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Calculation off-grid photovoltaic solar installation

To show the process of entering data into the application, let's make a practical example step by step to make it look like you are entering data and process variants.

It performs the calculation an off grid photovoltaic installation, use housing weekend.

STEP 1: We need to access the computing section of the website.


We select our location on the map

After you click on 'Select Map', we see a window with the Google maps."

Choosing the desired zoom level, we look at the location of the place you want to perform calculations. In this case the city of Bogota (Colombia)

Just click on the target, it returns to the previous screen with the captured location data (Longitude and Latitude), and also shows the optimum tilt and orientation (annual average) for that particular location.

Also, we can vary the angle of inclination, according to the possibilities of building (roof pitch, orientation South, etc ...). For this case, the following angles are chosen.


We can choose the type of power between AC and DC. Normally, if it is a home, for the current type of appliances and fixtures, choose alternating current, even if it were a boat, caravan, solar irrigation, or even a small house or application, we could choose DC option.

As we know, not all countries use the same voltage power, with voltages of 230 volts and 110 volts the most common.

How the installation is for Colombia, where the domestic voltage is 110 volts, choose the voltage and alternating current.


At this point, we chose to have housing consumption we want to analyze.

Do it click 'appliance', we get a screen where you can choose the appliance, the hours of daily use, the energy consumed and the consumption factor (according to the efficiency of the appliance).

If the appliance is not listed, you can add the tab 'other', and write the name of the device as well as the other parameters.

Clicking on 'Close and Save', it returns to the previous screen, to then access the window of 'Enlightenment'. Removing or adding elements, as in the appliance.

In the end, for our case, we would have the following summary:


For better optimize the installation, you must know the utilization rate of consumption.

Is not the same, or have the same needs for equipment, housing everyday a sporadic use (weekends, holidays, etc ...).

In our case, we chose the weekend option.

Also, we can choose the percentage of use for months, then, may have homes that are not used in certain months of the year.


Once elected, the initial parameters. We click on the 'Calculate' button.

Once elected, the initial parameters. We click on the 'Calculate' button.

We get a more detailed menu, where we will be able to detail the installation dimension and choose the equipment that best suit the installation, and the local market (brands, etc ...).


In this section, we can only choose the system voltage. By default, the program chooses the recommended option (12, 24, 48), based on energy demand per day. However, this voltage can be changed, at the whim of the user.

Other data also show that, although you can not change in these boxes, if they can vary, depending on the choice of consumption and other data that will come later.

In our case, we chose the same you provided the program as it will generally be the most appropriate ..


The election of the photovoltaic field, is directly related to Real energy daily, with the performance ratio (losses in cables, battery, DC / AC conversion, etc .....) and the chosen controller. So if we change controller changes the efficiency of the photovoltaic field and possibly the number of units required.

As observed in the capture, first shown the optimum inclination annual consumption. This inclination, once known consumption, is recommended by the website.

If we place the mouse over it, will give us other inclinations to bring more knowledge and that is the most appropriate choice (annual optimum inclination worst month). The orientation and inclination angles may vary returning to 'system data'.

Second, it shows the photovoltaic power needed to meet the energy demand of a drinking day. To this fact it has already been applied performance ratio and peak sun hours (HSP) calculated for the situation and pitch and yaw angles chosen.

The following shows the characteristics of the module. In this step, we can change the module, either by choosing one from the list, or adding our own module (for the latter, you need to register, but registration is very quick, and very few data are requested).

To add to a new module, after registration, will the following menu:

As noted, you need to insert a set of data, and insert the data sheet in pdf, which is very easy to get from the manufacturer's website. This, we think it necessary, to verify and validate input therefore have design errors will not leave the right way.

Returning to the previous screen, we see a line of color and a percentage. The color of the line, if green, tells us that the equipment and configuration, are suitable for this system, otherwise you will get a red line, warning that we must make changes in equipment and / or configuration. Shows the percentage degree of optimization of the equipment according to the needs.

This form of display optimization, it is common to other equipment.

Then, one can vary the number of elements in series and in parallel, depending upon the chosen maximum voltage regulator

If we vary these parameters will vary the degree of optimization discussed.

When making changes, disappear the details of the equipment, having to press again the 'Calculate' button, to recalculate with the new parameters.

This action will be necessary to effect it, every time you change any of the parameters in any of the equipment (module, controller, batteries, etc ...).

As observed in the capture, by changing the number of units in parallel, the percentage varies upward optimization.


The charge controller determines the charging efficiency of the photovoltaic field, so that if this equipment is less efficient, should increase the photovoltaic field and vice versa.

On the screen will appear governor characteristics, If we want to change or enter a new one, we can do it the same way as explained in the photovoltaic field.

In this section, you can only change the team and the program will fit the needs of the PV array.


The battery choice will be determined by the autonomy they want to give (in days), and the depth of discharge. By default the program displays three days of autonomy and a depth of discharge of 60%.

In our case, being setup for the weekend, we will vary to 2 days of autonomy, maintaining the depth of discharge to 60%. The program enables depths of discharge from 50 to 70%.

By having changed autonomy, we have changed the actual battery capacity, so we changed to a battery that is approaching to our needs.

Can also change the number of units in parallel, if you want to use 12 volt monoblock batteries, to reach the necessary optimization.


The choice of the investor, is determined by several factors: Tension System and consumption (as defined), the coefficient of simultaneity and a safety factor.

The simultaneity coefficient ranges from 0-1, with 0 for all loads off and 1 for all loads on, by default the program displays 0.7, but may be varied to convenience. The safety factor is a parameter that tries to keep the rating of the product is equal to or greater than necessary, avoiding that equipment operates at 100% capacity. Are recommended values ​​up to 80%.

With the correction of these parameters, helping us, again, with the bar of optimization, we can choose or add the equipment that best suits our needs.

n our case, we left the default program has calculated.


After you enter all data press the button 'Calculation Report'.

We will get a new screen with all the data that we have introduced and detailed explanation of the calculations performed.

This report can be printed and used to purchase our PV system with a better understanding of needs and equipment.