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Building Engineering Systems: BLDG 341 Professor B. Lee The PowerWall by Tesla Motors: An Energy Alternative

THE POWERWALL BY TESLA MOTORS: AN ENERGY ALTERNATIVE

AbdulRahman AlShowaier (6477089)

Andre Diep (27768354)

Maude Genet (9102515)

Nicholas Hudon (40004120)

Benjamin Maniraguha (40005306)

Department of Building, Civil and Environmental Engineering

Concordia University

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THE POWERWALL BY TESLA MOTORS: AN ENERGY ALTERNATIVE

Foreword:

We live in an era where the human race is widely dependant on electrical energy. We have come a long way in our understanding of electricity since the preliminary experiments conducted by famous pioneers such as Michael Faraday, Nikola Tesla and James Maxwell, just to name a few. This dependence on electricity has raised a number of concerns; due to the serious environmental damage it is causing. Over the past decade, we have really been witnessing a global phenomenon where scientists are leading the charge against ‘dirty’ energy towards clean, renewable energy. Non-renewable energy is not the only energy-related challenge the world, more specifically Quebecers, are facing. The already outstanding amount of energy consumed in average household is increasing readily. On this perspective, we should unite our efforts to decrease the world’s energy consumption to leave a better, green earth for our descendants.

Introduction:

Since the nationalization of electricity in Quebec (1944), the state-owned monopoly, Hydro-Quebec detains absolute control over the pricing and distribution of electricity in Quebec. They have the luxury of charging higher fees during peak hours while energy consumption is at maximum. Not only are we consuming high amounts of energy but also we are paying peerless sums for it. This creates an urgency to find an alternative to the current method. Telsa Motors, an automotive and energy storage company, a world leader in renewable energy innovations announced in 2015, the PowerWall1, a battery for home use. 1 "Powerwall." Tesla. Web. 30 Sept. 2015.

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It reduces energy consumption by storing solar energy, to be later used during peak hours as electrical energy for everyday household purposes. We researched the possibility of replacing Hydro-Quebec by the Tesla PowerWall.

Objective:

The main objective of our project is to maximize the electricity produced by the PowerWall system in order to completely cancel out Hydro-Quebec. The project was controlled by two main factors that we had total control over:

X1= The number of Solar Panels that were to be purchased.X2= The number of Tesla PowerWalls that were to be purchased.

With this in mind, to maximize the amount of electricity produced, we came up with the following objective function:

Z=a∗X1+b∗X2

Z=0.315 X1+2.325 X2**

Where:a = Maximum solar energy generated by the solar panels under standard** testing conditions. (Kwh)b = Maximum energy produced by the Tesla Powerwall. (Kwh)** Our standard testing conditions and other assumptions are as follows.

Assumptions

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The Tesla PowerWall was only introduced this year (2015), so most of the calculations will be done with the numbers provided by Tesla Motors. They concur that the 7Kwh weekly cycle model is the best for household use. Our research will be based on data accumulated mostly by Tesla Motors, Statitics Canada and Hydro-Québec. While both east or west located solar panels can be rewarding, we are assuming that the PV panels are places in to a position where the solar energy intake is at maximum. We also considered that the data collected would be from a perfect sunny day in July. The capital invested in the project is 20 000$, the installation fees are considered to be zero. We assume that the average house size in Canada is 1200 ft2. We took the Kyocera KD315GX-LPB2 as our solar panel of choice. Its dimensions are 65.43 in. x 51.97 in. x 1.8 in. It has a maximum power intake of 315 Watts.

2 “Kyocera KD315GX-LPB Review”, Web, Sept 30th 2015.

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Due to the following graph, we concluded that the average Canadian household consumes 33kwh of energy daily. We found that the PowerWall continuously gives off 2 kwh of power and 3.3 kwh of power during peak hours, with the assumption that we have 4 peak hours during the day we were able to calculate an average of 2.325kwh. Constraints:

We were subject to certain constraints while exploring the possibilities of using the PowerWall system to completely nullify electricity consumption from Hydro-Quebec:

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X1,X2>0 and integers: We are dealing with solid entities when we talk about

solar panels and batteries, thus we cannot have fractions or negative values.

X2<=9: The number of PowerWalls that one can attach to each other cannot

exceed 9.

X1<=52: The number of PVs that one can fit on an average Canadian roof

(1200 ft2) is 52, this is based on the area of one solar panel (65.43 in. x 51.97 in.) divided by 1200.

399X1+3000X2<=20000: The cost of one solar panel is 399$, and the cost of one PowerWall is 3000$. We want the final sum that is to be invested into the installation of the PowerWall system has to constrained by the amount of 20000$ (Maximum capital to be invested.)

7X2>=33: The amount of electricity that is used in an average Canadian house is 33Kwh, the amount of 7Kwh models have to cover a minimum of 33Kwh.

0.315X1>=7X2: The solar enegy that is captured by the solar panels has to be at

least equal to the maximum capacity of the PowerWalls to optimize the batteries’ charging capacity.

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Graphical Method:

To determine the number of PowerWalls and PV panels that were to be bought to maximize the amount of electricity produced to completely be independent of Hydro-Quebec, we used the graphical method to find out possible solutions. The feasible region is constrained between A, B and C.

X1 X2

Point A: 14.68 4.71Point B: 6.67 0Point C: 0 4.71

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Since none of the possible solution were feasible since they were either non-integers or zero (thus the possibility of buying either batteries or PV panels without the one other). Results Analysis:

The graphical method permitted us to find that the possible solution was between X1=]0,14], X2=]4,6]. We calculated the maximum value of X1 for X2=5 and 6 to give us our two possible solutions and compared them in a table in which we were able to shorten bind our results.

We found that the two possible solutions were X1 X2

12 55 6

. To put the

following results in perspective, we made the following table:

Amount of Solar Panels (X1)

Amount of PowerWalls (X2)

Electicity produced (Z)

[Kwh]Possibility 1 12 5 15.405Possibility 2 5 6 15.525

From the following table we are able to find that the optimal number of PowerWalls and Solar Panels to maximize the electricity produced by the system introduced by Tesla is respectively 6 and 5. This design would cost a total of 19 995$ and would produced 15.525 Kwh daily for the household.

Design Alternatives:

The first alternative that we could have is taking off the cost constraint, if money is not a factor for the consumer who takes on the

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following project we obtain a rather larger region, where we could install 9 PowerWalls and 52 Solar Panels. This would certainly increase the feasibility of our project. That is the only realistic alternative given the circumstances detailed in our assumptions. If we change our assumption by introducing a different solar panel (smaller in size or capable of in taking more energy from the sun), we would obtain a much different result because it would alter the value of a in our objective function.

Recommendation and Conclusion:

After researching on the PowerWall system suggested by Tesla Motors, we conclude that the optimal solution would be to purchase 5 Solar Panels and 6 PowerWalls to create electricity for your household, it would cost 19 995$ and would produce a total of 15.504Kwh of power daily. Despite being a great alternative, it would not create enough energy to completely cancel out Hydro-Quebec but it would cover the electricity needs during peak hours which would significantly reduce costs. Despite this, we would not recommend the average consumer to get it due to the cost. For testing and scientific purposes, it would definitely be a great alternative. The product is still in its preliminary stages of research and all the data collected was provided by Tesla who are, of course, selling their product. Time will give us a better perspective on the product.

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