Solar Power Calculating Tools Online

There are a lot of online solar power calculating tools that can help you size your solar power installation. These tools are great in order to determinate how much solar power you'll need to run your home appliances.

NREL's PVWatts® Calculator - Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations.

Off-Grid Solar System Calculator - Wholesale Solar custom designs Off-Grid Solar Home Power Systems. Calculate your appliance needs, get an approximate system size, learn what Off-Grid system is best for you!

CalculationSolar.com - free online platform, which perform calculation of photovoltaic solar installations anywhere in the world.

Solar Calculator (EnergySage) - Use this solar panel calculator to quickly estimate your solar potential and savings by address. Estimates are based on your roof, electricity bill, and actual offers in your area.

Solar Calculators (altE) - a number of useful tools to help estimate your electricity usage, sizing for your grid-tie or off-grid solar power system and more.

Solar Panel (Power) Calculator - online tool used in electrical engineering to estimate the total power output, solar system output voltage and current when the number of solar panel units connected in series or parallel, panel efficiency, total area and total width.

Photovoltaic power calculator - quick online calculation of solar photovoltaic power and energy (PV panels or systems).

Solar Power Calculator - this tool will help you determine the yearly savings you will earn when installing  a PV solar system for your home.

PV Calculator | PVshop.eu - PhotoVoltaic calculator for grid connected and PV off-grid systems in PVshop.eu. (EU)

Solar Energy Calculator | Energy Saving Trust - use the Solar Energy Calculator for an idea as to the benefits you may see from installing a solar PV system. This tool gives estimates based on information you provide, and a number of assumptions to indicate potential benefits. This is to help you decide whether a PV system is for you. (UK)

Solar Power Calculator   - an independent resource for calculating your solar power requirements and potential monetary savings. Find out if solar is right for you. (AU)

Amp & Watt Hour Calculator & Solar System design Tool - This Amp &Watt Hour Calculator is provided to help you make some basic electrical calculations and design your own solar power system. (AU)

Keep in mind that the above calculators are useful as a general guide for sizing your solar electricity system and you probably will also need advices and help from professionals.

Calculating Your Solar Power Requirements

One of the most important thing you have to figure out when planning a solar power installation is the size of the solar system you’ll need.

First of all you need to calculate how much power you use on a daily basis. Your electric bill will be of help for this or you can make your own calculation. The power consumption of appliances is given in Watts (eg 21" fluorescent light, 13W). To calculate the energy you will use over time, you have to multiply the power consumption by the hours of use.

The 13W light fitting, on for 2 hours, will take 13 x 2 = 26WH.

Repeat this for all the appliances you wish to use, then add the results to obtain your daily power consumption.

You have to determinate also how much energy your battery can store. Battery capacity is measured in Ampere Hours (Ah). Convert this to Watt Hours by multiplying the Ah figure by the battery voltage: for a 20Ah, 12V battery the Watt Hours figure is 20 x 12 = 240WH.

The more energy you take, the faster the battery discharges. Keep in mind, however, that deep cycle batteries which are usually used in solar power systems, should not be discharged beyond 50% of their capacity. i.e. 50 % capacity remaining. Discharging beyond this level will significantly reduce the life of the batteries.

To calculate the energy your solar panel can supply to the battery, multiply Watts by the hours exposed to sunshine, then multiply the result by 0.85 (factor to allow for normal system losses).

For example, the Solar 40W panel in 4 hours of sunshine, 40 x 4 x 0.85= 136WH. This is the amount of energy the Solar panel can supply to the battery.

On the basis of all these calculations you'll determinate the size and number of solar panels you'll need, the number of batteries, power inverter size, etc.