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

Sun, wind and… electricity

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 15–200 $.

Sun, wind and… electricity

Which and how to choose a source?

Sun, wind and… electricity

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 40–500 $. 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.

Sun, wind and… electricity

Sun, wind and… electricity

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 Europe, 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 Euro­pean cli­mate.

Sun, wind and… electricity

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 Europe, 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.

Sun, wind and… electricity

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 20–300 $. And if you need more ener­gy, then you should choose a more pow­er­ful wind gen­er­a­tor: mod­els that pro­duce sev­er­al hun­dred kilo­watt-hours per month, but their price will be high­er — 100‑1500$.

Sun, wind and… electricity

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

Sun, wind and… electricity

Comparative advantages and disadvantages of solar silicon cells

Monocrys­tal

poly­crys­tal

Amor­phous sil­i­con

Price

The tallest

Medi­um

Low­est

Pro­duc­tiv­i­ty, effi­cien­cy, %

~22

~15

~10

Light­ing Require­ments

High: it is rec­om­mend­ed to ori­ent the bat­tery so that the sun’s rays fall on its plane per­pen­dic­u­lar­ly

High: it is rec­om­mend­ed to ori­ent the bat­tery so that the sun’s rays fall on its plane per­pen­dic­u­lar­ly

Less demand­ing on the angle of inci­dence of sun­light

Effi­cien­cy in cloudy weath­er

Low Low high

Ser­vice life, years

~25

~20

~15

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.

Sun, wind and… electricity

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.

Sun, wind and… electricity

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 Euro­pean lands (in the Arc­tic and the Arc­tic), where, as a rule, quite strong aver­age annu­al winds (above 7 m/s) blow.

Sun, wind and… electricity

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.

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