I'm in the process of getting Solar installed and the Company I've chosen wants 15K for a single powerwall and 13K for a second. The second place choice installer wanted 15K for the first and 7K for a second one. Chose the first one because the panel output is way higher. The second battery price is so different I have to think that there's something wrong here. Pls let me know what your prices are like in this configuration. I've thought about just having the one installed and have reached out to other Tesla suppliers to add the second one after, but haven't had much response.