Solar Water Heaters, Are You Making Enough Saving From Your Installation?

Written by Raphael Osoro


Solar Water Heating is all about converting the “Sun Power” into “Heat” for water heating purposes, this is done using a solar thermal collector. SWHs are mostly used in “residential” areas and some industrial applications. The SWHs could be stand alone or hybrid together with other solutions such as electricity or gas. As of 2017, global solar hot water capacity reached 472 GWth.

How does this technology work?

When facing the sun, the collector heats a “working fluid” which goes to a “storage system” for later use. SWHs are of 2 types. 

  • Active – a pump is used for circulation
  • Passive – Natural Convection-Driven

They could use only water (mild areas), a mix of both water and a “non-freezing working fluid” or only the “non-freezing working fluid”. These mediums are warmed directly or with help of “light-concentrating mirrors”. 

Are You Making Savings From Your Solar Water Heater?

Energy bills can prove to be a nightmare especially when you don’t really understand what accounts for the high consumption. You would actually be surprised that 40-60% of your energy bills come from water heating. In a bid to reduce the high energy consumption arising from water heating, homeowners usually invest in solar water heating. A solar water heater basically consists of a collector panel and an insulated hot water reservoir. The collector panel normally has good thermal absorption properties which enable it to heat water directly using the sun’s rays. The heated water is then stored in the hot water reservoir for later user. This normally saves the end users on electric bills since they eliminate 40-60% of their bills that arise from water heating using electricity. However, you might have installed a solar water heater but still haven’t had a fair share of its numerous benefits.

Image of a typical solar water heater

Are you paying high electric bills even after having a solar water heating system installed in your home? Are your water bills getting higher since the installation was done? For most homeowners, the problem ends with the completion of the installation. Most users hardly know that they need to learn how they are making savings and how they can make best use of their systems in order to have a return on their costly investment. This article will touch on some of the common mistakes that make the user dig deeper into their pockets to fund their high electric bills even after a solar water heater installation. With relevant information, the end user will have less than a five-year payback period on their investment.

How often is your Backup Heater Running?

Most of the systems come with this wonderful smart controller that basically controls when the backup heater should come on in occasions where water has not been heated sufficiently. However, the big question is; do you know how to use this kit? Most users leave this work to their technician while it is the responsibility of every user to know how to operate the kit. It’s more like buying a television set and not being able to use its remote control. As we know, ignorance is expensive, and on this one, the ignorance is literally expensive as you will find out on your monthly bills. Learn to use these kits and put them off during the hot months when the sun is out. Minimize their running time even in cold seasons to avoid energy wastage and put them on holiday mode whenever you travel or no one is at home.

When you have a properly sized system, you will rarely have to put on the backup heater. With more than 9 months of good sunshine in areas rich in sun such as Kenya, you don’t need to have your backup heater on during this period. The nine months are enough to make a sensible return on investment. If you find yourself using the backup heater during these hot months, then something is wrong with your system. You might be using a wrongly sized system that can’t meet your demand, might be having a poorly insulated system, or the panel tilt and alignment on your roof is wrong. So before you run to switch on your backup heater, have these three issues checked. 

Wrong Installation of the System

Cheap is expensive. Unfortunately a good number of clients would love to make savings by having an unqualified technician do their solar water heating installation, not knowing that this could cost them a fortune in future. We have a couple of installations where the panels face the wrong direction or have the wrong tilt angle hence cannot harness the much needed sunlight for water heating. Not to mention another bunch with wrong positioning of the tank relative to the panels. These mistakes only mean an inefficient system and sometimes a system that does not work at all. 

Just like you have a qualified technician doing your wiring, the same should apply to solar water heating. You could pay a little more to get a qualified technician and the cost will be worth every penny. Have the correct installation done for you. That’s starting from the support structures, all the way to the mounting and plumbing. Remember you have spent quite some amount to buy the system, so don’t gamble with the installation bit.

Typical Installation of a solar water heater in Kenya

With the wrong system installation, you will heavily depend on your backup heater since the system does not give you sufficient hot water, and this directly reflects on your electric bills. So if you have made this mistake, have a licensed technician check whether your installation was done correctly and make changes where possible.

Poor End User Habits and Wasteful use of Hot Water

Most users will forget that every time they have a hot water tap running, they are draining hot water from the reservoir and having it replaced with cold water. If you have a 200 litre system, it means you can typically use 200 litres of hot water in a day. In the occasion that you run more than 200 litres, you are likely to have your taps running cold water. And you will either run your backup heater, or think your system is not working properly. That’s why it is very important to have a correctly sized system and to remain within the working limits of your system.

In order to avoid having a bad experience with your water heater, you could use some of these tips so as to make the best out of your system:

  • Schedule to make use of Hot Water when the sun is out. That means that the cold water getting into the reservoir will have time to get heated for later use
  • Avoid draining all the hot water in the evening. This means you will not get any warm water in the morning hence will need to put on your backup heater
  • Limit the use of hot water to activities that actually need the hot water. E.g. avoid using hot water for mopping the house or doing heavy laundry. 
  • Avoid staying too long in the shower
  • Use an instant shower instead of using the tank’s back-up heater in case only one or two people are having a shower and there is no hot water. You don’t need to waste energy heating a whole 200 litre tank only to use 40 litres.
  • Put off the smart backup heater controller when you have good weather or during holidays when you travel
  • Use hot water from your system when using the electric kettle. Warm/hot water boils faster hence means less running time for your kettle and reduced electric bills


Solar water heaters are a good investment that could save you from the nightmare of high electric bills. You only need to ensure that you are using the system correctly and have it properly installed for maximum efficiency. You also have better living standards with hot running water for cooking, showering and cleaning at no additional cost.

Written by Raphael Osoro.

Raphael Osoro, Guest Author