Wire-grid polarizers (WGPs) offer superior extinction, durability, angle of incidence, and heat resistance when compared to traditional organic polarizers. WGPs are found in applications such as high lumen lighting, laser devices, high lumen digital cinema projectors, LED packaging, and other integrated optical applications and are driving the need for over-coatings. Over-coating a WGP has been found to increase lifetime and durability. This research provides lifetime data on coated and uncoated WGPs. WGPs over-coated with 100nm of SiO2, 300nm of MgF2, and with no over-coating were heated to temperatures of 450 ºC, 500 ºC, and 550 ºC and timed until they reached a predetermined optical failure point. The activation energies were calculated by applying the Arrhenius model to the failure data. WGPs with no over-coating were found to have an activation energy ≥ 1.5329 eV, with silicon dioxide an activation energy ≥ 1.7197 eV, and with magnesium fluoride an activation energy ≥ 2.4577 eV. It has been shown that coating a WGP with an over-coating of silicon dioxide or magnesium fluoride slows the oxidation process of the aluminum nano-wires, thus increasing the lifetime of the WGP by 208% and 27,904%, respectively. Parasitic chemical reactions were not found to exist with silicon dioxide or magnesium fluoride when used as an over-coating.

Making electricity grids smarter and facilitating them with integration of renewable energy sources (RES) and energy storage are fairly accepted as the necessary steps to achieve a sustainable and secure power industry. To enable Net-zero energy and optimize power management for future homes or buildings, DC electric distribution systems (DC Nano-grid) find feasibility and simplicity for integrating renewable energy sources and energy storage. However, integrating the sources and loads in a simple, robust and smart way is still challenging. High voltage lithium-ion battery should be seriously considered concerning the overcharge/over-discharge risk. Dissipative cell equalization and its performance are studied. Non-dissipative equalization methods are reviewed using an energy flow chart. Typical charging schemes and the related over-charge risk are illustrated. A Lithium-ion battery charging profile based on VCell_Max/Min monitoring is proposed and validated with experimental results in an 8.4kW bidirectional battery charger for DC future home. For the DC future home emulator testbed, a grid interface converter, i.e. energy control center (ECC) converter, is reviewed with functions identification. A PV system with different configurations is compared to further expand the common MPPT region, and a DC-DC converter is designed as the interface between PV panels and DC bus, facilitating maximum power point tracking (MPPT) as well as fulfill the system energy management requirement. An 8.4kW multi-phase bidirectional battery charger with Si IGBT in DCM operation is designed to achieve high efficiency and to be the interface converter between lithium-ion battery and DC bus, enhancing the battery system management as well as increasing the system reliability. To integrate all the sources and loads in a simple, reliable and smart way, this thesis proposes a distributed droop control method and smart energy management strategy to enhance the Net-zero electric energy cost. All of the control strategies are applied to the DC future home with interactions among the energy control center (ECC), renewable energy sources, energy storage and load within a day/24 hours. System level energy management control strategies for Net-zero electric energy cost are examined and illustrated. A 10kW future home emulator testbed is built and introduced for concepts validation. / Master of Science

About a third of Mozambique’s population has access to electricity, and the same number in rural areas, where most of the population lives, is down to 5 %. Small-sized off-grid solutions are economical alternatives to increase the electricity access rate in rural areas, and solar power is a common energy source due to price and weather conditions. Still, the economical aspect is the main hindrance to an increased electrification rate in Africa. This report aims to investigate how to make electricity affordable, in a sustainable way, by answering the main research question “What is the capability, economically, socially, and technically, for a shared nano off-grid system in the village Linga Linga?”. This was done by performing a Minor Field Study in the village Linga Linga, in southern Mozambique, with the help of the non-profit organization Project Vita. A collective nano-grid photovoltaic (PV) system was installed to electrify three households, including nine houses and eleven people, where the wage earners are all women. Before the construction and installment of the PV system, the first round of two interviews was conducted to investigate the energy situation for the households. After the interviews, the main components of the energy system: PV panels, inverter, charge controller, batteries, and cables, were sized and purchased. The energy system was sized to cover an energy demand of eleven Light-Emitting Diode (LED)-lights, four 3 W and seven 5 W, lit all day and all night, and three outlets for charging cell phones eight hours a day. This corresponds to an energy demand of 1,369 Wh per day, and a maximum power demand of 77 W. The resulting system cost is 87,570 Mozambique Metical (MZN), or 1,400 United States Dollars (USD). When calculating the technical lifetime to be 20 years, three of the main components must be replaced. That results in a system cost of 122,470 MZN, 1,960 USD, and the cost per wage earner of the participating households is 4.3 % of the average Mozambican’s annual salary. After the system had been running for about a week, the second round of interviews was carried out. On the same occasion, the households were informed about the maintenance and usage of the system, and they were handed manuals and contracts to sign. The interviewees reported that they had been working for more hours a day, handicrafts being their main source of income, thanks to the electric lights. The women were positive about collective ownership and sharing electricity and stated that they prefer a collective system to separate ones, even for the same cost. The interviews showed that the energy demand was lower than what the system was sized for, meaning that a system designed for the actual energy demand would have been both cheaper and smaller. However, the energy behavior could change with time as society develops and the users get more familiar with electricity. No clear answers were obtained regarding the willingness to pay (WTP) for the system, and the interpretation is that the household, in their current situation, cannot consider buying an energy system comparable to the prototype built for this report, due to the system cost. A collective solar nano-grid in rural Mozambique is concluded to be a well-functioning solution and one of the more economical electrification alternatives. Although the prototype in this study was too expensive for the participating households to pay for by themselves, it could support sustainable development and open for possibilities like increased productivity and income. Moreover, it could be expanded by connecting more loads and upscaling to further cut the system cost per person and increase the societal benefits. / Ungefär en tredjedel av Moçambiques befolkning har tillgång till elektricitet, och motsvarande andel på landsbygden, där majoriteten av befolkningen bor, är 5 %. Mindre off-grid lösningar är ekonomiska alternativ för att elektrifiera landsbygden, där solkraft är en vanlig energikälla på grund av det relativt låga priset och väderförhållandena med goda förutsättningar. Den ekonomiska aspekten är dock fortfarande det främsta hindret för att öka Afrikas elektrifieringsgrad. Den här rapporten syftar till att undersöka hur elektricitet kan göras tillgänglig för alla, på ett hållbart sätt, genom att besvara frågeställningen ”Vad är möjligheterna, ekonomiskt, socialt, och tekniskt, för ett delat nano off-grid system i byn Linga Linga?”. Detta utreds genom att genomföra en Minor Fields Study i byn Linga Linga i södra Moçambique med hjälp av välgörenhetsorganisationen Project Vita. Ett nano-nätsystem drivet av solceller installerades, innefattande tre hushåll med nio hus och elva personer, med endast kvinnliga inkomsttagare. Innan byggnationen av solcellssystemet genomfördes intervjuer för att undersöka hushållens energisituation. De mest fundamentala systemkomponenterna; solcellspaneler, växelriktare, solcellsregulator, batterier och kablar, dimensionerades och införskaffades efter intervjuerna. Energisystemet utformades efter ett energibehov på elva Light-Emitting Diode (LED)-lampor, varav fyra 3 W och sju 5 W, tända dygnet runt, och tre uttag för att ladda mobiltelefoner åtta timmar om dagen. Detta motsvarar ett energibehov på 1,369 Wh per dag, och ett maximalt effektbehov på 77 W per dag. Den resulterande systemkostnaden är 87 570 Mozambique Metical (MZN), eller 1 400 United States Dollar (USD). För att räkna om systemkostnaden för en teknisk livslängd på 20 år måste tre av systemets huvudkomponenter bytas ut, vilket resulterar i en systemkostnad på 122 470 MZN, 1 960 USD. Kostnaden per inkomsttagare i de deltagande hushållen utgör då 4,3 % av den årliga moçambikiska medelinkomsten. När solcellssystemet varit i gång i en vecka utfördes en andra omgång intervjuer. I samband med detta informerades hushållen om skötsel och användning av systemet, och mottog manualer och kontrakt. Det framkom att kvinnorna, tack vare den elektriska belysningen, hade kunnat arbeta längre på kvällarna med sina hantverk - deras främsta inkomstkälla. De var positiva till det kollektiva ägandet av systemet och sade sig föredra ett delat system framför varsitt separat, även för samma kostnad per person. Intervjuerna visade att hushållens energikonsumtion var mindre än systemet var designat för. Ett system anpassat efter det verkliga energibehovet hade därmed blivit både mindre och billigare. Energianvändandet kan dock förändras i takt med samhällsutveckling och användarnas bekantskap med elektricitet. Inga tydliga svar angående betalningsvilja (WTP) för systemet mottogs, och tolkningen är att hushållen, i deras nuvarande situation, inte kan tänka sig köpa ett energisystem som är jämförbart med studiens prototyp, på grund av den höga systemkostnaden. Ett soldrivet kollektivt nano-nät på Moçambiques landsbygd bedöms vara en välfungerande elektrifieringslösning och ett av de mest ekonomiska elektrifieringsalternativen. Fastän studiens prototyp var för dyr för att de deltagande hushållen kan det ses stödja en hållbar utveckling genom att öppna upp för möjligheter såsom ökad produktivitet och inkomst. Systemet skulle även kunna expanderas genom att koppla in fler eller större last, och byggas i större skala för att dra ner systemkostnaden per person och öka samhällsnyttan.