As homes, businesses as well as policymakers wake up to the potential of self-consumption of power, distributed solar is becoming the talk of the town. While the end users look at rooftop solar as bringing down their overall electricity costs, governments see it as reducing the pressure on the grid.   

Quick to sense the trend, solar PV companies are also catering specifically to this segment with dedicated products and services. Manufacturers are designing and rolling out high-efficiency modules keeping in mind rooftop solar needs. Installers take care to make it an easy and smooth process.   

To discuss the latest in this space, TaiyangNews brought together stakeholders from the manufacturing, design and installation businesses during the 2nd Virtual Conference on Distributed Solar—Optimizing PV Power for Homes & Businesses. Day 1 of the conference was dedicated to residential rooftop solar.  

Presenting the keynote address, EUPD Research’s Data Manager Ali Arfa discussed the residential rooftop solar market developments post energy crises.    

Arfa pointed to the growth of solar PV capacity in the European Union (EU) from 124 GW DC cumulatively in 2019 to 279 GW DC in 2023. Last year, the annual additions of 63 GW DC represented 51% year-over-year (YoY) growth with Germany, Spain and Italy leading the tally.  

In terms of residential PV, Arfa said top residential EU PV markets installed a combined 17 GW DC in 2023. Germany, the Netherlands and Italy were the top 3 markets in terms of new additions. 

However, Arfa pointed out that the markets dominated by the residential segment are led by the Czech Republic with 85% of the market being residential with a 20 kW system size. Belgium and Austria follow next. He also sees governments encouraging large-size systems for this segment of 20 kW.  

Arfa said that the top 5 EU residential markets in 2023 had a net residential PV market value of around €1.7 billion out of the total €3.45 billion total residential PV value of the EU. This is expected to reach €2 billion in 2024 for the top 5 markets, out of €3.82 billion overall value.  

Arfa believes that while the problem of lack of skilled labor for the PV industry is gradually easing, it is now faced with another problem of increasing waiting time for installations. The reason is a high number of customer requests that points to the growing demand for residential PV in the bloc. Long waiting times are also because of the unavailability of components.  

In 2024, the bloc is expected to install 72 GW DC, taking the aggregate to 351 GW DC. The top 3 markets of Germany, Italy and Spain are expected to alone account for 45% of the new additions this year, according to Arfa.   

For the residential segment alone, Arfa says the EU will install 24 GW of new capacity for 20 kW installations in 2024. Germany, Italy, the Netherlands, France and Austria will be the top 5 markets this year.    

LONGi’s Product Marketing Manager Alina Liu presented the company’s very high efficiency solar modules Hi-MO X6 Ultra Black in the Artist series, for rooftop applications.  

Targeted primarily towards the European residential market that appreciates aesthetics in their rooftop panels, Liu said the Hi-Mo X6 has a stunning visual presence because it is consistently black from all angles.  

These panels are produced by the company on an exclusive production line to ensure color consistency. Further discussing the technical features of the module, Liu explained that there are no frontal gridlines on the BC cell, helping its all-black appearance. 

The manufacturer has used structure glass for its HPBC black cell with an anti-reflective coating that significantly reduces the intensity of the blue light reflection. No ribbon shielding maximizes light trapping. These factors make the cell appear pure black and also increases light absorption by about 2.27%, she added.   

Under low-light conditions, it generates 1.54% more electric current than TOPCon modules, Liu claimed. 

LONGi says the Hi-MO X6 Ultra Black product with a dual-glass structure has a maximum power of 435 W and a weight of 22.50 kg. It has installed the first of these panels in the Netherlands, calling the country the largest black module market in Europe. 

Talking about advanced storage solutions for today’s and tomorrow’s homes was the Managing Director Sales, Service & Finance at RCT Power GmbH, Dr. Eric Rüland.  

In 2023, the company started its 600 MW inverter factory in Germany with potential to expand it up to 1.2 GW. It produces batteries in China’s Suzhou.  

Rüland said the company’s battery and inverter solutions are based on the key aspects of the product being simple, flexible and efficient.  

RCT Power’s typical standard inverter solution has a 10 kW capacity and a 3-phase storage solution with 11.5 kWh of capacity. Stating the results of several tests, he claimed that a highly efficient PV storage system from RCT Power can save up to an additional €1,700 within the initial 10 years of operation. 

The company is planning to launch its new Power APP at the upcoming Intersolar that is aimed at enabling residential solar energy users to manage their electricity usage from various applications including heat pumps, electric vehicle (EV) car data, etc. It will help the customers disconnect from the grid. It also plans to unveil its 1-phase inverter at the event.  

Talking about the next-generation products for the rooftop solar segment, Trina Solar’s Product Manager Lukas Chao Ye talked about the company’s high-efficiency Vertex S+ panels. These cater to both residential as well as commercial and industrial (C&I) segments.  

Under Vertex S+, its small-factor monowhite model for rooftop solar has 455 W power output and 22.8% efficiency. It is targeted not only at Europe but also Japan, Australia and North America.  

The New Black module from the company is bifacial and all black for both residential and C&I applications. Power output is up to 445 W and 22.3% efficiency.  

Ye shared that the Vertex S+ rooftop module range is engineered from ultra-thin (1.6 mm) dual-glass for lightweight durability and enhanced resilience. Products in this range are designed by the company to fit diverse installations with flexible system deployment.  

These can provide enhanced mechanical load capacity, while also lowering the BOS costs for C&I installations with larger modules, he claimed.  

Additionally, the modules have a lower working temperature coefficient of -0.29%, providing up to 4% more power compared to mainstream modules that have a temperature coefficient of -0.34%. 

Ye listed some case studies from its Vertex S+ installations to show the consistent performance of this range of modules. The company provides a 25-year product and a 30-year power warranty on this range.   

The Sales Manager of DAH Solar, Sea Huang, presented the company’s innovative full-screen modules that he says solve dust and water stain problems. This module series was launched in 2024.  

Reflecting on the problem of accumulation of dust, water and snow by conventional module frames, Huang said these bring down power generation and can also cause hot spots from the reverse current effect of the shaded cells.  

He claimed that a 1 MW PV station can lose up to 179,580 kWh of power annually due to dirt accumulation.  

DAH Solar’s full-screen modules, developed over a period of 3 years, attempt to address this problem. A patented product, these panels are frameless on the front compared to a regular 5 mm frame for conventional modules. Sharing a project case study for a 1.04 MW power station, Huang claimed the company’s full-screen modules helped increase power generation by 8.61% over a year.  

According to DAH Solar, the full-screen module solution brings down extra maintenance expenditure, thus increasing power generation and also reducing costs by 6% to 15%.  

DAH’s full-screen module is based on n-type TOPCon solar cell technology. It uses rectangular cells, double glass, and a zero-busbar (0BB) configuration. Especially with the EU market in mind that appreciates aesthetics as well as high power output, Huang said the company is providing multi-color options in its full-screen module series.  

TSUN’s Vice President of Sales Ellen XUE talked about the company’s safe and powerful microinverter and storage system for residential applications. She claimed the company to be the 1st company from Asia to provide a plug & play microinverter solution to Europe.  

TSUN’s plug & play solution covers both residential as well as C&I solar segments. For the residential segment, it offers the TITAN microinverter and an all-in-one AC coupled unit (ACU).  

Its plug & play pre-assembled solution for balcony solar, XUE said, is easy for anyone to install safely for various installations with a DIY manual.    

The microinverter range for residential solar systems covers 300 W to 3,000 W peak output. Another 3.6 kW to 6 kW microinverter is to be launched by 2024-end.  

XUE introduced the company’s DC coupled unit (DCU) storage system that stores excess power works indoors as well as outdoors. It can work with most microinverter brands in the market and is connected between solar modules and a balcony microinverter. It can act as a portable battery bank that works not only during blackouts but also work if the family wants to use it for a camping trip.  

XUE admitted that the microinverters, though safe and portable, do not yet have the same market share as string inverters. This is because the microinverters are expensive in terms of cost per W.   

The CEO of LIFEPOWR Dries Bols talked about optimizing self-consumption and sales of solar power and how to smarten solar electrification at home.  

Bols pointed to the strong growth of solar power generation going into the grid and homes, but this is also leading to a lot of congestion and negative prices. The situation will get worse in the future as more and more people install solar.  

The current situation of solar curtailment and power prices imbalance is unsustainable as it discourages newer installations. Bols claimed this is also leading to residential solar installers go bankrupt in some places. He offered the example of Flanders in Belgium where residential solar sales dropped by over 70% in Q1/2024.  

Hence, this is where the company’s energy management system comes in to help improve the solar business case, said Bols.  

Calling energy flexibility an essential ingredient for the growth of the solar economy, Bols said demand response, storage and solar curtailment are the 3 factors that can bring back balance to the grid. For this, smart energy management strategy is a must.  

He explained that smart balancing and flexibility are necessary as well as achievable to curb solar power curtailment and optimize consumption and solar production based on energy market rates.   

Consumers should know what to do behind-the-meter, what time to inject back into the grid when the prices are the highest, and the time to consume when the prices are the lowest. With a smart energy management system, one can do this across different assets on local the system. Hence, it’s not only solar and storage, but also other large load appliances such as heating and cooling to save more.   

LIFEPOWR can aggregate a lot of these low-voltage delivery points together and offer them into the markets as one larger virtual power plant. Rewards then flow back to the individual users, so they really feel the benefits of being part of this bigger picture, explained Bols. Managing these imbalances smartly also contributes to reducing carbon emissions because a bulk of these imbalances are still covered by gas-fired peaker plants.  

Panel discussion  

Moderated by TaiyangNews Managing Director Michael Schmela, the panel discussion revolved around the residential solar market and business developments in Europe. One thing that all panelists agreed to was the interest in residential solar & storage growing beyond well-established European markets, in Eastern Europe.  

The Czech Republic came up as a strong market along with Romania, and even Poland and France.

Ali Arfa of EUPD Research believes residential solar and storage market will continue to see strong growth over the next few years thanks to national targets, including for distributed solar.   

TSUN’s Ellen XUE sees growing interest in self-consumption via plug & play balcony solar. Germany, Italy, Spain, Poland and even France are seeing an uptick in this segment. Interest in microinverters is steadily growing in Europe where there is a big potential for this unlike China which is more of a price-driven market still.  

However, RCT Power’s Dr. Eric Rüland believes the European market is still low against expectations. Though inventory hoarding is not a problem anymore, it is the consumers that are now not ready to invest in solar. Higher interest rates and the high cost of investment act as barriers.   

Yet the panelists stressed that increasing consumer awareness as well as the number of trained installers & bringing down costs will encourage this segment further. An increase in electricity prices and solar prices going down will be a catalyst to growth of solar in Europe going forward. Schmela also stressed the aesthetics of solar panels for a market like Europe.