Which fridge rating should we use to choose a more efficient fridge?
August 12, 2011 1:26 PM Subscribe
On a small solar system that trips out a lot, what's the most important rating on a replacement fridge to indicate efficiency: full-load amps, or kWh/yr?
posted by TheManChild2000 to home & garden (8 answers total) 3 users marked this as a favorite
We've got a small solar system (panels and batteries) in our off-grid weekend place, and we struggle with maintaining adequate charge on the batteries. I'd say about once every two months it trips out due to low battery charge. Batteries test okay with a hydrometer. This started up a few months after the system started up and has been an issue for years.
The weird thing is, we've barely got any load and our system should be fine to cover us. Several people have pointed at the fridge as the likely culprit, since our water pump is small, only runs in short bursts, and our septic pump hardly ever runs (and there's no TVs or computers). The builder bought the fridge and I'm sure it was cheap and way inefficient. It runs constantly, even when the house is below freezing.
We shut it off for a week and saw drastic improvement. Normally our batteries are drawn way down by night time and wouldn't reach full charge until close to 10am after they've been in full sun for several hours, but when the fridge was off they were fine at night and completely charged up by 7:30 am (on a cloudy day).
So we're shopping for a new fridge of a similar size (appx 18cu.ft.).
The complication is that nobody can really tell us what rating we should be focusing on. The two main ones are full-load amps, and kilowatt-hours per year.
It seems like FLA is an important rating but only with a fridge that runs a lot. Low is still good, but ideally we want a fridge that over the course of a year uses less total energy, because then the average impact on our solar system should be less. Which means I'd think we would want to focus on kWh/yr. And kWh/yr is basically just another measure of amps, but with a time component added. Also, all the FLA rating tells us is about the motor, but the kWh/yr rating seems like it also relates to how well the fridge is insulated.
So to reduce the impact on a smallish-solar system that gets drawn down at night, should we buy a fridge with the lowest FLA rating we can find? Or the lowest kWh/yr?