# Towards DC Energy Efficient Homes
## 3 Factors for DC Installations
### Generalization of Electric Vehicles  
Over the last ten years, the number of EVs sold across the world has increased considerably. HEVs have been a kind of springboard, and PHEVs are one step closer to pure EVs. Obviously, as long as EVs appear on roads, emissions may be reduced considerably, although this will be true if the origin of the energy is renewable. Nowadays, the number of EVs is very low, but, as the percentage of sales is increasing continuously, \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Device** & **Motor** & **Power (W)** & **DC Version** \\ \hline Fridge/Freezer & YES 1 & 100 & YES \\ Illumination & NO & 7.5 & YES \\ Dishwasher & YES 1 & 2400 & NO \\ Washing Machine & YES 1 & 2300 & NO \\ Clothes Dryer & YES 1 & 2800 & NO \\ Telephone & NO & 0.7 & YES 3 \\ Router & NO & 12 & YES \\ Printer & NO & 210 & YES \\ Laptop & NO & 150 & YES 3 \\ Monitor & NO & 13.3 & YES \\ Desktop & NO & 310 & NO \\ Radio & NO & 10 & YES \\ Blue Ray & NO & 8.5 & YES \\ DVD & NO & 11 & YES \\ Game Console & NO & 350 & YES 3 \\ Set-Top Box & NO & 6 & YES \\ Television & NO & 183 & YES \\ Coffee Machine & YES 2 & 1100 & YES \\ Toaster & NO & 1090 & NO \\ Extractor Hood & YES 1 & 146 & YES \\ Oven & NO & 3600 & NO \\ Cooktop & NO & 6600 & NO \\ Microwaves & YES 2 & 1270 & YES \\ Air Conditioning & YES 1 & 5300 & YES \\ Water Heater & NO & 2000 & YES \\ Heating & YES 1 & 5600 & NO \\ Charger & NO & 18 & YES \\ Dehumidifier & YES 2 & 72 & YES \\ Hair Dryer & YES 2 & 2100 & YES \\ Hair Straightener & NO & 100 & NO \\ Iron & NO & 2800 & NO \\ Vacuum Cleaner & YES 2 & 2400 & YES 3 \\ Elec. Toothbrush & NO & 2000 & YES 3 \\ \hline \hline \end{tabular} 1 DC motor and variable frequency drives; 2 DC motor; 3 it can be portable (uses a battery).  
\end{table} 
Table 1: Analysis of different household devices. recently surpassing 10% in some countries, there are good prospects [18]. The expected trends of the EV market are shown in Figure 1.  
Firstly, it has to be said that EVs convert over 77% of electrical energy received into power at the wheels, while conventional vehicles operate in the range of 12-30% [38]. This fact makes EVs more efficient than conventional vehicles, at least in terms of the process of energy conversion. Another issue to be taken into account regarding EVs is the battery cost. It is estimated that 30-40% of EV costs corresponds to the battery. Carmakers are working on solutions to this issue by sharing investments in battery plants or investing in their own plants. The result is that the trend of the noted percentages will reach 10% in the coming years [39]. The technological advances in batteries design are reducing weights and prices [40] and provide products that make EVs more accessible each year [41]. On the other hand, some cities and/or countries are establishing deadlines for conventional vehicles [42]. This situation will cause the general use of EVs to be even sooner. Although the driving range of EVs is shorter than the conventional vehicles, this is improving year after year. There are two recharging types that are available in most vehicles: a full recharge in 3-12 h and fast charge of up to 80% in half an hour. The ways to charge EVs depends on the connector used (presented in Figure 2) and are strongly related to the type of power used (DC or AC) [43; 44; 45]:  
* Unplugged: consists of wireless charging with three possible scenarios: at home, at a bus or taxi station (short time), or on-route. * AC: for regular charging of EVs. The power is converted into DC inside the EV, so long charging periods are required. The typical connector used for this type of charging is a Type 2. * AC and DC: an enhanced version of the previous one. The connector has additional power contacts (DC) for faster charging. The connector used is the CCS combo 2. * DC: fast charging due to exclusive operation of DC. The conversion from AC to DC is performed outside the vehicle. A Type 4 connector, also known as CHAdeMO, is the standard connector.