Stand Alone Solar Power system or Battery-Based Solar Power system

A battery based home power system could be the first choice if you are building in a remote location or where the utility is more than 400 metres or so distant from the home. It also maybe that you have decided the utility has become a big nuisance where you are paying a daily fee, sales taxes, suffering power surges, outages, living with a smart meter and then you are paying a ever increasing price for your electricity. It will not likely save you money to disconnect, but it might be worth the peace of mind, like growing your own potatoes. It is not an economics decision, but a choice of how to take control of the resources that support you. 

This is a system where the household electrical loads are energized by storage batteries and recharged by solar panels or a generator. An electrical device known as an inverter is usually used to change Direct Current (DC) battery electrical power into 120 volt Alternating Current or AC unless the dwelling runs entirely on low voltage DC current.

CHARGE CONTROLLER

The generation source whether it is solar or other doesn’t know when the batteries are fully charged so another piece of hardware known as a Charge Controller is necessary. High quality charge controllers can make a big difference on efficiency and battery longevity. 

With wind turbines and microhydro turbines there has to be a place to put excess power being generated (dump load) when the batteries are full or the turbine commences to spinning without any resistance and that can lead to over spinning and wear. Most household sized inverters also double as chargers that can regulate the charge from an AC power source like a generator again to maximize battery longevity.

This kind of independent power system is not connected to any source of utility power. To maintain the batteries charge homeowners might use one or a combination of the following: a solar panel array, wind turbines, microhydro turbines, and an internal combustion engine driven generators (These can be gasoline, propane, diesel, or biodiesel fueled). Solar is usually paired with a fueled generator. Wind is not very practical in most valley locations west of the Continental divide in NW Montana and the Kootenays. If you live in other areas or happen to be very near a ridge top wind might make-up a part of your energy portfolio. See Wind for more info.

A common misconception is that there is not enough sun here. In the West Kootenays there is on average about 1350 hours of full sunshine equivalent per year or 3.6 hours per day average. From November to late February you will find a need to run a generator every few days or rely on a microhydro system because our sun does not come in those months as you may well know.

The greatest challenge to those wanting to build or living off-grid with a stand alone battery based system is to learn how to live using less power.  The 2000 Sq Ft home in Montana we built in 2000-03 used about 3 kW hours a day in winter.  The alternative is bigger battery storage, and big generators, or lots of solar panels in various balanced scenarios. The problem with this, if not cost, is the waste when the sun comes back. Once those batteries are full the solar energy (electricity) stops flowing. It’s like being all dressed-up but having nowhere to go out.

How to use less power? Eliminate any appliance that employs resistive load heating. That’s base board heaters, portable electric heaters, toasters, toaster ovens, Electric ranges and stovetops, dishwashers with sterilizer and drying cycles, electric clothes dryers, hair driers. The one place I still find I use electric to make heat is in a bread maker. I wait for the sunny days to make bread and bake with the converted and inverted sunshine.

Probably the easiest way to make the transition to an off-grid lifestyle is to spend a year living in a wall tent or yurt while you are building your house. By the time you have the house livable and move in, you will feel like you are living like royalty on 2 kW hours per day.