Learn how to:



1. Using the map and getting climate information

Find your location on the Google map and click on it. The message below the map will display that it is fetching data for this location and will then display your latitude and longitude and some graphs once the data has been fetched:

  1. 1) Wind speed at 10m height. This is actually derived from the Nasa data, which gives the wind speed at 50m for this location, using a power law which assumes a terrain which is chosen from the dropdown list.
  2. 2) Solar energy per square meter per day on a surface which is tilted towards the equator at an angle from the horizontal equal to the latitude of your location.
  3. 3) The average number of no sun days for each month at your location. This is useful for estimating how much provision you need to make for storing energy to ensure a reliable supply during days when the available solar energy is low.
  4. 4) The average air temperature for each month at your location. This is useful for estimating your heating or cooling or insulation needs.
  5. 5) The average ground temperature for each month at your location. This useful for estimating how much energy is needed to heat water to a desirable temperature.
  6. 6) The average number of heating degree days below 18 degrees Celsius per month at your location. This useful for calculating how much heating would be needed for a month to keep the temperature inside your house around 18 degrees Celsius.
Important:

What needs to be understood is that the climatic data is averaged for each 1 degree latitude and longitude block on the earth surface which is an area of roughly 100km square around your location. This means that local micro-climates and local topography, the proximity of forests, mountains, etc. will cause the climatic conditions to deviate from these averages. These deviations can cause over or under estimation of the available energy in your location and it is important to understand that the values given are estimates and will give you a rough idea of the feasibility of using solar and wind energy at your location, but will not give you accurate energy yields and costs to the last kWh or monetary unit. Given the unpredictability of wind and solar energy at any location, you will still get a pretty good picture of how it could work for you in your region.



helpimage 2. Designing for electricity from renewable resources

Each appliance in your house draws an amount of electrical power which is expressed in the amount of energy used per second or watts (W). This rating is often expressed in this amount divided by a 1000, for which the unit kilowatt (kW) is used. This can normally be found on the specification sheet for the appliance or on a label on the device. The total amount of energy used is this power multiplied by the time it is in use. A kettle will typically draw 1000 Watts. If it takes 3 minutes to boil and you use it 5 times per day, that is 15 minutes per day that it draws this amount of power which gives a total energy use per day of 1000W x 0.25 hours = 250Wh or 0.25kWh. Some devices such as a refrigerator may draw about 400W when its compressor switches on and almost nothing when the compressor is off. It switches on intermittently during the day depending on various factors such as the ambient temperature and how often it is opened. It is therefore quite difficult to work out for how many minutes the compressor is switched on per day and it is easier to use an average consumption of say 50W and to say that it is used 24 hours per day.

Various appliances are obviously not used in the same way throughout the year. Examples of these are electrical heaters, air-conditioners, swimming pool pumps, etc. The input table allows you to enter a different value for the peak summer and winter months. The energy use for each month of the year will then be worked out by assuming a sinusoidal change between these two seasonal extremes.

There are a number of default appliances given in the table and if you do not make use of one of these, then you can simply enter a number 0 in the number or the rating field. If you use more than one of these devices, such as for example lights, then you need to work out how much you use each one on average and enter that as the hours used and then enter the number of the lights in the number column. So if you have 5 lights with each one switched on 3 hours per day in summer and 6 hours per day in winter, you enter 5 in the number column and 3 in the summer column and 6 in the winter column (depending on which month represents winter or summer in your hemisphere).

To add a new appliance to the list, simply click on the ADD button at the bottom of the list and enter the various values into the row that will be added to the table.

The monthly electricity use values are displayed in a graph on the right of the table as are the winter, summer and average consumption values. When you click on the climate data link in the menu on the left of the page, these values will be used as consumption values for each month and average values.

The climatic data is used to estimate the available wind and photovoltaic energy per day at your location for each month of the year. This information is displayed in graphs with buttons which allow you to select a system and to adjust each system's parameters. The system size and relevant parameters are displayed with each graph.

The wind energy is dependent on the type of terrain around you as well as the efficiency, height and diameter of your wind turbine. The model uses the power curve of the wind turbine selected by you to calculate the wind energy generated. You can select the height of the wind turbine from the dropdown list which lists the heights of masts supplied with the product that you have selected. A Rayleigh probability distribution based on the average wind speed for your location is used to determine the energy generated over the period of a month.

If you do not want to make use of wind power as part of your design, you can simply adjust the number of wind turbines to zero.

The photovoltaic energy is the estimated electrical energy which can typically be generated by photovoltaic panel selected by you. Changing the number of panels will adjust the amount of energy you can generate from these panels. It is assumed that these panels are facing towards the equator and are tilted from the horizontal at an angle equal to the latitude of your location and that there is no shading from trees, nearby structures or mountains during part of the day.

You can adjust the tilt or facing direction to ones that suit your situation. These adjusted values can be reset to their default values for your latitude by clicking on the reset buttons provided next to the facing and tilt parameters.

If you do not want to make use of photovoltaic power as part of your design, you can simply adjust the number of panels to zero.

Each energy source has a graph which shows the average electrical energy generated per day for each month according to the parameters that you chose for each source. The energy sources also allows the user to enter values for any grants, feed-in tarrifs, generation tarrifs and maintenance costs to determine savings and costs. The amounts enetered should be in the currency selected from the dropdown list.

The energy generated by the energy sources can be fed to either a standalone elctrical power system or a grid-tied system.

In the standalone system the generated power is fed to a battery charger, which charges a battery bank. When electrical power is demanded, the batteries supply direct current (DC) power to an inverter which converts the power to alternating current (AC) electricity which can be used by appliances. The battery charger and inverter have conversion efficiencies which affect the amount of energy that can be obtained from the system. By selecting suitable products and the number of days of reserve energy, the number of batteries and output energy of the system will be determined. The combined wind and photovoltaic energy per day is displayed in a graph.This is useful for areas of the world where the seasonal variation of solar and wind power complement each other. One would ideally want a seasonal profile of generated energy that follows the electrical energy demand. The demand values are updated when you change consumption values.By adjusting the parameters for wind and photovoltaic energy such as turbine height and diameter and panel area, one can in many cases get the combined generated energy to closely match the electricity use throughout the year. Another graph shows the shortfall of the generated electrical energy from the electricity required. By selecting a display format from the dropdown list below the graph, the shortfall can be displayed in kWh or the equivalent amount of fuel that may be needed on a monthly basis to run a generator to make up this shortfall.

In the standalone section there is also an input field for the cost of fuel to generate the standalone electrical energy which cannot be supplied by renewable sources. This amount is used to determine payback times and savings at the bottom of the page. The amount entered is in monetary units as selected from the currency dropdown list, so if diesel costs 20 US cents per litre, the currency dropdown list should be selected as US dollars and the amount entered as 0.20

In the grid-tied system the generated power is fed to a grid-tie inverter, which converts the direct current (DC) power to an inverter which converts the power to alternating current (AC) electricity which can be used by appliances or fed into the grid. The grid-tie inverter also allows electricity to be used from the grid if there is a shortage of renewable power. The inverter has a conversion efficiency which affect the amount of energy that can be obtained from the system. By selecting a suitable product, the output energy of the system will be determined. The combined wind and photovoltaic energy per day is displayed in a graph.This is useful for areas of the world where the seasonal variation of solar and wind power complement each other. One would ideally want a seasonal profile of generated energy that follows the electrical energy demand. The demand values are updated when you change consumption values.By adjusting the parameters for wind and photovoltaic energy such as turbine height and diameter and panel area, one can in many cases get the combined generated energy to closely match the electricity use throughout the year. Another graph shows the amount of electrical energy fed to the grid in various formats. By selecting a display format from the dropdown list below the graph, the shortfall can be displayed in kWh or the equivalent costs on a monthly basis.

In the grid-tied section there is also an input field for the cost of electricity from the grid. This amount is used to determine payback times and savings at the bottom of the page. The amount entered is in monetary units as selected from the currency dropdown list, so if electricity costs 10 US cents per kWh, the currency dropdown list should be selected as US dollars and the amount entered as 0.10



3. Designing for waterheating from renewable resources

Hot water use is difficult to determine as each person fills their bath differently or will take quick or long showers. The default values given in the hot water use table are taken from various sources and should give a good estimate of how much hot water is used in for a bath or during a 5 minute shower (power showers easily use twice as much). So if you happen to shower for 15 minutes at a time and your partner showers for 5 minutes, then you have to enter 4 in the times/day column. You can of course try and measure how much water you use per shower and modify the amount per activity column.

The seasonal variation in these activities are entered as times per day during the peak winter and summer month and the hot water use for the other months of the year are then calculated from a sinusoidal variation between these two extremes.

To add a new activity that uses hot water to the list, simply click on the ADD button at the bottom of the list and enter the various values into the row that will be added to the table.

The monthly hot water use values are displayed in a graph on the right of the table as are the winter, summer and average consumption values. When you click on the design board link in the menu on the left of the page, these values will be used as consumption values for each month and average values.

The climatic data is used to estimate the available solar heating energy per day at your location for each month of the year. This information is displayed in a graph with buttons which allow you to change the size of the system. The system size and relevant parameters are displayed with the graph. The solar energy is the estimated daily heating energy available at your location by making use of solar water heating panels which are tilted towards the equator from the horizontal at an angle equal to the latitude of your location with no shading during the day.

The dropdown list below the graph allows you to select either the heat energy or how much hot water can be heated to a temperature of 60 degrees Celsius with the available energy given the average ground temperature, which is assumed to be the inlet temperature of the water. A storage tank for the hot water can be selected and an additional fuel source chosen to heat water that cannot be heated by the available renewable energy. The shortfall of this amount of heated water from the required amount is indicated in various formats in a graph. The required hot water demand values are updated when you change consumption values on the energy use page. One option displays the monthly shortfall in kWh, which can be used to gauge how much natural gas would need to be consumed. Alternatively the amounts of LPG gas, oil or wood to make up the shortfall can be displayed assuming typical efficiencies using these fuels in a water heating system.



4. Assess the cost and savings of using renewable energy

The section at the bottom of each page will assist you in making a financial decision regarding your renewable energy design

You can choose the currency in which you want to work from the drop down list. You may also need to take a loan to finance the purchase and installation of the various renewable energy systems. In order for the loan repayments to be included in the cost of the renewable energy, you need to enter the interest rate at which the loan is borrowed as well as the term over which the loan has to be repaid in months.

To compare the renewable energy costs to the non-renewable energy costs, you need to enter how much the electricity and the heating energy costs you. If you are grid connected and your electricity costs you 12 pence (UK) per kWh then you need to enter the value in pounds, i.e. 0.12. The dropdown list next to the unit cost allows you to choose a different unit such as liters of diesel to operate a diesel generator if you are not grid connected. If you select liters of diesel, then you need to enter the price per liter, for example 1.20, here. A typical efficiency for a diesel generator and the energy content of diesel will be used to arrive at a price per kWh for comparison calculations. Similarly you need to enter a price per heating energy unit. So if your water is heated by electricity, you enter the cost per kWh electricity. If you use grid supplied gas and you have the price per kWh then you enter that with kWh selected in the dropdown list. If you use heating oil or LP gas you need to choose the appropriate unit from the dropdown list and enter the cost per chosen unit. Once again typical efficiencies for water boilers and the energy content for the chosen fuel will be used in the calculations.

Each of the renewable energy systems will have a system cost for the various panels, turbine, chargers an inverters. The product costs will be determined by the recommended retail prices for each product that you select. Each system will also have an installation cost which has to be entered. Various governments and regional governments provide grants towards purchasing a renewable energy system and the total grants received has to be entered in the space provided for each system. Various authorities also offer feed-in tariffs where the user is paid per kWh generated. This has to be entered in the space provided for each system. If you do not make use of a specific system, then simply leave the values as zero.

The results section gives various kinds of information to help you to make a decision.

The total electricity generation from the various systems that you included in your design in the design panel is used with the energy demand information that you entered in the energy use page to calculate how much electricity you will consume with and without the renewable energy systems. An average monthly cost is then determined for both cases which will include loan repayments, feed-in tariffs and the non-renewable electricity that has to be supplied to make up the shortfall between your electricity demand and the electricity supplied by the renewable energy systems.

The total hot water supply from the solar heating system that you included in your design in the design panel is used with the energy use information that you entered in the energy use page to calculate how much energy you will consume with and without the renewable energy system. An average monthly cost is then determined for both cases which will include loan repayments, feed-in tariffs and the non-renewable water heating that has to be supplied to make up the shortfall between your hot water demand and the hot water supplied by the renewable energy system.

The loan repayment component of the monthly costs and the annual feed-in tariff are given to give you an idea of how much the loan is costing you and how much you can earn from feed-in tariffs on your systems for the year. The monthly cost comparison is also given so that you can compare the total cost, which includes electricity and hot water, of non-renewable energy to that of using renewable energy during the loan term as well as after the loan has been repaid.

If you have logged in, the design name will be displayed on the left under Active Design. You can also add notes to the edit box on the left. All your values on the energy use page will be saved with your design when you click on the save button on the design board.



5. Saving your data

You have to log in to save your data or to retrieve a design previously saved by you. You can log in using the panel on the left hand side of the page by entering your email address and password and clicking the login button. If you have not saved your design before, simply enter your email address and your chosen password and click the login button. You will be sent a confirmation email to verify your account. Click on the link in the email to activate your account. Your email address will not be given to anyone else and is only needed to confirm that you are a real person with an email address and for reminding you about your password, should you forget it.

Once you have an account, you can save a new design by entering a name for the design in the box next to the add button and clicking on the add button.

If you have previously saved designs, they will be displayed in the dropdown list next to the save button after you have logged in. By selecting a design from the list, the designboard will be updated with your saved data. You can now continue with your design or modify it and save the updated design by clicking on the save button.

Important: Moving between pages

Any changes that you make to the design board page will be used in the other pages and will only be preserved and enable you to save your design (you need to be logged in) if you click on the menu link on the left of the page to move between pages. If you use the back button, this information will not be preserved.