Whole Home Solar Backup vs Critical Load Backup

Most clients who install solar panels just do grid-interactive systems that offset utility electricity usage. The solar panels cease to function during a power outage. This is (by far) the most cost-effective way to install and use solar panels in Florida, and the reason for the explosion of solar panel installations worldwide. However, there is obviously a desire for backup purposes during grid outages. To do that, batteries are required. The question becomes, should you do whole-home solar backup or critical load backup only?

A Whole Home Solar Backup System With Tesla Powerwalls
A Whole Home Solar Backup System With Four Tesla Powerwalls

Whole Home Or Partial Backup

Whole-home backup means you will have a seamless experience when the grid goes down. Power for your home clicks over to inverter power, fed by batteries. The batteries are recharged by the solar panels during the day. The problem is, most people need a LOT of battery power to back up their whole home for any sustained length of time. And that gets really expensive, really fast.

Critical load backup means you select individual appliances, lighting, and outlets in your home to backup. Common critical loads are refrigeration, lighting, well pumps, and outlets to run small appliances, televisions, and to charge devices. Non-critical loads are things like water heaters, laundry, ovens and stoves, and air conditioning. If you consider any of these things critical, you should be considering whole-home backup because these appliances use a large amount of power or energy over time, which puts you into the realm of a whole-home system anyway in terms of battery capacity needed or instantaneous power output needed. Pool pumps and sprinkler pumps are almost always out as a critical load unless you have a really efficient variable speed pump.

Choosing The Best Option

Even in whole-home scenarios, you might need to consider carving out some power-hungry things to stay within your available capacities. Common items are clothes dryers, sprinkler pumps, electric heating, pool pumps, large ranges, or air conditioners if you have multiple units. This carve-out can be done manually or through intelligent load shedding devices.

If you have deep pockets, you can definitely have it all and not change your lifestyle at all. But usually, it makes sense to incorporate common sense tradeoffs during rare power outages.

No matter how you look at it, solar with battery backup is complex and expensive. That’s why most people opt for simple grid-interactive systems. And, yes, you can go solar now and add battery backup later when prices are more attractive. But if you want battery backup now, it is absolutely possible. You just need to decide whether you have the need and the budget for whole-home backup or if critical load backup is sufficient.

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