For starters, yes, we have A/C and it works. I installed the first phase of my PV system last week and have been trying to go solar-only during this heat wave. Unfortunately, I only budgeted for 3 KW of solar in the first phase of this project, and the central A/C is about 3.5 KW. That means I can run the A/C fine during the day - drawing the difference from the batteries and charging them back up when the A/C cycles off - but at night, it's a straight 65 amp draw from the batteries. Due to the current heat wave, its also running more than it normally would, so the PV is struggling to keep the batteries up.
S.O. and I spent yesterday afternoon and evening downstairs in the basement where it was nice and cool and just turned off the A/C. It was about 11 PM when the movie we were watching finished so we decided to call it a night. Came upstairs, and it was 85 degrees. Yikes.
Rather than run the A/C to pump out almost 20 degrees of accumulated heat, we just opened all the windows hoping it would naturally cool down overnight and the A/C could cool it the rest of the way down in the morning.
We've also got a little 5,000 BTU (450 watt) window unit in the bedroom, so we brought the dogs in with us, closed the door, and turned that on. It's pretty easy on the house battery, and we slept comfortably.
When we got up around 6:30 this morning and opened the bedroom door, it was like walking into an oven. Despite the outside temp dropping to 70 degrees overnight, the house only cooled 2 degrees from 85 to 83. S.O immediately caved and turned the A/C on (don't blame him at all) and it's been been running constantly for about 2 hours now pumping out the accumulated heat. House battery is down to about 38% as of this writing, and the sun is just starting to hit the roof panels in useful amounts.
Today's forecast is 99 degrees and afternoon thunderstorms, so I may have to cave and switch back to utility power for the rest of the heat wave (the rest of the weekend is supposed to be cloudy and hot).
Lessons learned:
- Add more PV to the roof ASAP
- Buy S.O. something nice for going along with my solar-only shenanigans this week
- It would have probably saved energy in the long run to have run the A/C the whole time at a higher temp than leaving it off and then pumping out about 14 hours of accumulated heat.
- Updating the house's insulation is probably the next project I need to plan
Insulation seems incredibly important with those temps.
Just saw a video - not sure of origin so ymmv, about foam insulation blocks placed on the outside of walls, that are then missed to look like normal spackle. Seems great for anyone with a house with a shitty 50s attitude toward insulation and wall cavitys and needs some more space for that.
That's a project I'm gonna have to move up in priority. And yep, house is from the 50s and the block itself is basically the extent of the insulation. Plan is to have those foam insulation blocks installed but put siding over them rather than spackle.
One side effect of my PV install is that I have a lot of large, thick foam inserts that I have to get rid of. They're very similar in size and material to those foam insulation blocks, so I may hang onto them and ask the contractors if they can use them. That'll re-use something I'd otherwise be tossing out and also save some money on buying the foam panels, though I'm not sure how much those cost.
Don't forget the roof. Even if old insulation up there should replace with new. And definitely make sure the installers leave air gaps up there... I know people that fucked that up and had mold problems afterwards