Saturday, December 20, 2008

Solar Christmas Lights for a Greener Christmas


In accordance with the Holiday Spirit this post is all about having an environmentally friendly and green Christmas just by purchasing a set of outdoor solar Christmas lights to illuminate your home.
Solar Christmas Lights
Solar Christmas lights can help you save electricity and money, and they are convenient to use because they don’t have to be plugged in and there are no wires to worry about. Solar Christmas lights use LED or Light Emitting Diode technology instead of filament bulbs, which not only saves power and creates vivid light, but also stays cooler than typical bulbs and thus eliminate danger of fire.

When buying Solar Xmas lights you should be aware of charging times and lighting times. On average the outdoor solar lights will illuminate for about 7-8 hours while a few brands tout 12 to 15 hours of illumination time. Keep in mind that illumination time is affected by how fully the solar panel is recharged during the day. Also, an exceptionally cloudy, dark day will reduce the nightly illumination time.

Solar Christmas lights are becoming very popular, which has led to increased availability and design choices. They are available in many different shapes such as stars, bells, hearts, snowmen, snowflakes, Santa designs, and more.

If you want to impress your friends and neighbors you may look for some really impressive solar Christmas lights - those that come with a remote control and with options that allow you to create your own light show. Some solar Christmas lights even let you change the level of light output or change the color of the lights with the remote control.

So, buy a set of cool energy efficient solar Christmas lights and enjoy a Greener Christmas with your family and friends!

Friday, December 19, 2008

Estimate Your Roof's Solar Potential with RoofRay


Speaking of useful online tools, I should mention also a solar array modelling service, provided by RoofRay on their homepage. They use Google Maps and various other information to help you estimate the solar potential of your home or business before taking the financial plunge to invest in solar energy.

Using the site's modelling tools, you can evaluate how much solar energy your home could capture and how that would affect your monthly bills based on past weather conditions, current electricity bills, the slope of your house, as well as how many panels your roof can hold.

With Google Maps you can calculate the square footage of your roof and build virtual panels. Then RoofRay estimates the output potential of the roof, costs of installation, and ROI. Another section shows existing installations that have already been completed by other people, including specifics of the roof used and total peak power.

Of course, RoofRay does not replace solar experts, but undoubtedly could answer some of your basic questions, and generally it is a quite interesting online service that deserves our attention.


Updated 2021: Seems like this site is not working anymore, so you can try:      Solar Calculator (,  SUNSEI Solar Design Tool & Google Project Sunroof

Monday, December 15, 2008

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!
 - 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 | - P
hotoVoltaic calculator for grid connected and PV off-grid systems in (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.

Thursday, December 11, 2008

Calculating Your Solar Power Requirements


Solar Power System

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.

Tuesday, December 2, 2008

Basic Things to Consider Before Buying a Solar Electric System


Installing a solar power system requires very careful initial planning. First of all, you need to know exactly how much electricity your home uses each month. You may look up in your old electricity bills but also you should think about how your electricity needs will change over the next 10 years.

Solar photovoltaic panels can be installed on the roof, along a wall of the property or as standalone systems. If you are planning to install them on your roof, you need to make sure that the roof is strong enough to hold a solar panel because some of these panels can be quite heavy. A roof inspection (and any necessary repair) is recommended prior to a PV installation. Another thing you need to know is that the more sunlight modules collect, the more electricity they produce, thus the more energy your home will receive. Make sure that the roof (or wherever you intend to install your solar panels) is clear of any obstacles, such as trees or buildings, especially during peak production hours between 10am and 2pm.

Ideally, a solar system will go on a south/southwest-facing roof, although east and west facing roofs are good candidates, as well.

You should decide whether your system will be grid-connected, off-grid or hybrid. With a solar PV system connected to an electric distribution system (grid-connected) you can receive back-up power from it when your system doesn’t produce enough energy for your needs. When your solar PV system produces excess power, that electricity can be send back into the grid, and your local utility is required to buy it from you.


A grid-connected solar power system is easily integrated into the existing electrical infrastructure of a house and the system can provide decades of reliable and environmental friendly electricity production.

A stand-alone (off-grid) solar PV system is independent of an electricity distribution grid operated by a utility. The electricity is provided by solar power alone and stored in a battery for later use. Such systems typically make sense in remote locations.

The average solar PV panel last approximately 30 years and many manufacturer warranties last for up to 20-25 years. Solar PV panels are designed and installed to be low-maintenance. However, it is very important to have your solar panels cleaned regularly because they benefit from being hosed off with water twice a year, especially after long periods without rain. Dust or dirt may cause a 10-15% reduction in their efficiency.

Before buying and installing the panels it is also essential to make sure that you understand the installation regulations in your local area. In most cases it is wise to check with the local authority before installing your solar electric system.