Portable Solar Panels Information

a technician disconnecting a solar panel

How to Safely Disconnect Solar Panels

Simple Guide to Safely Disconnecting Your Solar Panels

Aniket

Written by qualified solar engineer Aniket. Last updated:

Solar panels should be disconnected by first turning the solar disconnects to the off position, both on the DC and AC sides. The wiring connections between panels should then be removed. There can be several reasons to disconnect a solar power system, the most common being for maintenance or repair purposes. Other reasons include moving to another place or, in some cases, to avoid electrical damage during upcoming severe weather conditions.

A good time to perform the system disconnect is when there is no bright sunlight. Unlike systems that use a controllable power source, solar power systems work on sunlight, which cannot be turned off, making it slightly more difficult to work on them safely. Read further to know how to safely disconnect solar panels.

Turning off Disconnect Switches/Circuit Breakers

The first step is turning off the disconnect switches or circuit breakers. Instead of remembering it that way, it is important to remember that the first step is to turn off any current flowing in the solar power system.

This helps avoid danger from electric current while working on the system. The direct current that the panels produce can be particularly dangerous, even at voltages below 100 V. Also, unlike the amps produced by a portable solar panel or two, a whole system might be producing a lot more, increasing the level of risk.

A system can have two types of circuit breakers or disconnects – one on the AC side and one on the DC side. Make sure to turn both off. The following is an image of DC and AC disconnect switches, which can be easily accessed to turn off.

image of DC and AC disconnect switches

Circuit breakers perform a similar function but can be fused. In most cases, modern solar systems will have disconnect switches. It is mandatory in many places to have them. Circuit breakers can also turn off the current flowing in a system; aka break the circuit, hence the name.

The following is an image of a combiner box with a circuit breaker (circled in red) for the DC side. Turning this off will prevent any current that the solar panels produce from entering the inverter.

image showing a circuit breaker in a combiner box

The AC combiner box will have a similar breaker, which can be accessed by opening the cover. It can also be located on or beside the inverter. Although only turning off the DC side minimizes the risk, it is good practice to turn the circuit breakers on the side of alternating current too. Additionally, for systems with energy storage, the battery bank will still be connected to the inverter, sending current on the AC side.

The NEC Article 360 details the requirements for the rapid shutdown of a solar power system. It states that disconnect switches are mandatory on both the DC and AC sides and should be in the inverter’s line of sight.

There can be a single point rapid shutdown switch that can turn the whole system off within a second in many cases. This switch can even be located away from the system, such as inside the house. This is important for quick response in the event of a fire or any other disaster.

Disconnecting Solar Panels From Each Other

In most cases, disconnecting the DC and AC side using disconnects or circuit breakers should be sufficient for the maintenance level you are going to perform. However, in some cases, you will need to go one step further and disconnect the solar panels from one another. This may be a requirement when you need to dismantle the whole system, repair your roof, and install the system again.

As mentioned previously, solar panel energy production cannot be ‘turned off’, since when the sunlight strikes a solar cell, it will keep generating electricity. Although modern connectors have reduced the risk of an electrical shock, it is always good practice to make sure they are generating zero or near-zero power.

This can be done by covering the panels with an opaque surface. A dark, thick cloth serves this purpose well in most cases. It is okay if every solar cell is not covered, as long as most of the panel is covered. Once covered, you can make sure that the panels generate minimum or zero voltage by using a multimeter.

image that shows disconnection of the MC4 connectors on solar panels

Thanks to easy MC4 connectors, power wires coming from the panels can be disconnected within seconds. Once removed, there is no current flowing among the solar panels. The next step, if applicable, is to remove the clamping nuts, bolts, and screws holding the solar modules on the mounting structures. Remove all of the clamping components carefully while holding the panels in place, then take them off one by one.

Disconnecting is even easier on a portable solar panel system with easy connections for solar and the electrical load. Especially, flexible solar panel kits will not require fiddling with clamping devices at all.

It is important to use insulating gloves while performing all the above operations, as solar safety is of the utmost importance. If possible, wear a hard hat and work shoes to minimize potential risks. Sloping roof solar systems can be harder to work on, and it is recommended to use a harness or, if possible, let professional technicians work on the system.

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a battery on the ground connected to a portable solar panel

Portable Solar Panel System Set Up Guide

Portable Solar Panel System Set Up Guide

Aniket

Written by qualified solar engineer Aniket. Last updated:

Have you ever looked at solar panels installed on buildings and wondered if you should get them? You probably would like to set up a small, portable solar system and get a first-hand experience on how to do it. Or maybe you are just a DIY-buff.

In either case, we’ve got you covered. This portable solar panel system set up guide will walk you through the steps in setting up your system – from sizing, component selection to the wiring and operation. Whether it’s for home use, camping, or for an RV, portable solar kits are a great way to ensure power supply away from the grid or during blackouts. Let’s see how to design and build portable solar kits.

Step 1 – The Power Requirements

Whether you want to set up a home solar panel system or a portable system, the first step is understanding the energy requirement.

Solar power is an extremely flexible source of power when it comes to size. You need to first decide how big a system you need, i.e., the amount of power required. The first step is to create a list of appliances that you want to power from your portable solar panels. This can include anything from some LED lights, mobile phones, a small table fan, or a coffee maker.

Next, add up the power consumption of these devices. Suppose the lights total 30 watts, mobile phones 10 W, the fan 20 W, and 30 or 40 W for other small devices.

Step 2 – The Solar Panels

Once you have calculated the amount of total power required, it is time to decide the size and type of solar panels. Let us assume that considering the appliances mentioned above, your total power requirement is 80 W.

In this case, it would be reasonable to go with 100-watt solar panels, accounting for efficiency losses and unpredictable sunlight levels.

You can either have a single 100 W, 12-volt monocrystalline solar panel or two 50-watt solar panels. You can choose between regular panels, flexible panels, and rugged, portable solar panels.

image showing portable solar panels

Although all solar panels function the same at the fundamental level, each of these has its advantages. Regular, rigid solar panels are the least expensive, while flexible solar panels are extremely durable and easy to carry.

Portable solar panels come with protected edges, making them slightly more durable. It’s easy to set them in the right position, thanks to mounting kickstands. It is thus convenient to install a solar panel system using portable modules. Portable folding solar panels are another, more compact option.

Step 3 – Battery and Charge Controller

A battery is needed to use solar energy during the night, and a solar controller for safe battery charging. Before deciding what size of batteries to buy, we need to know how much energy needs to be stored. The 100-watt, 12-volt solar panels we decided upon will generate about 400 Wh of energy, assuming you are at a location with 4 hours of full sunshine availability.

To have a battery bank that can store the entire 400-watt hours, the following calculation should give us the battery size in ampere-hours (Ah):

Wh ÷ V = Ah

Hence, 400 ÷ 12 = 34 Ah

Considering some buffer for battery efficiency and depth of discharge (the actual discharging level a battery can handle), it would be better to go with a 50 Ah or 60 Ah battery. Different types of batteries are available for solar kits, but to minimize maintenance hassles, go for sealed maintenance free options – either lead acid or lithium batteries. Preferably deep cycle batteries, if you want more energy per volume.

image of sealed battery image of MPPT charge controller

A solar charge controller is necessary for safe and optimal solar charging. In this case, you can go with a 12 V or 24 V charge controller. If you are going with a 24 V battery charge controller, you will need to have a 24 V battery bank; thus, you can have two 30 Ah, 12 V deep cycle batteries connected in series instead of one 50 or 60 Ah, 12 V battery.

Among the two types of solar charge controllers, PWM charge controllers are cheaper but also less efficient. The costs for battery charge controllers have dropped significantly in recent times. It is always recommended to set up a solar panel system using an MPPT controller to get maximum value from your system.

Step 4 – The Inverter

A power inverter is necessary to convert DC power from your solar panels or batteries to AC. You can use DC supported appliances that your batteries power directly, eliminating the need for an inverter. However, it is recommended to have an inverter-based system to operate regular appliances as well.

The inverter should handle the power conversion when all the appliances are being operated simultaneously, while also having some safety margin to account for a possible power surge. In this case, a 200-watt power inverter would be a suitable option. Pure sine wave inverters are recommended for their higher efficiencies.

Image of solar inverter

Step 5 – The Wiring

Now comes the most critical part of installing your own solar panel system – wiring. If you are going with a 12V system, you can have a single 100 watt 12 volt panel or connect your 2 x 50 W panels in parallel. If you are setting up a 24 V system, connect them in series by connecting the positive terminal of one panel to the negative of the second. The procedure is the same for regular or flexible solar panels. A solar panel system installation with two panels is usually more complex than single-panel systems.

image showing parallel and series connections

The same goes for the battery. If your system is a 24 V system, you will need to connect the battery terminals in series as shown below:

image showing battery connections in series and parallel

Your power inverter’s input rating will decide whether your system will be 12 V or 24 V.

Finally, there is the wiring of all the components together. The following is an easy wiring diagram that you should follow:

image showing wiring between components of a portable solar panel system

While setting up a solar panel system, ensure the panels are not exposed to the sunlight, as DC current can be harmful. It is crucial to connect or disconnect solar panels safely. Once all the connections are done, you can set up your panels facing sunlight directly at a suitable angle, hence starting your solar charging. Make sure your panels remain clean and scratch-free for the best experience.

Portable systems are a great way to power your essentials. They are also quick to set up, whereas rooftop solar panels take about 90 days to be installed.

You can always add more panels and batteries to it to increase your system capacity. Use the same step by step guide to design the extension to your portable power generator or get one of the starter kits and directly connect to your existing system.

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portable solar panel outdoors charging a lamp

How Many Amps Can a Portable Solar Panel Produce

How Many Amps Can a Portable Solar Panel Produce?

Aniket

Written by qualified solar engineer Aniket. Last updated:

A portable solar panel produces around 5-6 amps of current in direct sunlight. Most portable panels are sized at or around 100W, which comes with a ‘maximum current’ rating of 5.5-6A and a ‘maximum voltage’ rating of 17-18V. As the word ‘maximum’ suggests, these are output values at perfect or lab conditions.

Under real-world conditions, the amount of amps a portable solar panel produces may vary between 50-100% of the value mentioned above. The number of amps depends on factors such as exposure to sunlight, the angle of sunrays, and panel cleanliness. Portable solar panels are a great way to partly or fully power your appliances. Many RV/camper trailer owners or solar users use portable panels with a charge controller to charge batteries, which then power several devices.

Understanding Power Output of Portable Panels

Though the amps generated by solar panels is essential information, it is part of a larger equation. Understanding the basics of solar power output is essential to be able to set up a sound system. The following are some terms and their significance in choosing a portable solar panel:

Watts (Power):

The basic measure of a solar panel’s performance is ‘watts’. It is a unit of power and is the product of the voltage and amps (current) generation from the panel.

Watts (Power) = Volts (voltage) × Amps (current)

Every thousand watts is also known as a kilowatt (kW). Speaking of a 100W solar panel as an example, the following is how the volts and amps bring us to the value of a hundred watts:

100W = 18V × 5.56A

Amps/amperes (current):

Current is the transfer of electric charge, more precisely – electrons, from one point to another, which results in what we call electricity. The unit for measuring current is amperes, often called colloquially as amps.

Volts (voltage):

Voltage can be roughly described as the force with which current is flowing from one point to another. This force results from a difference in electric potential (difference in the level of charge) in two points.

Ampere-hours/amp hours (battery capacity):

As evident from the name, amp hours are the capacity of the battery, derived from the multiplication of amperes and hours. It indicates how many amperes can be delivered for the given hours a day. This is best understood with an example:

A 100Ah battery means 10 amps of current can be drawn from it for 10 hours or 5 amps for 20 hours.

10A × 10 hours = 100Ah

5A ×20 hours = 100Ah

This applies not just for energy drawn from the battery (discharging), but also energy supplied to charge the battery. Considering the 100W panel we discussed previously, it has a maximum current of 5.56 amps. Supposing the panel performs in ideal conditions (peak capacity), we can find out the number of hours required to charge the battery (100Ah) fully.

5.56A × x hours = 100 Ah

Hours = 100 ÷ 5.56 = 17.98

Watt-hour (energy):

While watt is the unit for power, it only signifies electricity generated or consumed per hour, which makes it necessary to have another unit that also takes into consideration the time for which the power was consumed or generated. Thus, the multiplication of watt and hour gives us watt-hour (Wh). Every 1000 Wh is also known as a kilo-watthour (kWh). For example, the 100W panel in discussion generating peak power for 4 hours will give:

100W × 4h = 400Wh or 0.4kWh

Pairing a portable solar panel with a battery

Solar panels are helpful devices to harness free, clean, and omnipresent energy. However, nights and cloudy days make it difficult to fully rely on solar. There can be times when there is more sunlight throughout the day than you need for power generation, and sometimes there is less than you need.

It is impossible to store sunlight, but batteries make it possible to store the energy generated from solar and use it later when direct sunlight is not available, such as during evenings or nights. Pairing a portable solar panel to a battery is relatively simple, whether it is a lead-acid battery or a lithium-ion battery.

A direct pairing involves making two simple electrical connections – connecting the positive terminal of the panel to the positive terminal of the battery and similar for the negative terminals.

As discussed previously, solar panels come with a voltage rating of 17-18V. Batteries, on the other hand, are nearly always rated at 12V. Pairing an 18V panel to a 12V battery is ideal for making sure the current always flows from higher potential (solar panel) to lower (battery) and not the other way. However, panels compatible with 12V batteries are often known as 12V solar panels.

Before you start pairing your solar panels to your batteries, make sure you go through a good set up guide for portable solar panel systems.

Charge Controller

While solar panels can be directly paired with batteries, installing a charge controller between the two is recommended. A charge controller helps charge the battery in a more energy efficient/optimum manner. Based on the amount of sunlight throughout the day, the voltage and the amount of amps a portable solar panel produces may be fluctuating and even zero at times. A charge controller ensures to smoothen these fluctuations while passing the power on to the battery.

Image showing solar panel, battery and charge controller connected

Typically, a charge controller satisfies the following purposes:

  • Control the rate at which current is drawn from the battery
  • Prevent overcharging of the battery
  • Prevent reverse current from battery to panel
  • Divert excess current (shunt charge controller) to another load
  • Monitor battery temperature

There are two main types of charge controllers – PWM (Pulse Width Modulator) and MPPT (Maximum Power Point Tracking). Without going into the technical details, MPPT charge controllers are more efficient and capable, since they can track the maximum power themselves to adjust the voltage and current level. They are slightly more expensive, but worth the expense and hence are becoming the common choice nowadays.

For more complex systems, a battery management system can be employed, which also performs the task of reporting the system’s status. Once installed, it can also help measure portable solar panel efficiency.

How Many Amps Does a 100 Watt Solar Panel Produce?

As mentioned before, a 100W solar panels generates about 5.56A current. Depending on the intensity and the hours of direct sunlight received through the day, the panel generates between 20- and 30-amp hours (Ah) throughout the day. But this does not mean a 30Ah and 12V battery should be sufficient. Why?

As batteries are not supposed to be discharged fully, doing so can damage the battery. Batteries can be discharged only up to 60% of their capacity, and up to 80% for a deep cycle battery. Hence, in our case of a 100W panel, a 50Ah, 12V battery is more suitable.

How Many Amps Does a 200 Watt Solar Panel Produce?

200W is now becoming a common size for portable panels, thanks to better efficiencies leading to decreasing panel sizes. A 200W panel, unlike a 100W panel, can have two different types of voltage outputs:

  • 28V (suitable for 24V system)
  • 18V (suitable for 12V system)

The following is the current generation from 200W panels:

  • For 28V panels – 7 amps
  • For 18V panels – 11 amps

Naturally, the values mentioned above and hence the amount of power produced depend on the factors discussed before. Considering we charge a 12V battery using a compatible 200W panel (18V), you can get up to 50-amp hours of daily solar generation, provided there is direct sunlight. Thus, a 60Ah deep cycle battery or a 75Ah regular battery should suffice in this case.

What Can a Portable Solar Panel Power?

a portable solar panel on the roof of a mobile home

Solar power is a tremendously flexible technology. It can be used to power anything from calculators and wristwatches to towns and cities. Portable solar panels can be used to power nearly anything. Using a bunch of 100W or 200W panels can power your RV or mobile homes, and even a proper residence if you have enough panels.

But the question is, what are portable panels best suited for? When it comes to solar panels, there is no ‘one-size-fits-all’.

The application of a panel mainly depends on the size and power rating it comes with. Portable panels are thus an excellent choice for camper trailers with a dual battery set up or simple off-grid camping set-ups, but not so much for home solar installations.

For an average system size of 6kW, you would require 60 panels of 100W capacity, compared to just 17 panels of 350W capacity. No doubt it would make your home more energy efficient, but at a higher cost.

This does not make much financial sense, as pairing many 12V solar panels increases the complexity of your system and increases your cost of solar panels significantly. Using the greater amount of wiring that comes with it is also against electrical engineering advice. Larger sized panels thus make a better choice for your home improvement upgrades.

However, portable panels make a perfect choice for city solar panel kits, such as off-grid kits for mobile cabins that can power a couple of led lights, a small fan, and a mobile device. Most people use portable panels to charge a 12V battery and then use it as their source of energy for a decided period.

Most top-rated portable solar panels even last for over 20 years, making them a great investment. Portable solar panels often replace the bulky and smoke-generating diesel generators. Along with improving your energy efficiency, this adds its tiny share to slowing down climate change.

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