Solar Hot Water – How Big a System Do You Need to Supply Your Home Hot Water Needs?

When considering Solar Hot Water (SHW) systems,it also pays to look at your home water usage.  While it is great to save money on a solar hot water system, it seems unreasonable to continue wasting a valuable resource.  Water supplied to your home has take energy to store and pump it to your door, no matter whether its is from a reservoir or ground water. So, rather than choosing a storage or heater unit on size, take a look at your real needs.  However, the fact is that a SHW unit can likely provide most if not all of your needs if properly sized and set up.  Even snowy climates an benefit from solar hot water units.  When you combine a solar hot water system with solar power, you can make very large savings on power consumption.  The great thing is, that if you are handy, DIY solar projects, either hot water or solar power, are quite achievable.

If we consider the number of people in the home, we can work back to typical usage volumes and from there to the size of the storage unit and the solar collector area.
A storage tank of  200 liters (50 to 60 gallons) is about right for up to three people if used with some awareness of your usage.  Larger systems of  300 liters (80 gallons) suite three to four people. With bigger families, you will need larger storage or possible some kind of “booster” to make up nay “solar shortfall”.  Depending on what you set your systems temperature at and the temperature of the incoming water, your system will need to reflect the size of the collector.  If you are living in snowy climates, the colder water takes more to heat and there will be heat loss unless the unit is properly insulated.

What does this mean in terms of collector sizes?  It is typical to allow about 2 square meters for each person up to 2 people, and after that you add one square meter for each person.  This allows for the seasonal variation of sun hours and solar heating. Lets face it, having a little more solar hot water capacity is always welcome especially when the heating is free.  The added cost of the extra collection unit adds little to the overall installation.  If you live in snowy climates or areas of lower sun intensity or hours such as the lower northern or southern latitudes, then you would always err on the bigger size of collector.