Solar water heating systems are benign alternatives to conventional heating solutions. They can end up saving a considerable amount of your electricity bills by harnessing heat from the sun.
However, a solar water heating system can seem like a substantial investment from a customer’s perspective. So, would it help if you install solar panels to get a regular supply of hot water? Also, will solar water heating work in your locality?
We bring you a comprehensive guide based on the solar hot water system to answer all these questions. This guide includes crucial info about solar water heaters, the working of the system, and how you can profit from such advanced hot water systems.
- 1 Solar Water Heating System Working
- 2 Solar Thermal Water Heating Components
- 3 Solar Water Heating Systems Economics
- 4 Factors To Consider While Installing A Solar Water Heating System
- 5 Frequently Asked Questions
- 6 Endnotes
Solar Water Heating System Working
Understanding the working of solar heating in depth can encourage people to reduce their carbon footprint in a much-needed era.
Step 1: Solar Collectors
Solar collectors are panels that a solar contractor fits on your roof. The function of these components is straightforward.
- Solar panels capture energy from the sun
- This energy in the form of heat increase the temperature of the water
These solar collectors contain tiny tubes. Water passes through these tubes, and the heat from the sun does the job of heating the domestic water.
Step 2: Water Transport
The solar system uses pipes that carry hot water from collectors and pass through a storage tank.
A coil is responsible for the heat transfer of the domestic hot water system. Depending on your requirement, the arrangement of this coil and pipe network can vary.
The pipes transport hot water to required parts of your house. Overall, renewable energy from the sun is utilised to heat the water.
Solar Thermal Water Heating Components
Before installing a full-proof solar water heating system, it is imperative to have basic knowledge about its functioning parts.
This knowledge proves helpful as domestic users can skip installing some items to reduce cost. Also, fewer items require low maintenance and prove as potential money savers.
Using solar power to heat water needs proper installation of energy-gathering items like collectors. Depending on the construction, materials and method of manufacturing, the cost of these panels varies considerably.
The solar thermal collectors use conduction, convection and radiation to heat water. Generally, two types of collectors are prominent in modern thermal systems.
Flat Plate Collectors
In these collectors, the glass directly faces the sun. The most significant benefit of these collectors is flexibility. You can fit these collectors on the roof or integrate them directly.
Flat plate collectors generally have a distinct set of pipe arrangements. Depending on their alignment, the function of these pipes vary.
- Headers are horizontal pipes that serve collection purpose
- Risers are small vertical tubes serving the purpose of heat exchange
An anti-freeze fluid from the heat exchanger is pumped to the flat plate collector’s headers. The fluid enters the bottom header and collects heat, eventually travelling up to the top header pipe.
The flat plate collectors are durable due to tempered glass construction. Thus, if you reside in a region with constant hailstorms, this type of collector is ideal for installing.
Evacuated Tube Collectors
Compared to flat plate types, tube collectors are more efficient and compact. These collectors are constructed from a series of glass tubes. The heat insulation in these tubes is the reason for a high level of efficiency.
The heat is trapped inside the tubes due to a vacuum effect. In other words, the vacuum creates heat insulation for the flowing liquid. These collectors are beneficial for heating a high volume of water.
The inner glass tubes of tube collectors are coated with a thermal absorber.
In simple words, a solar pump circulates hot water from the collector to the storage tank and thermal regulator. This pump is evident in most active solar water heating systems.
A pump can prove propitious if you live in regions where the surrounding temperature doesn’t fall to a freezing range. Also, solar pumps are beneficial to install indirect circulation hot water systems.
A geyser pump is the most common component in some solar water heating systems. However, their inclusion is subjective and depends on the area and region of the installed system.
A storage tank or cylinder accumulates hot water from the collectors when it’s not required. Depending on their utility, the storage tanks can be mounted at different positions.
- Roof mounting: In a thermosiphon system, a tank is mounted above collectors
- Split mounting: The tank is mounted on the ground and requires a pump for circulation
It’s a cliche that hot water floats above cold water. Hence, water from the top of a hot water cylinder is used for domestic or commercial purposes.
You can even insulate the storage tank to maintain the temperature of hot water for a prolonged period.
This component transfers heat from hot water to the home water supply. Depending on the final requirement of the application, a heat exchanger can find a custom installation.
- A heat exchanger can be in the form of a tube or coil in the storage tank
- Tubes containing hot water can be enclosed in a metal casing outside the cylinder
Thus, depending on the practicality of installation, solar thermal systems can use this component subjectively. During cold climates, an anti-freeze serves as a vital heat transfer fluid.
This fluid circulates in the solar heating system and protects the collector from freezing. Hence, a heat exchanger is integral for energy transfer.
Solar Water Heating Systems Economics
ROI, feasibility and renewable heat incentive are often essential points to assess the value of solar water heating systems.
Installing a solar water heating system can decrease your water heating costs by at least 50%. In the UK, solar water heating systems have an average lifespan of nearly 20 years.
On a general basis, a water heating solar system can cost between £2,000 to £6,000. This cost takes the installation of all the vital components under consideration.
The initial investment varies on various factors given below.
- Type of solar system
- Domestic renewable heat incentive
- Dwelling size
- Cylinder type
You can benefit from government grants like the renewable heat incentive for domestic (DRHI) and non-domestic purposes.
Annual Operating Cost Of Solar Water Heaters
Practically, customers need to pay attention to the payback period and estimated operating costs of solar thermal systems. To calculate the reduction in your water heating bills, three parameters are crucial.
- Auxiliary tank fuel type
- Local utility costs
- Solar energy factor
A solar energy factor (SEF) is the solar energy delivered by the system divided by the input gas or electrical energy. Generally, a higher SEF denotes an efficient solar thermal system. SEF ranges from 1 to 11, with a value of 3 being the most common.
Operating Cost For Electrical Auxiliary System
Annual operating cost (estimated) = 365 x (12.03/SEF) x cost of electricity (kWh)
The auxiliary electrical system functions as a power source for solar water heating system components. However, using pre-heated water in the system helps reduce energy bills to heat water using conventional sources like coal and electricity.
Operating Cost For Gas Auxiliary System
Annual operating cost (estimated) = 365 x (41045/SEF) x Fuel cost (BTU)
Here, BTU stands for British Thermal Unit. Usually, DIY hot water solar kits cost an average of £2,000. However, energy-saving from such a system works as a cost-effective investment for any household or commercial firm.
Minimising Costs By A Solar Hot Water System
You need auxiliary energy to support components like the solar pump. In most cases, pumping costs become negligible over time.
Using renewable energy to save money depends on various factors. For starters, the type of solar water heating system, panel construction, angle of roof instalment, etc., plays a crucial role in savings per year.
If you use LPG to heat water, a solar water heating system can save around £90 per year. On the other hand, if you use gas central heating, expect the savings to hover around the £50 mark per year.
Usually, a solar water heating system has an average of 7 years warranty period. In addition, these systems require low maintenance and simple installation procedure.
Factors To Consider While Installing A Solar Water Heating System
Using the sun’s energy to heat water is a great way to minimise carbon footprint and contribute towards a greener planet. Energy-saving is a benefit of such renewable energy systems. However, as customers, each setup needs to identify factors to maximise these benefits.
Types Of Solar Heating Systems
At this time, to simplify your selection process, consider two major types of hot water heating systems.
- Direct (Open-loop) systems
- Indirect (Closed-loop) systems
Direct systems are cheaper than closed-loop setups. They rely on heat transfer as water circulates through the solar collectors. They do not have freeze and overheat protection by default. You need to install a freeze extort pump and use freeze-tolerant collectors to nullify the lack of innate protection.
Indirect systems transfer heat from HTF to potable water by a heat exchanger. They offer to overheat and freeze protection. Also, these types of solar heating systems are comparatively expensive.
Availability Of South Facing Roof
Generally, a south-facing roof is ideal for mounting solar thermal panels. This position absorbs a high amount of solar energy and proves conducive to achieving max efficiency.
Also, the solar panels should be away from the shadow. Typical sources of shadow are trees, high buildings and chimneys. A 30-degree angle roof can help achieve high exposure to solar energy.
Depending on your location and collector angle, this direction can change without affecting the heating efficiency. Moreover, flat plate collectors and evacuated tube solar collectors are independent of their working principle.
Rebates And Tax Credits
At this time, the Smart Export Guarantee (SEG) is the UK’s lone solar panel funding scheme. This scheme compels suppliers to provide export tariffs to solar panel customers.
If you are a domestic customer with a solar panel system of up to 5 MW, you can avail of the SEG benefits. Also, solar panels can now offer a 5% tax reduction under the new VAT system.
Money Required For Installation
Last but not least, your budget is a vital factor while selecting a hot water solar system. You need to carry periodic maintenance, although being less stringent.
In most cases, a qualified solar installer can take care of these requirements at reasonable costs. Solar kits for hot water heating can often save money compared to a full-proof solar water heating system.
Calculate crucial aspects for maximising your savings and reducing initial investment. The following pointers can save your initial costs.
- Calculate the capacity of your existing water heater
- Request estimate from an experienced solar installer
- Enquire about the need for planning permission
- Have a precise idea of your current energy bills
Frequently Asked Questions
Do solar water heaters reduce energy bills?
In addition to reducing carbon footprint, harnessing the sun’s energy through solar water heaters can reduce your energy bills.
In some cases, you may need a backup heater. However, if you are using an immersion heater, a solar panel setup can reduce the reliance on such electrical gadgets.
Does the solar hot water system work at night?
The heating mechanism of this system works during the day. However, hot water is stored in an insulated tank. Thus, in the absence of the sun, hot water can be utilised as per requirement.
It is profitable to approach your local solar installer to get the best advice on insulation, heater, heat exchanger, and the type of solar water heating system.
How hot does water from solar systems get?
The temperature of hot water varies as per the sun’s intensity. On hot days, this system can supply water exceeding the 60 degrees Celcius mark.
Importantly, you should pay attention to cylinder size and the number of evacuated tubes to achieve desired temperatures.
A solar water heating system is becoming highly conducive to maximising energy savings. Still, you should pay attention to the whole setup before installation.
Generally, these systems require periodic but low maintenance and are pretty robust. At this time, you can expect around 1500 kWh heat per year from a domestic solar hot water system. So, a solar thermal system can prove a handy alternative to LPG and electrical heating sources.