Complete 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 not waiting for connection to the power grid, it was necessary to solve the problem of electricity supply for the next year. It was winter ahead and there was time to study the methods of autonomous power supply, and also to choose what would be better: an own solar power station, a wind generator or a compact hydroelectric station ...


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The first option was to get your own hydroelectric station. Silent work, own pond and fishing - all this looks great as long as you do not plunge into the theory. To extract energy, you must have a decent height difference, or a high flow rate. There is neither the first nor the second in our latitudes, so this option was noted right away. It is worth noting that in Russia they produce ready-made sets of mini-hydro power plants .

The second and most attractive option was a wind turbine. “So,” I thought. “After all, the wind is always there. Yes, and beautiful blades will spin slowly and romantically. " The deeper I penetrated the theory of wind power and read user reviews, the more my hair moved. Over time, I realized that it was impossible to live on one wind generator, if only because I live not in the edge of the steppes and not on the seashore 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 production of energy. Having also studied the wind power market, I learned that Russia has its own wind turbine manufacturers, but there were problems with a guarantee, so I turned my attention towards China, where there was a mass production of such devices. Based on the energy needs, I would like to have up to two kilowatts of power at the peak. As it turned out, such a windmill could produce 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, what winds blow in my region? I started digging and saw that NASA has more data and is easier to get. In general, the map of winds in the Russian Federation looks like this:



That is, if you put a windmill on a mast 10 meters high, you can count on an average annual wind of 4 meters per second. And this is despite the fact that the moving of the blades sometimes occurs only with gusty winds up to 5 m / s, and then the blades rotate with a smaller wind. But the production starts at 2.5-3 m / s, and the energy flow with such a wind will be only 200-300 W / h.
After reading some more experienced people, I realized that I must either live on a hill or lift the mast with a wind generator 15 meters to get more wind. We must remember that the windmill requires periodic maintenance (at least once every two years) and in the case of repair it will have to somehow be lowered.
And now let's estimate the accounting of such a windmill. We will take into account only the cost of the wind generator itself, a special controller to it and the mast. Batteries are not considered, as they will be needed in the battery, regardless of the energy source. I will quote the prices of finished devices in Russia. It may be objected that you can buy pipes in the same way, weld them and make a mast yourself or order a wind turbine from China. As my practice has shown at the stage of creating solar cells, the economic feasibility of these actions is only available if you have extensive experience in self-assembly.

A set of wind power (prices at the beginning of March 2015):
1. Wind turbine LOW · WIND · 48 · 2.5, 2.5 kW 48V with controller- 131880 r
2. Mast 15 m for wind generator SWG-E - 32500 r
Total per set: 164 380 rubles.
Somehow not very budget. With this money you can buy a generator of about 6 kW and 7,300 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 without stopping will work for 3175 hours or 132 days. It is clear that it is necessary to conduct maintenance on the generator and it will not work around the clock, but only at times of high loads or to charge batteries, but I thought that the wind generator is expensive for me.

Advantages of wind power: Cool, unusually, attracts attention. The worse the weather - the stronger the wind, and therefore more energy. There are exceptions - in case of hurricane wind, it is blocked to prevent failure.
Minuses: high initial input, large space for stretching for the mast (installation of the mast is possible without stretch marks, but requires a better foundation and construction is somewhat more expensive), wind dependence, noise

Turn to solar energy. Immediately noticeable advantages: the absence of any sound vibrations, the possibility of a gradual purchase of modules and stepwise increase in power.
The disadvantages are a little less obvious: a sufficient area with constant illumination, without shadow, is necessary. Weather dependence. Seasonality, as in the winter period, the output drops multiple, relative to the summer.

I switched to the sun and started purchasing modules. Having studied more than one forum and examined prices in Russian online stores, I decided to save money and turn to overseas 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 they bought two batteries of 100 W each at once. Even with the delivery, the cost came out about 7 thousand rubles apiece. So I got 4 batteries and started looking towards the controllers. It became clear that the efficiency of development can be raised only with the help of an MPPT controller. Having studied the market, I ordered an EPSolar Tracer 3215RN controller via Ebay. It belongs to the budget models, but allows you to connect to the input up to 150V and can withstand currents up to 30 A. With 12V batteries, it can digest up to 390 W of power, that is, my batteries accounted for just that. And if you raise the voltage to 24V, then the digestible power is doubled. That is, the controller, as they say, "for growth". In addition to my battery, I added another one at 190 Ah.
It became clear that the received energy must be expended, and the Chinese inverters did not fit for this at all. Got the idea 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 a peak of up to 3000 watts. That is, such an inverter will easily start all household electrical appliances with motors, as well as power tools. In the autonomous system, such a parameter as the idle 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 for.
I must say that before buying, I even found an OEM manufacturer of these inverters in China and contacted them to purchase directly. The profit at that time (the dollar exchange rate of 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 treat warranty obligations. And I understand that I did the right thing, since the warranty 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 the summer, I decided to purchase solar panels and it turned out that it was more profitable to buy batteries in Russia, as the Europeans raised the cost, and the popularity of solar energy grew, and I didn’t take batteries from the highest price level. Thus, my solar power plant was able to generate 800 watts of energy. I had to buy a new controller, since I categorically did not want to switch to the main voltage of 24 V. The new controller was twice as powerful and could digest the current to 60A. The main consumers remained with me: household appliances, power tools (the inverter was already 12 V) and lighting. I also ordered the second inverter through Ebay, bargaining with various sellers for a long time, offering my price (there is such a thing) and even bargaining about $ 30. When I made such expensive purchases, sellers, as a rule, sent the tracking code themselves, to track the package's travel, but it’s unreasonable to ask them themselves if they didn’t send it right away. All the packages I received and everything worked successfully.
Remembering that in the autonomous system it is better to duplicate important nodes, I got a 12V and 2000 W inverter with a modified sine. He rescued me when the main inverter went to repair, so this approach was justified. On the largest and most complex loads, like electric welding, I ran a generator. And here it became clear that the generator could be useful when working at idle. I began to look closely at chargers that could charge such a block of batteries.
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 estimated total capacity was 380 Ah and the charge current should be around 38A. Such devices were either very expensive, or were starting kits to start the car engine. Long choosing among our and foreign manufacturers, I came across a review of one user and began to dig further. Curiously, the Orion Vympel-50 ZU is produced by a Russian company based in St. Petersburg. Judging by the reviews, the company listens to the wishes of users and produces a fairly reliable and inexpensive chargers. The selected model allows you to produce charging current up to 15A and has five charge profiles with three manual settings for the lower and upper voltage limits. Simply put, you can customize the charging of almost any type of battery, which I needed. To get 10% of the battery capacity, it was required to take a pair of chargers and connect them in parallel. By the way, the sun was enough so that the charge was not required, but now this charger is working on the constant maintenance of the battery charge.



The diagram shows the switch to which the power lines from the inverter and the generator converge. This is a manual phase switch. A phase and zero are supplied to it from two power sources, and the output is fed to the load. Manually you can, through the opening position, select only one power source, so I protected myself from the possibility of closing two power sources. The option is extremely simple, but effective.

The result was a system that includes (2014 prices):
1. 8x100 W of solar batteries (~ 6500 r / pcs)
2. EPSolar Tracer 3215RN charge controller (~ 13000 r)
3. Controller charge mppsolar pcm60x ( ~ 16500r )
4. Solartronics 1500W inverter (~ 16000 r)
5. Inverter Mystery MAC-2000 (used for 1000r)
6. 2x 190Ah Battery (~ 8500 r / pcs)
7. Memory Orion Vympel-50 (~ 3000r)
Total: 118500 r

What can such a system? All summer I did without a generator, even in not very clear weather. In cloudy time, consumption was simply reduced, and in clear weather it was possible to successfully use a powerful power tool. The generator was started only for use of electric welding. In order to more effectively use the received energy, several tricks were used. The thermostat of the refrigerator was screwed to the maximum so that the refrigerator would work without stopping during switching on. Bottles with highly saline water were stored in the freezer, which served as cold accumulators and froze all day, giving the cold to the main chamber at night. The fridge itself was turned off at night. An electric breadmaker was added to electrical appliances, which consumed 650 Wh per hour with a peak consumption of 600 W per cycle. Bread was baked almost every day. Thus, energy production exceeded consumption, but for powerful work like a welding machine or iron, it was necessary to turn on a generator.

According to the results of the creation of the second version of the autonomy, we can conclude that:
a) you can buy complex electronics on Ebay
b) you can and should bargain before you buy on Ebay
c) the warranty obligations and the price difference between the device from China purchased from the Chinese and from Europeans should be correlated
d) the cost of solar panels is inevitably reduced and buying them at the moment is more profitable in Russia (applied to Russians)
e) key devices must be duplicated so that in the event of a breakdown they are not left without energy during the repair
f) it is necessary to separate the power supply circuits from different energy sources in order to prevent short circuits
g) there are Russian analogues of all these devices, which often surpass Western or Chinese analogues in their characteristics
h) when you purchase in our stores, you can agree on a warranty substitution of key devices for the period of repair, in the event of their failure

At the end of the article I would like to summarize some results. The constructed solar power plant was twice as cheap as a wind generator, but it is effective from March to October. In winter, its output is only enough to provide lighting for the house, so the fairly popular question in the autonomous power industry is “can the house be heated 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 batteries, and the second is a generator or a wind turbine. In case, if there is a hydropower station nearby, then the energy production is constant, with some exceptions.

Dear Habrovchane, I noticed that autonomous provision of energy and heat interested many, so the following material I would like to make as useful as possible. In the comments, in addition to questions, please inform us that it would be more interesting to you:

1. Fighting power engineering for mains electricity and common mistakes in designing solar autonomy
2. Reducing electricity costs in the presence of solar panels
3. We get not only electricity from the sun, but also heat
4. Is there life with a wind turbine?