Solar power station in Varna #2

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Solar power station in Varna #2


In August 2019, we built the second hybrid solar power plant in Varna. Customer purpose — reduce electricity bills and stock up on emergency electricity.

The client wanted to install solar panels on the roof of a small technical room. Unfortunately, the azimuth and angle of inclination of the surface are not optimal and part of the space has already been occupied by the solar collector for water heating.

Given the space available and the budget allocated, we decided to install 9 polycrystalline modules Trina Solar TSM-PE05H Splitmax 280 watts each. The total installed capacity is 2.52 kWp.

Installation of Trina Solar polycrystalline modules

The energy from the solar modules goes to Victron Energy controller BlueSolar MPPT, which constantly regulates current and voltage, providing the highest possible power for specific meteorological conditions.

This energy is then sent to the batteries and the hybrid Victron Energy inverter MultiPlus-II. The inverter converts direct current from batteries and solar panels to alternating current, directing it to consumers.

In addition to its own power of 2.4 kW, the inverter can transmit about 7 kW from the mains. In order not to limit the power of the users to the sum of these values, we connected the inverter not in series but in parallel to the mains using a current sensor.

Diagram for connecting the inverter

Power plant connection diagram

In this way, the inverter directs solar energy to both critical consumers who always have to work (lighting, alarm, CCTV) and non-critical ones, which only work when there is voltage in the external grid. And the current sensor ensures that the power from the inverter does not enter the common grid.

If the plant owner signs a contract for the supply of excess solar power to the grid, the current sensor will allow the system to know how much energy is directed to its own consumption and how much is exported to the general grid.

We put all electronics and fuses in a sturdy metal case to ensure the reliability, safety and aesthetic appearance of the system.

Assembly of the NENCOM hybrid solar power plant

Pre-installation of power plant

After installation, we updated the software of all components of the power plant to the latest versions and configured the system.

Battery Monitor software update

Battery Monitor Update

Charge controller software update

Charge controller update

When assembled, the power plant is placed in a passenger car, which speeds delivery to the point of installation. Additionally, pre-assembly and testing of the power plant saves time during installation.

Delivery of the NENCOM power plant to the site

Delivery of power plant to the site

We installed all electronics and batteries as close as possible to the solar modules to minimize energy loss in the cables.

Installation of NENCOM solar power plant

Installation of power plant

Four 12-volt batteries from Victron Energy AGM Super Cycle 125 A·h we connected in series to produce 48 volts. With a permissible dilution depth of up to 20%, they have a useful energy reserve of 4.8 kW·h.

Installation of batteries for solar power plants

Degrease the battery terminals

We divided the nine Trina Solar modules into 3 strings of 3 modules. At maximum power, the total panel voltage is 93.8 V, and the current — 26.85 A. The charge controller lowers the voltage to the level required to charge 48-volt batteries, proportionally increasing the current and maintaining total power.

Installation of solar panels in Varna

Roof-mounted solar modules

Solar panels extend beyond the roof to the left and right to maximize the use of available installation space.

Installation of photovoltaic modules in Varna

We installed the batteries under the stairs. Many cables are hidden in the cable and corrugated channels. A battery monitor was installed on the door of the power plant showing the main parameters.

NENCOM solar power plant

The controller and the inverter heat up when operating at full power, so we have provided large vents in the control panel housing. The temperature of the batteries and the air inside the control panel are controlled by special sensors.

NENCOM hybrid power plant

Not only does the metal case look great, it also significantly reduces the noise from the inverter. It also reliably protects electronics from dust, moisture and mechanical damage.

NENCOM logo on the hull

After starting the power plant, we set up remote monitoring of all system parameters. The owner of the installation can monitor its operation in real time, as well as see detailed statistics on energy production and consumption. We, on our part, can remotely change any system settings at the client’s request, as well as periodically diagnose the system without visiting the site.

Real-time observation example

In September, the power plant represented 32.7% of the total energy consumption of the house. Given that the photovoltaic system generates energy during daylight hours, when expensive daily rates are in place, the electricity bill this month will be approximately twice as low as usual.

Statistics of the operation of the solar power plant in Varna

30 day stats

The customer is very pleased with the result and is already dreaming of expanding its power plant. We suggest you watch a short video on how we built this hybrid solar system:

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Construction of photovoltaic systems
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