Solar Power Charge Controllers
A good Charge Controller is a must have item when you are using solar panels to charge lead acid batteries. The 6V Charge Controller from Silicon Solar takes the uncertain voltage generated by Solar Panels and conditions it to safely charge batteries without causing damage from overcharge. Learn More$13.25
A good solid reliable Charge Controller is a key component of any solar battery charging system. Solar PV charge controllers allow you to use the uncertain voltage of a solar panel and condition it to safely charge lead acid batteries. The CT-XR4A is designed to be used in conjunction with our ThinFilm solar panel series or any other commercial grade solar panels. Learn More$14.50
The TruPower 12V 7A Solar Charge Regulator is designed to control the charging from the solar panel to the battery and then draw power from the battery to the outputs. This keeps the whole solar system working properly. The TruePower 12V 7A is best used with “GridMaxx or TruPower” series solar panels. Learn More$29.95
Guardian 12V Charge Controller Prolong the life of your 12V batteries and keep gear ready to go with the Guardian 12V charge controller. When you're ready to roll on, so should your gear, batteries included. This charge controller connects between a GOAL ZERO solar panel and a 3rd party 12V lead-acid battery, to monitor the charging of the battery. Learn More$39.99
Steca Solsum F solar charge controller series are widely popular in small solar home systems with a 5 to 10 amp solar charging and load current capacity (up to 240 Wp). Large connection terminals fully covered PCB and an easy to understand display are all advantages of the Steca Solsum F solar charge controller series. Learn More$66.00
The TruPower 12V 30A Solar Charge Regulator is designed to control the charging from the solar panel to the battery and then draw power from the battery to the outputs. The charge regulator has a lot of features that are not found on other solar charge controllers. It can handle charge or discharge from either a 12V battery or 24V battery. Learn More$79.95
Our Zareba® 2 Mile Solar Powered Electric Fence Charger powers up to 2 miles of fence and can be used with the following fence types: steel/aluminum, poly wire/poly rope and poly tape. Made in the USA., this charger can be used in conditions with no weeds or light weeds. The solar panel features compartmental damage-resistant construction. Learn More$142.80
Our Zareba® 5 Mile Solar Fence Charger powers up to 5 miles of fence and can be used with the following fence types: steel/aluminum, poly wire/poly rope and poly tape. Patented mechanical heliotropic capability that allows the energizer to turn to face the sun, regardless of the direction the T-post faces. Made in the USA, this charger can be used in conditions with no weeds or light weeds. The solar panel features compartmental damage-resistant construction. Learn More$179.99
The Sunlight 20 is also able to control both the solar panel and battery charging from the solar panel. It attaches directly to lighting fixtures to allow charging. The Sunlight 20 has the ability to control discharging and/or overcharging of the battery. It allows you to pick a time schedule with the time control dial. Learn More$218.25
Solar charge controllers are rated and sized by the solar panel array current and system voltage. Most common are 12, 24, and 48-volt controllers. Amperage ratings normally run from 1 amp to 60 amps, voltages from 6-60 volts.
For example, if one module in your 12-volt system produces 7.45 amps and two modules are utilized, your system will produce 14.9 amps of current at 12 volts. Because of light reflection and the edge of cloud effect, sporadically increased current levels are not uncommon. For this reason we increase the controller amperage by a minimum of 25% bringing our minimum controller amperage to 18.6. Looking through the products we find a 20-amp controller, as close a match as possible. There is no problem going with a 30-amp or larger controller, other than the additional cost. If you think the system may increase in size, additional amperage capacity at this time should be considered.
MPPT Charge Controllers:
Outback Power’s MX60, an MPPT Charge Controller
Traditionally, you would assume that the nominal voltage of your battery and your solar panel array would be the same and that you would also choose that voltage for your charge controller. However, in recent years, a more efficient charging technology called Maximum Power Point Tracking (MPPT) has become available on some models of charge controllers. One of the interesting features of this technology is that it usually allows you to have a solar panel array with a much higher voltage than your battery bank’s voltage. The MPPT charge controller will automatically and efficiently convert the higher voltage down to the lower voltage.
MPPT Charge Controllers Save You Money on Wiring Costs:
A big advantage to having a higher voltage solar panel array is that you can use smaller gauge wiring to the charge controller. And since a solar panel array can sometimes be over a 100 feet away from the charge controller, keeping the cost of the wiring down to a minimum is usually an important financial goal for the whole project. When you double the voltage (e.g. from 12 to 24 volts), you will decrease the current going through the wires by half which means you use a quarter as much copper (or cable with half of the diameter). See our wire sizing seminar for more information.
So, for instance, you could have a 1000 watt solar panel array that operates at 48 volts DC and your battery bank is 24 volts DC. MPPT charge controller are rated by the output amperage that they can handle, not the input current from the solar panel array. To determine the output current that the charge controller will have to handle we use the very basic formula for power (watts), which is:
Power = Volts x Amps
Here we know the power is 1000 watts, the battery bank is 24 volts, so:
1000 watts = 24 volts x Amps
which gives us:
Amps = 1000 watts/ 24 volts
Amps = 41.7A
We still want to boost this value by 25% to take into account special conditions that could occur causing the solar panel array to produce more power than it is normally rated for (e.g. due to sunlight’s reflection off of snow, water, extraordinarily bright conditions, etc). So, 41.7A increased by 25% is 52.1A. In this case we’d probably choose a 60 Amp MPPT Charge Controller, like Outback Power’s MX60.
Another Benefit of MPPT Charge Controllers:
Because MPPT charge controllers can handle a different (but higher) input voltage from the solar panel array than the battery bank’s voltage, you can also use these charge controllers with solar panels that have odd voltages that don’t match any typical system voltage (i.e. 12, 24 or 48V). For instance, you could have a solar panel that has a nominal voltage of 57 volts and charge and battery bank that’s 24 volts efficiently with an MPPT charge controller.
Be aware that MPPT charge controllers have an upper voltage limit that they can handle from the solar panel array. It’s important that you make sure than there is no condition that the solar panel array voltage will go above this limit or you could potentially burn out the controller. You want to make sure that the open circuit voltage of the solar panel array does not go above this limit. You also want to give yourself a little bit of a margin for an error to take in account the possibility that a solar panel array’s voltage will actually increase the colder it gets. If you give yourself a 10% margin of error you should be fine.
Here’s an example:
We’ll use four 12 volt Evergreen 102 Watt solar panels all run in series for a nominal voltage of 48 volts and our battery bank is at 12 volts. We’d like to use BZ Product’s MPPT500 charge controller. If we look at the panel’s specification page we see that each panel has an open circuit voltage of 21.3V. That means the array has four times that (because there are 4 panels in series). So the array open circuit voltage is 21.3V x 4 = 85.2V. We’ll boost this up by 10% for safety and we get 93.7V. Now we’ll look at the MPPT500′s specifications and we see that it can take a maximum of 100 volts. So we’re ok!