What OSO RENEWABLE ENERGY can do for you…


Grid-Tied Solar


Grid-tied Solar (Photovoltaic):  Grid-tied solar is the simplest way to gather and store or bank the sun’s energy using a “Net Metering” program with your utility. It employs photovoltaic panels (PVs) or solar electric panels to create electricity when sunlight strikes their surface. This electricity flows in wires to an electronics device know as an Inverter that matches the electricity from the solar panels to that electricity which is flowing in the utility power being feed to your house. BC Hydro prefers to call this type of system as Grid-Connected Solar. The “Grid” is referring to the fact that the utility has a power transmission grid that is similar to our roadway grid. Like the roadways power can get on and off at many different locations. When you have a Grid-tied solar power system producing more electrical current than you home or business is using that extra current will flow out through your meter to the nearest electrical load or user. As it passes through your meter, The meter is measuring how much went out from your house and you are credited for that energy in how many kilowatt hours (1000 watts for an hour) you put on account. BC Hydro prints out your usage and your credits on each bi-monthly bill. Fortis does it similarly, but has a different contract system. For those in Ontario, Canada and several other US utilities, there is a feed in tariff system that pays homeowners handsomely for any power they produce in their system.  Oso Renewable Energy is hoping for a change in the politics and policies in BC, to launch a feed in tariff for renewable sourced energy including solar in BC.

The simplicity of “Grid-Tied” solar is there are no batteries which have a limited life and require another intermediate piece of hardware, a charge controller to regulate them from being over charged. This makes Grid-tied the most inexpensive solar electrical option to install, costing as little as $7 per rated watt installed compared to battery based systems that cost more than $10 per watt. The Return On Investment would depend on the cost of electricity you are avoiding. I have calculated a 3000 watt PV array will end up costing you about .22 per kWh over a 30 year system life in Southeastern BC. This is a roof mounted example with a fair dose of reality in the costs and energy harvest.

Grid-Tied systems also have the advantage of higher rated efficiency at 91-95% as compared to about 80-85% efficiencies found with battery based systems. Probably the greatest draw back with grid-tied direct PV systems in the rural Kootenays is no back-up power during grid power outages. The electricity your solar panels would produce is to variable to act as a power source without batteries to act as the capacitor in a back-up power situation.

Here at our home north of New Denver BC, we have a Grid-tied, and battery backed-up system. We bank our extra power on sunny days only after the batteries are charged to a certain threshold voltage. Should the utility supplied power go out or voltage drop below 106 volts as in a Brown-out, the inverter drops the grid connection and acts as an island power source for a set of “critical loads”, like the freezer, the solar hot water heater circulating pump, and several lights and particular wall plugs. The back-up power here is coming out of batteries which if it is sunny, are constantly being charged and if its not then we are drawing down the batteries. The size of the back-up batteries dictates how long and how much power can be used during the outage. Generators and automatic Generator start systems can be configured into this system adding power reliability in a prolonged grid power outage.

When the Utility gets their power restored, the inverter acts as a charger and refills the charge in your batteries. All these transitions are pretty seamless to you as the power user. The Outback inverters make the power source switches so fast you hardly notice the flicker of the lights and computers are not effected as it only takes 30 milliseconds for the inverter to restore power after the grid power goes down.

I would recommend a system like ours at Oso Renewable Energy if you need reliable power in the Kootenays.

You can also have a backup power system without the solar panels and solar charge controller. This system would be recharged either by restored utility service or a generator. See: Battery-Based home power system with Generator or Click here.

For an interesting perspective on Net Metering please follow this link: http://www.truthout.org/article/craig-morris-renewables-from-bottom-up

All products we install are CSA  and listed UL 1741.


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