Grid-tie net-metering solar electric systems were a game changer a decade ago. Net-metering allows Montanans to harness the sunshine generated on our long solar days, power any loads which are operating and feed excess power back into the utility grid for night and shorter winter days usage.
However, when the power goes out, grid-tied systems go down as well. That’s because it’s not safe to be pushing electricity back into the utility lines while workers may be working on them. Your inverter recognizes that the grid is down and shuts your system off.
It is anti-intuitive to have no power from our system when the sun is shining and grid is down. The solution to this is to add energy storage with batteries and the components which separate our system from the grid and power the home directly.
The relatively new lithium batteries have been a game changer. After several years of running this equipment in our shop and helping a number of early adopters, we can now recommend this solution. It is really excited for us to be working with lithium finally as a result of all the electric vehicle advancements in batteries. We are utilizing the LG Chem battery with the StorEdge inverter (indicating storage as well as energy production). On a regular grid up basis, we are putting power into our homes and excess into the grid. When the grid goes down the system automatically separates from the grid and powers our important, backed up loads as we do not typically power all the loads in the home.
Part of the installation is to identify and isolate important household loads. We have two different electrical breaker panels in the house. The main panel which you have in place and an additional sub panel that takes specific circuits, like the refrigerator and freezer, lights and communications. This system is excellent for those that are concerned about power in a natural disaster.
Basically, when the grid is down you operate like an off-grid home. The batteries are charged by the solar array and discharged by your loads. The battery state of charge is managed by you and you dictate the loads to operate. So, how long will the battery last? It is up to you and the amount of sunlight you receive. Depending on your consumption this could be hours or months.
These systems can also be programed for self-consumption. This allows the battery to take the loads of the house each evening as the sun sets, discharging the battery through the night on a daily basis. With the cost structure at present from our utilities, we have no direct cost advantages with this option. If this is of interest give us a call and we can dive into the details.
Call SBS Solar today for your free solar estimate. 406-541-8410.