FAQ

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.

GeoThermal vs GeoExchange, what’s the difference?

These terms are often used interchangeably, particularly in the context of heating a building.  In reality, the term GeoThermal implies the direct use of heat generated at great depths below the Earth's surface.

What ends up being called GeoThermal in the building heating industry is more aptly referred to as GeoExchange, which is a central  heat pump based heating/cooling system that pumps heat into or from the ground or a body of water.  These systems are also  called Ground Sourced , Water Sourced or Earth Coupled Heat Pump Systems.

What will solar pool heating do for me?

Solar pool heating will extend you pool season a few weeks on either end of the season and will greatly reduce your heating costs.

With an unglazed collector, how big does my collector need to be?

In BC, the general rule is approximately 50% of the pool surface area is required in collector area. Deeper pools will be performing better with a higher percentage of collector area. Other factors such as such as wind can increase collector size, if your site has a natural breeze the efficiency of the collector will be decreased because it is unglazed.

With an off grid system what happens when my batteries are charged and I don’t need any more energy?

Once the batteries are charged a controller sends the energy to what is known as a diversion load, also known as a dump load. This is usually a water or air heater. Such a diversion load is sized to handle the full peak production capacity of the turbine.

How do I determine the wind speed for my site?

There are a few options here, one is to purchase a retail weather station and install it where it will provide representative data to your site. Keep in mind that if installed on your house it will show lower figures than at the actual installed height of a wind turbine. The another option is to purchase a small wind turbine and install it and monitor the power it produces, this option costs more however it also offers you a small amount of power which you can use on an isolated load.

Why do I need a water license?

Water is a limited resource and in BC is owned by the crown. The authority to divert and use surface water is obtained by a license. The Water Stewardship program is a means of protecting the water and facilitating a sharing process for this limited resource while continuing to meet the need ecosystem which it supports.

For information on the water stewardship division please check out their website.

Here is a link to Water License Application Forms

How much of the flow in the creek can I use in my micro hydro system?

The short answer is not all of it, the correct answer comes from a specialist which will look at the factors such as whether or not the creek is fish bearing and calculate what the minimum in stream release will need to be in order to sustain the natural eco-system within the creek. This number is often expressed as a percentage of the mean annual discharge (% MAD).

How do I figure out how much power I can generate from my creek?

The micro hydro power equation:

Power [kW] = Flow (l/s) * Head (m) * Constant * Efficiency

The constant is the specific density of water (1000 kg/m^3) times the gravitational constant (9.81 m/s) all divided by 1000 which is 9.810 (many people in the trade round this number up to 10 which in end doesn't through of your numbers)

Efficiency of the system is commonly assumed to be approximately 50% until designed. This may seem low however this is the efficiency of the penstock, turbine, generator and balance of system.

Example:

Power [kW] = Flow (l/s) * Head (m) * Constant * Efficiency

2.5 l/s * 30 m * 10 * 50% = 375 Watts

How much head do I need for a micro-hydro system?

The more the better, due to the relationship of flow and head more head is always better. Typically micro hydro systems have head anywhere 3 - 300 meters. Please read the power question and answer for more information.

How much flow do I need to generate my own power?

Micro hydro systems need flow and head in order to generate power. If you have very little head you need a very large flow and inversely if you have lots of head you don't need a very large flow. So there is no simple answer to that question, please see the power question.

Where can I put the tower for my wind turbine?

Towers need to be located in an area where there is an area known as the fall zone around the tower which the radius is the same as the tower height. This is a safety precaution so that in the event of the tower falling it does not fall onto your or your neighbors’ house.  Depending on the type of tower chosen crane access may also be required.

What are my options for towers?

There are a few different types of towers. There is the mono pole, the guyed pole and the trussed towers. Trussed towers are not very common anymore due to their aesthetics. Guyed poles are easily serviceable and do not require a crane for installation. Mono poles are the best in terms of aesthetics however require a crane for installation and servicing.

How high should the tower be?

The best case is to have the tower at least twice as tall as the nearest obstruction. The wind speed increases the further away from the ground and obstructions which is due to friction. We recommend a minimum pole height of about 30m. In Europe 40 meters is the shortest pole from most manufactures.

Why is wind turbine cut in speed so important?

Just like an airplane wing there needs to be a minimum wind speed before there is enough lift to take off. Wind turbines also need a certain speed of wind in order to start producing any electricity. Some areas have average wind speeds below most manufacturers cut in speed. This is also why elevation above obstructions is also important. If you would like us to assess the potential of your site please fill out the webform.

How much power can you get from the wind?

Power is directly related to the cube of the wind speed. Wind power increases exponentially with wind speed. In order to generate power the wind speed must be above the cut in speed of the wind turbine. The higher the tower and the least obstructions will result in less turbulence and a higher wind speed and therefore more power. In order to calculate accurately you need wind speed data from on site or from the nearest weather station. If you would like us to assess the potential of your site please fill out the webform.

With a grid tied system, what happens if I am producing more electricity than I am using?

With a grid tied power system any energy produced that you don't use is sold to BC Hydro through an agreement know as the Net Metering. BC Hydro will credit you for electricity that you provide to their system and if you have a large system or use very little energy you could be net zero. Net zero means over the course of the year you produce all of the energy you need.

With a grid tied system, what happens when the power goes out?

On a basic grid tied power system the inverter is dependent on the grid.  You would be without power if the grid signal is lost. If you invest in a battery backup system, when the grid goes offline you will be the only house in your neighbourhood with electricity!

What if it can’t fit on my roof or what if my roof isn’t facing south?

If your roof is not a suitable location for photovoltaics, we can mount the modules on racks or poles. Racks are typically stationary but they can be made to tilt for seasonal optimization. Poles can be stationary, however poles are often used with trackers which allow the modules to follow the suns path through the day.

Can it go on my roof?

Yes,  We have installed photovoltaics on all types of roofing including:

  • metal
  • asphalt
  • cedar
  • tile
  • flat

What is “BALANCE OF SYSTEMS”?

Balance of systems is the components which complete the system. Photovoltaic modules are the means of collecting the suns energy, however in order to use the electricity in our houses we need to condition it into AC (alternating current) so that it is compatible with our appliances. There also needs to be components for safety. Balance of systems typically includes combiner boxes, breakers, disconnects, inverters and batteries when off grid.

What is “GRID TIED”?

When a power system is "grid tied" it is connected to the utility provider such as BC Hydro. By connecting to the grid you do not need batteries to provide peak loads and you can sell excess electricity to BC Hydro through the net metering program. Batteries can still be part of the system if you wish to have a backup system.

How big of a power system do I need?

That depends on your goals and if you are connected to the grid or not.

Grid tied systems can be as large as you want. Often budget or emission offsets are influencing factors in the final decision.

Off grid systems are sized based on a load calculation which comes down to a balance of lifestyle and budget.

Can a wind turbine be put on the top of my building or house?

Yes, We are a dealer for a roof mounted turbine known as Swift. These turbines are designed to be quiet and perform well in turbulent wind which is associated with being close to buildings. These are popular in commercial application and we warn potential residential customers that their may be some vibrations detectable from within the house.

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