By reading the letters below, you will save yourself time and move a little further in making a decision to purchase one or another option for a solar energy system. Based on these questions, we will try to explain how the photovoltaic system in general and its elements in particular function.

The undisputed leader is the following question

## 1. I have a house (I am building a house) 80 sq. m (120, 150, 2000 sq. m). There is no electricity (they plan to bring it up in 202 … year). What can you advise?

We can advise the following. Free and unlimited electricity is available only in the outlet with a centralized power supply. And we do not think about its consumption when you turn on a particular device. With an allocated power limit, say, for an apartment of 3.5 kW, which is determined by the introductory machine, you can uncontrollably spend 3.5 * 24 hours = 84 kWh of electricity per calendar day.

The figure that determines the useful area of \u200b\u200bthe house is not the basis for any calculation, since it is not clear whether one 100-watt light bulb will burn there or a variety of household appliances will be used. Any device has nameplate power (constant value) and operating time (variable value).

Multiplying power and time, we get the average consumption for a particular device. Naturally, this figure is more than abstract, but it is already the basis for obtaining an average figure for energy consumption and, as a result, for calculation. It should also be borne in mind that the energy consumption in the daytime and in the evening is different. Accordingly, if it is more during the day, then the generated energy is spent without a special discharge of the battery. If the main expenses are in the evening, then the battery capacity and battery power should be designed with a certain margin, since

A) The batteries need to be recharged the next day.

B) battery life is directly proportional to the number of charge-discharge cycles

The next most popular question follows logically from the previous one.

## 2. I have a house (I am building a house) 80 sq. m (120, 150, 2000 sq. m). There is no electricity. A 6 kW station is required.

There are three concepts of power for an autonomous power system. These three concepts determine the quality characteristics of your power plant. So, the power can be NOMINAL. This concept defines the amount of energy that can be generated and consumed on a clear sunny day (poured into the battery pack per hour). The solar battery has a nameplate capacity.

Let’s say 250 watts means the installed power of the system is 250 watts. And, finally, power has a QUANTITATIVE EXPRESSION correlated with time. This concept determines how much energy you can directly spend in one cycle of the system. A cycle is a calendar day. On average, a 250-watt battery on a clear summer day in central Russia generates 1200-1300 watts. So, when asking a similar question, which of the capacities do you mean:

The final and important one is definitely the average daily intake. So, we have a 1000 watt inverter – this is the rated power, there is a 250 watt battery – this is the installed power, there is a 100 Ah battery – this is the energy intensity of the system, there is a load of 200 watts. Take the ideal cycle of the system.

The battery is in a charged state. At 11 am on a sunny day, we connect the load and all the energy generated by the battery feeds it, the battery does not discharge, as the sun moves, the generation decreases and the load slowly begins to “suck” energy from the battery. Dependencies are all non-linear, but potentially with such a load, the operating time can be 10 – 11 hours. But we are approaching the next cycle, that is, the day with a completely discharged battery, and all cash generation goes to charge it.

## 3. We plan to live in a country house all year round, the average energy consumption is 4 kWh per day, how the system will work in winter and the optimal composition of the equipment.

Solar radiation values vary greatly depending on the time of year. The most problematic period for generating solar energy is the period from November to January, due to the predominance of cloudy weather, short daylight hours and “low sun”. The system will generate electricity in the presence of daylight in any case, but the efficient generation of sunlight into electricity occurs only with direct solar radiation. Depending on the density of cloud cover.

the efficiency of power generation can drop by 5-10 times. Therefore, on cloudy winter days, the system will not be able to generate the power you need, and in this case, electricity consumption will come from batteries, which are an integral part of autonomous solar energy systems. An objective reality is that for a guaranteed power supply it is necessary to use at least a portable gas generator. The qualitative significant difference between such a reserve and simply using a generator to power a house is obvious:

Breaking stereotypes of thinking, offering a generator as just a backup to a solar power plant is sometimes difficult. Since citizens think something like this: “Oh, it doesn’t work in winter, well, it’s not necessary, I’ll just buy myself a generator (!!!) It will cost less.” But it is by no means more convenient, since fuel, noise, motor resources. Consider the operation of the power system in central Russia for such an average daily energy consumption and year-round use in tandem with a generator.

Composition:

The installed capacity of the system is 1000 watts, with such an installed capacity, generation in central Russia is determined by the following histogram. That is, let’s say in June the average daily theoretical generation will be 150/30 days = 5 kWh (this is the average value, on some day more, on some less), and in October 50/30 = 1.7 kWh As you can see from March to September everything is wonderful.