How to add a OffGrid Solar-System to a house that already has grid-power ?
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.
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.
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.
Special thanks to OffGridEnclave community member nirreskeya for providing Pics and Infos to present this as Project. We are happy to present another great Off-Grid cabine Project for reference and ideas. Enjoy
Location: North-Central United States – Climate Zone 7
All framing is 16 inch on center. Main floor joists are 2×10 inches, walls and 2nd floor joists are 2×6, and roof rafters are 2×8. Roof pitch is 12/12 (45º). Everything is insulated with R-19 fiberglass.
Construction began in 2012. Total cost so far is around 13,000 USD and completion should top out around 15k. This includes a small amount for labor, specifically installing most windows, the roof, and the house wrap in 2013. It also includes some second-hand materials that reduced costs.
Total Size : 400 ft² usable space
12×16 main room
12×6 covered porch
12×8 loft bedrooms (2) upstairs with…
12×5 landing/hall between
Power System 400 Watt Solar Panels 2x AGM Lead Acid Batteries at 24 Volt : 35 Ah 60A MPPT charge controller 1,6 kW Inverter
Heating 14 kW Stove for wood logs or coalbrickets. (can be leveld down to 3kW )
Water Wash water is sourced from snow in winter, rain gutters/barrels in summer, and an on-property creek when those fail. Drinking/cooking water is sourced in town and brought in jugs.
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