The Inverter Size Calculated Is Smaller Than I Expected Why
Running AC appliances on a solar system demands a lot of energy from the batteries.
Keeping the number of AC appliances to a minimum will help keep the size of the system down.
Weve calculated the inverter size to run only your largest AC appliance with no other AC appliances running at the same time.
If you already have a larger inverter, use that but keep your maximum load as low as possible or youll drain the batteries fast.
For more information and to understand the implications of a large inverter on your solar system, check out our inverter calculator.
Here Are 3 Tips To Get The Most Of Your Solar Panel System:
- Device Efficiency It is also important to consider basic efficiency in RV solar applications. Use devices that require less power: change lights to LED or use newer flat screen TVs instead of older, less efficient tube type televisions.
- Device Run Time Also try to reduce your overall power usage. For example a light that is turned on may use 50 watts of power where a light that is OFF doesnt use any power. The less power we use, the less power the solar panels have to produce. Be vigilant about conserving your RVs power.
- Solar Panel Output Knowing how many watts your panels will produce in a given day will allow you to better understand your power budget for that time frame.
- Battery Bank Capacity Having a good idea of how many Amp Hours you have in your battery bank will let you plan your off-grid consumption. Wait to run really large loads for when you have a full battery bank in your motorhome.
- Time Of Year Depending on the time of the year, solar charging times can be longer or shorter. Time of the year can also impact the overall charging your panels are able to receive when mounted flat.
- Geographic Location The further north you are and the more cloudy your location averages can impact how much sunlight your solar panels can turn into electricity. Extreme northern locations may require tilt mounts to achieve optimal solar output.
A solar panel system for your RV will usually require the following elements:
- Ability To Read And Follow Instructions
Do The Calculations By Hand
I do not recommend this method compared to an actual energy reading, like Method 1. But if you are trying to get a ballpark number, this might help. What you need to do is figure out what each appliance uses for power and multiply it by the amount of time it will be operating. Write everything down in a spreadsheet to keep track of it and add up the result.
This tends to be a less accurate way to get an estimate but could get you a quick and dirty estimate of power use.
This method might be important if you need to run something like a CPAP overnight or other critical pieces of equipment. For these, add the number to the overall estimate or even the real world data you collected above if it was not included in the test.
To figure watt hours, multiply the appliances watts by the time it will run. Then add them all together to get your estimate.
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How Much Battery Should I Install
The calculator states the minimum size solar battery bank you need to provide the load youve indicated.
However, if you only install that amount of battery, you must have the ability to fully recharge them every day.
Otherwise, youll discharge your batteries faster than you can top them up and end up with flat batteries pretty soon.
If you have a reliable source of recharging, like a hook up facility to shore power, you may not need any extra battery.
But if living off grid and rely on charging the leisure batteries from solar panels or the alternator, you may need to consider increasing the amount of battery.
Whatever you decide, there is no point installing a battery bank greater than you can reasonably expect to charge.
Determining Your Available Space For Solar Panels
Regardless of the method you choose, you should have a pretty good ballpark or exact watts that you know you need.
Next comes a realistic understanding of how much space you have to work with both on and around your RVs exterior.
You should note thatits possible that your wattage needs might be more than the available square footage you can reasonably use.
So, calculating your available space, and the panels you choose will help you pair your RV solar array to the type of battery you need to maintain capacity.
These days solar panel technology continues to evolve. Photovoltaic cells are starting to become more and more capable of generating more electrical charge per square inch than even a decade ago. So, be sure to read the fine print on any solar panel you are shopping for.
As a general rule of thumb though, a 100-Watt solar panel is capable of producing up to 30 Amp Hours of charge in a single day.
Just bear in mind that this is a ballpark estimate and it relies on nearly ideal full-sun conditions during a long summer day.
If you are going to be camping under thick tree cover, or the weather is filled with dark storm clouds, the photovoltaic cells could end up producing less than this.Ultimately, unless you are going to be camping in the desert with a wide-open sky overhead at all hours of the day, chances are you are only going to see 70 to 90% of possible peak production.
Planning for 75% production capacity when designing your system will give you the best results.
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Windynation 100 Watt Solar Panel Off
Price: $439.99 Buy Now
Best: Runner up
The fact that WindyNation gives RV owners the option to purchase a battery with their solar kit is a huge plus! Image source:
WindyNation offers a 100 watt, 12 Volt solar panel kit that is great for boondockers who dont use a lot of power. The kit includes one panel with a power output of 100 watts, a 20 amp PWM charge controller, four Z-brackets for mounting, cabling, and solar connectors. It also includes a 100 Amp-hour absorbed glass matt lead-acid battery.
According to WindyNation, this panel will produce 350 watt-hours of electricity per day. That isnt a lot, but the charge controller included is able to handle up to four 100 watt panels, so you can expand the system in the future. This kits great online reviews and included equipment are what make it our best overall runner up RV solar kit.
- Comes with a lead acid battery
- Cabling and mounting equipment included
- Charge controller allows for future system expansion
- High user reviews on Amazon
- Only one panel, so it wont cover all of your electricity usage right off the bat
- Inverter not included
Price: $499.68 Buy Now
Best: Portable RV solar setup
Go Power!s kit may not have the ability to mount to your roof, but its perfect for those just looking for portable solar power. Image source:
Price: $230.35 Buy Now
Best: Flexible solar panel for RV
Renogys 100 W flexible solar panel makes it easier to add a few solar panels to your roof. Image source:
Figuring Out How Much Solar You Need To Add To The Roof
Now that you have the Watt hour or Kilowatt hour energy required, you can figure out how much solar you need to meet your needs.
This can be a very tricky calculation to get completely accurate. Why? Because how much power solar panels actually make varies, depending on factors like location, season, weather, etc. What we will try to do, instead, is get a ballpark figure for the time of year and location you will be in.
To start, we can assume that a 100-Watt solar panel will generate on average 350 Watt hours of power per day. So if you need 1500 Watt hours, then a rough estimate would be
1500Wh / 350Wh = 4.28W or 428 Watts of solar
The above calculation is a very rough estimate. We can get much more accurate numbers with a tool called PVWatts.
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Summary Of How Much Solar Do You Need On Your Rv
The answer for Sizing RV Solar System is pretty obvious when you think about how much solar you will need when considering the factors above. The answer is always more. The reason is that when you have bad weather or intense shading, more panels will produce more power. There are areas and times when you will go off-grid that even the most meticulously designed RV system will not produce enough power. You can add safety margin and extra batteries to help with these times, but there will be times when it just wonât be enough.
My suggestions for designing your RV Solar System:If you run through this process, you will have a good idea of how many panels will make the best system for your RV.
- Start by adding as many solar panels as your budget allows
- Then reduce the number of solar panels to match what your solar controller can handle
- Then reduce the number of solar panels that can easily fit on your RVâs roof
Your solar panel charging system will be designed to take power from the sun to charge your batteries and power your inverter. See some of the components in an RV solar system.
Should I Upgrade My Rv Batteries
If youve had the same batteries for a couple of years and it appears that they cant hold a charge anymore, its an easy upgrade to do. You can buy new, better batteries, that are drop-in ready.
The absolute best upgrades when it comes to RV batteries nowadays are lithium batteries like the Battle Born Lithium 12V batteries. These can be discharged lower than 50% without being damaged, but have other limitations like not being able to charge in freezing temperatures. They might also require a new converter/charger in your camper.
Otherwise, gel or AGM batteries are popular upgrades. A 12V battery like the Renogy 12V 100Ah Gel battery is an easy drop-in replacement. Two of these wired in parallel would give you 200Ah of battery capacity .
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What You Need To Know To Correctly Calculate Your Solar Array And Battery Bank Needs Check Out These Three Easy Steps That Include Sizing Your Battery Bank Calculating Your Power Needs And Determining Your Solar Requirements
So you’re considering switching to an RV solar panel and wondering where to start? Look no further because todays post will cover what you need to know to correctly calculate your solar array and battery bank needs. Well do this in three steps that include sizing your battery bank, calculating your power needs, and determining your solar requirements.
Sizing Your Battery Bank
To estimate your total energy requirements for an RV solar panel, sum the daily usage of all the appliances in your RV like our example below. You can find common watt ratings with a quick Google search or by looking at the labels on your appliances. In the extended example below, a total of 139 amp hours are needed daily.
Amp Hour Calculation: Watt Hours ÷ Volts = Amp Hours
As mentioned above, batteries are rated in watt hours or amp hours. For this example, you would need a battery or bank of batteries with a capacity that adds up to more than 139 amp hours or a means to recharge at a rate that is equal to or faster than the rate youre consuming. Remember, these calculations are on a daily use basis.
Calculating Power Needs
Current Calculation: Watts ÷ Volts = Current
Determining Solar Requirements
What Batteries Are You Using
Many people feel that the battery bank is the most critical component in any solar system. It doesnt matter how much power your solar panels generate if you have nowhere to store it for when the sun stops shining.
Lead-acid batteries have been the standard in RV electrical systems for years, thanks to their easy availability and low cost. However, they have many disadvantages like requiring frequent maintenance, being damaged if you drain them below 50% of their capacity, and they have a short lifespan, to name a few.
Lithium-ion batteries are a newer technology that offers many advantages over their lead-acid counterparts. They provide greater capacity, efficiency, and depth of discharge, both of which are critical if youre relying on your batteries and solar system as the primary source of your electrical power. Additionally, lithium batteries weigh about half of what lead-acid batteries do, require no maintenance, and usually last more than ten years.
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How Much Solar Do You Need For Your Rv
5390 views19July 15, 2020July 16, 2020The BoonDoctor
How much Solar do I need for my RV?
200 watts of solar is the bare minimum to keep a battery bank topped off, and thats while your RV is not in use. But if youre using your RV, you will need more.I install a 700 watt solar package for toy haulers with great results. This seems to be the sweet spot for many RVers with small inverter use.
How Much Battery Storage Do I Need
Take the Total Watt Hours from Step One, for example, 3000Wh. This is your one-day storage requirement but this leaves little room for variations in use and supply. One days storage is your bare minimum power. The recommendation for off-grid use is to multiply this bare minimum times three for 3 days Wh of storage needed.
3000Wh3000Wh x 3 = 9000Wh
This gives you the range of Wh of storage that you will need.
Batteries are usually purchased in Ah. We are basing all our calculations on 12V batteries. You will need to adjust the math if the batteries are a different Voltage
Take the Wh and divide by 12V for the amount of usable storage power in Ah that you will need.
3000Wh/12V = 250Ah
- Space for storage of batteries
- Ability to recharge your batteries from solar and likelihood of bad weather
- Ability to recharge your batteries from a fuel generator, if needed
- Type of battery chemistry, lead acid cannot be depleted more than 50% but carbon foam and silicon dioxide can be depleted to 100%. You will need fewer days of reserve power if you are able to access the full power of the battery bank if needed.
- Ability to adjust consumption if solar conditions are not good
- Number of days you will need power before recharging from shore power
Solutions:If you need 250Ah of available power at minimum, then that would look like this:
- 500Ah of lead acid batteries, can only use 50%
- 350-500Ah of carbon foam batteries
- 350-500Ah of silicon dioxide batteries
- 350-500Ah of li-ion batteries
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Calculating Your Wattage Needs In A Real World Test
Sometimes referred to as the Camping Test it tends to give you the best real-world result.
You just have to be prepared to have a few hiccups along the way on a boondocking, off the grid adventure.
Ideally, you want to pick a location thats close enough to a reliable source of backup power.
That way if something goes wrong, you can just plugin, or take a short drive home.
If you happen to have a big enough backyard, you might want to just set up at home for the weekend and keep your RV completely disconnected from the house.
This is admittedly an easier thing for a couple to do, than it is for a family with small children, who are all too tempted to run into the house and play their favorite video games.For this real-world test to work, you want to try to live like you normally would.
Dont go out of your way to conserve power use, or over-use electricity, which will skew your results when it comes time to determine your battery and photovoltaic solar panel needs.Youll also need to get your hands on a battery meter, which is something youll likely need in the end anyway.
Once its connected to the system you can monitor the discharge levels of your batteries.
Ideally, you dont want your lead-acid batteries to dip below 50% as it could damage or shorten the batterys overall lifespan.
When youre done, you can use the amount of power consumed to determine your wattage needs.
How Do I Convert Watts To Amp Hours?
Other Ways To Charge Your Batteries
The ideal situation for your solar panels are to be stationary for a long period of time in direct sunlight. Your RV may have other sources of power already equipped.
Installed Generator: Most motorhomes have a built-in generator that can charge your batteries while you are using your electronic devices. The more devices that are using the generator, the less is going toward your batteries
Alternator: Newer motorhomes have a second alternator installed for the purpose of charging your house batteries. Older RVs may only have one, but the alternator charges both the engine and house battery banks.
Shore Power: When you are plugged into a campground or your homes grid, like your generator, it is charging your batteries while running your electrical devices.
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Best Rv Battery For Boondocking
For many years AGM or other types of deep-cycle batteries have been the main-stay of serious RV life but this is changing rapidly.
Lithium phosphate technology is changing the way we think about batteries. They are lighter and last much longer. The only drawback at the present time is the price, which can be more than twice as much.
New RVs Class C size come with a 120Ah lithium phosphate battery, which is a good basis to begin with.
A good example of the kind of package youre looking for is the Scandinavian Affinity Camper Van with 360 watts solar panels and a 120Ah battery you can always add some!
Are flexible solar panels any good for RF roof mounting?
Ive often seen it recommended but I wouldnt do it myself. After all, they are made for fixing on uneven surfaces while RV tops generally have large enough flat areas to mount rigid solar panels.
Rigid is always strongest, although 4 to 5 times heavier, which isnt really an issue with a camper van.
Buy individual components, rather than a kit. Kits just come more expensive IMO. Panels are cheap nowadays and a good MPPT controller isnt going to break the bank.
The biggest expense is going to be the LiFePO4 batteries, and they are for life. Go RVing!