If you’re new to the world of solar in the RV world, then maybe you’re wondering how a solar system works, who installs them, how much solar you need, the cost and also the type of battery you need to store the power from the solar panels, if you’re in search for information for these solar basics we will answer your questions here.
Solar Basics For Newbie RVers
How Does a Solar Power System Work?
There are three main components that enable your RV to get electricity from your solar panels. These are:
The Solar Panels
Basically, how these panels work is very simple. What happens is that the solar panels acting as the source of renewable energy converts energy from the sun into electrical energy. The electrical energy then runs through the wires joining all the solar panels together into the solar charger controllers.
Solar Charger Controllers
Now what happens here is that the solar charger controllers, control the flow of power from your solar panels, to your batteries. The solar charger controller prevents your batteries from being overcharged.
Even though you can directly connect your solar panels to your battery, however, if we were to directly connect our panels to our batteries, without a solar charge controller, you would encounter a couple of problems. Some of these problems are:
- If you are to connect your solar panel to your batteries without the charger controllers in line, your batteries will get charged during the day, and then once it becomes dark, the battery will discharge the power stored back to the panels, to warm them up, depleting your batteries.
The control your solar charger has over this problem is the ability to see that the power is coming from the panels, and there is enough power to be sent to the batteries to start charging the batteries. And when it notices that the power from the panel isn’t sufficient to charge the batteries effectively, it will disconnect the panel from the battery.
- The solar charger controllers also prevent your batteries from being overcharged. If you didn’t have a solar charger in the loop, you would effectively boil your batteries, and damage them by overcharging.
- This is the most important thing a solar charger controller does, thus to protect your batteries by charging them correctly. This is done by charging your battery with a lower voltage. A higher amperage going to the batteries can actually damage the batteries.
The batteries are basically your power storage unit. They store the power, and in general, the more battery capacity you have the more power you can store, and the more power you can use.
Most batteries store DC power. However, most devices in your rig do not use DC power. What they use is AC power. So now, how does the power get converted from dc to ac? Well, with the help of the inverter, this is possible. The inverter converts the 12 volts DC power to 120 volts AC power.
But this doesn’t just supply electricity to the rig directly. Before electricity is supplied to the rig, this AC power goes through the breaker box. The break-box acts as a surge protector. So, from here the power is then supplied to the outlets.
One last piece of the solar puzzle is the battery monitoring kit. This helps you keep track of how much power is coming in and out of your batteries.
Can You Install a Solar Panel on Your Own? Or Do You Need a Professional?
Well yes, you can install a solar for your rig yourself. This is very simple to do and because the voltages are so low, you wouldn’t get hurt that bad. And if you follow the steps I will outline below, you should be good to go. However, I highly recommend you let a professional do the job if you do not trust in your skill, or better still let an experienced friend help you.
How Much Solar Do You Need?
If you’re thinking of setting up an off-grid solar system, but you’re not sure of the amount of power you need, the number of solar panels, the watts, how many batteries and what kind, the kind of inverter you need. This can be very confusing. Hopefully this guide, will help to simplify the process.
The first and most important thing is to figure out what you will be using your solar for. This entails, what kind of appliances you will be using, and the kind of electronics you will be using. For example, are you going to use a few LED lights, with a small fridge, running seven days a week? Or maybe you want a solar system just to run a few lights when the sun is down at night? This is going to make a big difference in how you calculate everything.
Now let’s assume that with your solar system, you want to power two laptops, a small USB fan, charge batteries, and electronics, now let’s say if you want to power these electronics for 8 hours a day and seven days a week, how do you make sure that you can power these electronics? Here are a few steps to figure this out.
Step 1: Figure out the energy consumption rate of all the appliances and electronics you might want to run. Every electronic device or appliance has a power rating written somewhere on the device. You might find it on the power adapter of the appliance, sometimes on the, it can be found directly on a little sticker behind the appliance.
Step 2: What is most important, is to find the output wattage of each appliance. This is often written in the format, Output: 5W or, Output: 12 Watts. It doesn’t necessarily have to be 5 W or 12 Watt, the magnitude of wattage will vary from time to time.
However, some devices do not have the output wattage written behind the device. They provide you with the output voltage and output current in Amps or milliamps of the appliances.
To find the output wattage, simply multiply the output voltage by the output currents to get the output watts of the device. If the currents are in milliamps, convert it to amps, what you have to know is, a 1000mA gives you 1A. So with this, you should be able to convert the output current from milliamps to amps. The output wattage basically tells you how much power an appliance consumes.
Step 3: From the assumption we made, let’s say the two laptops take a total of 105 watts, the battery charger takes 5.2 watts, the small USB fan consumes 2.5 watts, and your electronics takes about 10 watts. This gives a total of 122.7 watts. Well, it is good to round that to 125 watts. After all, these are figured out, you then figure out how long you want to use these devices, so as stated earlier, assuming we are using these devices for about 8 hours a day, and seven days a week. Once you have these figured out, all you have to do is to input them in a solar power calculator you can find online.
Step 4: When you’re on the website with the calculator, what you will require is, the total wattage, the hours for which you will be using these appliances, charge controller efficiency, for this, your charger controller will either be a PWM or an MPPT. A PWM has an efficiency of 80% and MPPT has an efficiency of 92%. So depending on the type of charge control you have, you input the respective efficiency. Finally, you will be required to input an approximation of how many hours of sun you get daily.
Once you have all these values inputted, you click on calculate. And the solar power calculator will provide you with the Minimum system size, Recommended system size, Recommended battery size for both 12V and 24V batteries.
So, as you can see, finding out how much solar you need isn’t very complicated, once you find out the output wattage for every item and for how long you want to use each item.
One last thing to keep in mind with your solar power system is the inverter. And for the inverter, bigger isn’t actually better. Usually smaller is better. When choosing an inverter, you need to find out what the maximum amount of wattage you will be using at the same time.
So, if you’re using a total of 1000 watts at the same time, and you get a 500-watt inverter, the inverter fuse will blow and it wouldn’t work. In this scenario, you will require a 1500-watt inverter or anything above a 1000 watt.
The reason you need an inverter with a power rating higher than the total power is that an inverter is a machine, and it also consumes power off the solar system, so the bigger the size of the inverter, the more power it will take.
How Much Would a Solar System Cost?
For a typical solar system, which is 600W or less, four 6V AGM batteries which gives you a 440 amp-hour,
2000-watt sine inverter with the remoter, the solar panels, and everything could cost you about $7000- $10,000. This includes labor and installation materials.
However, if you’re just doing basic solar, which doesn’t require you to power all your outlets, then you can do basic solar consisting of two AGM batteries, a battery monitoring system, together with solar panels, then you should be estimated to spend a total of $3000 to $5000. Depending on the final scope of the solar system and the battery system.
What are the Solar Battery Types Available?
There are four main types of batteries:
- The 12v Deep Cycle
For these, you can go and pick them up at Walmart, and put them in your RV. The advantage of these batteries is that they are easy to get and relatively cheaper. They are a bit of a hybrid, and they are decent at starting appliances and decent at deep-cycle. The depth of discharge on these batteries is about 50%. This means you do not want to bring these batteries past 50% before charging them back. If you do, then the battery begins to sulfate, which damages the battery. This is one of the leading cost of killing the battery.
- Golf Cart Batteries
When buying these, you will have to buy them in pairs. They usually come around in 215-amp hours and 235-amp hours. The more the amp-hours, the taller they are. This battery is great at handling deep discharge, and cycles the RVs usually go through. However, you do not have to take it past 50% as you would with the 12-volt battery. Golf cart batteries usually give you more amp hours and more power as compared to the 12 V battery. However, they are more expensive than the 12-volt battery.
- AGM batteries
These batteries come sealed, and there is nothing you can do to add water to them. And what makes this as an option for most RVer is that it has no maintenance. And because you do not have the water in there sloshing around, you can actually mount them in other positions, if you need to do that for your battery bank. Another great thing about these batteries is that they store better than the other two batteries, this means they do not discharge more than you charge them. Also, they charge much faster than the other two types of batteries mentioned earlier.
However, for these types of batteries, you will need a converter charger to match these AGM batteries because they take a different charge cycle than the other two. Well, the downside of these batteries is that they cost double the price of the 6-volt golf cart batteries.
- Lithium Batteries
These batteries are much more efficient than the other types. They have an efficiency of 99%. They also require no maintenance. They perform better in low and high temperatures than the other types of batteries. They are lighter in weight compared to the other batteries and last longer than the lead-acid battery and the AGM battery. They also charge up to four times faster than the lead-acid batteries, and for these batteries, you can discharge them past 50% and they will still be good for use. However, these batteries are expensive.
What’s the difference between Parallel and Series Connection?
Depending on the type of battery, there are two ways you can connect these batteries these are:
If you had two 12-volt batteries, and you’re going to wire them together to be one battery bank thus parallel, you’re going to connect the positive terminal of one battery to the positive terminal of the other and the negative terminal of one battery to the negative terminal of the other. You then connect your loads to each of the batteries. Essentially, what you have done is that you’ve created a battery bank. so because you connected them in parallel, it’s going to remain a 12-volt battery bank, but their amp-hours are added together. So if each has an amp hour of 100, then you get a total of 200 amp-hours.
If you are to wire 6-volt golf cart batteries to get 12 volts, you will have to wire them in series. This can be done by connecting the positive terminal of one battery to the negative terminal of the other battery, and then you connect the charger to the open positive negative terminals.
So basically you’ve built a big 12-volt battery. So for the series connection, you add the voltage of the two batteries together giving you 12 volts, but the amp-hours stays the same. So if each battery is 235 amp-hour, the total amp-hour will be 235 amp hour.
I hope this guide was helpful and it answered all the questions about solar you needed, and you’re more confident about the RV solar power system than before.
*Disclaimer – I am not a licensed technician, I highly recommend hiring a licensed technician for installation or consultation.
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