Simple pressureless solar water heater

Pressureless solar water heater

In this configuration the system is used as “add-on” to an existing water system with a boiler.
While not able to run around frost temperatures or below ( 0°C ), it is a easy and comfortable way to produce hot water.

The collector/tank was mounted onto 8cm X 8cm wooden beams with proper screws.
For easy acces, a position on a “half roof” was choosen. The installation took about one day (with some modifications to the support frame).
The water installation is in parallel with the existing hot water boiler.

As connection 16mm semi flexible pipe(PEX – AL Henco) was choosen using compression fittings.

The device is an unpressurized tank (160L model with 18 vacuum tubes) with a heat exchanger coil. Overall the system does not need much space, the installation is pretty straight forward and the price is relative low.

Advantages:

-Does not need much space, very compact build.
-Since the tank is pressurless it has a basic overtemperature protection (evaporation cooling effect)
-Easy assembling/plumming
-Can go ruffly 2days with the 160Ltank and 3 people using it (without the sun shining)
-About 20 year life time expectancy
-Easy to integrate into existing hot water heating systems
-Higher efficiency compared to heatpiped models
-Needs about 6h of good sunshine to heat it up
-Better low shunshine efficiency compared to flat panel termal heater

Disadvantages:

-does not support freezing temperatures(has to be drained)
-hard water can cause a few issues down the road

Special thanks to OffGridEnclave community member Dank_meme_kong for providing Pics and Infos to present this as Project.
If you would like to see more pictures or read up on details of the build join our community discord server.

How to add a OffGrid Solar-System to a house that already has grid-power

How to add a OffGrid Solar-System to a house that already has grid-power ?

Situation

The following situation is a very common occurrence. It’s one we’ve had come up in the community a lot, and for most people in a semi urban environment this is the most likely scenario: The House already has a grid connection. However you want solar to have the option to be self sufficient if need be, as well as saving considerably on electricity costs.

Solution

The most easy solution for this is a OffGrid Island setup with a grid input connection. Basically it means to build a self-sufficient solar system with a battery, using a OffGrid-AllinOne-Units to then connect the existing grid power to the system. This also allows for an easy connection of a gasoline generator.

Types of OffGrid-AllinOne-Units

There is 2 main types of OffGrid-AllinOne-Units.
OffGrid Island Inverters with grid input option and Hybrid Inverters.

” While both systems aim to maximize the use of solar energy, their main difference lies in the way they handle storage of energy.  In an Off-Grid Solar System, the inverter will attempt to use solar energy for “self-consumption” by sending it directly to load or use it to charge battery.  If there’s any excess solar power, nothing will be done as there’s simply no more room for energy storage.
On the other hand, a Hybrid Solar System will still attempt to maximize the use of energy through load or charging battery, and any excess power will simply be “fed” to the grid, which act as a nearly limitless power storage. “(1)

Installation – Legal

In many countries the injection of solar power into the grid using a hybrid inverter will require some sort of paperworks and legal permits. Make sure to double check your legal situation before installing a hybrid inverter.

Going with a OffGrid Island setup with a grid input connection is more often the easiest solution, as one does not need to touch the existing house electric to install and operate it. The grid input can be done with a normal plug. One simply plugs the OffGrid Island setup into the existing electric system of the house like any other household device.

Using one of these devices also makes it easy to have a seamless fallback to grid power in case of no solar power present and the battery being empty. Most OffGrid Island Inverters will have detailed configuration options on primary power source, fallback source and such.

Configuration

This Video details configuration options for a Mpp-Solar OffGrid Island Inverter. Most other solid brands like Victron will have similar options but possibly different apps for the interaction.

Community

If you have any questions, ideas or input dont be shy…. join our community discord server.

(1) Source: https://www.mppsolar.com/v3/product-overview/