Full energy autonomy or how to survive with solar panels in the outback (part 5. Sun Catcher)

In the European part of Russia, the sun finally began to shine brightly enough and long enough to be able to maintain its autonomous system without the involvement of external energy-electric networks and generators. But there are a few tricks that allow you to collect a little more energy with small modifications to your existing system. The first is tracking the sun, the second is tracking the point of maximum power of solar panels. Let's start with the first and most interesting - the solar tracker.

“The moped is not mine,” but to understand the principle of action is very clear.



The above tracker can even be purchased on Ebay . It costs about 52,000 rubles at the end of April 2015 in Russia, and is able to hold only a couple of panels with a total power of up to 600 watts. And since the issue is very difficult with the payback of solar energy, with the addition of such a tracker, solar energy will pay for itself for a rather long time. Therefore, the popularity of homemade trackers with various controls is extremely high.

A remark should be made and the feasibility of installing a solar tracker should be assessed. Such a device allows to increase energy production with the same number of solar panels by 1.6 times due to the longer exposure to the sun on the panel and the optimal angle of installation of the joint venture relative to the sun.

It is worth highlighting the main tasks that will have to be solved when tracking the sun:
1. Create a fairly strong platform that will not only support the weight of the panels themselves, but also gusts of wind. A tracker with 4-6 or more panels can be considered a large sail.
2. Create the mechanics of turning a heavy platform with high windage.
3. Create a mechanics control logic for tracking the sun.

Let's start with the first paragraph. It is advisable to place arrays of batteries in such a way that they do not obscure each other and are attached multiple to the required voltage.


Such a tracker requires a powerful foundation and strong iron. Of all the devices tested, actuators are best suited to control the turntable. The control mechanics are clearly visible in the next picture.


This tracker allows you to control the position of the solar panels in two planes. However, it is possible to make control only horizontally, and vertically change the angle a couple of times a year (in spring and autumn).

As for the logic of the entire system, there are several ways to go:
1. Tracking the brightest point
2. Turning and tilting by timer (sunrise and sunset are known and constant for each day)
3. Hybrid option that combines a constant rotation angle and finding the maximum brightness

The first way you can implement it yourself or buy a finished device from the Chinese. The first to control the tracker in one plane The


second to control the tracker in two planes


Roughly speaking, the Chinese want $ 100 to track maximum brightness at one point. It is clear that these systems are not very difficult for a person who understands the principles of the controllers, therefore, a similar system can be assembled 10 times cheaper.
It will look like this

Well, project details and implementation can be found here . The project is not mine, so I will not plagiarize.
You can read more about independent manufacture of a solar tracker on the profile forum , where we experimentally calculated the optimal designs and the best equipment for this task.

Tracking the Maximum Solar Power Point (MPPT)
In the second part of my cycle, I talked about two different types of solar controllers. MPPT (Maximum Power Point Tracking) controller also monitors the sun, but from a different position of the entire system. For a simple explanation, I will give a graph and an explanation after.


The graph shows that the maximum power removed can be obtained when the maximum power is at the point, which will always be on the green line. An ordinary PWM controller simply cannot do this. In addition, the MPPT controller allows you to connect an assembly of series-connected solar panels. This method of connection significantly reduces energy loss during transportation from solar panels to batteries. The economic feasibility of acquiring the MPPT controller appears if the power of the installed joint ventures is more than 300-400 watts. Based on my experience, I can say that it is worth purchasing a solar controller “for growth”, unless a powerful energy system is created immediately, which with a margin covers the needs of the house. By the method of successively increasing the number of solar panels, I came to a power of 800 watts - this is not a lot, but this is quite enough for a summer house in the summer, so that I don’t have to go to power grids at all. According toto the calculator, my power system will averagely bring from April to August 4 kWh of electricity per day. If you do not use an electric stove and microwave for cooking, then this amount of energy is enough for a comfortable life for a family of 4 people. But there is still a powerful energy eater in a private house in the form of a boiler for preparing hot water. To heat an 80 liter boiler, just about 4.5 kWh of electricity will be needed. Thus, autonomy should pay off at least by heating water or servicing other consumers.
In the last articleI talked about a hybrid inverter that can use priority energy from solar panels and only take the missing from the network. How does this relate to the solar controller? The fact is that the Russian company MicroArt has recently started to produce its own MPPT controllers , which can be connected to inverters of the same manufacturer via a common bus. Well, since I already have a hybrid inverter installed, with the new season I decided to try a new controller.



I must say that it looks brutal with respect to the two previous controllers that I already have in my household. Metal case, radiators on the sides (Chinese models have radiators on the back wall), dark gray steel case. Recently, I began to like that in my household the controllers begin to "communicate" with me in Russian. Previously, there were pictograms, numbers and English inscriptions. It can be considered a whim, but it's nice. In this article, I will not compare the new controller with previous models, but I will take out testing with Chinese models in a separate text. Perhaps, in the same place I will consider the feasibility of acquiring a more or less powerful controller, operation features and reliability.
The biggest advantage of this controller for me is the ability to pump the right amount of energy so that there is no borrowing energy from the battery, which reduces its resource. Of the three models that are presented by the manufacturer, I chose the most popular and optimal voltage / current ratio - ECO Energy MPPT Pro 200/100 controller. Based on the characteristics of the device, we can say that the controller supports an input voltage of up to 200 V and an output current of up to 100A. Considering that my assembly of 24 V batteries (12/24/48/96 V battery voltage is supported), the controller will allow me to give a maximum power of 2400 W, that is, I have a double supply for increasing solar panels. The maximum controller power is 11 kW at 110V on batteries (buffer voltage). The controller communicates with the hybrid inverter MAP SIN Energy Pro HYBRID v.1 24Vvia the I2C bus and can instantly add power when the inverter provides information on increasing energy consumption. The interaction of two devices of the same company is, as a rule, a well-developed system, so it comes down to plugging one lace into the necessary device connectors and activating the necessary parameters. I was interested in the statement of the manufacturer of this controller that this MPPT controller can also instantly add power when using an inverter of any other manufacturer. It became interesting how this is implemented. Everything turned out to be extremely simple: the

current sensor is hung on a positive wire leading to the inverter (which is why the inverter manufacturer is unimportant) and using the Hall effectthe controller calculates the power consumption. Here the logic of the solar controller itself comes into operation and it pumps up the right amount of energy. All the controllers known to me rely on the battery voltage, and only taking it into account increases the charge current.
Continuing the study of the controller's capabilities, I was faced with the fact that it is equipped with three relays, the operation of which can be programmed. For example, with enough sunny weather and no electricity consumption at home, you can start heating an additional boiler or pool. Consider the reverse option: there is no sun, the voltage of the batteries has dropped to a critical level, when the inverter can simply turn off, and energy consumption continues. Then you can start a separate benzo / diesel generator by simply closing the relay. But for this, the generator must have a dry start contact or a separate automatic start system or SAP (also called ABP - Automatic Reserve Input). Since I, like most summer residents, have a simple Chinese generator, but with a starter,automation .
Back to the controller. Its installation is standard: first, the battery terminals are connected, then the solar terminals are connected and settings are made. By connecting an external current sensor, you can observe how much power the inverter consumes in real time.
So, we unwind the wires, mount the controller and start saving. The following photo shows the inverter in hybrid mode, when only part of the energy is consumed from the network, and the main one from solar panels.


The solar controller is specially connected through an external current sensor to demonstrate operation with any other inverter manufactured by a third-party manufacturer.


Summary The
solar controller complies with the declared characteristics and really boosts energy, even I will be connected to a “foreign” inverter by means of a current sensor. The hybrid inverter really pumps solar energy into the network (in the photograph of the 200 watts consumed, half, that is, 100 watts comes from the sun. The controller will always take the minimum 100 watts from the network, and taking the rest from the sun is a feature of the device). Simply put, the kit from the moment of connection began to pay for itself. Unfortunately, spring has suddenly changed into a blizzard, and in the near future it is unlikely to be able to observe the high efficiency of the kit (hybrid inverter + solar controller), but since May I have been counting on the almost complete coverage of my energy needs due to the sun.

Announcement
In the next, final article, I will compare the three solar controllers I have and try to answer all the questions that arose during this material cycle. If any topic remains unsolved and it will be interesting to a large number of Readers, then I will try to get together and give out separate material. And now I am ready to answer questions. May the Force of the Sun come with you !