Solar Charge Controller

It has been a while since I have posted any Solar Power articles because I have actually been upgrading the electrical system at my rental property where I am installing the solar panels.  I just got done installing new utility boxes and meters and I really have not had a chance to tie the solar panels into the house electrical system yet.  I am still looking into the best system to use to tie my panels into my utility box.

However, my panels have been up on my roof and I use them at night to run low voltage DC lights in my house and in my garage.  The only problem is that I have to disconnect the system when I am not at home because the panels could over-charge my batteries.  Even when I disconnect the panels, they are still keeping my batteries topped off with the amount of sunlight they are getting.  I just can’t believe how much FREE ENERGY I am wasting by disconnecting the panels!  So how do you avoid this issue and make sure that you are getting the most power you can from the sun?  Get A Solar Charge Controller!

So what is a Solar Charge Controller and what does it do?  A Solar Charge Controller is a device that is installed directly in between your solar panel and battery bank and it helps protect your batteries from overcharging/discharging, and also helps to prevent an overload or short circuit in your system.  They are great for helping you keep your batteries working to their optimal level.  Additionally,  a good solar charge controller can also help to prevent the battery bank from reverse charging a solar panel – acting as a blocking diode if your solar panel system does not have a one-way diode already installed.

Most Solar Charge Controllers can be used with a 12volt or 24volt battery bank system and can handle anywhere from 50 watts to 400 watts of power.  It really depends on the wattage and amps coming out of your solar panels that will help guide you toward a solar charge controller.  There are also two types of solar chargers available –  PWM (Pulse Width Modulation) and MPPT.  I will explain these in another post, but for these purposes, a PWM controller is fine.

Solar Charge controllers are really easy to install and do not require any electrical skills to get into your system.  You simply connect the solar panels to the charge controller, and then connect the charge controller to the battery bank or appliance/lights you want to run.  That easy!

Solar Charge controllers are available for different wattage and amperage (amps) useage and needs.  To determine what size solar charge controller you need,  look for the watts and amps producted by your solar panel.  For example, I have a 45 watt solar panel kit from Harbor Freight on my garage powering some lights.  When you read the box, it says that each of the three solar panels are “Maximum current, 3000 mA. 15 watts max per panel. Peak voltage: 23.57 volts open current”.  So the max power voltage may be guesstimated by dividing 15 watts by 3000mA or 3 amps equaling 5 volts. If wired in series, which they are, they will produce 15 volts with is common for a 12 volt system (wiring in series change the voltage and wiring in parallel changes the amperage).  So I know I need a solar charge controller that can handle at least 15 volts and at least 25 amps.  So I purchased a 30 amp 12-24 volt solar charge controller.  Solar Charge Controllers are easy to find on ebay, and can be purchased for as little as $40.

When looking for features in a solar charge controller look for the following:
1) maximum power-point tracking (MPPT)
2) a low-voltage disconnect feature and load terminals. This makes wiring much easier and allows the controller to disconnect the load from the battery if the battery-charge level drops below a safe level.
3)  a low-voltage cut-off 

Some Models of Solar Charge Controllers:
1) Pro Star

2) Morning Star:
12-volt Sunsaver Model #SS-10L at 10 amp and Model #SS-20L at 20 amp. Use the 20-amp controller for solar arrays in the larger 150 to 200 watt size range, and the 10-amp controller for smaller array sizes.

Related posts:

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  11. Grid Tie Solar Inverter
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One comment

  1. Sat Anlage says:

    awesome blog, do you have twitter or facebook? i will bookmark this page thanks. lina holzbauer

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