do this would be to add up all of the average usage of the electric devices and appliances in your cabin. Appliances should state in their owners manual and often on a label somewhere how much power they use on average. If the number they give is yearly kWh, divide that by 365 to get daily usage in kWh. If the number is just in Watts, then multiply that number by how many hours per day its in use then divide that by 1,000 to get the number of kWh per day.
For example, a 400 Watt appliance that runs constantly will use 400 Watts times 24 hours divided by 1,000 which is 9.6 kWh per day. Many appliances are only used occasionally, like a toaster. That might get used 30 minutes per day. So a 500 Watt toaster uses 500 Watts times 0.5 hours divided by 1,000 which is 0.25 kWh per day.
How many lightbulbs are there in your cabin? Whats their output? A 60-watt bulb uses 60 Watts. Multiple 60 watts times the number of bulbs to get total Wattage for all the lights in your cabin. Now multiply that times the approximate number of hours per day that each light is on. Divide by 1,000 and voila! You have kWh per day.
For your reference, the average home in the US uses about 900 kWh per month but can range from 200 up to 2,000 or more. 900 kWh per month equates to about 30 kWh per day.
How Many Solar Panels Do You Need For 1000 Kwh Per Month
A family with several siblings can easily reach a monthly consumption of 1,000 kWh. In places with expensive electricity, this results in monthly electric bills of over $200. However, solar power is an effective solution to reduce energy expenses.
As explained above, the number of panels needed to reach 1,000 kWh per month changes depending on local sunshine and panel wattage. To simplify calculations, solar radiation is specified in peak sun-hours per day. Weather scientists calculate this value by measuring the total sunshine in a location and converting it to equivalent hours of peak sunshine.
- Peak sun hours should not be confused with daylight hours
- Since sunlight is moderate in the early morning and late afternoon, these hours do not count as complete peak sun hours
- You may find a site that gets 12 hours of average daylight, and 6 peak sun hours per day
There are many online databases that provide peak sun hours based on site coordinates, including the Atmospheric Science Data Center from NASA. Once you know the peak sun hours, estimating the number of solar panels needed for 1,000 kWh is simple.
- The first step is calculating the kilowatts needed. You must simply divide the average daily kWh by the peak sun hours
- Assuming a 30-day month, an electricity generation of 1,000 kWh is equivalent to 33.33 kWh per day
- If the site gets 6 peak sun hours per day, you need 5.56 kilowatts
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