Autonomous power plant for a country house

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Autonomous power plant for a country house

30.05.2020 02.10.2020

«I need complete independence from energy suppliers» — said the owner of the house under construction. We at NENCOM love such tasks, so the conversation quickly turned to discussing technical solutions.

House with an area of 200 m2 located in Varna region, on a large plot in the middle of a field near the village of Pripek. There is a well on the territory for the needs of the family, as well as agricultural experiments, and the electricity is temporarily shared by colleagues from a neighboring company.

Tractor in the field

Experimental varieties of wheat grow in the yard

We need to create a heating system and an autonomous solar power plant. It was decided to divide the project into several stages.

First, even in the process of building a house, we installed a boiler and pellet Mudlark burner with Wi-Fi module, pellet hopper, radiators, 500-liter boiler and the same volume buffer tank for the heating system. We also laid the cables for the future power plant from the roof to the technical room in advance, so as not to make unnecessary holes in the house after the construction is completed.

We pre-assembled the small components of the future power plant in a metal cabinet 120×90×22×cm,; to speed up the installation on site.

Метални шка­фове NENCOM за слън­чеви елект­ро­цен­трали

Pre-assembly of power plants

As soon as the roof of the house was ready, we proceeded to install the equipment. For this project we chose monocrystalline, solar panels Risen 330 watts.

Preparation and installation of Risen modules

Risen RSM120-6-330M

The southern slope of the roof has an angle of 40° and the area is enough to fit 60 modules. In the first phase we installed 20 modules with a total peak power of 6 600 Wp.

Installation of Risen solar modules on the roof of the house

The solar panels are divided into 4 strings by 5 modules. In each string, the modules are connected in series, and the strings themselves are connected in parallel with each other. This allowed us to get the optimal operating voltage for the charger controller Victron Energy MPPT 250 | 100.

The first number in the controller name means the maximum allowed input voltage: not more than 250 volts. The second number — maximum output current: up to 100 amps. The voltage at the output of the controller is determined by the battery. In our case, the battery voltage during charging is about 55 volts, so the maximum power of the charging controller in this configuration will be approximately 5 500 watts.

RISEN photovoltaic modules after installation

We installed lithium-iron-phosphate BYD Battery Box Premium LVL, in the technical room with a useful reserv of energy 15.36 kWh.

Battery BYD Box Premium LVL

BYD Battery Box Premium LVL

This is The first one in Bulgaria BYD battery, from the latest generation «Premium». Compared to the previous generation, the new battery has increased energy density and improved electronics.

Autonomous solar power plant NENCOM

On this stage, we installed a Victron Energy MultiPlus-II inverter with a power of 4 kW, and the possibility to add additional inverters to increase power. MultiPlus-II can work as substantive and connectted with an external network or generator.

BYD Battery Box and monitoring system VRM Portal

Real time monitoring on the system

We launched the system at the end of May and the owner of the house immediately started using it actively. During the day, various pumps were running and a 500-liter boiler was being heated, and in the evening — usual consumption for the needs of the family. We now have complete statistics for 4 months, from June to September.

Statistics for the operation of the solar power plant for 4 months

As can be seen from the graphs, the total energy consumption during this period is 2 765 kW·h. Only 11 % of this energy is taken from the grid, mostly at night. In September, the need for irrigation decreased, so the network is not used at all. Consumption of solar energy (direct and battery) for 2 457 kW·h.

On a typical summer day, you can count on a stable > 3 kW power from solar panels for 7-8 hours.

Generation of a solar power plant on a sunny summer day

Solar generation on July 25

Normally, it takes a little more than three hours to heat water in a 500-liter boiler from 45 to 60 °C using a 3 kW water heater.

Generation of a solar power plant on a sunny summer day

In summer, this is more than enough to save energy for other needs and charge the battery, but in winter there will be a shortage. Therefore, we plan to install additional solar modules in future.

The price of this solar power plant in May 2020 was 35 000 BGN (17 900 €) with delivery, installation and VAT.

Лого на NENCOM върху мета­лен шкаф за елект­ро­цен­трала

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