At Project Solar, our top battery pick for a home solar system is the Enphase IQ 5P. These batteries are smart, efficient, and pair perfectly with the microinverters we use (also from Enphase).
There are a couple different ways to use this battery model, and the cost and features vary with each. Keep reading to learn more about which configuration ("backup" vs. "consumption") is right for you.
Consumption Batteries & Battery Arbitrage
With rising utility rates and evolving net-metering/solar buyback policies (especially in California), a new feature of battery storage has become popular: battery arbitrage.
Arbitrage involves using a battery solely to offset electrical costs, rather than electricity backup. Enphase's consumption battery configuration uses battery arbitrage, storing electricity for use during peak grid usage times, when power is most expensive.
While all backup batteries will require a System Controller to disconnect from the grid and run autonomously during outages, consumption batteries don't include this component.
This means that your system won't run if the power goes out, but it also means a significantly less expensive battery, since there is less equipment to purchase and install.
Backup Batteries & Outage Protection
Saving on electricity costs isn't the only reason customers purchase solar batteries. Using a solar battery like a generator allows you to keep producing and using your solar power, even when the grid is down.
Backup battery configuration involves additional equipment, so it is more expensive, but it also has different user modes for different situations. Here's a description from Enphase of these options:
This profile maximizes your use of your own solar power while reducing your dependence on electricity from the utility grid.
This profile minimizes your electricity bills by reducing consumption from the utility grid during peak hours when energy rates are highest.
This profile keeps your batteries fully charged so you are always prepared for a power outage.
As you can see, batteries in backup configuration are able to arbitrage as well--they just have the added feature of off-grid backup as well.
When deciding on a solar battery set up with Project Solar, we recommend taking a look at a few factors, at minimum:
1. The typical frequency/length of outages in your area. If you don't have severe power outages often, installing a consumption battery (or not installing a battery at all) may be the most economical choice.
2. Your area's net-metering/solar buyback policy. If your utility company has a close to 1:1 ratio for exported power buyback, you most likely don't need a battery--your project will be more cost-effective without one. If you're concerned about outages, a backup battery or a portable battery bank will be your best bet.
Some utilities provide--or are planning to transition to--less advantageous net-metering policies (or none at all). If this is your situation, a consumption battery can greatly improve your savings.
3. Cost. Batteries are pretty expensive, which is why we don't always recommend them. However, customers who are looking to navigate tiered or "Time-of-Use" utility rates can save a great deal by installing a consumption battery.
One IQ 5P in backup configuration will cost $8,500, while a battery in consumption configuration only costs $4,000 (fully installed, before any incentives). This price difference comes from the absence of the System Controller, which manages grid disconnection.
If you have any further questions about batteries, our Customer Experience Team would be happy to help you: Contact Us, or check out more Help Center articles below.