How do you build a photovoltaic system with battery storage.

With rising electricity prices and low compensation for self-generated electricity, solar systems with battery storage are becoming more and more attractive. In the event of a power outage, such solar storage systems can also be used as a bridge for medium to longer periods of time, as the system automatically disconnects from the grid using an appropriate inverter and operates autonomously.

Our battery systems can be used in the following systems:
PV storage, solar storage for cars, emergency power storage, zero feed-in, power station, etc.

Before setting up a solar system, a few requirements must be taken into account. For example, choosing the optimal location for the solar modules, the storage size and the charge controllers or inverters are essential in order to be able to benefit from the stored solar energy. In addition, the solar system should be designed according to your own needs and the location of the system. In principle, the design of the solar system can be somewhat larger so that the system can also be used in the winter months.

In the following example,  the components and how they are interconnected.

The generators

For example, four standard Victron BlueSolar photovoltaic panels with 360 watts each can be used as generators for a 48V solar system. The power of a module can be increased by U_MPP x I_MPP calculate (38.4 V_MPP and 9.38 A_MPP, MPP = Maximum Power Point). The total output of the solar modules is 4 x 360 Wp = 1440 Wp.

The charge controller

In order to store the power of the modules in the battery, a solar charge controller must be used. This converts the voltage of the photovoltaic module into the voltage of the battery. In this case, to 48V. (The voltage range of our 48V LiFePO4 battery is between 40V and 58.4V) Solar charge controllers are divided into PWM and MPPT charge controllers. A PWM charge controller works with pulse width modulation, in which the voltage of the solar module is adjusted to the voltage of the battery while the current remains the same. With the modern and much more efficient MPPT charge controller (Maximum Power Point Tracking), the electrical load of the solar module is set so that the maximum power can be drawn from the solar modules.

The battery system

In this example, a 48v 280Ah battery storage, with a continuous discharge power and continuous charging power of  10240W Watt is used. Further technical information about this system can be found here.

When comparing electrical storage options, lithium iron phosphate technology stands out with its advantages over other storage technologies. The high  Safety with only slightly lower energy density, compared to lithium-ion or lithium polymer batteries, enables applications where high fire protection requirements can be met. Compared to lead-acid and AGM batteries, higher  Energy extraction is possible, while at the same time the cells have a significantly higher cycle stability. This speaks in favor of purchasing battery systems with LiFePO4 technology.

The inverter

In order to make the stored energy usable for home devices, an inverter must be used. A pure sine wave voltage is essential for sensitive electronics.In this example, the "Victron MultiPlus 2" inverter is used. This has the special properties that it can automatically switch between mains voltage and battery supply within milliseconds. Zero feed-in is also possible by making the appropriate settings in the software. In the event that little power is generated by the solar modules over a longer period of time, the battery can be charged via the mains voltage. In this way, in the event of a power failure, the system could automatically switch to battery supply and continue to supply the in-house devices with electricity. How long this supply can be maintained can be found in the performance comparison of our battery systems.

Safety (aspects) and commissioning

For applications with mains voltage, commissioning must be checked and approved by a specialist. For your own safety, systems that run on mains voltage must always have integrated protective devices such as residual current devices and fuses.

For smaller applications, such as a balcony power plant, smaller battery systems with smaller  Inverters, solar charge controllers and photovoltaic modules. This depends on the case  case varies.

The following circuit diagram can be used as an example for basic considerations. Consult your electrician to clarify any questions regarding the connection to the public grid and the design of the photovoltaic system.

If you have any questions or suggestions, please feel free to here through our contact form or under kontakt@lifepo.de to reach.

All information is provided without guarantee.