generator – Page 3 – Graves On SOHO Technology

Connection Options for Backup Power

A spate of recent storms over the past month has much of Houston once again thinking about strategies for backup power. The crazy derecho weather event on May 16th had parts of the city without power for up to 6 days. This particular event was our first time actually using the backup power strategy we put in place after Winter Storm Uri in 2021.

Unlike a hurricane, this storm was very short-lived. Largely a wind event, it raged past just after 6pm and was truly gone by 9pm. We were fortunate. Our pecan tree took a beating, but we only lost power for about 10 hours. Even before the rain stopped, I had the Predator 9500 invertor running, just as I had planned.

As detailed previously, the Predator 9500 inverter powers the entire house, including our 4T central air conditioner. So, we were comfortable overnight. Only in the morning did we see the carnage the storm wrought upon all the trees in the neighborhood.

Parallel Kits for the Predator 9500 (or similar) Inverters

February 9, 2024
Michael Graves
Home

Our strategy for whole house backup power involves a portable inverter generator connected to the house using an inlet and mechanical interlock. As is my habit, I did quite a bit of research to arrive at this strategy. Now that we have a couple of years experience with its use, I am happy to share that knowledge with those who are following down the same line of thought.

One of the most common questions I see in various online space involves how to deliver more power by connecting a pair of inverters in parallel. On the surface, it’s a simple question, but as ever, there’s some detail to the answer.

For the sake of this discussion I’m going to consider the Predator 9500, AIVolt AT20-2100001E, Duromax XP9000iH, Pulsar 9500, and Genmax GM9000iE. These five popular models are all made in the same Chinese factory. They vary only slightly from one to the next. They all have a built-in facility for parallel operation.

Backup Power: 9kW-ish Portable Invertors

Just a few days before Christmas 2021 we bought a Predator 9500 portable invertor generator. Back then, it was one of the first of a new generation of inverters delivering 7,500 watts continuous power, with 9,500 watts peak.

The Predator brand is sold by Harbor Freight. The 9500 model was introduced in 2020 at $1899. Demand was strong, and they were in short supply for a long while. By the time supply was improved the list price had gone up to $2399. It has since gone to $2499, but you can still get them for less during special promotions. We managed to get ours using a last-minute pre-Christmas coupon good for a discount of 25%!

Over time, similar models have emerged from several other companies like Genmax and DuroMax. It’s quite apparent that these are all made by the same manufacturer. They vary only a little in specific features and the color of the plastics.

Three Inverter Generators

Not long ago, Gavin’s Garage offered an unboxing video of the Pulsar PGD95BISCO Super Quite Dual Fuel 9500W Home Use Backup Portable Inverter Generator.

How-To Geek: Be Careful Before Running Your Computer From a Gas Generator

October 10, 2022
Michael Graves
infrastructure

The web site How-To Geek has long been a useful resource. Last week they published an article entitled, “Be Careful Before Running Your Computer From a Gas Generator.” Given our experience during the Great Texas Freeze of 2021 this hits close to home. It’s a reasonable article overall, but it has a couple of holes that I’d like to fill.

Mr. Butler is absolutely correct, a traditional generator can be a problem when running sensitive electronics like computers or TVs. We discovered this in February 2021 when our reasonably new furnace would not run reliably on the generator. I would not have guessed that a gas-fired furnace would present a problem. However, the electronically controlled, variable speed blower struggled to start when connected to the dirty and lumpy generator power.

He suggests using a UPS to protect your sensitive devices from the generator. That’s a nice idea, but there is some subtlety to that as well. The type of UPS matters.

Uninterruptible Power Supplies (UPS)

Our older, admittedly inexpensive, line-interactive UPSs absolutely freaked out when connected to generator power. They saw the variability in the generator output as something to be corrected, but way beyond their scope. They reacted very badly, cyclically putting backup power in/out of circuit every couple of seconds.

NYT on Household Energy Monitors

Last week the New York Times Wirecutter ran an article whose headline posed a question; Do You Really Need a Home Energy Monitor? It’s an interesting question.

They say only that you might save some money. Maybe. And they even question that assertion. Well, we installed a Shelly 3EM last year for reasons that the Wirecutter article completely fails to mention. So, I thought it worth sharing our experience.

Decisions: 2021 Household Projects

December 29, 2021
Michael Graves
infrastructure

As we come to the end of the year, I’m looking back across a range of substantial household projects. We rather famously lost power for a few days back in February 2021 during an unusually cold snap. This lead to some additional thinking about household projects, including the new air conditioner. Specifically, how best to adapt our home to operation without utility power? After all, the Great Texas Freeze of 2021 was not the first time we lost power for days. We were without power for several weeks after Hurricane Ike in 2008.

The most common approach that we see around the neighborhood is the installation of a standby generator. These are permanently installed systems that startup and take over when utility power fails. Generac, Kohler and Cummins are the most common brands. They typically run on natural gas and I’ve seen systems from 14 kW to 32 kW hereabouts.

Standby Generator vs Air Conditioner

Given the position of our home on the lot, and the location of the gas meter and breaker panel, it’s not really practical for us to install a standby generator. It would be prohibitively expensive given the required location of the generator. We’d need to run buried pipe for natural gas, and conduit for electrical cable, a considerable distance. The cost of the installation is much more than the generator itself. The entire project cost is as much as a new air conditioner, for a benefit that that would only occasionally be realized.