A good way to make your own renewable hot water and cut down on your electricity bill is to install a solar water panel system at home. But before going out and buying any system, here are a few tips to help you find the best option.

1. Number And Size Of Panels

A solar water panel is usually 1 meter wide by 2 meters long. Depending on the how much hot water you need, 1 to 3 panels is usually enough. The number panels needed can easily be calculated by a reputable solar installer.

If your current solar how water system does not make the water hot enough, always first try adding more panels to the system before getting a new system. To make sure the new panels will fit the old system, it is best to use the same supplier.

2. Types Of Panels

There are 2 main types of solar water heating technology: flat plate and evacuated tube technology.

Flat plate technology, the older of the two, is also the most affordable and widely used. Though it is not as effective at heating water in overcast or windy conditions, it's solid design and fast return on investment make it a good solution in sunny, warm regions.

Evacuated tubes a.k.a. "concentrated collectors" have two advantages: they are effective at heating water in weak sunlight and they are less prone to frost damage in winter. The cons of using concentrated collectors are that the tubes cost more and can be easily damaged (but they can be replaced).

3. Tank Location

Your solar water heating system can be setup in two ways: either with the tank inside, separate from the panels, or with the tank on the roof directly above the panels.

On-roof Tank: a.k.a. "Passive Solar Hot Water System"

Here, the tank is installed directly above the panels on the roof. It is a passive system since it uses only water pressure and natural physics to keep the water flowing - as water is heated and rises up the tank, it draws in cool water from the mains, which flows through the solar heat collectors and into the tank.

If the tank is mounted too far away from the showers and other hot water outlets, it may not be the best option. The further the tank is from where it is needed, the longer it will take to receive the water, and it will be slightly cooler from traveling through the pipes. A tank jutting out from a rooftop is not a very aesthetically appealing sight either.

Indoor tank: a.k.a. "Split Solar or Active Solar Hot Water System"

Here, the solar collectors are on the roof, with the tank installed inside where your current tank is. For the tank to collect the heated water, a small electric pump is needed. Though power is used to pump the water in the system, the cost is recovered from increased energy savings, since the indoor tank is protected from the elements and insulated the hot water better.

The benefit of an active system is that you can place the tank in the best position, so that hot water is quickly available. Also, there is usually built-in frost protection, where in cold conditions warm water is pumped back into the collectors to prevent them from frosting up and cracking.

The only real disadvantage of active solar water heaters is their cost.

4. Coatings On The Panels

A variety of coatings can be put on a solar water panel, which determines how well the water is heated and how long the panel will last:

Black Paint: This is the lowest grade coating. Though is is very cheap, a lot of strong, direct sunlight is needed to heat the water. It is alright to use it in hot, sunny climates, but it will generate insufficient heat in cooler, temperate regions.

Anodized Coatings: Also known as "selective coatings", they are very common in residential water heating systems. The solar water panels are anodized with aluminum oxide and sometimes copper. When observed under a microscope, the coatings create a very uneven surface, resulting in a greater surface area for the sun to shine on - this allows the panels to absorb as much as 80% of all solar heat. Anodized coatings can be damaged easily, but their protective glass cover helps them last for years.

Black Chrome: This is an advanced technology used in U.S. households without sun-facing rooftops. Like selective coatings, black chrome is excellent at absorbing any sunlight, even in cloudy conditions.

The only problem with this type of coating is its harmful health risks during the manufacturing process. This has made it less popular in Europe, where better technology, such as selective coatings, is available.

5. Frost Vulnerability

In extremely cold regions, frost can be a factor. In winter, heavy frost can freeze the water in the panels. As the water freezes, it expands and could potentially crack the panels. This can be avoided in two ways: either with closed-loop systems or with frost valves.

If you live in a region that has gets much frost, then a closed-loop system is best. Here, instead of water, glycol is placed in the panels. As the glycol is heated it is transferred to a heat exchanger where it heats the water. Though closed-loop systems are more expensive, glycol never freezes, making the panels insusceptible to frost damage.

If you only experience occasional frost, a frost valve is sufficient. As the temperature drops, the frost valve opens, allowing water to be released out of the panels and preventing frost damage. Just make sure the frost valve has a manufacturer's warranty before investing in one.

So what have we learned?

Before you plan to buy and install any solar water panel system, ask yourself the following questions to help you make an informed decision:

• How many people live in the house? - since the average person needs fifty liters of hot water a day, this will help you calculate the number of panels and the size of tank needed.

• Where is the hot water needed in the house? - if the panels are far away from the taps, it would make sense to install an active solar water heater.

• Does the roof receive a lot of direct sunlight? - this will determine what kind of coating to get on the collectors.

• Are winters extremely cold? - if not, then a frost valve will suffice.

• How much can I afford to spend, and how long am I prepared to wait to get my return on investment?

So you can see, there are many deciding factors when getting a solar water panel system for home. With your new-found knowledge, hopefully you can buy the right system for your circumstances and not get ripped off in the process.