Solar battery storage

A self-powered home combines solar energy and a battery to independently power your home day and night. During the day, solar panels may produce more energy than your home uses. Your battery stores that excess solar energy and makes it available to your home even after the sun has set. Through an app, you will have full visibility into your self-powered home showing solar production, battery status and home energy consumption.

The solar battery can detect an outage, disconnect from the grid, and automatically restore power to your home in a fraction of a second. You will not even notice that the power went out. Your lights and appliances will continue to run without interruption. Solar energy will continue to power your home and recharge the battery. Without the battery, solar will shut down during an outage.

It is different on a site-to-site basis and based on a personal preference. Most homes will need 2 or 3 batteries, unless your home is extremely energy-efficient. An average home consumes about 28 kWh per day, which means an average house would need two Tesla Powerwall 2 batteries to supply a day’s worth of regular energy consumption. The total number of batteries you need is a personal choice depending on how much power you want or need to store and what types of devices you hope to switch on during a grid outage. Each system is fully customized to maximize the homeowner’s financial benefit and to reach their goals. To get a full picture of how many batteries you might need, contact Rooftop Solar about your objectives and review your energy usage history.

This is another question that’s hard to answer. It really depends on the weather, brightness, shading, and outside temperature. In perfect conditions with no loads and a maximum 7.6kW of solar power, a Tesla Powerwall 2 could charge in 2 hours.

AC battery systems (such as the Tesla Powerwall 2) are able to be retrofitted to homes with an existing solar installation, but they are slightly less efficient compared to the common DC battery systems. This is due to losses in the conversion from DC to AC power, first the DC solar energy is converted to AC by the solar inverter, then back to DC to be stored in the battery and finally back to AC when it is needed by the appliances (with typically 3-5% losses in each conversion). This adds up to approximately 89% round trip efficiency compared to around 95% efficiency with a DC coupled battery (such as a LG Chem).

AC battery systems require a separate solar inverter for the solar panels. DC battery systems use the same inverter as the solar panels. Rooftop Solar can help you choose the battery system that is right for your house.

An AC battery system is only designed to operate in off-grid (back-up energy) mode for short durations (until the battery is depleted) and is not designed to function as an dedicated off-grid power system. If you are looking for a true off-grid battery system, Rooftop Solar can design a custom system specifically for off-grid applications

Your solar battery system will operate if the utility grid goes down, and your home will automatically switch over to the batteries. If the sun is shining when the grid goes down, your solar panels will continue to charge your batteries and stop sending any energy back to the grid. The unit that relays power from your system to the batteries isolates all the power in the house from the grid. This ensures the safety of line workers and is an automatic process when the grid goes out.

Battery systems are eligible for the 30% solar tax credit when it is installed with solar. Your utility may have additional incentives as well.

The batteries can be installed indoors or outdoors and can operate within a wide range of temperatures. At the extremes of the temperature range, your battery may limit charge or discharge power to improve battery lifespan. If you are in an area that is often outside of the 32°F to 86°F range, we recommend that the batteries are installed indoors. To optimize performance, avoid installing batteries in locations exposed to direct sunlight or subject to extreme temperatures. Additionally, while humidity and rain do not pose a risk, batteries should not be installed in locations subject to flooding or near water sources such as downspouts, faucets or sprinkler systems. In order to maintain proper ventilation, batteries should be kept clear of debris such as leaves and dense brush, and areas of accumulated snow. Batteries should not be installed in habitable areas or on external walls of bedrooms. While they are fairly quiet, they do emit low level noise and vibrations.