Press "Enter" to skip to content

Posts published in “Solar panel”

solar panel convert sunlight to DC current.

Why Inverter undersizing is a bad idea?

Sheng Zhang 0

What is undersizing? Some solar installers like to buy a smaller inverter than the maximum power of the PV system, e.g. an inverter with 3KW for a 3.5KW PV system.

Why undersizing? Saving money was one reason. In the past, inverters were much more expensive, so the savings from undersizing were correspondingly much greater, at that time you could save € 200-300. Nowadays the inverter is already that there is no longer a big difference between 3KW and 4KW inverters, often a difference of only 10 € -50 €. Some solar installers also deliberately take a size smaller in order to keep more profit for themselves.

Above is an example from the flash list of a 365Wp solar module from Canadian Solar, which has a measured output of approximately 6-8W more than 365Wp on average. Due to tough competition, manufacturers are forced to give more power than stated, already 364.99W falls into the lower category of 360Wp modules. That is also one reason why the inverters should not be undersized. In a large system with 50-100 modules, the discrepancy can be even bigger than you think. So it's better to be one size larger than smaller.

With a 3 KW inverter, the output power is limited to 3KW, i.e. although the maximum input PV power is often 4KW, the output will always be 3KW. This means that you could have installed fewer modules if you had taken the smaller inverter, because the output of a 4KW PV system and 3kW system is the same if you use the 3KW inverter in both systems.

Undersizing the inverter is not only financially meaningless, it also poses a great technical risk. Solar modules are nowadays more and more powerful. The STC output below 1000W / m² and 25 ° C of a module is not achieved in most times, but there are always peak times. In winter, for example, the voltage of the module is significantly higher than in summer, although the solar radiation is weaker, even in winter on good days at low temperatures, 100% PV output and even more can be achieved. Snow also reflects a lot of light onto the module. In systems with 70% regulation, this is limited, you only lose valuable energy. But there are also systems where they are not regulated to 70% or the regulation does not work, in this case undersized systems are particularly at risk. Without overvoltage protection, the inverter would be damaged. If you insist on a warranty claim in the event of defects due to undersizing, you do not have a chance. In case of an undersizing, the manufacturer will not accept any guarantee.

So it is not worthwhile to undersize, rather to oversize it a little. If you have a 3.8KW system, you prefer to use a 4KW WR instead of a 3.5KW, you are on the safe side.

What is a Micro Inverter? Is that only for balcony?

Sheng Zhang 0

Micro inverter is the smallest inverter that is suitable for from 300W up to 2250W PV modules.
But it is not just a mini inverter for mini systems, as many often think of balcony systems immediately. The micro inverter was actually invented to replace the large string inverter.

Disadvantages of string inverters, which we all know: very high voltage on a string, often 400-600 volts, poor shadow management, often more expensive optimizers have to be on hand, a whole string must be connected to a single MPPT, etc.

Advantages of micro inverters on the roof, which are often not known, very low safe voltage, mostly 30-80 volts, perfect shadow management, no optimizers required, each module (sometimes two modules each) has its own MPPT! thus each module can be individually controlled and optimized.

SolarEdge used to have an expensive concept with a data logger / optimizer for each module, which can now be achieved with much cheaper micro inverters. It took a while until the price of micro inverters got so low that it is worthwhile to rely on this newer technology. If you include the advantages of module-level optimization of micro inverters, it is often cheaper to mount 5 - 10 micro inverters on the roof instead of 1 string inverter + 20 optimizers.

Now to the balcony system: balcony system is a nice invention that has become more and more popular in Germany in recent years. But it is not the idea of the Micro WR manufacturer. Therefore, there is often no ready-made solution, you have to take care of the extension cables, Schuko plugs, etc., which is actually very simple. Manufacturers do not make ready-made balcony systems, only the Micro WR with its accessories. We also do not offer a balcony system, as otherwise we would be in competition with our business customers. We remain wholesalers and not balcony systems providers.

In the USA, Australia and Brazil, the micro inverters are only sold in large numbers for roof-top systems because they know the advantages better there. The trend reversal will soon come in Germany as well. At some point when you hear the name micro inverter, you immediately look at the roof, no longer at the balcony.

Why are prices rising?

Sheng Zhang 0

Solar products have become more expensive, which many solar manufacturers and dealers have already felt since the beginning of 2021. We already predicted this price development on our website at the end of 2020 and many of our customers have benefited from it and saved a lot of money with our Christmas campaign.

As we regularly exchange information with manufacturers in China and import goods, we have seen the trend earlier and earlier and can see the prices for the near future.

The prices of solar modules reached a historic low in June/July 2020, due to the VAT reduction in July, many dealers sold very little in May/June and were under great pressure at that time. In July, VAT went up to 16%, customers stormed into the shops and bought all the goods. But manufacturers and traders were not happy for long. Because of the pandemic, the world was running anything but normally. China beat the pandemic first and has been producing at a normal pace again since April/May 2020. The rest of the world, however, had stopped production. The ships bring containers from China to all corners of the world with Chinese products, but could not bring any containers back to China. The shipping company is extremely reluctant to ship the empty containers to China. From July 2020 onwards, the price of containers will rise steeply. Within 6 months, the price of shipping a 40-foot container has risen from €1000.00 to a maximum of €15,000.00. Some wonder why the price has risen so much, we can't understand it either. Partly, of course, it is the high costs, but partly it is also due to greed on the part of the shipping company. Despite high shipping costs, it is very difficult to book a ship. Even if the goods are on the water, it takes much longer than usual for them to reach the port.

Inverter and storage manufacturers (both belong together as almost all inverter manufacturers also offer their own storage solution) have the same problem as with solar modules with the extremely increased sea transport costs. The pandemic has made many smart products big sellers. The Bitcoin hype has had a phenomenal impact internationally. Smart cars, smart buildings, countless IoT products are booming. All these products are based on micro computer chips. Unfortunately, the chip shortage has also affected inverter manufacturers. Solar inverters tend to be on the back burner for chip manufacturers as these products are already very cheap and not as profitable as most other products. We have already experienced price increases from major inverter manufacturers, Goodwe and Growatt have already officially announced a price increase of 10-20%. Price is unfortunately only one problem with the inverter, but the biggest problem is delivery time. Even if you are willing to put more money on the table, you simply don't get any inverters at the moment. Many products are already sold out, and supplies will not arrive for another 2 or 3 months. Not only Chinese inverters are affected, German and European inverters are also hard to get, because inverters that are manufactured in Europe are also waiting in vain for component deliveries from China.

In September, a large ship made headlines, the Ever Given, which blocked the Suez Canal. The canal is unblocked again after two weeks. But the impact only becomes apparent later. Many goods on the ship are confiscated by the Egyptian government. You never know when they will be released again. Due to capacity problems, manufacturers cannot simply deliver so many goods, because there are simply no goods. It is not like toilet paper that many countries are in stock to produce. Solar modules, for example, come almost exclusively from China. In Europe, many countries have long holidays and the ships wait in a very long queue in front of the port. The port lacks the staff to handle so many ships and goods at once.

Corona continues to be a reason for the poor availability. Many shipping companies have reported that there is a shortage of healthy seafarers at the moment. Most of the seafarers are from India. Massive cancellations have been reported due to the extremely high infection rate in India. Many ships have to be delayed indefinitely because they are not sufficiently manned. Even if you want to pay the high fees now, you often don't get available ships.

Many countries have printed a lot of money to fight the pandemic and stimulate the economy. In the long run, this also leads to an increase in material and labour costs for manufacturers. Many products will slowly become expensive in the future because there is simply too much money on the market.

The largest inverter manufacturers in China

Sheng Zhang 0

The largest inverter manufacturers in China by units sold(MW) worldwide:

  1. Sungrow 35000 MW
  2. Huawei 28000 MW
  3. Growatt 9830 MW
  4. Ginlong (Solis) 8878 MW
  5. Goodwe 8122 MW
  6. Sineng 6000 MW
  7. Chint 5318 MW
  8. Sofar 3980 MW
  9. Hopewind 2019 MW
  10. Kstar 1725 MW

The brands marked in green are available from us.

Bifacial Solar Panel

Sheng Zhang 0

As the name suggests, the bifacial modules are solar modules that are built with solar cells on both the front and the rear. The rear side produces different amounts of electricity depending on the direction and angle. It does not produce any electricity if the back is not exposed to the sun at all.

Is the bifacial module worth it? The question is justified because it has always been assumed that bifacial modules are more expensive than monofacial modules. But it's not true at all. Because with the bifacial module, the manufacturer is only allowed to sell the front side power, the rear side cannot be charged. That's why only the weakest cells go to the back, so the back is ALWAYS free! For this reason you can say that the bifacial module is always worthwhile, because the back is free!

Why does it seem that bifacial modules are more expensive? It's because of the glass. Bifacial modules only exist in connection with glass-glass modules, because cells cannot be installed on the back without the second glass layer. The glass-glass module is more expensive than the glass-foil module because of the glass material and the complicated manufacturing process. Bifacial is a free addition from the manufacturers so that customers can benefit more from the glass-glass module.