Column: Backup power is advisable in case the grid goes down

As Hawaii residents we’re acutely aware of how vulnerable we are to natural catastrophes. If we get whacked by a Category 5 storm (think Hurricane Maria in Puerto Rico), recovery time could be weeks or even months.

You’d think that with solar panels on your roof, there’d be a simple backup power solution, but as my co-writer Rob Kay and I realized, it’s not that straightforward.

Virtually all photovoltaic systems are linked to the grid and are called “grid-tied.” These systems generate energy, consuming it when the demands are there and back-feeding it to the grid when you don’t need it. It’s a great money- saver, but if Hawaiian Electric Co. goes down, no matter how many panels you have, you won’t have power.

Joe Saturnia, founder of Honolulu-based Island Pacific Energy, says this year is a good time to acquire a PV system with batteries or upgrade to a NEM+. (More on that later).

Federal residential tax credits, which allow you to save 30% of the cost of installing a solar energy system, are good through 2019 in their current form. (After 2019, however, they will go down to 26% and then stagger down to zero by 2022). When you combine federal and Hawaii tax credits, which covers up to 35% of the cost of equipment and installation, you could recover more than half the cost of your solar system.

Nowadays, says Saturnia, batteries are usually part of the mix, so if you do get a new system, you’ll have backup.

Of course, not everyone needs a new system.

What if you have an existing solar system under HECO’s NEM (Net Energy Metering program) and want to add enough battery backup to keep the fridge going and a few lights on?

Mike Tanuvasa, founder of Honolulu-based Solar­Tech Industries, says the cheapest and easiest way is to pick up a gasoline or propane generator from Home Depot or Costco that will cost in the neighborhood of $500. It’s inexpensive, but you’ll need to store gasoline or propane at your home.

If you’d prefer battery backup built into your existing NEM system and you want to leverage federal and state solar credits, Tanuvasa says you’ll have to upgrade to HECO’s NEM+ program, which means “adding a second PV system to your home.”

This kind of system would entail panels, an inverter and a battery. Figure on spending at least $7,000 (after tax credits) for a NEM+ system that would ensure some limited backup power if the grid goes down.

So, can’t you simply add a battery backup to an existing PV system?

The answer is yes, according to Josh Porter, a Maui-based solar consultant and founder of Solar Coaster, a renewable- energy-themed radio show on KAOI in Wailuku. However, without adding solar panels you won’t be able to use the available tax credits since they are based on PV, not batteries.

“The minimum price of a typical battery for this purpose,” says Porter,” is around $7,000 for the equipment. But you’ll most likely need other gear as well, such as an additional inverter, a host of electrical equipment and possibly rewiring your house to automatically route electricity from your battery to your home when the grid goes down.”

Added up, with the cost of installation, installing a battery could easily be a $12,000 proposition. Furthermore, you won’t receive tax credits to reduce these costs.

The bottom line says Porter, is that if you already have PV and want a battery backup, it is going to be a significant investment.

But won’t the price of storage eventually go down?

Yes, says Porter, the cost of batteries, inverters, panels, etc. will drop.

Maybe one day the price of storage eventually will be equivalent to a Honda generator, but that could be decades away.

Is spending a minimum of $7,000 worth it to have peace of mind that comes with having battery backup in case of an apocalyptic weather event?

Having a working refrigerator and lights at your home if the grid is down for a month could be well worth the price.

That’s something only you can decide.

Mike Meyer is chief information officer for Honolulu Community College. Reach him at mmeyer@hawaii.edu. Rob Kay is a freelance writer and can be reached at robertfredkay@gmail.com.