I'm having solar and the powerwall installed in a couple of weeks and my intention is to have it installed outside. This is what we planned for and I think it will be the best overall location for me. East facing wall and right next to my meter. They told me being outside has no net effect on the powerwall.
I was curious what others thought about mounting it inside (say an unheated garage) vs outside in the sun.
Only Tesla knows the long term aging requirements of their battery chemistry; are we sure we are qualified to even guess this ourselves? In other words, you're second-guessing the Tesla engineers? Well then, in that case, I'll go ahead and pretend we ought to second-guess them. I would tend to agree, but that's just because I'm a logical and often careful person that gets into things more than other people. I cannot pretend to know the answer, but only to make uneducated guesses, based upon what I've heard about other batteries.
I'd be curious how being in direct sunlight affects it. If anything, I'd rather put it in the shade. But, in San Francisco, space is such a premium, perhaps you could build some sort of shading element into your property rather than move your planned PowerWall location.
During our 108º days, the PowerWall v2s' fans were blowing rather substantially; they were straining in the outside heat. That was a very rare event, probably one day per decade average above 105º, and record breaking for that full temp. But, it made me consider that a more conditioned space would be better for the PowerWalls overall, if it was a well ventilated non-living space with some conditioning and plenty of room for the batteries to breath and no sound communication through nearby walls to living spaces. That list of restrictions makes it basically an impossible thing in practically any installation, except those who are single-story and have ample space inside a semi-conditioned garage far from living quarters in an extreme climate area, in which case, I would recommend it; humans don't prefer to live in extreme climates, so often land is cheaper in those climates, and therefore, homes are often built with more space available, and in those types of climates, usually you would have such space available or designable, so overall, that concept at least works out architecturally with typical land uses. In our case, we have no air conditioners, so there was no place I could think of that was cooler, but that could be changed in the future if our climate changes. Therefore, unless you have extreme weather, such as living in very wet (they aren't rated for super or even very wet areas), very hot (we're trying to use logic based upon what we know of other batteries), or very cold (most likely their specifications say what the limit is) weather, then outside should be fine. Tesla's comment that it has no "net effect" basically addresses this. I wonder if Tesla's comment would be equivalent if their target installation was in Mexico, Canada or in the Amazon, or even less extreme, like Florida, Montana, or Puerto Rico.
The only time I ever hear the fans of the PowerWalls are when I have reason to be near them, such as when I walk past them on the way to or from my car, or bringing out trash. They are 25 feet and a whole room away (including two walls) from the closest living space, and almost a hundred feet (and at least four walls) from the nearest sleeping space. If our weather ever changes into out-of-spec weather (let's say 125º every day with monsoon rains, and -5º every night), then they are improperly installed, and as part of our overall weatherization upgrade, would encase them into a semi-conditioned space to keep them in-spec. Of course, that kind of weather would introduce a list of interesting other problems far more onerous than a simple weatherization project for our home, like what kind of civilization we'd be living in, where work would be, humans, infrastructure, etc..
Generally speaking, San Francisco is so cold that if it were not for your statement that they'd be in the sunlight in the morning, I'd say for you not to worry about it. In fact, San Francisco is so cold that them being in the sunlight in the morning might turn out to be a good thing; what does a thermometer set outside in direct morning sunlight measure for you in the hottest days in your expected installation location? Approximately 90º? Or is it closer to 110º? I'd be much more worried about 110º than 90º, but then, I don't even know if their battery pack shields against direct sunlight, and what their chemistry optimal ranges are, so that's just superstitious guessing at best.
The closer to room temperature, the longer will Powewall last, in terms of years..
Find the most stable temperature, sunny outdoor placement definitely is NOT.
Here's Wikipedia's information on your location's climate:
Estonia is situated in the northern part of the
temperate climate zone and in the transition zone between
maritime and
continental climate. Estonia has four seasons of near-equal length. Average temperatures range from 16.3 °C (61.3 °F) on the islands to 18.1 °C (64.6 °F) inland in July, the warmest month, and from −3.5 °C (25.7 °F) on the islands to −7.6 °C (18.3 °F) inland in February, the coldest month. The average annual temperature in Estonia is 5.2 °C (41.4 °F).
[133] The average precipitation in 1961–1990 ranged from 535 to 727 mm (21.1 to 28.6 in) per year.
[134]
In that climate, I would absolutely agree with you that the PowerWalls should be in a stable indoor temperature regime. If possible, I'd prefer that overall in any location, but compared to San Francisco, you have what I would refer to as extreme weather.
But your comment is more than that; you're basically saying, the PowerWalls are probably like computers, in that they prefer human living room temperature ("stable temperatures"). I'd tend to agree, just out of experience, but not any true specific knowledge about this particular product. That's why I'd
prefer a conditioned garage space.
I've already said multiple times that in the future, I think all garages will be conditioned spaces, since EV's prefer and allow conditioned spaces, since they need less ventilation because they are far less toxic than ICE's (internal combustion engines), and their batteries prefer to be in a narrower temperature range than gas engines. This would nicely fit with the PowerWall installations being interior to the same garage spaces as the electric cars; they'd need to be positioned not to be causing noise to living spaces
and away from crash-prone areas in the garage for the cars going in and out, and not in places prone to being buried by storage, since they still have fans that need to work to moderate their temperature.
