I read he was buying 'A 100Ah battery' in place of AGM batteries.
A lot of people seem to think absorbed glass mat batteries are some kind of panacea. In reality most of the hoopla is just that, a lot of marketing jargon. Their best application is a race car or boat, or where off-gassing is a severe disadvantage, where there is a lot of vibration, or where it is necessary or convenient to mount other than vertical, and the fact that they don't need watering. Otherwise they perform similarly to any lead-acid battery. They do hold a charge a little better, but the chemistry isn't that much different, and their capabilities are not that much greater, other than the 'mount-in-any-position' advantage. I surely wouldn't spec them for a powerwall type of application. And they're WAY more expensive than FLA's. They can't hold a candle to LifePo4.
What mistersandals said.