Do Solar Water Heaters Work In The Winter?

In the last decade, solar technology has started to become more commonplace in households across the country. Because of this, an increasing number of homes and businesses are seeing the benefits of using solar energy to heat, power and sustain their spaces. While it continues to gain popularity, there are some misconceptions and questions about how it works, especially in the winter months when the sun is not as strong.

A big question for those who are not well versed about solar power is how the panels work in the dead of winter. This is a very valid question if you live in a temperate region and aren’t very familiar with solar. Before you install your solar water heater, it is good to get these questions answered. If you are thinking about getting a solar water heater, here are the types of solar water heaters and how they work against the harsh cold of winter. 

How Solar Heaters Work In The Winter

The first thing to remember is that solar water heaters are not meant to completely replace your water heater. A typical solar water heater will be able to heat 60-80% of the water you use over the course of that year. From the months of April to September, most of your hot water will be solar heated. 

In winter, the percentage of your hot water heated by the sun can drop to as low as 20% since there are shorter days and weak sun in December. That’s why practically every solar water installed in the US will be connected to a backup conventional water heater to ensure that your hot water needs continue to be met even in January.

How Does A Solar Water Heater Work?

Solar water heaters come in a wide variety of designs, all including a collector and storage tank, and all using the sun’s thermal energy to heat water. Solar water heaters are typically described according to the type of collector and the circulation system. Each is unique and while they all have the same function, some work better for larger families and some work better in warmer climates. Here’s a look at all the different designs and types to help you choose which one would be best for your home or business.

Types Of Circulation Systems

Here we have the types of systems and how they work and deal with cooler temperatures. Make sure you choose the right system for your region and climate. 

Direct Systems

Direct systems circulate water through solar collectors where the water is heated by the sun. The heated water is then stored in a tank, sent to a tankless water heater, or used directly. These systems are preferable in climates where it rarely freezes. Freeze protection is necessary in cold climates.

Closed-loop/Indirect System

A closed-loop (also called indirect) system uses a non-freezing liquid to transfer heat from the sun to water in a storage tank. The sun’s thermal energy heats the fluid in the solar collectors and then the fluid passes through a heat exchanger in the storage tank, transferring the heat to the water. The non-freezing fluid then cycles back to the collectors. These systems make sense in freezing climates.

Active/Forced-Circulation System

An active (also called forced-circulation) system uses electric pumps, valves and controllers to move water from the collectors to the storage tank. These are quite common in the US. 

Passive System

A passive system requires no pumps because it uses natural convection to move water from the collectors to the storage tank as it heats up.

Collector Types

Batch Collector

Also called Integrated Collector Storage (ICS) systems, these heat water in dark tanks or tubes within an insulated box, storing water until it is drawn. These are generally not recommended for cold climates.

Solar Flat-Plate Collector

Flat-plate collectors typically consist of copper tubes fitted to flat absorber plates. The flat-plate solar collectors are probably the most fundamental and most studied technology for solar-powered domestic hot water systems. Flat plate collectors are typically sized to contain 40 gallons of water. Two collectors provide roughly half of the hot water needed to serve a family of four. 

Evacuated Tube Collectors

Evacuated tube collectors are the most efficient collectors available with each evacuated tube similar to a thermos. These collectors can even work well in overcast conditions and operate in temperatures as low as -40°F. Evacuated tube collectors can cost twice as much per square foot as flat plate collectors.

Upgrade and Save with Solar!

Independent Water Service has proudly been serving Yakima and Kittitas counties since 1986. We now serve as your local solar water heater provider as well and are here to help you with all of your solar heating needs. We provide easy to install and maintain systems that save you time and money in the short and long term with many benefits to you and your home’s value. 

To get your free quote, give us a call today with any questions you may have on our solar powered heating systems. Independent Water Service’s expert technicians are here to provide you with the best service and help you save money with solar power.