How to Get right wattage rv solar panel for my RV and Yacht?

Calculating Peak Sun Hours

As we know，Standard Test Conditions(STC),solar panels only generate their rated power when they are being hit by 1000W/m2 of sunlight at 25°C,this is referred to as . The issue is further complicated because the intensity of the sun varies throughout the day, and at different times of the year.

So to get accurate solar panel wattage ,we need to consider the Peak Sun Hours per day.

One Peak Sun Hour is defined as one hour of sunlight at 1000W/m2.

The amount of sunlight in one peak sunshine hour matches the rated sunlight intensity of your solar panels. So if we can calculate the average number of peak sunshine hours per day, you can calculate how much electricity your solar panels will produce in an average day.

There are some software that can query the peak sunshine hour of various regions.

To make the work easier,we have come up with the table below to help you find a number that is more specific to your needs. These are still only estimates, as they cover wide areas with large ranges in solar irradiance.

Average peak sun hours in different regions and seasons

You will need to choose one to check how many electricity from the right wattage RV solar panel,it depends on where and when you will be using your RV or yacht.

Considering Losses

As mentioned earlier, the rated power output of solar panels is affected by temperature. Solar panels can get quite hot when they are running, and as they get hotter, their efficiency goes down. Therefore you have to take this loss into account when make your system.

Solar panels also lose power due to other factors such as soiling, shading and after longer time, so you also need to consider these in your calculations.

To simplify things, We recommend using 20%.

In fact,our ETFE Portable solar panel blanket conversation can reach 98%. Take 20% as losses just for safer.

Calculating how many watts of RV  solar panel/solar module you need

The next step is to decide within how many hours you want to charge your batteries off the solar.

Generally, you will want to size your system to charge the batteries in one day (especially if you are using AGM batteries as fully charging them daily will extend their lifespan).

Alternatively, some people with several days of autonomy may want to only size their solar for one day of energy usage, and rely on alternator charging for the rest.

Here we will show how to calculate how many watts of solar panel are required to charge your batteries in one day, and you can adjust the calculation to suit your situation.

The steps in the calculation are:

• Multiply your usable battery Ah by the battery voltage to get the total usable watts of the battery system. (don’t forget that only 50% of AGM batteries should be considered “useable”)
• Divide that by the number of peak sun hours, so you know how many watts you need to generate per hour.
• Multiply by 1.2 to add allow for the 20% losses we just discussed.

The calculation is therefore:

Battery Ah x Battery voltage / Peak Sun Hours * 1.2 (20% losses) = Required solar in Watts

Let’s do an example:

Assume you have a 200Ah, 12V, Lithium battery. You tend to stay in SE USA and decide to size the system for spring and summer.

The equation becomes:

200Ah x 12V / 5.7 * 1.2 = 505W

Since you probably can’t find exactly 505W of solar panels you would probably round this up to 550-600W, and then buy 3* 200W panels, or 4* 150W panels, etc.

And Future Tech Ltd 100W RV solar panel blanket and 200w solar blanket is most popular.

Flexbile solar panel from Future Tech Ltd 100w 200w 300w is more convenient to install on the roof of your RV and Yacht.

Especially our flexible solar panel with monocrystalline solar cell are bended,more fit for the roof of your caravans.

AT End

After above calculation,maybe your roof space is not enough to put right wattage flexible solar panel or rigid solar panel. Do not worry, as long as your system is also set up to be able to charge from an alternative source, such as a portable power station as emergency.

If you have the space for the solar system you want, but just can’t afford it right now, you could also consider installing fewer solar panels, but then buying a larger charge controller to allow you to add more panels later.

Solar charger controler most choices is from 12v 5A 12V 10A 12 15A 12V 30A for off grid solar system.