Design of a Out Grid System

FACULTY OF ELECTRICAL ENGINEERING

Electrical Power Engineering of Industrial and Distribution Networks

Design of off-grid power system

Author: Pau Miralles Ferrs

Teacher: Lukas Prokop

TABLE OF CONTENTS

1. INTRODUCTION __________________________________________________________________ 4

2. OFF-GRID POWER SCHEME _______________________________________________________ 6

3. INSTALLATION ___________________________________________________________________ 9

4. POWER CONSUMPTION ANALISYS _______________________________________________ 12

5. DESCRIPTION OF INDIVIDUAL COMPONENTS ____________________________________ 16

6. DESIGN OF INDIVIDUAL PARTS OF THE SYSTEM __________________________________ 20

7. PLANIFICATION AND COST EVALUATION ________________________________________ 26

8. CONTROL SYSTEM ______________________________________________________________ 28

Introduction

1. Introduction We live in a society where all the things that we need are provided by

others; water, electricity, food

Off-grid living consists in that, reduce the necessity and dependence from

third persons regarding to our lives.

In this Project, I will try to design a smart off-grid power system in a family

house, using solar panels and batteries. The main idea of this is to have a

self-sufficient house, and the goal is to have reliability, carbon emission

reduction and cost reduction at long-term.

The cost of this kind of installations has dropped about 30% in the last 6

years, so in the present is a very nice option to consider

The best option is to calculate the complete system and find the best

technic and economic solution for this.

The main parts of this installation are:

Solar panels: This dispositives are used for using the solar power to

convert it in electricity using the fotovoltaic energy. If you need more

panels in the future, you can enlarge it easily, with easy installation.

Charge controller: It have two basic functions:

-Avoid overloading and deep discharge of the batteries, as this can cause irreversible damage to them.

-Prevent battery discharge through the panels in less light periods.

For enlarging the system, is better to use a charge controller that allows more panels, then you can enlarge it easily.

Inverter: Its function is to convert from DC that the fotovoltaic installation

gives, to AC, which is needed for almost all the electronic components in

the home. Is better to have it a little bit bigger inverter than the calculated,

but you can add more inverters in the future.

Design of Off-Grid Power SystemTtulo del Proyecto 3

Introduction

Batteries: The main function of the batteries in this systems is to

accumulate the energy produced during the light hours, for being used at

the night or during long periods of bad weather. Another important function

of the batteries is to provide a higher intensity that the fotovoltaic panel

can give.

Other components: We need an aluminium structure big enough for our

solar panels, and the cables, that will be purchased according to our

needings.


Off-Grid Power Scheme

2. Off-Grid Power Scheme For the installation, we have three options:

-Only direct current (DC)

-Only alternating current (AC)

-Direct and alternatinc current: We will use this option, the main advantage

of this, is that the installation is simpler, and we can use less section

cables. This type of installation needs a senoidal converter.

Our scheme will be like this:

We will have the photovoltaic panels on the roof. The main danger of

working with CC is that we have to bear in mind the polarity of the panels.

The first step is to identify the positive and negative terminals. For making

the connection between the panels and the charge controller we will use

always terminal, and the cabling has to have an insulation for 1000V,

because is outdoor and maybe there is humidity.



For battery installation, we need a room with conditions which ensure the

proper operation of the battery bank:

- Protected from meteorological inclemency, and with a nice

temperature for their work (if we have low temperature, the battery

capacity decreases, and if we have high temperature, it decrease the

batterys life).

- It have to be properly isolated for prevent abrupt changes of the

temperature.

- It have to be a dry and ventilated, in order to prevent accumulation

of gases that are produced with the battery charging. Is better to

have openings in the top of this room, for prevent risks of fire or

burst (Hydrogen is lighter than the air and it tends to accumulate at

the top).

- It have to have an easy accessment, for having an easier

maintenance.

The battery has to be as nearest as possible to the panels and to the

charge controller, in order to reduce losses by voltage drop, and less

length of the cabling.

Is not good idea to place the batteries directly on the floor, is better to

have a small height to electrically isolate the ground, like this:



Controller: We have to keep in mind the polarity, we will connect the cables

using terminals. Its reccomended to connect the battery at first, after the

solar panels, and at finish the consumption.

We will install an automatic switch at the battery output in order to prevent

from dead shorts.

Converter: It has to be as nearest as possible from the batteries, in order

to prevent voltage drop. This is the way to connect the converter:


Installation

3. Installation For the installation of the solar panels, we have three possibilities:

- Floor: Is the most used in groups of panels. The advantages are that

the structure dont have wind influence, and its easy to assembly.

- Wall: Its tipycal in home installations. The disadvantage is that you

can only install it in the south wall. It have not problems with the

wind too.

- Roof: Is the most used, and we will use this installation. You can

have a nice place for assure a perfect otrientation of the panels. The

drawback can be, as the floor, they can be covered by the snow.

Orientation: We live in the northern hemisphere, so we have to put the

panels oriented to the south.

Inclination: Solar radiation incident on the panel can differ depending on

the angle it forms with the horizontal. Depending on the inclination, the

solar energy can change, and will be maximum when the position of the

plate is perpendicular to the radiation.

The optimal tilt over a year can change, therefore, for fixed panel

installation, is usually choosen the best inclination for the winter, which is,

improve uptake in winter against a catchment loss in summer.

In the next table, we can see the relationship between latitude and the

angle with more power for winter and summer.


Installation

Latitude in the installation place (in

degrees)

Tilt Angle (Winter) Tilt Angle (Summer)

0 15 15 15

15 25 Same as latitude Same as latitude

25 30 Latitude +5 Latitude +5

30 35 Latitude +10 Latitude -10

35 40 Latitude +15 Latitude -15

>40 Latitude +20 Latitude -20

This is the map and the place where I will install the off grid system.


Installation

I have chosen this place in the mountains, because is where my

grandparents have a house, and it can be a good opportunity to improve

the electric installation, because the only possibility to have electricity

there is a gas power unit.

The latitude in this point is 0.06, so we will have the solar panels at

15 from the horizontal line, oriented to the south.


Power consumption analysis

4. Power consumption analysis

We will use as most as posible, energy efficient appliances, in order to

reduce the power consumption, and consequently, the cost of the off-grid

installation. This is our house:



Electronic devices in every room:

- DC devices:

Equipment Power (W) Number of devices Working hours/day

Total Energy (Wh)

Lighting in room 1 (Dormitory) 5 3 3 45

Lighting in room 2 (Bathroom) 5 2 2 20

Lighting in room 3 (Dormitory) 5 2 2 20

Lighting in room 4 (Washroom) 5 1 0.5 2.5

Lighting in room 5 (Toilet) 5 1 0.5 2.5

Lighting in room 6 (Hall) 5 6 4 120

Lighting in room 7 (Kitchen) 5 4 4 80

Total Power 95 W 290 Wh

- AC devices:

Equipment Power (W)

Number of devices

Working hours/day

Total Energy (Wh)

Washing machine (137 kWh/year)

365 1 1 365

TV 43 1 4 172

Fridge (149 kWh/year) 17 1 24 408

Laptop 70 1 6 420

Mini Oven 1500 1 0.5 750

Hair dryer 1200 1 0.2 240

Electric table grill 1800 1 0.3 540

Total Power 4995 W 2895 Wh

Total Power (DC + AC) = 5090W

Total Energy (DC+AC) = 3185 Wh



Description of appliances.

We will use the most efficient appliances in the market. They are a little

bit more expensive, but the cost will be reduced because we will need less

solar panels and batteries.

In the lighting part, we will use for all the house 5W Led Bulbs, they will

be distributed across the ceiling of the all the rooms in the house.

5W MR16 DC12-18V Cool White Spot Bulb

Link: https://www.myled.com/p1760-5w-mr16-dc12-18v-

cool-white-spot-bulb.html

For the appliance, we will always see the energy labelling, that is the same

for all the European Union:

The energy labels are separated into at least four categories:

The appliance's details: according to each appliance, specific details, of the model and its materials

Energy class: a colour code associated to a letter (from A to G) that gives an idea of the appliance's electrical consumption

Consumption, efficiency, capacity, etc.: this section gives information according to appliance type

Noise: the noise emitted by the appliance is described in decibels.

We will try to choose all from A to A+++, to get the maximum efficiency.



Washing machine: Siemens WM14Y740EE

Energy efficiency class: A+++

-30% more economical (137 kWh/year) than the standard value (196 kWh/year) of energy efficiency class A+++.

Link: http://www.siemens-home.es/electrodomesticos/lavadoras/libre-instalacion/WM14Y740EE.html

Television: Samsung UE40H6400AW

Energy efficiency class: A+

Power consumption: 30W

Power consumption in standby: 0,3W

Link: http://www.samsung.com/us/video/tvs/UN40H6400AFXZA

Fridge: Bosch KGE36BW41G

Energy efficiency class: A+++

Power consumption: 149 kWh/year

Link: http://www.bosch-home.co.uk/our-products/fridges-and-freezers/fridge-freezers/KGE36BW41G.html?source=browse

Mini Oven: 23 litre mini oven & grill with double hob


Link:https://andrewjamesworldwide.com/UserControls/productIndividual.aspx?ProductID=36

Hair Dryer: X5 Superlite


Link: http://www.amazon.com/X5-Superlite-1200W-Ceramic-Ionic-Travel/dp/B001FSK73G/ref=sr_1_12?s=hpc&ie=UTF8&qid=1418528668&sr=1-12&keywords=hair+dryer+1200

Electric Table Grill: Electric Teppanyaki Barbecue Table Grill


Link: http://www.amazon.co.uk/Andrew-James-Electric-Teppanyaki-Barbecue/dp/B003USP2WA/ref=sr_1_3?ie=UTF8&qid=1418529005&sr=8-3&keywords=electric+grill


Description of individual components

5. Description of individual components Solar panels: We will use Nousol solar panels, with excellent efficiency,

based on the use of innovative photovoltaic technologies.

Physical Characteristics:

Solar cells laminated with TPT/EVA bi-layer for long life. High efficiency monocrystalline cell High efficiency with high transparency low iron tempered glass cover. Anodized aluminium frame. Sealed for protection from hars enviroments. Junction box with by-pass diodes. Outstanding low light perfomance. IP65.

Mechanical data:

Electrical data:



Charge controller: We will use a Steca Solarix PRS 3030 (30A). In this,

several LEDs in various colours emulate a tank display, which gives

information on the batterys state of charge. The Solarix PRS charge

controllers are equipped with an electronic fuse, thus making optimal

protection possible. They operate on the serial principle, and separate the

solar module from the battery in order to protect it against overcharging.

Main features:

- Automatic detection of voltage

- Voltage and current regulation

- PWM control

- Current compensated load

disconnection

- Automatic load reconnection

- Temperature compensation

- Integrated self test

- Monthly maintenance charge

Electronic protection functions:

- Overcharge protection

- Deep discharge protection

- Reverse polarity protection of

load, module and battery

- Automatic electronic fuse

- Short circuit protection of load

and module

- Overvoltage protection at

module input

- Open circuit protection without

battery

- Reverse current protection at

night

- Overtemperature and overload protection



Inverter: Our inverter will be a Cotek with 1500 W True Sine Wave. It

can feed sensitive electronic equipment.

Main features:

- True sine wave output (THD


Detailed features in the inverter (we will use the second in the table):


Design of individual parts of the system

6. Design of individual parts of the system

The power installed on the house is 5090W, and we consider that we

have a constant power consumption of 3185 Wh every day of the year.

With the data that we have (estimated yeld of the appliance) we will

calculate the solar daily requirement that the solar field have to supply.

At first, we have to know the solar irradiation in where we will place the

installation.

Here are the maps of the Solar Irradiation in Europe and Spain:



And for being more exact, this is the table for my coordinates with the

average daily sum of global irradiation per square meter received by the

modules (kWh/m2):

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Av. year

2.96 3.96 5.32 5.77 6.54 7.2 7.24 6.45 5.29 4.35 3.27 2.71 5.09



Panels:

For calculating our needings, we will use this formula:

Ar = 1200 X Ed / Id

Where:

Ar: Panel size (Wp)

Ed: Electricity usage (kWh/day)

Id: Irradiation (kWh/m2/day)

Then, we need:

= 1200 3.1855.09 = 750.884 = 750.884195 = 3.85 In our installation, we have to use at less 4 solar panels, which we will

connect in parallel, then we will have 780 Wp Power.

Charge controller:

For sizing the charge controller, we have to forecast the intensity peaks,

then we use a correction coefficient (25%)

Icont=1,25IscNparallel mod

Icont = 1,255,724 = 28,6A

We will use a 30A charge controller.



Batteries:

To size the batteries, we need this parameter:

Dodmax: Maximum depth of discharge, in lead acid batteries, it is between

0.6 and 0.8, so I will use 0,7.

Autonomy days: I will choose 5 autonomy days, for being sure that if we

have some cloudy or bad weather days, we wont be without electricity.

Eelec: We calculated it before, is the energy expended in one normal use

day in the house.

The accumulated energy in the batteries with the correction factor is:

= 1,1 ( ) ()

= 1,1 5 31850,7 = 25025

And the needed capacity will be:

= ()

= 2502524 = 1042,7

Then, if we are using 345 Ah batteries, we need 4 batteries for having

this capacity. We will have 4345=1380 Ah



Inverter:

The size of the inverter have to be the maximum power of the appliance

that can work at the same time. For this, we have to use the peak power,

which can be 4 times bigger than the nominal one. Then we will do it

20% bigger for security.

= 1.25 (4 ( + ) + + ) = 1.25 (4 (365 + 17) + 70 + 43 = 2051,2

Then, we will use an inverter with 3000 W peak power. For sure we

have to take care of dont have the hair dryer, oven Connected at the

same time, if we do that, the circuit breaker will stop the electricity.

----------------------------------------------------------------------------------

Knowing all of this information, we can do the complete energy analysis

during the year using PVGIS

Location: 4016'15" North, 03'29" East, Elevation: 353 m a.s.l.,

Solar radiation database used: PVGIS-CMSAF

Nominal power of the PV system: 0.8 kW (crystalline silicon)

Estimated losses due to temperature and low irradiance: 9.2% (using

local ambient temperature)

Estimated loss due to angular reflectance effects: 2.9%

Other losses (cables, inverter etc.): 14.0%

Combined PV system losses: 24.2%



Ed: Average daily electricity production from the given system (kWh)

Em: Average monthly electricity production from the given system (kWh)

Hd: Average daily sum of global irradiation per square meter received by

the modules of the given system (kWh/m2)

Hm: Average sum of global irradiation per square meter received by the

modules of the given system (kWh/m2)


Planification and Cost Evaluation

7. Planification and Cost Evaluation At finish, we have to know how much will cost all the off-grid

installation.

We will choose a kit with all the components together, because it will

be less expensive than purchasing one by one.

This kit is sold without the inverter, and the price is 2758.62.

Included in the kit:

4 panels 195W/24V (ref: 11000017) 1 solar carge controller Steca 30A/12V LEDs (ref: 13008005) 4 batteries monoblock 6V/345Ah C100 open acid lead of deep download (ref: 14009618). 4 sets of positive and negative terminals for battery. 4 sets of connetors male and female for the panel connection.

http://www.nousol.com/index.php?page=shop.product_details&flypage=tpflypage.tpl&product_id=856&category_id=56&option=com_virtuemart&Itemid=53&lang=en&vmcchk=1&Itemid=53


The prize for the inverter will be 920.72

http://www.nousol.com/index.php?page=shop.product_details&flypage=t

pflypage.tpl&product_id=552&category_id=59&option=com_virtuemart&

Itemid=53

Total prize for the solar kit:

2758.62+920.72= 3679.34

The cables will be purchased depending of the needings for the home, but

they are not very expensive.


8. Control system My control system will be a door locker/unlocker system.

It lets you lock and unlock your door through a smartphone app,

either on demand or automatically, and it lets you send passes to other

people who have the app.

Advantages:

Keyless: The encrypted technology of this locker is safer than keys

that can get lost and codes that can be copied.

You can control when people have acces to the home. For example

you can issue a key that works 24/7 for a family member, or one that

works a couple of hours a week only for the cleaning person.

Log record: There is a log record in the smartphone where you can

see who entered and exited.


It works with 4 AA batteries, then, doesnt matter if there are no

electricity, maybe because a problem, you will can open the door. When

the batteries get low, the device send reminders to the smartphone.

Features:

Auto-Unlock: with Bluetooth connection, when you approach to the

door, it automatically unlocks the door without touching anything.

EverLock: When you go out, if you are far from the door, it will be

locked automatically, then you dont have to worry if you left your door

unlocked.

Easy install: The device replaces the interior portion of the existing

deadbolt and does not require to change the exterior door hardware, it will

be installed in more or less 10 minutes.

The prize of this device is 250$, and you can buy it in Amazon:

http://www.amazon.com/dp/B00OHY14CS/ref=asc_df_B00OHY14C

S3454105?smid=ATVPDKIKX0DER&tag=mysimon-wireless09-

20&linkCode=df0&creative=395093&creativeASIN=B00OHY14CS


Design of off-grid power system1. Introduction2. Off-Grid Power Scheme3. Installation4. Power consumption analysis5. Description of individual components6. Design of individual parts of the system7. Planification and Cost Evaluation8. Control system

Documents

Design of a Out Grid System