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 day usage.
However, when the power goes out, grid‐tied systems go down as well. This is because it’s not safe to be pushing electricity back into the utility lines while workers may be exposed to the conductors. 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 the and grid is down. The solution to this is to add energy storage with batteries, and their components, which separate our system from the grid, powering 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 exciting 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.
So, when the power goes out, grid-tied systems go out too. Your inverter (the big box near your meter that converts DC electricity created by the panels into usable AC current) recognizes that the grid is out and shuts your system off. The solution is to add batteries into your solar electric system for short term back up. Check out this SBS Solar Battery Back-up Video for a more information.
Part of the installation process 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 an extended power outage. 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 energy 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 data 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.