Increasing the cost of electricity keeps people looking for new energy sources. Especially for those who live in areas with unstable power grid, this is certainly a nuisance. One alternative way is to re-use solar energy by installing a solar inverter. Because the sun is a source of energy that will never run out and environmentally friendly. Photovoltaic (PV) solar systems convert solar radiation into electricity by using photovoltaic effects.
Electricity generated can be used in several ways such as:
• Sales to electrical suppliers
• On-site direct consumption
Switching to solar is not an easy decision, there are many things you need to know before using solar power. Indeed, using solar is the same with investing for the future.
Here are some reasons why many people switch to solar:
- Reduce electricity bills
Installing solar for the first time will cost you money. But remember that this is a long-term investment. The number of benefits you can get, one of them is decrease your electricity bills because you no longer need to rely on the power grid. It also depends on the type of solar power system you use and the rules for solar users of each country.
Using solar energy for your own consumption also avoids you from unexpected power bills. For homeowners and companies can regulate the electrical outage by installing solar.
- Cleaner energy
Using solar power means reducing greenhouse gas emissions, where climate change and pollution are the biggest effects of greenhouse emissions. Installing solar panels can reduce about 13,600 kg of CO2 per year, this is equivalent with planting about 80 trees each year to reduce the same carbon footprint.
- Flexible
The presence of the latest solar technology enables a solar system to have a storage power supply, thereby people can optimize the value of their solar self-consumption. So anywhere and anytime you can still produce energy independently.
- Easy and safe
The amount of solar power equipment on the market such as inverters and solar panels makes users easier to produce their own energy, and safe and easy to install.
Solar inverter
A solar Inverters is a device that convert energy from solar panels, DC to AC energy that required by household appliances. When the solar panel is usually placed on the roof of the house, then the inverter is always placed on the wall. To protect it from the extreme weather, it is advisable to place the inverter in a shaded room such as a garage, laundry room, etc.
There are many types, models and sizes offered by inverter manufactures. For example, solar with a capacity of 2-4 kW is very suitable for home owner. Some current inverter manufacturers also provide the monitoring application, where installers and users can view and manage their solar power performance.
There are 3 types of PV invertes on the market:
1. On grid
2. Off grid
3. Hybrid grid
On grid mode
On grid or grid tied mode is a PV self-consumption without batteries and connected to the network. Installation on grid requires:
- – Photovoltaic modules
- – A network inverter (also called “on-grid” or “grid tie”)
- – Electrical protection (refer to UTE C 15 712-1)
The purpose of this self-consumption without storage is to avoid higher energy production than site consumption. On grid soalr system is the simplest self-consumption to install among other systems.
Solar panels capture the sunlight and convert it into DC electricity, then sent it to an inverter. Then the inverter will convert DC to AC which will be used to turn on the home appliances.
If there is surplus electricity, it will be injected into a public distribution network or will sell to a power supplier. Due to the absence of the battery as a power backup, this system is not recommended for an isolated area. Because if a power outage occurs, the on grid system will automatically shut down.
Off grid mode
Off grid solar or stand-alone mode is a PV self-consumption that is not connected to the network and using solar battery as a power backup. This installation requires:
- – Photovoltaic modules,
- – A PWM or MPPT solar charger (also called « regulator », « DC / DC converter », etc.)
- – A battery bank (which, commonly, has a nominal voltage of 12V, 24V or 48V)
- – Inverter (or DC / AC converter)
- – Electrical protection (refer to UTE C 15 712-2)
The sunlight captured by solar panels will be used to charge the solar battery as a power backup. If the battery is fully loaded, it will be used to turn on the appliances.
The advantage of off grid mode is that you can become energy independent wherever you are. For about three decades this system has been helping isolated areas.
You must considere the amount of sunlight that is obtained in that area if want to use an off grid mode. Because the sun is the main source of energy.
Next, consider the battery capacity. As a major component of the off grid system, the solar battery requires routine maintenance and should be replace when the lifetime is over.
Adding component such as generator may be needed if the solar power does not provide enough energy and there is a problem with the solar battery. In fact the purchase and maintenance of these components cost you more.
Hybrid mode
Hybrid mode is the most effective and efficient for self-consumption system. This system combines the advantages of on-grid and off-grid solar inverter.
In this case, the installation comprises:
- – Photovoltaic modules
- – A hybrid inverter (connected to the grid with the capacity to manage a battery bank)
- – A battery bank
- – Electrical protection (refer to UTE C 15 712-3)
Hybrid mode is perfect for those of you who want full of self-consumption. Any energy gained from PV panel will be streamed directly to household appliances and batteries as backup power. If there is an excess of production you can return it to the power supply network.
For the energy conversion part, in recent years it has been possible to improve the overall efficiency of solar installations and to simplify the implementation by using hybrid inverters (see diagram below). These « all-in-one » Imeon-Energy solution replace the inverter and charger.
In order to ensure a constant supply of electricity without oversizing the solar PV system, it is possible to couple a generator to this type of device. The most relevant solutions on the market allow the generator to be controlled (start / stop) via a relay or dry contact depending on the battery voltage and / or load the threshold.
There are two types of AC electrical in the solar inverter:
In a single phase there is a current flowing through one wire and one return path called a neutral. Single phase is suitable for residential needs. While the three phases has three alternating current wire, so this phase can flow more power which is make the three phases more suitable for industrial activity.
Solar self-consumption
In the second case, we are talking about photovoltaics in the context of self-consumption. PV (photovoltaic) self-consumption means to consume directly electricity from the solar energy that you produced. Some countries promoted the use of PV self-consumption such as China, France, Australia, Germany, UK, etc.
The solar battery system
Here are the things you have to consider before choosing a solar battery:
- Depth of Discharge (DoD): used to describe the conditions of charge and complete discharged of the battery.
- Capacity and power ratings: capacity is the total amount of electricity that can store in a solar battery (kWh). Nevertheless, the capacity in the battery cannot give out how much electricity of the battery can provide. Therefore battery capacity and rating are important to know how much electricity can be generated and how long electricity can last.
- Battery lifespan: the battery ability to charge gradually will decrease over the time. It depends on the type of battery and the environmental conditions that may affect the battery, such as high temperatures or high charge and discharge currents can negatively impact the life of batteries.
- Roundtrip efficiency: it defines how much percentage of battery energy can be used from the energy needed to store it.
- Manufacture: when selecting a solar inverter, you must make sure that the battery used is compatible with the inverter and has been tested before by the battery and the inverter manufacturers.
Currently, there are two types of solar batteries on the market: lithium battery and lead acid battery. We hear often both types of batteries, especially with lead acid battery that have been used for decades and dominate the option for off grid solar system.
While the new lithium battery was introduced in the 1970s. By 2016, lithium-ion is being used for large-scale for solar system. Although lithium batteries are newer than lead acid batteries, but lithium has more advantages than lead acid.
Lithium has great electrochemical potential and it is the lightest type of metal. The weight of the lithium battery is only one third of the lead acid battery. The production of lithium batteries also requires less material than lead batteries.
This makes lithium battery cleaner and can reduce the environmental damage. While the lead acid battery requires more material and production energy, it leads to the amount of pollution generated and harmful the environment.
Lithium battery relatively has higher lifespan than lead acid battery. The average life of lithium battery is 8 to 16 years and the lifespan between 3000 and 6000 cycles at 80% DoD. While lead acid battery’s lifespan is between 400 and 800 at 50% DoD for gel and AGM battery types, and 1000 to 2000 at 50% DoD for OPZ and OPZS battery types.
This battery life depends on the battery manufacturer and how we take care of it. Some conditions can also trigger battery damage and reduce the lifespan. Such as extreme weather might affect battery storage capacity.
Here are some battery manufacturers:
Pylontech (daughter company of ZTE) US2000B
| SPECIFICATION | BASICPARAMETERS | US2000B |
| Nominal | Nominal Voltage (V) | 48 |
| Nominal Capacity (Ah) | 50 | |
| Physical | Dimension (mm) | 440*410*89 |
| Weight (Kg) | 24 | |
| Electrical | Discharge Voltage (V) | 45 ~ 54 |
| Charge Voltage (V) | 52.5 ~ 54 | |
| Peak DischargeCurrent (A) | 5kW@15s | |
| Peak Charge Current (A) | 5kW@15s | |
| Others | Communication | RS232，RS485，CAN |
| ChargingTemperature | 0℃~50℃ | |
| DischargingTemperature | -10℃~50℃ | |
| ShelfTemperature | -20℃~60℃ | |
| Certification | TÜV / CE / UN38.3 | |
| Design life | 10+ Years（25℃/77℉） | |
| Cycle Life | >6000 ( 80% DoD) | |
| Compatible inverter brands | Imeon Energy
Victron Energy Solax Power Goodwe |
| TECHNICAL SPECIFICATIONS | |
| Celltechnology | Li-Ion (NMC) |
| Nominal energy | 6.7 kWh |
| Usable capacity | 5.4 kWh |
| Nominal voltage | 55.7 V |
| Charge end voltage | 61.5 V |
| Discharge end voltage | 41.0 V |
| Max. dischargecurrent | 80 A |
| Max. discharge power | 300 A (3 sec.) |
| Max. discharge performance | 6500 W |
| Efficiency | 97% |
| Depth of discharge | 80% |
| Expected cycles | >5,000 |
| DIMENSION | |
| Width | 675 mm |
| Depth | 475 mm |
| Height | 537 mm |
| Weight | 95 kg |
| Charge temperature (max.) | +0°C – +45°C |
| Dischargetemperature (max.) | +0°C – +45°C |
| Optimal storagetemperature | +10°C – +25°C |
| Scalability | Max. 12 systemsparallel |
| Communication | CAN/SMA ready |
| Protection class | IP21 |
| Warranty | 7 yearsfair value warranty |
| Compatible inverter brands | SMA
ImeonEnergy |
| Model | B-BOX LV Residential |
| Usable Capacity | 4.9 – 19.6kWh |
| Warranty | 10Yr limitedwarranty |
| Voltage | 48V DC |
| Efficiency | 97% |
| SupplyCapacity | 5.0kW min. |
| Weight | 35kg per module |
| Dimensions (Cabinet) | 1700mm x 640mm x 320mm |
| Installation | Indoors or Outdoors |
