Full energy autonomy or how to survive with solar panels in the outback (part 2.5. Practical)
Having lived one summer with a pair of solar panels and without waiting for the connection to the power supply, it was necessary to solve the problem of power supply for the next year. Winter was ahead and there was time to study methods of autonomous power supply, and also to choose what would be better: our own solar power station, wind generator or compact hydroelectric power station ...
The first option was to get our own hydroelectric power station. Quiet work, your own pond and fishing - all this looks great until you plunge into the theory. To extract energy, one must have either a decent elevation difference or a high flow rate. There is neither the first nor the second at our latitudes, so this option was immediately noted. It is worth noting that Russia produces ready-made sets of mini-hydropower plants .
The second and most attractive option was a windmill. How so, I thought. “After all, the wind is always there. Yes, and beautiful blades will spin slowly and romantically. ” The deeper I got into the theory of wind energy and read user reviews, the more my hair moved. Over time, I realized that it is impossible to live on one wind generator, if only because I live not in the edge of the steppes and not on the shore of the sea or ocean, where there are constant winds. In addition, if there are forests around, or at least forest belts, this significantly affects the speed and strength of the wind, and therefore, the generation of energy. Having also studied the market of wind farms, I learned that Russia has its own manufacturers of wind turbines, but there were problems with a guarantee, so I turned my attention to China, where mass production of such devices was established. Based on energy needs, I would like to have up to two kilowatts of power at its peak. As it turned out, such a windmill could produce even more, but then I looked at the chart.
It turns out that 2 kW of energy can be obtained with the wind at a speed of 9 m / s. The question arose, and what winds blow in my region? I started digging and saw that NASA has more data and it's easier to get it. In general, the wind map for the Russian Federation looks like this:
That is, if you put a windmill on a mast 10 meters high, then you can count on an average annual wind of 4 meters per second. And this despite the fact that stragging of the blades sometimes occurs only with a gusty wind of up to 5 m / s, and then the blades rotate with a smaller wind. But production starts at 2.5-3 m / s, and the influx of energy with such a wind will be only 200-300 W / h.
After reading a few more experienced people, I realized that one must either live on a hill or raise a mast with a wind generator by 15 meters to get more wind. It must be remembered that the wind turbine requires periodic maintenance (at least once every two years) and in case of repair it will need to be lowered somehow.
Now let's estimate the accounting of such a windmill. We will consider only the cost of the wind generator itself, a special controller for it and the mast. Batteries are not considered, since they will be needed in an autonomous environment, regardless of the energy source. I will quote the prices of finished devices in Russia. They may object to me that in the same way you can buy pipes, weld them and make a mast yourself, or order a windmill from China. As my practice has shown at the stage of creating solar panels, the economic feasibility of these actions is available only if you have extensive experience in self-assembly.
A set of wind energy (prices at the beginning of March 2015):
1. Wind turbine LOW · WIND · 48 · 2.5, 2.5 kW 48V with a controller -131880 r
2.Mast 15 m for the SWG-E wind generator - 32500 r
Total for the set: 164 380 rubles.
Somehow not very budget. With this money, you can buy a generator for about 6 kW and 7300 liters of AI-92 gasoline at a price of 32 rubles per liter. At a flow rate of 2.3 liters per hour, the generator will run 3175 hours or 132 days without stopping. It is clear that it is necessary to conduct maintenance of the generator and it will not work round the clock, but only at times of high loads or to charge the batteries, but I thought that a wind generator was expensive for me.
Pros of wind energy: Cool, unusual, attracts attention. The worse the weather, the stronger the wind, which means more energy. There are exceptions - in a hurricane wind, to prevent failure, it is blocked.
Cons: high initial contribution, a large space under the mast extensions (installation of the mast without extensions is possible, but requires a better foundation and the design is somewhat more expensive), wind dependence, noise
Let us turn to solar energy. The advantages are immediately noticeable: the absence of any sound vibrations, the possibility of a gradual purchase of modules and a stepwise increase in power.
Cons are a little less obvious: you need a sufficient area with constant lighting, without a shadow. Weather Dependence. Seasonality, since in winter, production decreases by a factor of relatively summer.
I switched to the side of the sun and began to purchase modules. Having studied more than one forum and studied prices in Russian online stores, I decided to save money and turn to foreign sellers. The issue of warranty and reliability was raised, so I chose European suppliers of Chinese panels . At that time, they had a rather interesting offer when buying two batteries with a capacity of 100 W each. Even with delivery, the cost exceeded about 7 thousand rubles apiece. So I got 4 batteries and started looking towards the controllers. It became clear that production efficiency can only be raised with the help of the MPPT controller. After exploring the market, I ordered through the Ebay controller EPSolar Tracer 3215RN. It belongs to budget models, but it allows you to connect up to 150V to the input and can withstand currents of up to 30 A. With 12V batteries, it is able to digest up to 390 watts of power, that is, my batteries accounted for just. And if you raise the voltage to 24V, then the digested power is doubled. That is, the controller, as they say, "for growth." In addition to my battery, I added another 190 Ah.
It became clear that the energy needed to be consumed, and the Chinese inverters were not suitable for this at all. The idea came to get an inverter with a pure sine wave. This pleasure is expensive, but having studied several options, including Russian ones, I decided to take a Chinese device under a European name. This inverter is capable of delivering 1500 watts to consumers for a long time, at peak up to 3000 watts. That is, such an inverter will easily start all household electrical appliances with motors, as well as a power tool. In the autonomous system, such a parameter as Idling current is very important. In this device, this parameter was from 600 to 1000 mA, which is not very good, but tolerable, since the work was usually carried out under load and during daylight hours, the conversion losses were more than compensated.
I must say that before buying, I even found an OEM manufacturerthese inverters in China and contacted them for the purchase directly. The benefit at that time (the dollar exchange rate was 30-32 rubles) was about 30-40 dollars, but with the guarantee from the Chinese it is more difficult, so I preferred to buy in Germany, knowing how the Germans relate to warranty obligations. And I understand that I did the right thing, since the guarantee for the inverter is 24 months and I had to send it for repair twice. I only paid for one-way shipping, so I think it was worth it.
Closer to summer, I decided to buy solar panels, and it turned out that it was more profitable to buy batteries in Russia, as Europeans raised the cost, and the popularity of solar energy increased in our country, and I didn’t take batteries from the highest price level. Thus, my solar power plant became able to generate 800 watts of energy. I had to buy a new controller, because I categorically did not want to switch to the main voltage of 24 V. The new controllerwas twice as powerful and could digest current up to 60A. The main consumers I have remained the same: household appliances, power tools (the inverter was already at 12 V) and lighting. I also ordered the second inverter via Ebay, bargaining with various sellers for a long time, offering my price (there is such a fad) and even bargaining about $ 30. When I made such expensive purchases, sellers, as a rule, sent a tracking code to track the parcel’s travel, but it’s not shameful to ask if they didn’t immediately send it themselves. I received all the parcels and everything worked successfully.
Keeping in mind that it is better to duplicate important nodes in the autonomous system, I acquired a bu inverter for 12V and 2000 wattswith a modified sine. He helped me out when the main inverter was leaving for repairs, so this approach paid off. For the biggest and most complex loads, like electric welding, I started the generator. And then it became clear that the generator could be useful when it was idling. I began to take a closer look at chargers that could charge such a battery pack.
A bit of theory. Lead-acid batteries are usually charged with a current of 1/10 of their capacity. Since I had two 190Ah batteries connected in parallel, the calculated total capacity was 380 Ah and the charge current should have been around 38A. Such devices were either very expensive, or were starter kits for starting a car engine. For a long time choosing among our and foreign manufacturers, I came across a review by one user and began to dig further. What is curious, the memory of Orion Pennant-50manufactured by a Russian company based in St. Petersburg. Judging by the reviews, the company listens to the wishes of users and produces fairly reliable and inexpensive chargers. The selected model allows the charging current to be supplied up to 15A and has five charge profiles with three manual settings along the lower and upper voltage limits. Simply put, you can configure the charging of almost any type of battery, which I needed. To get 10% of the battery capacity, it was required to take a couple of memories and connect them in parallel. By the way, the sun was enough so that the charge was not required, and now this charger is working to constantly maintain the battery charge.
The diagram shows a switch into which the power lines from the inverter and generator converge. This is a manual phase switch. Phase and zero from two power sources are supplied to it, and the output is supplied to the load. Manually, through the opening position, you can select only one power source, so I protected myself from the possibility of shorting two power sources. The option is extremely simple, but effective.
The result was a system that includes (prices of 2014):
1. 8x100 W of solar panels (~ 6500 r / pc)
2. EPSolar Tracer 3215RN charge controller (~ 13000 r)
3. mppsolar pcm60x charge controller ( ~ 16500r )
4. Solartronics inverter 1500W (~ 16000 r)
5. Mystery MAC-2000 inverter (used for 1000r)
6. 2x 190Ah battery (~ 8500 r / pcs)
7. Orion Pennant-50 charger (~ 3000r)
Total: 118500 r
What can such a system do? All summer I did without a generator, even in not very clear weather. In cloudy times, consumption simply decreased, and in clear weather, you could successfully use a powerful power tool. The generator was started only for the use of electric welding. To harness the energy received more efficiently, several tricks were used. The refrigerator thermal relay was turned to the maximum so that the refrigerator worked without stopping when turned on. Bottles with very salty water were placed in the freezer, which served as accumulators of the cold and froze all day, releasing cold at night into the main chamber. The refrigerator itself turned off for the night. An electric bread machine was added to the appliances, which consumed 650 W * h with a peak consumption of 600 watts per cycle. Bread was baked almost every day. Thus,
По итогам создания второй версии автономки можно заключить, что:
а) покупать на Ebay сложную электронику можно
б) торговаться перед покупкой на Ebay можно и нужно
в) следует соотносить гарантийные обязательства и разницу в цене между устройством из Китая, купленное у китайцев и у европейцев
г) стоимость солнечных батарей неизбежно снижается и закупать их на данный момент выгоднее в России (применительно к россиянам)
д) ключевые устройства должны дублироваться, чтобы в случае поломки не остаться без энергии на время ремонта
е) обязательно разделить цепи питания от разных источников энергии, чтобы не допустить замыкания
g) there are Russian analogues of all these devices, which often surpass Western or Chinese counterparts in their characteristics
h) when buying in our stores, you can agree on a warranty replacement of key devices during repair, in case of failure
At the end of the article I would like to summarize some of the results. The constructed solar power station cost half the price of a wind generator, but it is effective from March to October. In winter, its generation is enough only to provide lighting for the house, so the rather popular question in the autonomous energy industry “is it possible to heat a house with solar panels” can be answered negatively. If full autonomy is required all year round, then only a combination of two energy sources will allow you to live in a bright house. One of the sources is solar panels, and the second is a generator or a windmill. In case, if there is a hydroelectric power station nearby, then the energy production is constant, with some exceptions.
Dear Khabrovchans, I noticed that the autonomous provision of energy and heat has interested many, so I would like to make the following material as useful as possible. In the comments, in addition to questions, please inform me that it would be more interesting to you:
- Struggle with power engineers for network electricity and typical mistakes in designing solar autonomy
- Reduce energy costs with solar panels
- We receive not only electricity from the sun, but also heat
- Is there life with a windmill?