Archive for the ‘Solar Panel Charger’ Category

I made a short 11 minutes informative video on Solar Panel Charger available on youtube. For pictorial presentation of this article, please watch the videos here: Video 1 of 2Video 2 of 2

The transcribed version is as follow:

Hi, this is Jay from solar-panelreview. Today I like to share some information with you about Soltek Solar Panel Charge Controller. The Charge Controller that we are going to talk about is SPS20 made by Soltek Powersource rated at 20 amps. It has lcd display and led indicators. It uses automobile type fuse rated at 20 amps which is easily replaceable. (Camera is now on the battery:) Here we have a deep cycle battery meant for marine or RV. This particular one is 81 AH capacity. It is a brand new battery and never been charged before. It has been sitting on the shelf for the past 6 months.

Keep in mind that our purpose is to have a Review on Solar Panel Charger. It would be nice to find out how the state of the components are initially. We have a meter here. Of course the ground goes to ground. We are measuring voltage so the positive lead goes to V. If you want to measure current you use the other connection. This particular one is for resistance. In this case we are measuring the voltage.

To be able to review components properly we have to make notes of the state of the components not only after complete connections, but also prior to operational stage. That is why in the video I am interested to find out how much voltage off the battery we can read. Here are the positive and negative terminals of the battery. What I am reading here is 5.9 volts. It should usually be 12 to 14 volts, but since it has been unused for the past 6 month it is so low.

We have shell solar module; sp75; rated at 75w. (I am just reviewing the label at the back of the PV): Maximum Circuit Open Circuit Voltage is specified at 600v and as far as fire rating goes it is Class C. Short circuit current of 4.8 and rated current at 4.4 amps. Open circuit voltage 21.7 v and rated voltage at 17 volt. A 15 Amps Series Fuse is specified. For wiring, they recommend Copper AWG 14 minimum and the insulation of copper wire to be good for temp of 90 degree C or better.

The junction box is plastic and a couple of diodes inside. To review how the inside of junction box looks like, go to the address on the screen. (

It is worth mentioning that sp75 comes with 20 feet of 2 wire gauge 12 direct burial type cable. On the next clip we show you how to connect these components together.

Let’s have a quick review on solar panel by finding out what the open voltage of the PV is before connecting it to anything else just for curiosity. It is the same solar panel, 75 watt one. The meter is set for volts dc, black is common and red lead is connected to V for voltage. Some meters are different; the red lead/jack is good for measuring volt and resistance. In this case we are measuring the voltage across the solar panel. The black cable you see in the video is coming out of the solar panel. As you can see we are measuring open voltage of the Solar panel because it is not connected to anything else. The Voltmeter is reading 19.1 volts, and if I move a little bit away so my shade is not on the panel we are reading about 20.8 Volt. And I should mention that the panel is not totally under the sun, it is underneath a covered deck. Later on I will move it to an area which has more sun exposure on it. Let’s put back the connectors so it doesn’t make a short and blow the fuse.

I just want to point out something here. So far I have connected the solar panel to the charger controller. Manufacturer recommends removing the automobile type fuse while wiring it up. We are assuming that we haven’t work with this solar charge controller and we want to get a feeling of it. The first time we connect it, the current led is on and the charging led is on. As you noticed it is not connected to the battery yet. It is only connected to the PV. When we look at the led indicators it is switching between current and voltage. Even though I am not supposed to connect the fuse yet, but it is the whole purpose of the video to look at the whole thing from different angle. Solar Panel Charger Review would be beneficial if we test it under other conditions not specified by the manufacturer. (On the video screen, it reads: We are doing an experimental test, and we do not suggest you to perform these tests. We recommend following safety procedures). Voltage is reading 2.2 volts. It is switching back and forth from current to voltage. We want to find out how the components behave when they are not connected completely. (Voltage reading of 2.2 volts is ambiguous due to fuse not in the circuit).

I am hoping to get a closer shot of the LEDs. The led current is on. The battery is not connected. The voltage led came on. Since the bat is not connected, we are not reading a meaningful value here. Since there is no battery there is no charging. Let’s do the next step and connect the battery now.

Here we have the battery, the solar panel, and the charge controller all connected together. I placed the solar panel in an open area so there is more sun on it. Let’s see what we can learn from it. Basically it is showing that the battery is charging because Battery Charge Monitor LEDs are illuminating back and forth. I want to zoom in with the camera a bit more. Voltage is showing 14.3 volts. As you can see it is charging well. The weather is sunny and bit of cloud. For the purpose of understanding how sun is positioned, I should mention that today is April 8th, 2010. You can see the solar panel and here is our charge controller. The charging led is on indicating charging the battery at 1.3 amps, and the voltage is fluctuating between 12 to 4 volts. The battery charge monitor LEDs as you can see (in the video) are flashing.

The fact that the display switches back and forth between voltage and current is very handy, I like it. We don’t have to press a button. All we have to do is to be patient. Thank you for Watching the video or I should say than you for reading this article.

Jay from

Posted on April 13, 2010

Video production on April 8, 2010


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Let’s take a look at a Solar Panel Charger made by Soltek Powersource (SPS Energysolutions) model SPS 20 Charge Controller. The picture gives an idea of how it looks like. It is a 4.25” by 7.50” device with a depth of 0.75”.

It is meant for flush mounting inside an RV or in a recessed in area. It has an LCD display and a row of 11 LEDs underneath it to indicate the charge status.

Consider these points during the installation of any type of solar panel chargers:

- Connect the battery polarity accordingly.

- Connect the solar panel to corresponding polarized terminals of the Charge Controller.

- Do not exceed the recommended voltage and current of the SPS 20 (26 volts and 25 Amps).

Remember that this solar panel charger can withstand the maximum current of 25 Amps for not more than 30 seconds. It is designed for normal working condition at maximum 20 Amps.

At the back side of the unit there is a durable plastic sheet with the explanation of how to connect this Charge Controller to Arrays and Batteries.

The front panel metallic sheet is quite strong. I measured its thickness to be 0.084”. Electronic printed circuit board is mounted on the back of this plate by four aluminum studs. There are also two transistor attached mechanically to this plate for the purpose of heat dissipation.

The LCD display and LED status lights makes this solar panel charger a low consumption unit. Its Quiescent Current is specified at 20 mA or 0.02 Amps which is quite low.

At the end of its manual, there is a “Faceplate Mounting Template” for easy installation. There are some troubleshooting hints and explanation at the end of the Installation and Operation Manual.

What I like about this Solar Panel Charger is the location of the Fuse. It is a readily available 20A automobile fuse. The fuse is well accessible (sticking out about 0.3”), and don’t worry, you don’t need a special plastic clamp tool to get it out.

This Controller is designed to be mounted indoors, and in a location that is close to the batteries. The reason is battery gets charged more efficiently with shorter run of wires.

I am in the process of making a visual demonstration of this unit. I keep you updated once it is ready.

Happy Solar Battery Charging Day,


April 6, 2010

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Solar Panel Charger is a common part to any Solar Power system. It’s basic functionality is similar to a normal charger. Since a solar panel charges lead-acid battery types, we like to look into a simple charger that does that.

Any charging device consists of several parts outlined below:

- Power conversion and conditioning.

- A regulation device.

- Feedback circuitry.

- In some models an optional battery temperature monitor.

- Indicators and status lights.

In the diagram below you can identify these functional parts.

Power conversion and conditioning circuit is designed based on the source of the power. In a Renewable Energy system powered by solar panels, the source of the power is of course the photovoltaic panels. So in this case there is no need to down convert high voltage to lower levels.

The regulator provides a constant voltage. The resistor designated as R1 senses the current to the battery. As the battery reaches to the full charge, it demands less current. This reduction in current through the R1 resistor is sensed by the LM301A comparator. In conjunction with the transistor, the LM301A reduces the voltage applied to the battery when the battery is getting close to full charge.

The LM334 is the temperature sensor for the battery. As the solar panel charges the batteries, they start to heat up due to chemical reactions inside the battery. The temperature sensor makes sure the solar panel charger is not over heating the batteries.

The LEDs in the circuit are for indicating the status of the charge. When the battery is floating (Not accepting charge any more), the lower LED turns on. While the solar panel is charging the battery, the upper LED is illuminated.

In our future articles we would investigate into other types of Solar Chargers.

Thank you for visiting our site, and good luck in your research.


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