a) Hybrid Solar Systems
A hybrid solar system (aka “grid-tie with power backup”, is basically a grid connect solar system with batteries combined with an off-grid system. The electronics continuously monitor the batteries, the solar panels and the grid and decide:
- When to charge/discharge the batteries.
- When to connect/disconnect from the grid
This may sound very similar in cost and complexity to an off grid system. But the crucial point to understand is that, because your system is not totally disconnected from the grid, you save a lot of money on system Components. The grid is always there if you need an electricity top up. This means that your system needs fewer batteries and depending on grid failures no need for a backup power source (i.e. expensive diesel genset).
b) Off-Grid Solar Systems
"Off-grid" systems, which do not tie into the power grid, run on a combination of solar panels, batteries and often a backup generator running on gasoline, diesel or Gas.
Off-grid systems are expensive to own and operate, mostly due to the cost of batteries. However with clever System sizing and with the incorporation of a generator costs can be significantly reduced. An off-grid system gives you true energy independence.
c) Grid-Tied Solar Systems
A "grid-tie" solar system is one that ties into the power grid, pulling electricity from the grid when needed, then pushing excess electricity back into the grid when the local customer isn't using the full capacity being generated by PV panels (photovoltaic). As long as the grid stays up, it's a clever solution because it reduces or even eliminates the customer's electric bills while generating clean energy. Because of the very fact that these systems are tied into the power grid, however, they all have a safety feature that disconnects them from the grid when the grid goes down. In other words, if the power grid goes offline, your entire grid-tie solar array becomes instantly useless and you can't power a laptop computer even if you have 100KW worth of solar panels installed. In a grid-tie system, they all are instantly shut off.
