FAQ

Solar Hot Water

How does a solar hot water system work?

Solar Hot water systems convert light into heat through solar collectors mounted on your roof.  A heat transfer fluid is pumped through the collectors and back down to a heat exchanger located at your solar tank.  The heat exchanger transfers the thermal energy from the fluid to the potable water in your solar storage tank. 

The solar storage tank is connected to your regular hot water tank, providing solar heated water to the traditional hot water system.  On clear sunny days the solar system can heat the water up to working temperature (55˚c - 60˚c) and on cloudy days it acts as a preheat to the regular system.

How much sun do I need?

Generally, a solar window of about 5 hours a day throughout the year is recommended for optimum collection.  Please fill out our webform for a site assessment of your property.

Do we get enough sun in B.C. for these systems to work?

Yes, solar hot water systems work very well in our climate and can provide between 50%-60% of our annual hot water.  On clear sunny days we can expect a solar hot water system to provide 85%-100% of our hot water. 

On the flip side, because we can experience long spells of dark and cloudy weather (especially in the winter) our systems act as a preheat (producing some but not all the energy) to your standard hot water system.  The solar hot water system acts a preheat to the boiler, tempering cold mains water before it enters the hot water tank (or on-demand boiler) resulting in less electrical or gas consumption.

As a testament to Solar working in our climate, we can look at countries like Germany and China where solar hot water is a standard appliance in the home.  These countries are the leaders in Solar Hot Water systems and here in Southwest B.C. we receive more sunshine than them.

Can you install solar hot water on my old house?

Yes, in fact the majority of systems we install are retrofits. The main considerations needed are:

  1. South facing roof space for collectors
  2. Space in your mechanical room for the solar preheat tank

We run our insulated line sets (piping from collector to mechanical room) in the interior or exterior of the building depending on difficulty and disruption to the living space.  Browse our photo gallery to see some examples of our work.  If you would like us to assess the potential of your building please fill out the webform.

Does SDHW work with on demand hot water heaters?

Yes, it works very well and means your on-demand heater will consume less gas or propane.  It is important to check the maximum entering water temperature the unit can receive.

Can it go on my roof?

Yes we have installed collectors on all types of roofing including:

  • Metal
  • Cedar
  • Asphalt
  • Tile
  • Flat

How much hot water will my system provide?

Your solar hot water system can provide between 50-60% of your annual hot water load.

What is the difference between a Flat Plate Collector and an Evacuated Tube Collector?

Flat plates have one large absorber plate in an insulated box with a sheet of glass covering the collector. Some flat glazed collectors use tempered glass and some use a special solar glass. Solar glass is also tempered, but it has lower amounts of iron in it making for more radiation passing through the glass. Most absorbers are selective surfaces which simply mean they have coatings which allow more energy to be absorbed than emitted. Flat plate collectors have a low profile and when mounted on roofs look very much like sky lights.  Flat plate collectors work very well in the moderate climate of Southwest British Columbia.

Evacuated Tubes collectors have a series of vacuum bottles with heat pipes inside them. The vacuum insulates the absorber from the air much like the glazing on the flat collector however it is offers a slightly more insulation. The heat pipe is a small pipe full of refrigerant which transfers the energy collected from the length of the pipe to a bulb on the top. This bulb is fitted into a wet or dry manifold which transfers energy into the working fluid. Tube systems have higher efficiency when dealing with very high temperature differences like colder climates.

What happens when it is below freezing outside?

In order for solar hot water to function in our climate every system needs freeze protection.  Our system utilizes a 50% food-grade glycol as the working fluid which provides freeze protection down to -30˚C.

Can I heat my house with the solar hot water system?

Yes, solar heating can be done but a seasonal storage system is required.  In B.C., we heat in the winter when our solar resource is at its minimum.  To overcome this you can either oversize the amount of collectors on your roof or increase your storage.

In the first scenario of over sizing your collector array, you develop a problem in the summer as to what to do with the excess heat generated by the large system.  It can become an issue of inefficiency to continually dump heat from the oversized system in the summer.

The second scenario involves creating a thermal storage system (thermal mass) to store heat in the summer and shoulder seasons, and pull it out in the winter when you are heating.  This can be combined with a heat pump, or gas boiler.  The thermal storage must be sized to adequately store enough heat to make the system feasible.

What happens when my tank is up to temperature and it is still sunny out?

Solar hot water appliances needs overheat protection to prevent the system from stagnation condition. Stagnation of the thermal fluid on a sunny day can cause the fluid to boil and breakdown.  The Enerworks Solar collectors feature a patented, passive self-regulating mechanism that allows hot air to vent preventing overheating when collector temperatures are in excess of 125˚C.

Will the glazing break if covered with snow or small branches fall on it?

The Enerworks collectors we use have special low-iron tempered glass. The tempering of the glass makes it much stronger and is the same as glass used for skylights, sliding-glass doors, and automobile windows.  The Enerworks collectors are fully tested and CSA approved.

What is the life span of the system?

Solar hot water systems have been known to last in excess of 25 years and are simple and inexpensive to maintain.

Can I heat my pool?

Yes, both glazed and unglazed collectors can be used effectively for pool heating. See our page on Solar Pool Heating.

Can I heat my hot tub with solar?

Yes, technically it is possible but may void your hot tub warranty.  In general it has been found to be more cost effective and efficient to heat your domestic hot water.

Am I eligible for any Grants?

Yes, most likely you are - check out our Grants and Loans Page

What is the payback time on a Solar Hot Water System?

Several factors affect the payback time on a solar hot water system including system cost, hot water consumption, regular fuel type and inflation of fuel prices.  General estimates for payback is between 5-15 years depending on these factors.

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