How to build a photovoltaic system with battery storage.

With the rising electricity prices and at the same time low payments for the electricity generated, 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 long periods of time, as the system automatically connects itself to the grid using a corresponding inverter and acts autonomously.

Our battery systems can e.g.b used in these 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. The choice of an optimal operating location for the solar modules is essential, the storage size and the charge controllers or Inverter to take advantage of the stored solar energy. In addition, the solar system should be designed depending on your own needs and location of the system. Basically, the design of the solar system can be slightly larger so that the system can also be used in the winter months.

The following example looks at the components and how they are linked to each other.

The generators

As generators for a 48V solar system, e.g.b Four commercially available Victron BlueSolar photovoltaic panels, each with 360 watts, can be used. The power of a module can be calculated by U_MPP x I_MPP (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 and the current remains the same. With the modern and significantly more efficient MPPT charge controller (Maximum Power Point Tracking), the electrical load on the solar module is adjusted so that the maximum power can be taken from the solar modules.

The battery system

In this example, a 48v 280Ah battery storage is used, with a continuous discharging power and continuous charging power of 10240W watts. 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 level of safety with only a slightly lower energy density, compared to lithium-ion or lithium-polymer batteries, enables applications in which high fire protection requirements can also be met. Compared to lead-acid and AGM batteries, higher energy consumption is possible, while at the same time the cells have 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 through appropriate settings in the software. In the event that little power is generated by the solar modules over long periods of time, the battery can be charged via the mains voltage. This means that in the event of a power failure, the system could automatically switch to battery power 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 voltages, the commissioning must be checked and approved by a specialist. For your own safety, protective devices such as FI switches and fuses must always be integrated into systems that run on mains voltage.

For smaller applications, such as a balcony power plant, smaller battery systems can also be combined with smaller inverters, solar charge controllers and photovoltaic modules. This varies from case to case.

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

If you have any questions or suggestions, you can contact us here using our contact form or at kontakt@lifepo.de achieve.

All information is provided without guarantee.