Grid tied, Battery back-up and OFF grid systems.

There are three basic types of solar installs on residential and commercial buildings:

Grid-tied with no energy storage, grid-tied with a battery back-up, and 100% off-grid systems with a larger battery and no connection to the power grid.   

Grid-tied Solar Arrays:

The most common and least expensive type of solar install is a grid-tied system with panels and inverters. These systems generate power during the day, and if that power is not used in real time it goes back to the power grid on a one to one basis, as a net metered system.  

Here in Florida most electric companies participate in “one for one” net metering.

About 90% of the systems installed by Tampa Bay Solar are simple grid-tied solar arrays that use net metering to store extra power, which is returned to the customer when the sun goes down. Net metered systems also build up credits during the low usage months from January to April, those credits carry forward to be used during high usage months in the summer.

Grid-tied systems have lower costs and a faster ROI, so many of our clients start with a grid-tied system and add a battery back-up later.

One note here: as of September of 2022 there are a handful electric cars on the market that have the capability to back-feed electricity to your home during a power outage. Because this technology is relatively new we have limited information on how this process will work.

Keep your eye on future blog posts here on our website for more information about how this will be implemented.

Solar arrays with emergency battery back-up.

These systems add energy storage to an existing grid-tied system. Designed for emergency use, these systems are perfect for clients who experience periodic power outages, especially after tropical storms or hurricanes. These systems require panels, an inverter, battery systems and an energy management system that keeps the battery at full charge and can shift to battery power when the power grid goes through a blackout.   

There are inverter systems that are built specifically for battery back-up, if you already own a grid-tied system these systems can easily be added to your existing system. 

Here in Florida most of our clients want enough back-up power to run an air conditioning unit, and this presents a challenge because starting any air conditioning unit requires at least 10,000 watts of on demand power. This is why it makes sense to talk with a sales rep who has experience sizing these systems.

On demand power is important, but storage capacity is also crucial during a long term blackout. If your system does not have a enough storage capacity it will brownout then blackout as the charge runs down to zero. For this reason most battery back-up systems feed kilowatts to a critical load subpanel with limited breakers powered by the battery; this might be a well pump for drinking water, kitchen appliances, internet and air conditioning only.

If your battery runs out of charge in the middle of the night it will recharge as the sun comes up in the morning.

In this regard your sales rep will look at your on-demand power requirements, storage requirements, and actual power generation from your solar array during the day.

To conserve battery power at night (during a blackout) we recommend that any high energy usage takes place during the day, when most of that power can be drawn from the solar array, not draining the battery.

Off-grid systems

Tampa Bay Solar designed an off-grid system for a client in Tampa back in 2018. This client owns a 4,000 square foot home that was designed to be highly efficient, with a solar array and solar hot water on the roof and a 40 kilowatt lithium iron phosphate battery in the garage. This system has never been connected to TECO, our client moved into the home in June of 2018 and has lived these with his family since then.  

Tampa Bay Solar also builds off-grid construction trailers with panels on the roof and battery storage systems built into the unit. See below:

Most solar installers in Tampa have zero experience with off-grid applications, we’re proud of our unique experience in this niche. We know how to do the custom jobs that national solar installers won’t (or can’t) tackle.   

The biggest challenge in configuring a 100% off-grid solar install is in balancing power production from the solar array with enough storage capacity to keep the power running through the night.

There are larger costs with 100% off-grid systems because of the need for power generation (more panels) and the extra battery storage required to make it through low solar output days.

OTHER back-up systems.

One of the alternatives to a battery back-up is a whole house generator that runs on gasoline or propane.

We don’t install anything that burns fossil fuels.

The drawback to a gas or propane generator is the noise of a running engine during use (solar with a battery is silent) and the difficulty of refueling your generator during an extended blackout combined with fuel shortages. You will also have to be careful about the carbon monoxide exhaust from these systems.  

Solar combined with batteries will recharge every morning, even in cloudy weather, with zero noise and zero air pollution.

What’s next?

Our sales team has weekly training sessions pertaining to new tech advances in solar and the latest storage technology. We would love to have a conversation with you about your options, costs, and feasibility for your home or business.

If you own a grid-tied system we can explore your battery back-up options.

Call me today : 813. 391. 3895

Ben Alexander

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