EPEVER solar charge controller

Why Do You Need a Solar Charge Controller?

by Solar PanelsVan Life
EPEVER solar charge controller

A Solar Charge Controller is a regulator for your batteries used to prevent overcharging and discharging. Solar panels are connected to the solar charge controller, as are the batteries. The Charge controller sits in the middle – it’s the link between batteries and solar panels.

You need a solar charge controller to ensure your batteries aren’t overcharged. The voltage on your solar panels can range from 16 to 32 volts or more. For example, a “12 volt solar panel” will actually produce around 18 volts, and without a load, closer to 21 volts. A “24 volt panel” will be producing around 32 volts, and without a load, close to 45 volts.

Your solar charge controller takes care of the higher voltage and ensures that your batteries are receiving the correct voltage. A 12 volt battery is fully charged at 12.6 volts. But to actually charge that battery, the input voltage needs to be over 14 volts usually, and the exact number will depend on the type of battery you have. Some people have their electrics set up as a 24 volt system. If they only had a “12 volt solar panel” – where the maximum voltage would be around 17 volts, it’s not going to have enough voltage to get the batteries charging.

A solar charge controller also prevents power from leaking back, from the battery to the solar panels at night time. Depending on the type of solar charge controller you have, it may have many other useful features, such as allowing you to stop the battery from being over discharged.

With batteries such as AGM or GEL, the amount of power they need from the solar panels changes. If they’re low on charge, they’ll absorb a lot more power. As they get closer to fully charged, they need to soak up less power – slow down the rate of charge, and this again is where the solar charge controller comes in.

PWM vs MPPT Solar Charge Controller

There are two different types of solar charge controller you can install. PWM stands for Pulse Width Modulation and MPPT is short for Maximum Power Point Tracking.

PWM controllers are an older technology and not as efficient as the newer technology MPPT solar charge controller. A PWM solar charge controller, being an older technology are generally cheaper than an MPPT solar charge controller.

A PWM solar charge controller probably still has it’s place in the scheme of things. If you’re only using it in a really small power system, perhaps an 80 watt solar panel to keep keep a battery for some shed lights used occasionally charged up.

However, MPPT controllers are so cheap these days that for most situations I’d recommend using an MPPT controller. At the time of writing, a 30 amp EPEVER Tracer MPPT Solar charge controller comes in at around $209 from Sunny Tech Solar. That would allow you to have up to a 390W solar panel at 12 volts, or 780 watts of solar at 24 volts.  

My Solar Charge Controllers

I’ve got four solar charge controllers. An EPEVER 30 amp charge controller in the van. The motorhome, because there are three different electrical systems has 3 charge controllers. A 30 amp Fangpusun PWM charge controller, a 10 amp EPEVER MPPT controller and a 40 amp EPEVER MPPT controller.

I like the Fangpusun PWM charge controller, it’s easy to use and has served me well. I bought it back when MPPT technology was a little out of my budget.

See more about my electrical set up here.

The EPEVER Solar Charge Controller

I’ve used EPEVER solar charge controllers for a number of years now without any problems. They’re easy to use, the terminals are easy to connect your wires to, and there are a couple of good accessories – the MT50 and EPEVER Solar Station Monitor.

The MT50 is connected to your charge controller and allows you more control of functions, settings and display. It gives more functionality than what you can access from the basic charge controller unit. They’re available at most RV or Motorhome stores such as RV Supercentre. People that have them say they’re worth having, but I don’t have one. I may get one, or two, in the future, but at the moment I’m using the EPEVER Solar Station Monitor.

The EPEVER Solar Station Monitor

Downloading and Installing the EPEVER Solar Station Monitor

The EPEVER Solar Station Monitor is software that you can download from EPEVER and install on your computer. I’ve got it running on an old Windows 7 laptop as well as a newer laptop. It works successfully on both.

All the files you need should come zipped in your download. Unzip the folder and install. It pays to read the instructions! The RS485 cable plugs into the communications port on the charge controller and into the USB port of your computer. I spent a little while searching on the internet for drivers for the RS485 cable, when they were actually included in the download.

You’ll need to purchase the RS485 cable. I bought my cable from Sunny Tech Solar.

The EPEVER Solar Station Monitor Interface

It’s nothing flash, seems like it was coded in the 1990’s (it probably was), probably in C# with Windows Forms, but does what it says on the tin.

You’ll need to set up your ‘solar station’ with the add station button top left. At first it can seem a bit confusing or complicated, but most people will be able to figure it out or at least know someone who can help.

I decided to use the Solar Station Monitor because I had bought ‘drop in’ Lithium batteries, that weren’t really ‘drop in’ batteries. They needed the charge settings to be changed otherwise I was getting high voltage spikes.

The Solar Station Monitor has given me the ability to input the exact settings I want. By clicking on Parameters (P) I can access the following panel which gives you the option to select your desired settings.

You can monitor in real time your load – the blue line, the input from your solar panels – the red line, and the charge going into your batteries, the green line.

The following screenshots relate to the Lithium batteries in my motorhome. Two 100 amp hour Lithium Valley batteries in series giving 100 amp hours at 24V. The Solar panels are two 370 watt panels.

The image below shows the load (blue line). That includes the Samsung 255L fridge, but in it’s off cycle, the Laptop being used plugged in and charging – just over 2 amps of draw (fridge and laptop), mobile phone plugged in charging – jumps up to just over 3 amps, the Samsung 255L fridge kicks into it’s cooling cycle, the large brief jump is the water pump being used momentarily.

The image below – Load is only the Samsung 255L fridge. The fridge cycles on and off as needed, and this is when it is in an off cycle.

Image below – fridge is cooling

Image below – fridge cycles – off, on, off, on. The one blue spike is the water pump.

Image below – fridge cycle on – every so often, perhaps twice a day it seems to do a cycle where it draws a lot higher amps.

Overall I find the EPEVER solar charge controllers to be great. And the Solar Station software gives me the option to see what’s going on if I need or want to, as well as tweak the settings for the charging inputs etc.

In the near future I plan to take some screenshots of the usage in my small van. Using the same batteries set up in parallel as 200 amp hours at 12 volts, running a 40 litre Waeco fridge, 1100 watt Nomad Pure Sign Wave Inverter with laptop, phones, and lights, a much smaller system, but also only one 270 watt solar panel.

In the meantime, be sure to check out Lake Aniwhenua – one of my favourite freedom camping spots!

How Many Solar Panels Do You Need?

by Solar Panels

I’ve often sat outside my van or motorhome, soaking up the sun, wondering how many solar panels do you need on the roof. The panels I have seem to work great, but I wonder if there is an optimal amount of solar panels to put on your RV, motorhome or van. I decided to do a bit of digging on the internet to answer the question of how many solar panels do you need on your roof.

Benefits of Solar Panels

Having solar panels on your motorhome, van or RV is a game changer. Instead of relying on the vehicles alternator to charge your house battery, you get free energy from the sun. There’s no need to be driving, using expensive petrol or diesel for your batteries to charge. You can park up by the lake, river, beach or the middle of nowhere, and as long as you have daylight your batteries will charge.

Generally speaking, solar power is easier and safer to install than AC mains supply. You can get your solar system professionally installed or you can do it yourself. An AC mains supply where you hook up to camp ground power should be done by a professional and must be signed off by a professional before it is legal.

There’s no moving parts or mechanics to maintain with solar panels. Compared to a generator or wind turbine solar panels are efficient, virtually maintenance free, and silent. So, how many solar panels do you need?

How many solar panels do you need on the roof?

How Many Solar Panels Do You Need? Two Schools of Thought

There are at least two schools of thought on the question of how many solar panels do you need to have. Some people will give you a definitive answer, and others will say it depends.

There are formulas you can use to work out how much power each appliance you intend to use consumes, and from there you work out how many hours a day you’ll use them, which gives you an estimate of your daily power usage and therefore how much output you need from your solar panels. You can even find nifty calculators online that you can input the numbers and it will provide an answer.

The other school of thought is that you can never have enough solar panels, or at least – the more the better and get what you can afford.

I’d pick a mix of these two, I’m probably in the middle although leaning towards the, “you can never have too much solar”.

You can input numbers and come up with a figure on paper, but do you really know every appliance you intend to use and for how long each day? What if you only want to charge a laptop computer initially, but later on find you need to run two laptops plugged into good sized monitors all day? Possibly a bit far fetched but not unheard of.

Solar is very dependent on the weather and season. What if you get two or three weeks of bad weather that limits your daily charging? When working out your numbers by the first method all this needs to be factored in. In winter there are less daylight hours and the sun is lower which equates to less charging.

I have 1100 watts of solar panels on my motorhome which is approximately two thirds of the roof space covered. As one person put it, no one ever regretted having too much solar but many have regretted having large battery capacity and not enough solar. In reality, numbers on paper can be very different to motorhoming in real life.

My van has one 270 watt panel. Given I don’t use as much electricity in the van my 270watt panel is adequate. Click here to read about my solar and electrical set up in my motorhome and van.

The Different Types of Solar Panels

There are three main types of solar panels that you’ll hear about. Monocrystalline, polycrystalline and thin-film solar panels.

Monocrystalline panels are the oldest type of panel and also the most developed technologically. They’re made from a single (mono) crystal silicon solar cells. They’re considered to be a premium panel with a high efficiency and output. They’re recognizable by their black, uniform appearance.

Polycrystalline panels are less efficient although often more affordable. The polycrystalline cells are also made from silicon but in contrast to the monocrystalline panels, these are made from many (poly) fragments of silicon crystal melted together. These panels appear bluish in colour and speckled as the light reflects of the many crystal fragments.

Thin-film solar panels are thin and flexible. They’re made from layers of semiconducting materials such as silicon, copper indium gallium selenide and cadium telluride. These panels tend to have a lower efficiency compared to crystalline panels.

Best Type of Solar Panel

You’ll likely be choosing between monocrystalline and polycrystalline panels. The best type will depend on your circumstances. How much roof space do you have and what can you afford? Polycrystalline panels are somewhat cheaper but less efficient, you might need more of them, whereas if your roof space is limited you might choose to pay a bit more for monocrystalline panels which will be more efficient but less of them needed. How many solar panels do you need for your installation? It’ll likely be dependent on the type of panel you install.

Fixed Solar Panels or Portable?

During my travels I’ve seen motorhomers with portable solar panels. This can be an option to supplement your panels on the roof or an option if for some reason you don’t want to mount panels to your roof. Keep in mind however, that a portable panel is probably not going to provide enough energy output for a normal to moderate user of power. It may be fine if you just want to charge a phone, laptop, run your lights at night and a few other small items, but you’d need to watch your usage.

A portable panel would be ideal to supplement your existing panels on the roof. Panels flat on your roof don’t put out as much power as a panel aimed directly at the sun. In winter, being able to point your panel at the sun can make a huge difference to the panels output. Therefore in winter time a portable panel would be ideal to supplement what you have on the roof.

In the summer time you may want to park your vehicle in the shade during the hottest parts of the day. Having a portable panel with a long lead means you can still get charging for your batteries if you can place the panel in the sun while your vehicle is in the shade.

How Many Solar Panels Do You Need for Cloudy Days?

Your solar panel will work on most cloudy days. A very cloudy day with really thick dark clouds may mean that it won’t work at all though. But on most cloudy days you’ll be able to get solar output although it will be a lot less than on a sunny day. This is the reason you want to have as many solar panels as you can. So how many solar panels do you need to get you through cloudy weather? On a cloudy day one solar panel might put out 1amp. If you have two you now get 2 amps. Four panels equals 4 amps. There are other factors at play, but in short this is the principle idea behind having plenty of solar. On those cloudy days you’ll have enough to get by.

Solar Panel Maintenance

To get the most from your solar panels you should ensure they’re clean. Even a small amount of debris, dead leaves or dirt on your panel can reduce it’s output dramatically. A mild detergent in water is safe to use on your panels. During cleaning you can also inspect any connections that you can see to ensure they’re secure and free from damage.

What Components Do You Need for a Solar Power Set Up?

Your solar panels are connected by cable to a solar charge controller. This in turn is connected to your battery. Your battery gives you power, either as 12 volt, 24 volt or even 48 volt depending on your system. Most motorhome, van or RV set ups will be 12 volt. You may also have an inverter which can provide you with mains power.

The charge controller is an important part of your solar power system. There are two types of controller. PWM and MPPT. For more about solar charge controllers read our thoughts here.

Your battery is connected to the charge controller. There are many types of battery available including lead acid, GEL, AGM, Carbon, and Lithium. Check out our guide about batteries for your motorhome, van or RV here.

Check out our tips for van life traveling here.