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How Does Photovoltaic Water Heating Work?
A photovoltaic water heating system uses solar panels to convert sunlight into electrical energy, which is then used to heat water in your boiler or storage tank. This setup allows you to reduce electricity consumption from the grid and thus lower your water heating costs.
A photovoltaic system for water heating consists of the following components:
1. Solar panels (e.g., Trina Solar 440 W)
2. Water heating controller (e.g., GETI GWH03W 4000W MPPT)
3. Boiler with heating element (we recommend one with two heating elements – one powered by solar panels, the other by the grid)
4. Cabling and connectors (MC4 connectors, solar cables)
5. Breakers and protection elements (surge protection, DC breakers, fuse switches)
6. Mounting structure (for roof installation or freestanding systems)
Note:
This system is easy to install and does not require complex regulation or batteries. However, we strongly recommend professional installation.
Function of Each Component
• Photovoltaic Panels
Photovoltaic panels convert sunlight into electricity. They consist of photovoltaic cells that generate direct current when exposed to light. In our e-shop, we offer the monocrystalline Trina Solar 440 W panel, which is part of the water heating kit. It provides high efficiency and reliability, is easy to install, and ensures long service life.
• Water Heating Controller
The controller is a key part of the system, optimizing operation and minimizing energy loss by powering the heating element directly from solar panels. It uses MPPT (Maximum Power Point Tracking) technology to maximize solar energy yield and heating efficiency. Some models also help reduce grid electricity use. One such model is the GETI GWH03W 4000W MPPT solar inverter.
• Boiler with Electric Heating Element
The boiler stores hot water for the household. It includes an electric heating element powered by energy from the solar panels. Some boilers have two heating elements - one connected to the 230V grid, the other to the MPPT controller output connected to solar panels.
• Cabling and Protection Elements
Cabling connects the system’s components and transmits electricity. Protection elements such as breakers, fuse disconnects, and surge protection protect the system from overload, short circuits, or surges (e.g., from lightning).
Recommended:
For efficient water heating with photovoltaics, we recommend the following kits, which include a basic set of components for easy installation by a professional:
You can find the key differences in the following table:
Key Differences:
1. Kit Power Output (number and type of panels)
• Kit 04291191 (7 panels, 3080 W) - highest output, ideal for larger households or year-round use.
• Kits 04291190 and 04291192 (5 panels, 2200 W) - lowest output, suitable for lower consumption (e.g., small homes, seasonal use).
• Kit 04291189 (6 panels, 2640 W) – mid-range, a universal solution for typical households.
2. Controller (Inverter)
• GETI GWH02D (Kits 04291189 and 04291190): Advanced inverter with LED display, temperature sensor, and temperature control. No Wi-Fi.
• GETI GWH03W (Kits 04291191 and 04291192): More advanced model with Wi-Fi, remote control, and mobile app monitoring. Ideal for smart homes.
3. Wi-Fi and Mobile App
• Kits 04291191 and 04291192 support remote control - for example, activating grid heating via mobile.
• Kits 04291189 and 04291190 do not have this feature.
4. Input Voltage and Compatibility
• GWH03W (Wi-Fi models) supports a wider voltage range (160–420 V), offering greater flexibility and allowing future expansion with more panels.
• GWH02D operates in a narrower range (160–350 V).
How Cost-Effective is a Photovoltaic Water Heating Kit?
The main differences between the compared kits lie in output and inverter features.
Even smaller systems with five panels can cover up to 75% of the annual hot water consumption for a family of four. Systems with six or seven panels can fully cover the demand - and a seven-panel kit may even generate excess energy. This allows households to save up to several hundred euros per year on electricity bills - without any compromise on comfort. System power, inverter type, and features like Wi-Fi or a temperature sensor directly impact efficiency and ROI.
A graph illustrates how each GETI photovoltaic kit covers the annual hot water energy needs of a family of four (approx. 1800 kWh/year).
How Much Can You Save?
For a family of four with an annual water heating consumption of approx. 1800 kWh and electricity cost of 0,26 €/kWh, the yearly savings are:
• Kit 04291190: up to 435,14 €
• Kit 04291189: up to 522,13 €
• Kit 04291192: up to 460,71 €
• Kit 04291191: up to 644,99 €
Which GETI Kit Should You Choose?
Kit 04291190 – 5 panels, no Wi-Fi
• For: Small households or vacation homes (2 - 3 people) with no need for remote control.
• Pros: Lower cost, sufficient for basic needs.
• Cons: Lower output, no Wi-Fi/app.
• Annual savings: up to 435,14 €
Recommended for: Cottages, apartments, or low hot water users.
Kit 04291189 – 6 panels, no Wi-Fi
• For: Typical families (2 adults + 2 kids) wanting a strong price/performance ratio.
• Pros: More power than 5-panel kits, reliable and easy to use.
• Cons: No remote access, manual settings only.
• Annual savings: up to 522,13 €
Recommended for: Households not needing app monitoring but wanting strong performance at a good price.
Kit 04291192 – 5 panels, with Wi-Fi
• For: Smaller households or holiday homes.
• Pros: Lower cost, sufficient performance.
• Cons: Lower total power, no Wi-Fi, app.
• Annual savings: up to 460,71 €
Recommended for: Cottages, apartments, low hot water users.
Kit 04291191 – 7 panels, with Wi-Fi
• For: Larger households, year-round use, or demanding users.
• Pros: Highest performance, best savings, Wi-Fi and remote control.
• Cons: Higher initial cost.
• Annual savings: up to 644,99 €
Recommended for: Families with larger boilers (150–200 L+), high hot water usage.
Frequently Asked Questions
1. How long does a photovoltaic water heating system last?
Quality solar panels, like Trina Solar, last 25 - 30 years and usually come with a 25-year power output warranty. Inverters typically last 5 - 10 years but can last longer with proper installation and maintenance. The whole system can reliably operate for more than two decades.
2. Does the system work in winter?
Yes, but with lower efficiency. The system works in low temperatures and diffuse light. While winter days are shorter with less sunlight, it can still significantly reduce grid energy use - especially on sunny days.
3. What’s the ideal system size for a family of four?
For an annual consumption of about 1800 kWh, a 2.5 - 3.0 kWp system is ideal: 6 to 7 panels of 400 - 450 W each.
Recommended kits:
• Kit 04291189 (6 panels): great price/performance ratio
• Kit 04291191 (7 panels): maximum efficiency with Wi-Fi monitoring
4. How can I monitor system performance?
Most kits allow monitoring directly on the inverter’s LED display, which shows:
• Current panel output
• Water temperature
• Whether heating is solar or grid-based
Advanced models (e.g., GETI GWH03W) support Wi-Fi and a mobile app for performance history, forced heating, and remote temperature control.
Final Recommendation
Photovoltaic water heating is one of the smartest ways to significantly reduce household energy costs. It's an investment with a fast return and ongoing savings. With easy installation, long lifespan, and maintenance-free operation, it’s ideal even for beginners in solar technology.
When choosing a system, consider household size and hot water consumption. For a four-member family, a 2.5 - 3 kWp system (6 - 7 panels) is optimal. If you want remote monitoring and control, go for a Wi-Fi-enabled kit.
You’ll get hot water nearly free for most of the year, reduce energy dependency, and take a step toward energy independence.
Choose the kit that suits you best - and start saving today!
