Energy storage systems

It is a photovoltaic panel that generates electricity from solar radiation; the direct current output of a PV panel is later converted by an inverter into alternating current for household use and for charging a backup battery. To ensure the durability and productivity of your station, it is important to choose the right PV panels.

At the moment, the most common types of PV panels are monocrystalline and polycrystalline panels. Apart from manufacturing techniques, solar panels can be different in output, efficiency, size and so on. If space is limited, it is better to choose more efficient PV panels. Currently, the output of a monocrystalline Longi Solar PV panel is 440 W. The engineering and installation center “Teplocel” advises choosing only trusted manufacturers of photovoltaic panels, such as Longi Solar, Jinko Solar, Ja Solar, Panasonic, Sunpower, Hanwha and so on.

A grid-tied inverter is responsible for converting direct current electricity generated by PV panels into alternating current to power household appliances. As a rule, inverters can be different in operating voltage, efficiency, a number of MPPT trackers and so forth. They can be equipped with a real-time monitoring system or not.

Sometimes, due to the complexity of a roof, or if there is a need of using several surfaces, two or more grid-tied inverters are required. An inverter must be equipped with AC/DC protection, which will be explained below. We recommend using high-quality grid-tied inverters of leading world manufacturers, such as Fronius, Huawei, SolarEdge, SMA, Kostal and so on.

Stand-alone or off-grid inverter is an important component of an energy storage system. It is exactly a stand-alone inverter that converts alternating current delivered by a grid-tied inverter into direct current used to charge backup batteries. If necessary, electricity from the utility grid or batteries can be supplied through the stand-alone inverter and converted into alternating current to use for domestic needs.

We recommend using reliable off-grid inverters from the world’s best manufacturers such as Victron Energy, SMA, Imeon and so forth.

Backup batteries for an energy storage system are characterized by different parameters, the most important among which are battery capacity, depth of discharge (DOD) and cycle life. Capacity shows how much energy the backup battery is able to store. There is also such a parameter as usable capacity that shows how much energy can be actually taken out of the battery. The best backup batteries are those with usable capacity maximally close to nominal capacity.

The quality of a battery also depends on its DOD that shows the level beyond which the battery should not be discharged while using. If DOD is 100%, then usable and nominal capacities are nearly equal. It is also important to take into consideration the battery efficiency rate that determines how effectively electricity is stored and used.

• Solar panel mounts and racking
  PV panels can be mounted both on a building’s roof or front and on the ground (static or tracking type solar power systems). PV array can also be part of an adding to the structure – for instance, a weatherproof solar canopy. We recommend installing quality mounts and racking made of aluminum and stainless steel, because not only this affects the operation of your system, but also the durability of the roof as well. Mounts and racking must be rustproof and weatherproof (resistant to strong wind, rain, hail and so on).
• Internal lightning protection
  To ensure safe and lasting operation of an energy storage system, it is necessarily to install protection equipment for grid-tied and off-grid inverters. Such equipment consists of AC/DC protection and ensures stable operation of the system in the event of overload, short circuits, voltage swing and suchlike. Mandatory components of internal lightning protection are circuit breakers, fuses and residual current devices. It is worth mentioning that according to manufacturers’ requirements, with overvoltage protection equipment installed improperly or missing any of mandatory components, the inverter is not subject to warranty repair in case it breaks down or fails.

• Grounding and external lightning protection
  To protect cable lines and PV panels from a direct lightning strike, we install external lightning protection: busbars, lightning rods, equipotential bonding busbars, surge arresters and so on. In the case of ground-mounted PV systems, their grounding is mandatory. For external lightning protection, as well as for grounding systems, only corrosion-resistant metals, such as zinc plated and stainless steel or aluminum are used.

Installation of an energy storage system is carried out by our specialists in compliance with all the electrical regulations and standards, State Construction Norms (DBN), safety rules and so forth. Approximate cost of installation is 10% of the cost of equipment, and the final cost is defined after a site visit has been conducted and the system has been designed.

Installation of an energy storage system includes the following tasks:

•       Mount installation
•       PV panels installation
•       Doing electrical wiring
•       Installation of grid-tied and stand-alone inverters
•       Internal lightning protection installation
•       Batteries installation
•       External lightning protection installation and grounding
•       Commissioning and start-up