To maximize power output in on-grid solar systems, simply increasing the wattage of the solar panels is not enough.
It requires a well-coordinated system to achieve optimal power generation.
In this blog post, we will explore the key points for increasing power output in on-grid solar systems based on a case study.
Case analysis:
As shown in the picture below, we recently received feedback from Mr. Don in New Zealand.
He installed and used a PVMars 3kW grid-connected solar system. — Click on the picture to zoom in and view the content.
He mentioned in the email that the system produced 241 kWh in just 19 days, an average of 13 kWh per day. It saved him $53. — the higher-wattage system saves even more on electricity bills.
For example, PVMars’ 3 sets of 10kW grid-connected solar systems have saved about 90,000 PAB a year for Panama users. — click on the orange font to jump to the relevant content to learn how they did it.
And this 3kW grid-connected solar system includes:
10 pieces of 300W monocrystalline solar panels.
A set of aluminum roof solar panel brackets.
A 3kW grid-connected inverter (220 VAC).
A set of copper 3-core PV cables.
If he uses 500 watts, or higher wattage solar panels that can save installation area, and reduce the cost of brackets, accessories, etc. Why didn’t Mr. Don do this?
Let’s learn why PVMars’ professional solar team designed, it this way to maximize on-grid solar systems’ power generation efficiency.
Choose the right solar panel wattage to increase power generation:
It is generally believed that higher-wattage solar panels occupy less area and generate more power.
However, the solar panel needs to be connected with other equipment of the whole system, at the same time, so it needs to be compatible with other equipment to achieve optimal power generation efficiency.
Take the 500W model as an example: it has a large wattage and a large amount of power generation, and there is no need to design more solar panels, which reduces costs and can generate the same amount of power.
And their rated operating voltage is 41.18V. After six 500W solar panels are connected in series, the total power is 3000W.
The minimum PV input voltage of the 3kW grid-connected solar inverter is 80V, the optimal PV input voltage is 360V, and the maximum PV input voltage is 600V. A solar panel’s input voltage must be in the range of 80V-600V.
According to the principle of physics, the voltages in series are added — the positive poles are connected, the negative poles are connected, and the circuit forms a path.
Current flows from one positive pole to the other negative pole, and the total voltage adds up.
In the case of six 500W solar panels connected in series, the PV input voltage becomes 41.18V x 6 = 247.08V
In conclusion,
The input voltage of 6pcs 500W photovoltaic panels is 247.08V, which does not reach the optimal 360V of the grid-connected inverter.
This on-grid solar system will not achieve 100% power generation efficiency, if a 500W solar panel is used for connection.
On the other hand, a 300W solar panel works at 36V.
After 10pcs 300W solar panels are connected in series, the total working voltage is 360V. This is the most efficient PV input voltage of the 3kW grid-connected solar inverter.
When designing an on-grid solar system, the input voltage of the solar panel should be equal to, or higher than the optimal PV input voltage value set by the inverter.
Only in this way can power generation efficiency be guaranteed.
While it is still possible to configure a 500W solar panel, is it the most effective option?
PVMars’ team of experts believes this needs to be considered from multiple angles.
If your installation space is limited, and within an acceptable voltage range of an on-grid solar system, we recommend choosing a solar panel with a higher wattage.
That would reduce solar panels, but also save costs. However, this may result in low power generation efficiency.
In the case of enough installation space, such as that of Mr. Don, PVMars recommends choosing a grid-connected solar system configuration with higher energy efficiency.
Additionally, the market is flooded with many grid-connected solar system configuration options, which can affect the overall system cost.
Below are some factors that may affect the final cost.
4 factors that affect grid-connected solar systems' price:
1- Solar panel quantity and wattage:
Differences: The larger the wattage, the smaller the quantity, and the corresponding reduction in price.
Points to note: Adapt to the best PV input voltage of the grid-connected inverter. If mismatched voltages reduce energy production.
2-Bracket Material:
Difference: Stainless steel/aluminum alloy/aluminum materials have price differences.
Note: Of the three materials, stainless steel is the most expensive and contains chromium, an expensive metal. At the same time, it has corrosion resistance, high strength, and is lightweight.
3- Grid-tied inverters:
Differences: anti-backflow/islanding effect, number of MPP input ports, and maximum PV current connected.
Note: The anti-backflow feature is designed to protect the current generated by the solar panels, from flowing back into the grid during a utility grid outage. The purpose is to not affect the maintenance workers to deal with the power grid problems.
Anti-islanding is used to protect household loads, or industrial equipment. If your inverter does not have this function, additional configuration is required.
However, the number of MPP input ports is insufficient, resulting in a decrease in the accessible PV current, so it is necessary to increase the combiner box to connect more solar panels in parallel. This will inevitably increase the cost of the entire grid-connected solar system.
4- Cables:
Difference：Copper 3-core vs. aluminum 3-core material.
Note: Since the MPP interface terminals of the inverter are generally copper wires, it is recommended to use copper wires for better conductivity, and durability. Aluminum wires corrode at high temperatures.
Finally
Choosing the most appropriate on-grid solar system configuration depends on various factors.
While higher-wattage solar panels may offer advantages in space savings, ensuring compatibility, and meeting optimal PV input voltage requirements is critical.
PVMars recommends considering the installation environment to determine, the most suitable configuration for optimal power generation and cost-effectiveness.
Using these factors, and consulting with a professional, homeowners like Mr. Don can install the highest-quality grid-tied solar system, that meets their specific needs while maximizing power generation efficiency.
Contact us to plan your own grid-connected solar system!
