Alternative energy sources for the home: solar panels and wind turbines

The most widely used alternative sources of electricity are solar panels and wind turbines. Both technologies are well developed, equipment prices are gradually decreasing, and now, for example, a solar module with a capacity of 200–250 W can be purchased for 15–20 thousand rubles.

Which and how to choose a source?

First, decide on the amount of electricity you need. Are you going to build your home’s power system entirely on solar or wind power, or use it as an emergency power system? After all, the price tags are very different. For an emergency system (with an output power of 200-500 W), one or two solar modules and additional equipment are enough — in total for the amount of about 40-50 thousand rubles. But completely switching to autonomous power supply will cost much more. For example, a solar-powered system with an output power of 2500 W will cost 300–400 thousand rubles. A similar order of numbers is in the price tags for wind turbines.

Directly the choice of the type of «green» source depends on the climatic and geographical features of the area. For example, for low-latitude regions with cloudy weather (for example, in the Crimea), solar panels are best suited. In open areas, on hills and on the sea coast, which are characterized by continuous strong winds, wind turbines have proven themselves well. In most of European Russia, there are few places with a climate that is ideally suited for one type of electricity generator or another. In such conditions, it makes sense to install both types of generators, which will insure each other. Of course, such a system turns out to be much more expensive — but what can you do, these are the features of the Russian climate.

Solar panels

Currently, two types of these devices have become widespread: silicon and film. Each of them is divided into types:

1. silicon monocrystalline. Each individual light-receiving module is made on the basis of a silicon wafer cut from a single crystal. These batteries are characterized by the highest efficiency (up to 22-24%), but also the highest cost;
2. silicon polycrystalline. The plate of a separate module has a structure consisting of several silicon crystals, due to which the device is reduced in price by about half. Efficiency 13–15%;
3. silicon amorphous. At a cost of 20 percent lower than polycrystalline, the efficiency is about 6-8%;
4. film, based on cadmium telluride, copper selenide, polymeric materials, etc. They have appeared recently and are not widely used, but are considered by many manufacturers as very promising. The efficiency and cost are approximately 20% higher than those of amorphous ones.

The most widespread panels today are polycrystalline and based on amorphous silicon. These modifications are easier to manufacture and cheaper than single-crystal-based panels, and in addition, amorphous silicon-based batteries do not require direct exposure to sunlight, they reproduce electricity more efficiently in diffused lighting and, accordingly, are better suited for central Russia, where there are many cloudy days. For regions with a predominance of clear weather (Crimea, Central Asia), on the contrary, it is better to use mono- and polycrystalline batteries.

Wind turbines

The wind generator converts wind energy into electrical energy. Modern models are already able to operate with a small wind (2–3 m/s), although the optimal wind speed for their operation is higher and is usually 10–12 m/s. At a wind speed of 3 m/s, such a wind turbine will produce approximately 5% of the power of the possible, at a speed of 7 m/s — about 50%. Therefore, when choosing a generator model, it is necessary to take into account the average annual wind speed in your area, this indicator is always indicated in the description.

Choose a wind generator and the magnitude of the monthly current generation. You must calculate how much electricity you will need. Let’s say you decide to be economical and limit yourself to emergency lighting, the operation of a circulation pump and the ability to charge a smartphone or laptop. Then you will need an output power of 150–200 W, which is approximately 50–100 kW • h per month. Such output will be provided by low-power models, they can be purchased today for 20-30 thousand rubles. And if you need more energy, then you should choose a more powerful wind generator: models that produce several hundred kilowatt-hours per month, but their price will be higher — 100-150 thousand rubles.

The same is true for solar panels. The required amount of electricity is calculated, and on the basis of the calculation, modules are selected so that their combined performance meets your needs with a guarantee. The calculation is a little more complicated, since the amount of monthly current generation varies greatly from time to year. In summer it is maximum, and in winter it barely reaches 10–20% of the summer one. Therefore, choose solar panels depending on whether you are going to use them only in the warm season (during the summer season) or all year round. In addition, the efficiency of generation is highly dependent on how well you position the solar panels. If they could not be deployed in the right direction and at the right angle, then the efficiency of energy generation will noticeably decrease — by 20-30%, or even more. Therefore, it is better that the calculations on the required performance of the batteries, taking into account their location, be done by a specialist.

Approximate scheme of a hybrid wind-solar installation

Comparative advantages and disadvantages of solar silicon cells

Where and how to install batteries and wind turbines

Solar panels should be located as far as possible so that sunlight falls vertically on them. In the Northern Hemisphere, solar panels are deployed in a southerly direction, at an inclination corresponding to geographic latitude. In practice, solar panels are usually installed on the south slope of the roof. If this is not possible, then the batteries are placed in a less favorable position, while the performance calculation should be adjusted. You may need to increase the number of modules.

It’s good if you have a margin for mounting space, on which you can install one or more additional modules in the future. Because sooner or later you will come up with the idea that it would be nice to increase the performance of the system.

Solar panels must be installed so that they can be serviced. This applies not only to repair work, but also to cleaning — it must be done regularly, removing fallen leaves, dust and dirt from the panels. Especially important is the availability of panels for year-round use due to the need to clean them from snow.

Wind generators are recommended to be installed on the highest part of the terrain. You should not save on the mast: at a height of 8–10 m, the wind strength increases by about 30%. The windmill can make noise during operation, so it is better to install it no closer than 20 m from the house. Fortunately, low-frequency noise that affects health and wildlife is produced only by wind turbines of very high power — from 100 kW and above. Therefore, light and low-power models of wind turbines are sometimes installed on the roofs of buildings, and for such cases it is desirable to use damping pads.

Wind generators have proven themselves especially well in the northern Russian lands (in the Arctic and the Arctic), where, as a rule, quite strong average annual winds (above 7 m/s) blow.

Optional equipment

In addition to current generators (wind generator or solar battery), you will need:

1. Inverter — converts the direct current generated by the solar panel or battery into alternating current with a power of 220 V.
2. Rechargeable batteries (ACB). They accumulate a reserve of electricity in case of peak demand or for the situation when the generator does not produce current (for example, solar panels at night).
3. Charge controllers are devices responsible for directing the flow of electricity generated by the generator. Without them, the generator will have to be manually disconnected from the battery every night and at the end of each charge. In addition, controllers increase generator efficiency by 30-50%.
4. Generator mount. In the case of a wind turbine, this is a mast 8–10 m high. For solar panels, these are rooftop brackets or free-standing structures.

As practice shows, you will have to pay about the same amount for a set of equipment as for a generator.

• Source: Ideas for Your Home Magazine#227