FAQ: What is inside the junction box on the back side of the solar panel?
Answer: The junction box contains terminal wires (+ pole), (- minus) and also by-pass diodes.
The purpose of bypass diodes is to shunt the current around a shaded, weak or damaged panel. Otherwise there is the risk that full current from the rest of the panels will pass through the shaded panel and cause overheating damage. In this case the bypass diodes conducts, thereby allowing the current from the good solar cells to flow in the external circuit rather than forward biasing each good cell.
Larger panels have more diodes to provide as much as possible power, even if part of panels is damaged or shaded.
Schutten panel 250Wp Poly has 6 diodes. Two over each section see picture above.
Schutten panel 140Wp Poly has 2 diodes. One over each section.
All Schutten panels have by-pass diodes to avoid any damage.
FAQ: Difference between the Poly and Mono solar panels?
Question: What is the technical difference between the 250Wp Poly and 250Wp Mono solar panels?
Answer: In fact there is not much difference. In 2014 the solar technology has progressed to same levels both for poly and mono types of cells, so that there is no significant difference between the technical specifications of these two panels. The only difference is visual: some customers prefer the mono panels, because the cells are of the same color and seem to look nicer. Also the black frame solar panels are usually made with mono type of cells, so black color panels are often mono. On the other hand the poly panels are usually sold in higher quantities and the price for poly panels is little bit lower.
Note: on internet, there are some older articles that discuss the differences between the poly and mono panels. In the past times the mono panels used to be more stable and more yield-efficient. Keep in mind that these articles and the tests were made usually several years ago. The results are no longer valid, because the modern panels have very similar performance.
See our offer for solar panels at EV-POWER.EU.
FAQ: The solar panels and the snow – how to install properly?
The solar panels are designed to resist the heavy winds and the pressure from the loads by thick layers of snow. What requirements are defining the module load resistance?
The solar panel load resistance depends on the selection of frame and glass, also is affected by the way a solar panel is installed. Solar panel should have the ability to resist strong winds and heavy snow (for example snow thickness in some areas of northern Europe, or in the mountains may reach up to 2 m). The poor load resistance can lead to solar cell occur micro-cracks. Unfortunately some producers lower the costs through reducing the thickness of aluminum alloy frame and solar panel glass, in fact weaken load resistance ability of solar panel. In addition, installers could further improve module stability and load resistance by adding multiple module supports (see pictures).
Infra-red thermal camera for solar panel inspections
The photos show the real example of testing results using the infra-red thermal camera. From top to bottom:
1) One section of the solar panel is poorly connected inside the junction box. The whole section generates less power and overheats.
2) Junction box overheating. The overheating of the junction box due to poor cable connection inside. It causes the over heating of the solar cells above the box and causing poor power performance.
3) The dirt from birds excrement. The panel itself is 100%. However the dirt covers a particular cell that does not work properly and overheats extremely. As a result the performance of the whole solar panel will decrease. The panels must be clean from this kind of dirt!
4) A defective cell. There is no visible reason of the malfunction. Only the thermal-camera is able to discover this kind of manufacturing defect.
Be sure to contact GWL for support on the thermal analysis.
Harvesting the additional energy from the solar panels
Using more solar panels in parallel with once micro-inverter provides additional power. With the price of solar panels dropping, it seems feasible to have more panels per single inverter.
From the graphs you can learn about the example of the extra energy in comparison between a 500Wp solar panel (two 250Wp panels in parallel) and single 250Wp and 290Wp.
Multiple solar panels connected to single micro inverter
The graphs are showing the energy yields from multiple solar panels connected to single micro-inverter with a 230Watt rating. The graphs show results from a 250Wp panel, a 290Wp panel and two 250Wp panels in parallel making an equivalent of a 500Wp solar panel.
At 100% sunshine, the solar panels will provide full energy. At peak time (noon time) the maximal power from the solar panels will exceed the power rating of the MicroInverter. The micro inverter will keep working at the max rating of 230Wp, the surplus energy from the solar panels will not be harvested and it will be changes into heat at the solar panels.
At 60% sunshine, the solar panels provide only part of the energy. The 250Wp and 290Wp panels’ energy yield is less than the maximal power of the micro-inverter. The two 250Wp panels in parallel (500Wp) provide sufficiently more energy.
At 40% sunshine, it is clearly evident that the yield from the two 250Wp panels in parallel (500Wp) gives a full power and the energy harvested is much higher than from single panels.
Conclusion: These graphs show the reason why it is beneficial to have more panels connected to single MicroInverter to yield more energy in low sunshine periods.
Wireless access point with solar and wind power
The example of our customer installation of a wireless-link access point in a mountainous area with no power from the grid. The access point is powered by solar panels and a small wind turbine.
GWL/Power is able to provide the basic components for the installation: solar panels, cables, MPPT solar charge regulators, LiFePO4 batteries, remote monitoring. Check with us if you need a solution like this.
GWL/Power - your energy anywhere!
Using the GridFree to reduce the consumption of Telco equipment
The computer network operators need to pay a lot of money for the electricity. Reduce the consumption of the electricity by installing simple GridFree solution.
Be sure to contact us for details on the GridFree products.
FAQ: What is the max solar power for the 10Amp MPPT controller?
Answer: The the power rating for the MPPT controllers is given by the voltage [V] and the current [A]. The max current [A] of the MPPT controller is fixed and cannot be over reached.
This means the voltage of the batter will determine the power rating. With the “half of the voltage” (12V versus 24V) you get only “half of the maximal power”.
For example: for the MPPT Solar Regulator 12/24 V, Tracer 10 A, Input 100V (TR-1210RN) the maximal power is about 240W at 24V:
12V 10A ——> nominal 120W (up to 140Wp of max panel rating)
24V 10A ——> nominal 240W (up to 260Wp of max panel rating)
In order to have a 240Wp (250Wp) power rating of the panel, you need to use the 24V battery. With the 12V battery, the max power is only 120W (up to 140Wp).
EUFREE solar panels with Extended Warranty 30 Years and Guarantee from TUV NORD
Extended Warranty 30 Years
- All panels tested one by one during production
- The production process inspected and monitored
- Verified parameters recorded for customer reference
- Extra long warranty for all customers
- Fast replacement of defective products
- Insurance from global insurance company
Guarantee from TUV NORD
- Technical parameters verified by TUV Nord
- Solar panels produced from certified components
- The panels are compliant with CE standards
- Approved quality and production inspection
- The products meet all specifications and tests
Check the offer of the Schutten EUFREE solar panels.
FAQ: 3-phase connection with the Micro Inverters
Question: I intend to make 3-phase connection with the MicroInverters to the grid. What do you suggest?
Answer: There are three options with the MicroInverter installation on the 3 phase system:
1) Balanced installation (mainly for Grid-Tied systems)
With the balanced installation the number of inverters per each phase is the same: in the 24 pcs installation, you will install 8 inverters to each phase (3x8 pcs).
See details here: http://gwl-power.tumblr.com/post/36901093005/micro-inverter-an-easy-way-with-3-phase
2) Demand-based installation (mainly for Grid-Tied self consumption systems)
With the demand-based installation, the number of inverters per phase is fixed according to the power demands on each phase. For example if phase L1 has 50% of long term average power demands, L2 has 30% and L3 has 20%, the number of inverters will match this average power demand: 12 inverters in L1, 7 inverters in L2 and 5 inverters in L3.
3) Dynamic installation (mainly for GridFree full self consumption systems)
With the dynamic installation, the number of inverters per phase is not fixed at all. The individual inverters connect in steps according to the actual demand on each phase. For example if the demand on the phase L1 is 2300Watts, 10 inverters will be connected to L1.
If the demand increases more will connect to provide the extra power. This way the energy form the inverters is used in the most ideal way to match the consumption.
See additional details here: http://gwl-power.tumblr.com/post/36900205193/micro-inverter-allows-simple-energy-management
FAQ: energy loss on solar cables for parallel panel connection
Question: I want to connect solar panels in parallel. What should I keep in mind?
Answer: For a typical 240 WP panel, the MPP voltage is 30V and the current is 8 Amps. If you connect the panels in parallel, the voltage will be the same (30V) and the current will increase. For two panels you get 16 Amps, for 3 panels you get 24 Amps.
However it is important to keep in mind that the loss of energy is growing with the square of current: W = R * I ^2. If you increase the current two-times, the loss of energy will increase 4 times (2^2 = 2x2 = 4) , if you increase the current 3 times, the loss of energy will increase 9 times (3^2 = 3x3 = 9).
For example if you have a cabling with the resistance of 0.1Ohm, with the flowing current of 8 Amps , you will loose some 6 watts of energy on the cabling. With 16Amps you will loose some 26 Watts and with 24 Amps you will loose some 58 Watts of energy.
That is why for the parallel connection, it is very important to use proper copper cables with thick diameters to reduce the energy loss.
For grid-connected installations it is advantage to place the MicroInverters right to the panels. This helps to avoid the energy loss.
Six panels, six micro-inverters - a simple household installation
Making your solar installation is easy. See another project based on the solar panels with the microinverters.