How to build a solar power plant

In this article I want to tell you how you can build a small standalone power plant powered by solar panels, what do you need, and why the choice fell on those or other components of the power plant. For example we need to make electricity in the summer house, trailer security, in the garage, but on a budget, and want a minimum of means to get something. And at least we need light, power and charging small electronics, as well as sometimes we want for example to use a power tool.

Solar power

Photo of solar panels on the roof of a house, two panels 100 Watt

To do this, at the minimum, we will need a solar panel at 200-300 watts, you can certainly and 100 watt all, and even less if you need quite a bit of energy. But it is better to take stock, and immediately determined on what voltage to build the system. For example if you want to feed from a voltage 12, it is better to buy the panel on 12 volts, for example, two panels 100 watts, which will give 700-800 watts of energy per day. When there is sun here and from one panel have a lot of energy, but it is better to take 2 or 3 things to make and in cloudy weather, and in winter the energy was also, as in cloudy weather output falls 5-RS and the more panels will be better.

At 12 there are lots of electronics and various chargers, the majority of our cars have onboard network 12 volts and this voltage is almost everything, and it's available. For example work from 12 volts led strip, which are well suited for lighting, led light bulbs 12 in any store. Also for charging phones and tablets have car adapters that are 12, 24 volts make 5 volts. Such adapters have or USB output one or two or more, or with wire for a particular model of phone or tablet, in General, to charge electronics from 12 volts no problem.

If you need to feed from a 12 volt laptop, it also has a car charger adapter that 12 volts are doing 19V. In General, almost all has to be powered by a twelve volt, even boilers, refrigerators and electric kettles. Also there is a TV on the 12 volts that the diagonal 15-19 inches and are usually placed in the kitchen. But of course if the power of the solar panels and small capacity batteries too, you can count on the fact you can constantly make use of powerful consumers do not have, except in the summer.

If everything is done on 12 volts, then the advantage of energy saving, since the inverter 12-220 volt also has the efficiency to about 85-90%, and cheap inverters idling consumes 0.2 to 0.5 ampere, and is 3-6 Watt/hours, or 70-150 watts per day. Agree that just because 70-150 watts of energy per day to spend not want this for example will suffice to additional several hours light, led ribbon, worked for TV 5-7 hours, or charge the phone a dozen times this energy. In addition to this when working on the inverter is lost 10-15% of energy, and in the end the total amount of energy lost on the inverter turns out significant. And especially it is not rationally when we are from 12 volts do 220 volts, and then into the wall outlet turn on the power supply at 12 volts, or 5 volts. In this case, the efficiency of the entire system is very low because much energy is spent on the conversion.

Devices and adapters for 12v

For example, some types of converters operating on 12 volts, and some devices running on 12 volts, such as maker, kettle, fridge. Lighting 12

The only inconvenience was that little 12 volt power tool, and it is not a common practice, also in selling hard to find refrigerators, pumps. So if you want to feed from its plant something else besides all small electronics, without inverter 12-220 volt will not do. And here we must consider that the inverter has an efficiency of, and some devices are not particularly cheap. All this entails the need to increase in proportion to the consumption of the battery capacity, and power of the solar panels.

There would be two options, or to optimize everything on low voltage 12 volts, or then move immediately to all on 220 volts. Well, still you can simply install the inverter and use it when you need it, and everything runs continuously, for example the lights, TV, charger, nourish from 12. In this case, you may get even a cheap inverter with modified sine wave.

Through the inverters with modified sine often refuse to work the pumps and refrigerators, as well as the frequency and shape of the voltage is not suitable for demanding equipment. But through these inverters work normally bulbs on any Alt, power tools - drills, grinders, and so on, and electronics with switch mode power supplies for example modern TVs and other electronics. In General, to accurately no problems it is better to take the inverter with pure sine wave output, and then if something fails due to inverter - loss will be more than the savings.

By the way if you will feed all through the inverter

The system can be built not only on 12 volts, but for example 24 or 48 volts. The main difference however is that the thickness of the wires required is much less, as the current through the wires will be less. For example if we have a system 12, the charging current through the wires will reach up to 12 Amps, and if in MPPT controller, up to 18 Amps. And to keep the wire was heated and non-losses, the wire should be thick, and the farther the solar panel from the battery wire should be thicker.

So for example for the current 6 Amps wire size should be 4-6 sq. cm, and if we talk hamper, then the desired wire 10-12kV.cm. And if we have 50 Amps, and wire should be thicker than welding (50kV.cm), not to hot and not-losses. Here to save on thickness and not lose energy system built on Walt or 48 volts. In the case of 48 volts the wire thickness can be reduced four times, and on this to save properly. And inverters are on 24 volts and 48 volts. So is there and controllers, I think you understand the basic meaning of this economy in the wires and less loss on the transfer of electricity from the solar panels to the batteries.

Controllers there are two types, this MPPT and PWM controllers. The first type can with solar panels to squeeze up to 98% power at a higher cost. And PWM controllers is simple and the charge current, that is, with them, the current from the solar panels only 60-70%. MPPT controller works better in bright sunlight and high voltage solar panels makes a lower voltage Walt, and more current. While the conventional PWM controllers are not able to convert, but in cloudy weather, when the current from the panels is very small, such controllers give a little bit more energy in the batteries.

What controller to buy here, I think not clearly identify someone with the sun to take all the energy, and someone at the sun and so the energy comes stock, but in cloudy weather you want a little more. In principle, if instead Dorogov MPPT to buy another solar panel, how-time and compensated for by the advantage of MPPT , and plus in cloudy weather will be more confused. I personally lean more towards conventional controllers, because when the sun is energy and so nowhere, and when it is not, then there is excess solar panel will help a lot. For example, three panels on Wat will give conventional controller 18 Amps, and with MPPT will give 27 Amps. But when the gloomy weather, the three panels through the MPPT will give for example 3 amps, but as a regular controller for about 3.6 Amps, and if you buy instead of MPPT fourth panel, the increase in current will be up to 4.8 amps.

This is all I bring, for example, the difference of course for Sunny days 18 and 27 Amps much, but if and when 18 Amps anyway batteries per day charged, then more power anyway when charged, the controller will shut off the panel, and they just so happen to be lighted by the sun. But when there is no sun, and the extra amp rejoice, therefore, better more panels than an expensive controller.

About batteries for Autonomous systems

The battery is probably the most expensive and important part of the system, they are very capricious and rapidly deteriorate, their many styles and they must apply gently, or they will quickly lose capacity and spoil. On this and the controller need to buy smart, so it can be adjusted for different types of batteries, or there should already be preset settings to work with different types of batteries.

To take the car starter batteries very quickly lose their capacity of Autonomous systems that are only 1-2 years and they already lose 90% capacity. This is due to deep discharge, so as cheap controllers disable the consumers when Walt, and car batteries are not designed for this, so if you use them, do not discharge them more than 11.8 to 12.0 volts.

Traction batteries are more durable and can be discharged to 80%, but they are more expensive, and also not desirable to discharge up to 10 volts. There for example helium batteries, which are critical to re-charge. Subtleties lot, and it is better to learn not to waste their money.

Alkaline batteries are very robust, but also very expensive. And if lead-acid batteries have an efficiency of 85-90%, then alkaline batteries lose a little bit here, and if they exploit charging and discharging large currents, their efficiency significantly deteriorates. Not the best these batteries especially in winter here and so little energy comes, and the batteries give up to 30% less energy than it receives from the solar panels. Although it appeared like alkaline batteries with improved efficiency, but the picture in General is.

Lithium-iron-phosphate batteries are the most promising for Autonomous systems, they have a high efficiency of 95-98%, and not afraid of under-charge, deep discharge and high current discharge-charge. But they are also expensive and require advanced BMS system to control the state of the cells in the battery. If such a battery is charged or discharged beyond, he permanently loses the capacity or cell generally stops working. But the condition of the battery BMS monitors and it also deals with the balancing of the battery, so if something goes wrong, it will protect the battery and all will be disconnected and it will not spoil.

In one article all not describe, but the main I tried to mention and describe, to make it clear to those those who are not familiar with. More information can be found in other articles of the section. But in General at the moment, judging from my own experience, build a small power plant without inverter, and all the electronics to feed from 12 more profitable, but if they all translate 220-e volts, then build the system on 48 volts. Especially in winter, even a little excess energy. Also the batteries I have this winter lithium-iron-phosphate (lifepo4), and energy in General is significantly higher than when using the car battery, plus lifepo4 not spoiled, and no loss of capacity, although they are a month was not contracted until the end, and continuously discharged before disconnecting.