Often, messages about the struggle for the environment and the development of alternative energy sources slip through the network. Sometimes they even report on how a solar power plant was made in an abandoned village so that local residents can enjoy the benefits of civilization not 2-3 hours a day while the generator is running, but constantly. But all this is somehow far from our life, so I decided to show and tell by my own example how a solar power plant for a private house works and works. I will tell you about all the stages: from the idea to the inclusion of all devices, and also share my operating experience. The article will turn out to be rather big, so those who do not like a lot of letters can watch the video. There I tried to tell the same thing, but it will be seen how I collect all this myself.
Initial data: a private house with an area of about 200 m2 is connected to the power grid. Three-phase input, total power 15 kW. The house has a standard set of electrical appliances: a refrigerator, TVs, computers, washing machines and dishwashers, and so on. The power grid does not differ in stability: the record I recorded is a shutdown of 6 days in a row for a period of 2 to 8 hours.
What you want to get: forget about power outages and use electricity, no matter what.
What can be bonuses: Make the most of the energy of the sun so that the house is powered by solar energy as a priority, and the disadvantage is taken from the network. As a bonus, after the adoption of the law on the sale of electricity by private individuals to the grid, begin to compensate for part of their costs by selling surplus generation to the public grid.
Where to start?
There are always at least two ways to solve any problem: study yourself or entrust the solution of the problem to someone else. The first option involves studying theoretical materials, reading forums, communicating with the owners of solar power plants, fighting the internal toad and, finally, buying equipment, and then installing it. The second option: call a specialized company, where they will ask a lot of questions, select and sell the necessary equipment, or they can install it for some money. I decided to combine these two methods. Partly because it's interesting to me, and partly in order not to run into sellers who just need to make money by selling not exactly what I need. Now it's time for theory to understand how I made the choice.
The photo shows an example of the "development" of money for the construction of a solar power plant. Please note that the solar panels are installed BEHIND the tree - thus, the light does not reach them, and they simply do not work.
Types of solar power plants
I note right away that I will not talk about industrial solutions and not about heavy-duty systems, but about an ordinary consumer solar power plant for a small house. I am not an oligarch to scatter money, but I adhere to the principle of sufficient reasonableness. That is, I don’t want to heat the pool with “solar” electricity or charge an electric car that I don’t have, but I want all the appliances in my house to work constantly, without looking back at the mains.
Now I will tell you about the types of solar power plants for a private house. By and large, there are only three of them, but there are variations. I will arrange, according to the increase in the cost of each system.
Grid Solar Power Plant - this type of power plant combines low cost and maximum ease of operation. It consists of only two elements: solar panels and a network inverter. The electricity from the solar panels is directly converted to 220V/380V in the home and consumed by the home power systems. But there is a significant drawback: for the operation of the SSE, a backbone network is required. In the event of an external power outage, the solar panels will turn into a “pumpkin” and stop producing electricity, since the operation of the grid inverter requires a core network, that is, the very presence of electricity. In addition, with the existing grid infrastructure, grid inverter operation is not very profitable. Example: you have a solar power plant with 3 kW, and the house consumes 1 kW. The surplus will “flow” into the network, and conventional meters count the energy “modulo”, that is, the meter will consider the energy given to the network as consumed, and you will still have to pay for it. Here the question logically approaches: what to do with excess energy and how to avoid it? Let's move on to the second type of solar power plants.
Hybrid Solar Power Plant - this type of power plant combines the advantages of a network and autonomous power plant. Consists of 4 elements: solar panels, solar controller, batteries and hybrid inverter. The basis of everything is a hybrid inverter, which is capable of mixing the energy generated by solar panels into the energy consumed from the external network. Moreover, good inverters have the ability to prioritize the energy consumed. Ideally, the house should first consume energy from solar panels and only when it is lacking, get it from the external network. In the event of the disappearance of the external network, the inverter switches to autonomous operation and uses energy from solar panels and energy stored in batteries. This way, even if the power goes out for a long time and it's a cloudy day (or the power goes out at night), everything in the house will function. But what if there is no electricity at all, but you need to live somehow? Here I turn to the third type of power plant.
Autonomous Solar Power Plant - this type of power plant allows you to live completely independently of external power networks. It can include more than 4 standard elements: solar panels, solar controller, battery, inverter.
In addition to this, and sometimes instead of solar panels, a low power hydroelectric station, a wind farm, a generator (diesel, gas or gasoline) can be installed. As a rule, there is a generator at such objects, since there may be no sun and wind, and the energy supply in the batteries is not infinite - in this case, the generator starts up and provides energy to the entire object, simultaneously charging the battery. Such a power plant can be easily transformed into a hybrid one, when an external power grid is connected, if the inverter has these functions. The main difference between an autonomous inverter and a hybrid one is that it cannot mix energy from solar panels with energy from an external network. At the same time, the hybrid inverter, on the contrary, can work as an autonomous one if the external network is turned off. As a rule, hybrid inverters are commensurate in price with fully autonomous ones, and if they differ, then it is insignificant.
What is a solar controller?
In all types of solar power plants there is a solar controller. Even in the network solar power plant, it is, it is simply part of the network inverter. Yes, and many hybrid inverters are available with solar controllers on board. What is it and why is it needed? I will talk about a hybrid and autonomous solar power plant, since this is just my case, and I can acquaint you with the network inverter device in more detail in the comments, if there are requests in the comments.
A solar controller is a device that converts the energy received from solar panels into energy digested by an inverter. For example, solar panels are manufactured with a voltage multiple of 12V. And batteries are made in multiples of 12V, it just so happened. Simple systems for 1-2 kW of power operate from 12V. Productive systems of 2-3 kW already operate on 24V, and powerful systems of 4-5 kW and more operate on 48V. Now I will consider only “home” systems, because I know that there are inverters operating at voltages of several hundred volts, but this is already dangerous for the home.
So, let's say we have a 48V system and 36V solar panels (the panel is assembled in multiples of 3x12V). How to get the required 48V for the inverter to work? Of course, 48V batteries are connected to the inverter, and a solar controller is connected to these batteries on one side and solar panels on the other. Solar panels are going to a deliberately higher voltage in order to be able to charge the battery. The solar controller, receiving obviously higher voltage from the solar panels, transforms this voltage to the desired value and transfers it to the battery. This is simplified. There are controllers that can lower from 150-200 V from solar panels to 12 V batteries, but very large currents flow here and the controller works with worse efficiency. The ideal case is when the voltage from the solar panels is twice the voltage at the battery.
There are two types of solar controllers: PWM (PWM - Pulse Width Modulation) and MPPT (Maximum Power Point Tracking - maximum power point tracking). The fundamental difference between them is that the PWM controller can only work with panel assemblies that do not exceed the battery voltage. MPPT - the controller can work with a noticeable excess voltage relative to the battery. In addition, MPPT controllers are noticeably more efficient, but also more expensive.
How to choose solar panels?
At first glance, all solar panels are the same: the cells of the solar cells are interconnected by bars, and on the back side there are two wires: plus and minus. But there are many nuances in this matter. Solar panels are made from different elements: amorphous, polycrystalline, monocrystalline. I will not campaign for this or that type of elements. Let me just say that I myself prefer monocrystalline solar panels. But that's not all. Each solar panel is a four-layer cake: glass, transparent EVA film, solar cell, sealing film. And here each stage is extremely important. Glass is not suitable for any, but with a special texture, which reduces the reflection of light and refracts the light incident at an angle in such a way that the elements are illuminated as much as possible, because the amount of energy generated depends on the amount of light. The transparency of the EVA film determines how much energy gets on the element and how much energy the panel generates. If the film turns out to be defective and becomes cloudy over time, then the production will drop noticeably.
Next come the elements themselves, and they are distributed by type, depending on the quality: Grade A, B, C, D, and so on. Of course, it is better to have quality A elements and good soldering, because with poor contact, the element will heat up and fail faster. Well, the finishing film should also be of high quality and provide good sealing. In case of depressurization of the panels, moisture will quickly get on the elements, corrosion will begin and the panel will also fail.
How to choose the right solar panel? The main producer for our country is China, although there are also Russian manufacturers on the market. There are a lot of OEM plants that will stick any nameplate ordered and send the panels to the customer. And there are factories that provide a full production cycle and are able to control the quality of products at all stages of production. How to find out about such factories and brands? There are a couple of reputable laboratories that independently test solar panels and publicly publish the results of these tests. Before buying, you can enter the name and model of the solar panel and find out how the solar panel corresponds to the declared characteristics. The first laboratory is and the second . If the panel manufacturer is not on these lists, then you should think about quality. This does not mean that the panel is bad. It's just that the brand can be OEM, and the manufacturing plant also produces other panels. In any case, the presence in the lists of these laboratories already indicates that you are not buying solar panels from a one-day manufacturer.
My choice of solar power plant
Before buying, it is worthwhile to outline the range of tasks that are set for a solar power plant, so as not to pay for the unnecessary and not overpay for the unused. Here I will move on to practice, as and what I did myself. To begin with, the goal and the initial ones: in the village, electricity is periodically cut off for a period of from half an hour to 8 hours. Shutdowns are possible both once a month, and several days in a row. Objective: to provide the house with electricity around the clock with some limitation of consumption for the period of disconnection of the external network. At the same time, the main security and life support systems must function, that is: the pumping station, the video surveillance and alarm system, the router, the server and the entire network infrastructure, lighting and computers, and the refrigerator must work. Secondary: TVs, entertainment systems, power tools (lawn mower, trimmer, pump for watering the garden). You can turn off: a boiler, an electric kettle, an iron and other heating and high-consuming devices, the operation of which is not momentarily important. The kettle can be boiled on a gas stove and ironed later.
As a rule, a solar power plant can be bought in one place. Solar panel vendors also sell all related equipment, so I started my search starting from solar panels. One of the reputable brands is TopRay Solar. They have good reviews and real operating experience in Russia, in particular, in the Krasnodar Territory, where they know a lot about the sun. In the Russian Federation there is an official distributor and dealers by region, on the above sites with laboratories for testing solar panels, this brand is present and far from the last places, that is, you can take it. In addition, TopRay, a solar panel seller, is also engaged in the production of controllers and electronics for road infrastructure: traffic management systems, LED traffic lights, flashing signs, solar controllers, and more. For the sake of curiosity, I even asked for their production - it is quite technologically advanced and there are even girls who know which side to approach the soldering iron from. Happens!
With my list of Wishlist, I turned to them and asked them to assemble a couple of complete sets for me: more expensive and cheaper for my house. I was asked a number of clarifying questions about the reserved power, the presence of consumers, the maximum and constant power consumption. The latter was generally unexpected for me: a house in energy saving mode, when only video surveillance systems, security systems, Internet connection and network infrastructure are working, consumes 300-350 watts. That is, even if no one uses electricity at home, up to 215 kWh per month is spent on internal needs. This is where you think about conducting an energy audit. And you will start to turn off charging sockets, TVs and set-top boxes, which consume a little bit in standby mode, but decently accumulates.
I will not torment, I settled on a cheaper system, since often up to half the amount for a power plant can take the cost of batteries. The equipment list is as follows:
- - 9 things
- Single Phase 5KW Hybrid Inverter - 1 things
- Battery - 4 things
Additionally, I was offered to purchase a professional system for mounting solar panels on the roof, but after looking at the photos, I decided to get by with homemade mounts and also save money. But I decided to assemble the system myself and spared no effort and time, and the installers work with these systems all the time and guarantee a quick and high-quality result. So decide for yourself: it is much more pleasant and easier to work with factory mounts, and my solution is simply cheaper.
What does a solar power plant provide?
This kit can produce up to 5 kW of power in standalone mode - this is the power I chose a single-phase inverter. If you buy the same inverter and interface module to it, then you can increase the power up to 5 kW + 5 kW = 10 kW per phase. Or you can make a three-phase system, but for now I'm content with that. The inverter is high-frequency, and therefore quite light (about 15 kg) and takes up little space - it is easy to mount on the wall. It already has 2 MPPT controllers with a power of 2,5 kW each, which means I can add the same number of panels without buying additional equipment.
I have 2520 W solar panels on the nameplate, but due to the non-optimal installation angle, they give out less - I saw a maximum of 2400 W. The optimal angle is perpendicular to the sun, which in our latitudes is about 45 degrees to the horizon. My panels are set at 30 degrees.
The battery assembly is 100A * h 48V, that is, 4,8 kW * h is stored, but it is extremely undesirable to take energy completely, because then their resource is noticeably reduced. It is advisable to discharge such batteries by no more than 50%. This lithium-iron phosphate or lithium-titanate can be charged and discharged deeply and with high currents, and lead-acid, whether liquid, gel or AGM, is better not to force. So, I have half the capacity, and this is 2,4 kWh, that is, about 8 hours in a completely autonomous mode without the sun. This is enough for the night of operation of all systems and there will still be half the capacity of the battery for emergency operation. In the morning the sun will rise and begin to charge the battery, simultaneously providing the house with energy. That is, the house can function autonomously in this mode, if energy consumption is reduced and the weather is good. For complete autonomy, it would be possible to add more batteries and a generator. After all, in winter there is very little sun and it will not be possible to do without a generator.
I start collecting
Before buying and assembling, it is necessary to calculate the entire system so as not to be mistaken with the location of all systems and cabling. From solar panels to the inverter, I have about 25-30 meters and I laid two flexible wires with a cross section of 6 sq. mm in advance, since voltage up to 100V and current 25-30A will be transmitted through them. Such a margin over the cross section was chosen to minimize losses on the wire and deliver energy to the devices as much as possible. I mounted the solar panels themselves on self-made guides from aluminum corners and attracted them with self-made mounts. To prevent the panel from sliding down, a pair of 30mm bolts looks up on the aluminum corner opposite each panel, and they are a kind of “hook” for the panels. After installation, they are not visible, but they continue to bear the load.
The solar panels were assembled into three blocks of 3 panels each. In the blocks, the panels are connected in series - so the voltage was raised to 115V without load and the current was reduced, which means you can choose wires of a smaller cross section. The blocks are connected to each other in parallel with special connectors that ensure good contact and tightness of the connection - they are called MC4. I also used them to connect the wires to the solar controller, as they provide reliable contact and quick closing and opening of the circuit for maintenance.
Next, we move on to installation in the house. The batteries are pre-charged with a smart car charger to equalize the voltage and connected in series to provide 48V. Further, they are connected to the inverter with a cable with a cross section of 25 mm5000. By the way, during the first connection of the battery to the inverter, there will be a noticeable spark on the contacts. If you have not confused the polarity, then everything is fine - rather capacious capacitors are installed in the inverter and they begin to charge at the moment they are connected to the batteries. The maximum power of the inverter is 100 W, which means that the current that can pass through the wire from the battery will be 110-2,5A. The selected cable is sufficient for safe operation. After connecting the battery, you can connect the external network and the load at home. Wires cling to the terminal blocks: phase, zero, ground. Everything is simple and clear here, but if it is not safe for you to fix the outlet, then it is better to entrust the connection of this system to experienced electricians. Well, the last element I connect solar panels: here, too, you need to be careful and not mix up the polarity. With a power of 4 kW and improper connection, the solar controller will burn out instantly. But what can I say: with such power, from solar panels you can do welding directly, without a welding inverter. This will not add health to solar panels, but the power of the sun is really great. Since I additionally use MCXNUMX connectors, it is simply impossible to reverse the polarity with the initial correct installation.
Everything is connected, one click of the switch and the inverter goes into setup mode: here you need to set the battery type, operating mode, charging currents, and so on. There are quite understandable instructions for this, and if you can handle setting up the router, then setting up the inverter will also not be very difficult. You just need to know the parameters of the battery and configure them correctly so that they last as long as possible. After that, hmm... After that comes the fun part.
Operation of a hybrid solar power plant
After the launch of the solar power plant, my family and I have revised many habits. For example, if earlier the washing machine or the dishwasher started after 23:500, when the night tariff was working in the power grid, now these energy-intensive works have been transferred to the day, because the washing machine consumes 2100-400 W during operation, the dishwasher consumes 2100-XNUMX W. Why such a spread? Because pumps and motors consume little, but water heaters are extremely voracious. Ironing also turned out to be “more profitable” and more pleasant during the day: the room is much brighter, and the energy of the sun fully covers the consumption of the iron. The screenshot shows a graph of energy generation by a solar power plant. The morning peak is clearly visible, when the washing machine was running and consuming a lot of energy - this energy was generated by solar panels.
For the first few days, I went to the inverter several times to look at the output and consumption screen. After that, I installed the utility on a home server, which displays the inverter operating mode and all power grid parameters in real time. For example, the screenshot shows that the house consumes more than 2 kW of energy (AC output active power item) and all this energy is borrowed from solar panels (PV1 input power item). That is, the inverter, operating in hybrid mode with the priority of power from the sun, completely covers the energy consumption of devices due to the sun. Is this not happiness? Every day a new column of energy production appeared in the table, and this could not but rejoice. And when the electricity was cut off in the whole village, I only found out about it by the squeak of the inverter, which announced that it was working offline. For the whole house, this meant only one thing: we live as before, while the neighbors go for water with buckets.
But there are solar power plants at home and nuances:
- I started noticing that birds love solar panels, and as they fly over them, they can't help but be overjoyed at having high-tech equipment in the village. That is, sometimes solar panels still need to be washed from traces and dust. I think that when installed at 45 degrees, all traces would simply be washed away by rain. The output from several bird tracks does not drop at all, but if part of the panel is shaded, then the drop in output becomes noticeable. I noticed this as the sun went down and the shadow from the roof began to cover the panels one by one. That is, it is better to place the panels away from all structures that can obscure them. But even in the evening, with diffused light, the panels gave out several hundred watts.
- With a high power of solar panels and pumping from 700 watts or more, the inverter turns on the fans more actively and they become audible if the door to the technical room is open. Here, either close the door or mount the inverter on the wall through damping pads. In principle, nothing unexpected: any electronics heats up during operation. Just keep in mind that the inverter should not be hung where it can interfere with the sound of its work.
- A proprietary application can send alerts by e-mail or SMS if an event occurs: turning on / off the external network, low battery, and the like. But the application works on unsecured SMTP port 25, and all modern mail services, like gmail.com or mail.ru, work on secure port 465. That is, now, in fact, mail alerts do not come, but I would like to.
Not to say that these points are somehow upsetting, because you always have to strive for perfection, but the existing energy independence is worth it.
Conclusion
I believe that this is not my last story about my own solar power plant. The operating experience in different modes and at different times of the year will definitely be different, but I know for sure that even if the electricity is turned off on New Year's Eve, it will be light in my house. According to the results of the operation of the installed solar power plant, I can say that it was worth it. Several outages of the external network went unnoticed. I learned about a few only by calls from neighbors with the question “Do you also have no electricity?”. The running numbers of electricity generation are immensely pleasing, and the ability to remove UPS from the computer knowing that even with a power outage everything will continue to work is nice. Well, when we finally pass a law on the possibility of selling electricity by individuals to the network, I will be the first to apply for this function, because in the inverter it is enough to change one item and all the energy generated, but not consumed by the house, I will sell to the network and get paid for it. In general, it turned out to be quite simple, effective and convenient. I am ready to answer your questions and withstand the onslaught of critics who convince everyone that in our latitudes a solar power plant is a toy.
Source: habr.com