Sustainability with PortaWell® and Solar Charging

Sustainability is a key element especially when it comes to water. Clean water is required in any emergency and survival situation and your ability to produce drinkable water for you and your family or small group will be an asset.

Some people worry that the PortaWell® system requires electric power to operate. However, this is what gives you the ability to produce sufficient water in a short amount of time. In a grid down or off-grid situation you may not have access to electricity, so your ability to provide your 12V power will determine how long you can survive. The good news is battery technology has advanced significantly in the past decade, and the ability to have and sustain a dependable 12-volt supply is more attainable and affordable than ever before. 

A simple system consisting of a 12-volt battery, a small solar panel with charge controller and the correct interconnecting cables can assure you have power to run your PortaWell. This will supply you and your family with life sustaining water as long as you have an adequate source of surface water and sunshine.

At myportawell.com we don’t sell solar panels for a simple reason. These components honestly can be obtained at lower costs than we could sell them for. Instead, our desire is to help you understand more about the use of solar for sustaining your PortaWell® system.

The PortaWell® system requires a 12V power source — here are some possible power sources you could use:

• 110V Outlet
  • Using a 110V AC adapter is an option to power your PortaWell® system. In a grid down or off grid situation this won’t be an option, but many portable power stations or generators have AC inverters available.
  • In those situations, we recommend using the 12V power option on your generator or portable power station because it will use less energy and be more efficient. (The inverter has power loss when converting from DC to AC power).
• Portable Power Station
  • There are many options today for these portable power stations and they have a large range of different capacities. These are probably our favorite option for powering your PortaWell® system as they are compact, portable, and often very easy to recharge.
• 12V battery
  • When we think of this option, we often think of our car battery. Yes, you can use your car battery to power your PortaWell® system, however, we would recommend you only rely on that in a pinch or as a last resort.  This is because car batteries are designed to provide high cold cranking amps for a short time and have a very low depth of discharge tolerance.
  • Instead, we recommend purchasing a LiPO4 battery instead of a lead acid battery. The LiPO4 batteries are much lighter and support many more charge cycles compared to a lead acid battery. A small 5AH LiPO4 battery costs less than $50 and can run your PortaWell® system for an hour and produce 40 to 60 gallons during that time. It can be recharged in as little as a few hours (depending on your solar setup and sunlight conditions).

Your PortaWell® system should not be run directly off a solar panel because a 12-volt panel doesn’t provide the correct, well-regulated voltage. 

Using solar energy to charge your 12V power source involves two main components — the solar panel(s) and a charge controller. It is perfectly acceptable to run your PortaWell off a battery while charging your battery at the same time with a solar panel and charge controller. 

Note that some portable power stations have a built-in charge controller and therefore you can connect solar panels directly to them for easy charging.

Let’s talk about some things to be aware of about solar panels, batteries, and charge controllers.

Solar Panels and Batteries

Your solar panel should be sized no greater than the maximum wattage your 12-volt battery size or Portable Power Station specifies.  This limit for a 12-volt battery (especially lithium-based batteries) depends on the amp-hour capacity of the battery.  To maximize the number of charge/discharge cycles a battery will provide, care should be taken not to:

• Charge the battery too quickly.
• Discharge the battery too quickly.
• Discharge the battery too far before recharging.

There are differing opinions on what limits to follow but as a compromise I use the following guidelines to maximize the useful charge/discharge life of my battery:

• Charge/discharge rate  should be less than approximately .5 C where C is the capacity rating of the battery in amp-hours, so for a 5 amp-hr. battery rating the charge/discharge rate should be kept to 2.5 to 3 amps (.5 x 5 = 2.5).  This amperage is the typical output of a 50-to-60-watt solar panel.  Using a 100-watt panel to charge this small battery would be too much but would work just fine for a 10-amp-hour battery or larger.
• Lithium based batteries can be discharged to a much greater depth of charge than similar rated lead-acid based batteries and still have a good service life.  However, I try to never run the battery flat and limit the depth of discharge to about 80%–meaning the battery still has 20% capacity when I recharge it.

Other considerations for battery care:

• For long term storage it is best to store a lithium-based battery with 60% to 80% of full charge rather than the 100% recommended for lead acid batteries. 
• Because of self-discharge, a lead-acid battery should be charged every three months and  lithium-based battery every 6 months to a year.

There are many options for solar panels from online vendors.  A 60-watt panel can be listed for as low as $50 and as high as $200–so which should you choose?

In my experience I have found the $50 panels work just as well as the $200 ones.  They are all made in China so what the brand is makes little difference. 

My favorite portable system for powering and sustaining my PortaWell consists of a foldable 12-volt, 60-watt panel with a 5-amp-hr LiPO4 (lithium iron phosphate) battery and a 10-amp charge controller. 

A similar setup can be purchased for under $150 if you look carefully.

Solar Charge Controllers

A 12-volt solar panel will typically generate 18 to 21 volts depending on the temperature, sunlight intensity and angle to the sun.  The desired charging voltage for a lead-acid or LiPO4 battery is ~14.5 volts. 

A Solar Charge Controller provides the interface between a solar panel and a battery.  Modern solar charge controllers sense the state of charge of the battery and then adjust and control the charging voltage and current to safely and fully charge a battery.  When the battery is full, the charging current  is reduced or stopped (depending on battery type), to prevent overcharging and damaging the battery.  

Solar charge controllers are rated by voltage and maximum current.   A 12-volt charge controller rated 10 amps is sufficient to charge a 5 amp-hr. battery using a 60-watt solar panel.

Modern solar charge controllers fall into two categories:  Pulse Width Modulated (PWM) and Maximum Power Point Tracking (MPPT).  The MPPT type has certain advantages over a PWM including greater efficiencies especially at higher panel voltages, but for small solar charging setups (< 100 watts @ 12 volts) the increased cost is generally not worth it (MPPT costs 2 to 4 times more than PWM). There are many low-cost charge controllers that claim to be MPPT but are not really. 

A 10-amp PWM charge controller can be purchased on-line for a little as $15 to $20.

Connecting Cables

The only other thing to be aware of in purchasing a solar panel, is the configuration of the output cables.  Connections that must be made include solar panel to charge controller and charge controller to battery.  It is disappointing to purchase these components only to find the cable connector plugs are not compatible. 

Solar Panel connector plugs—These are typically one of three types.

1. MC4 connector—This connector is more common on larger solar panels but may be found on smaller ones (less than 100 watts) as well.
2. Barrel connector—This connector comes in a variety of configurations but the most common is 5 mm x 2.1 mm.

3. Anderson Power Pole—This connector is more common on branded portable solar panels.

The simplest configuration to connect your solar panel to the charge controller uses the barrel connector (number 2 above).  PortaWell carries premade pigtails that attach to screw terminals of most charge controllers and connects to the included SAE to battery clamp connector included with your PortaWell. 

For any of the other solar panel plug configurations, pig tail transition connectors can usually be found online, or you can make your own.