Categoria: Energia

Author: stefania Rinnovabili

Raggiunto un 23,26% d’efficienza con il nuovo fotovoltaico tandem dell’Helmholtz Zentrum

(Rinnovabili.it) – La ricerca tedesca si unisce a quella lituana per migliorare il solare di nuova generazione. Un gruppo di chimici della Kaunas University of Technology in collaborazione con i fisici dell’Helmholtz Zentrum di Berlino, è riuscito a raggiungere un nuovo record di resa per il fotovoltaico tandem perovskite-CIGS. Il risultato finale è stato un 23,26% d’efficienza di conversione della luce in elettricità, che rappresenta attualmente il più alto valore mai raggiunto al mondo per questa tipologia di celle.

Nel campo solare, il fotovoltaico multigiunzione costituisce la soluzione più promettente per superare i limiti tecnici delle convenzionali celle a giunzione singola. Come lo stesso nome fa intuire, questa tecnologia prevede di impilare diversi materiali semiconduttori, con altrettanto differenti band gap, per ampliare l’assorbimento dei fotoni, catturando e convertendo così parte dell’energia che altrimenti andrebbe persa. La tecnologia risulta  dunque particolarmente interessante sotto il profilo dell’efficienza e, inoltre, permette di produrre celle a film sottile utilizzando substrati flessibili.

>>Leggi anche Il silicio stupisce ancora: nuovo record per il solare multigiunzione<<

Il fotovoltaico tandem progettato dal gruppo tedesco-lituano combina cristalli di perovskite e (di)seleniuro di rame indio gallio (CIGS), semiconduttore che possiede attualmente il più alto coefficiente di assorbimento tra i materiali impiegati nelle celle solari.

Una delle novità del lavoro e del nuovo record raggiunto risiede negli strati di contatto tra questi due semiconduttori: molecole organiche a base di carbazolo. Queste molecole sono state funzionalizzate, ossia gli è stata data una particolare proprietà chimica, incorporando gruppi di acido fosfonico, che si dispongono in quelli che sono noti come monostrati autoassemblati (SAM).

Il merito va al team della della KTU che è riuscito a sintetizzare molecole che si assemblano in monostrati, in grado di coprire uniformemente qualsiasi superficie, comprese quelle ruvide delle celle solari CIGS.

“Di solito il problema con la fabbricazione dei tandem perovskite-CIGS è la superficie ruvida della cella inferiore, che è difficile da coprire uniformemente con processi convenzionali basati sulle soluzioni. Il nostro metodo consente di formare lo strato di elettrodi sottile da 1-2 nm, rivestendo tutta l’area. È un processo economico ed efficace: le molecole si depositano sulla superficie da soluzioni diluite e si forma uno strato selettivo denso di molecole”, spiega Artiom Magomedov della KTU. “Il fotovoltaico tandem a film sottile rappresenta il futuro dell’energia solare, in quanto più economico e potenzialmente molto più efficiente”, ha aggiunto il professor Vytautas Getautis, capo del gruppo di ricerca lituano.

>>leggi anche Celle solari multigiunzione, nuovo approccio per renderle economiche<<

Author: Vanya Ignatova Schneider Electric Blog

In installations with photovoltaic production, the building electrical energy consumption does not always match the photovoltaic production. The degree of this mismatch depends on the building activity and its consumption profile, but it is globally true for a majority of buildings.

Residential buildings and hotels consume more energy in the morning and in the evening when solar irradiation is low. Load consumption is therefore not synchronized with the photovoltaic power production profile. Under these conditions, photovoltaic self-consumption is effective only if a good portion of end-user usage is shifted to the hours of sunlight.

Office buildings, schools, and shopping malls generally experience the majority of their electrical consumption during the daytime. However, on weekends or other days off, these buildings have a quite different consumption profile, characterized by lower flat consumption. Moreover, the majority of schools and universities curtail their activities during the summer months and so consume much less energy, or in some cases almost no energy at all.

Industrial buildings may have generally flat consumption but also experience periods of low demand, depending on the organization of their activities. This is another case where the photovoltaic production profile does not match consumption well.

Indeed, solar power is characterized by a daily production profile that depends on weather conditions, with no production at night. Combining these considerations with the variability of different buildings’ consumption profiles—including variations due to changing seasons and the days of the week—it is quite difficult to match building consumption with photovoltaic production. Therefore, excess photovoltaic production happens relatively often, even when the photovoltaic system is sized so that it does not exceed the building baseload consumption.

Alternatives for managing excess solar production

When the locally produced power exceeds the consumption loads, there are several possible options for managing the excess power:

• Inject it to the grid
• Limit the photovoltaic production
• Store the photovoltaic excess to use it later
• Shift some loads to the period of photovoltaic production

These technologies are explained in the video “Four ways to manage excess photovoltaic production,” the second installment in a new video series produced by Schneider Electric’s technical communication and training group.

Of these four alternatives, two hold great promise for the future.

Storage systems that store the excess of the solar production and make the electricity available for use later in the day can be very effective. Today, however, this option is costly and often has a long payback period. To improve the return on investment, storage can be associated with other use cases, such as providing a backup power supply, improving demand response, and avoiding peak power usage to enable subscribing to a low power contract. This approach is more fully explained in another video in this series.

Load management is a very attractive option that consists of simply making some loads operate during the period of photovoltaic production, when that is possible. These loads must be flexible and manageable through the control system. Examples include electrical vehicle charging, water heating, and HVAC (heating, ventilating, and air conditioning) to a certain extent. 

The load management strategy has obvious advantages: It is cost effective, easy to implement, and guarantees a quick payback. Unlike a storage integration solution, it does not require the installation of additional equipment and thus presents a better profitability.

When a load shifting strategy is not enough to absorb the total excess of photovoltaic production, it can be used in association with a storage system. In that case, load shifting offers the additional benefit of reducing the size—and optimizing the use—of the storage system.

As the below video suggests, a combination of the four possible options—grid injection, power limitation, storage, and the very attractive alternative of load shifting—frequently turns out to be the best way to manage excess photovoltaic production.

Storage and other topics related to self-consumption of solar power are addressed in other installments of this blog and video series.

Learn more about Schneider Electric Solar, including new products and services for applications from residential solar to utility-scale power plants and how Schneider Electric’s cloud based, demand-side energy management software platform collects, forecasts, and automatically optimizes distributed energy resource (DER) operations.

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Author: Jeff M Miller, PE Schneider Electric Blog

“Once in a while an innovative technology will catch my eye as an industry GAME CHANGER! Like when I first learned about ArcBlok^TM for low voltage motor control centers (MCCs).”

In the past 2 decades awareness of arc fault hazards necessitated evolving codes and standards to protect personnel. Since then, many solutions have arisen to protect personnel and critical assets. Each of these solutions (e.g. policies, procedures, maintenance setting switches, arc flash relays, PPE, arc resistant gear, etc.) have up and downsides. The amazing thing about ArcBlok is, that it not only addresses the hazard, but also addresses many of the short falls presented by other solutions.

The severity of an arc fault hazard is determined by the energy released and its ability to harm personnel or equipment. The largest hazard produced from an MCC lineup would be from a line side incident before the main circuit breaker. ArcBlok isolates the line side conductors and reduces the likelihood of accidental contact with those conductors and the potential for arc faults.

What You Need to Know

1. ArcBlok reduces energy released and the potential for damage.
2. ArcBlok is a passive technology reducing negative consequences of human error.
3. ArcBlok reduces the arc duration and self-extinguishes it in less than one cycle!
4. ArcBlok has been tested and assessed using ANSI/IEEE Std. C37.20.7-2017, Annex H Motor Control Centers (UL 845).
5. ArcBlok is less costly than arc resistant MCC construction and provides operational resiliency that arc resistant gear does not.
6. ArcBlok comes with additional features for even more benefits!

Where You Can Learn More

Stay tuned for future GAME CHANGING TECH articles!

Ever wonder how much pressure is inside the cylinder of a running gas engine, such as a lawn mower? Find out! **Help me make more videos by visiting the link below. All donations, big or small, would be greatly appreciated. Thank you!
http://paypal.me/electronicsNmoreYT Bobby Tectalabyss: Thanks for your generous $5 donation!
Jeff Barr: Thanks for your generous $25 donation! **For GREAT deals(Usually cheaper than EBAY) on other electronics, drones, automotive tools, household items, phone accessories, locksmith tools, & much more, please visit the link below and SAVE IT AS A BOOKMARK on your computer or smartphone to Banggood for future purchases. (Your purchase supports my channel!) Home Page: https://bit.ly/2COi2P0
Flash Deals: https://bit.ly/2HBu9oq **Try these money saving coupon codes: affiliate6 or aff7off or f8aaf1 or 781622 or 5719ed or elec** or ask if other codes are available! Thanks For Watching! ***If you enjoy watching my videos, then be sure to SUBSCRIBE, POST LINKS to my videos on other websites & blogs, rate "THUMBS UP", and check out my video playlists. Doing so helps to ensure that many more videos will be uploaded to my YT channel in the future. (Views are absolutely essential to ensure this channel remains in an active state)***