Thinking about solar in Tucson. (DIY grid tie with battery?)
Some background: I am currently on-grid. Base rate is $0.125/KwH. and an EV Charging rate of $.0625 Overnight up to 400 KwH per month. They offer to purchase excess solar power at $0.04/KwH I am located in Tucson (Pima County).
Here is my usage data (Bought EV in April) 2023-10-25 01:00 to 2023-11-25 00:00 821
2023-11-25 00:00 to 2023-12-25 00:00 538 2023-12-25 00:00 to 2024-01-25 00:00 799
2024-01-25 00:00 to 2024-02-25 00:00 696 2024-02-25 00:00 to 2024-03-25 01:00 525
2024-03-25 01:00 to 2024-04-25 01:00 1947
2024-04-25 01:00 to 2024-05-25 01:00 2326
2024-05-25 01:00 to 2024-06-25 01:00 3219
2024-06-25 01:00 to 2024-07-25 01:00 2948
2024-07-25 01:00 to 2024-08-25 01:00 3273
2024-08-25 01:00 to 2024-09-25 01:00 3009
2024-09-25 01:00 to 2024-10-25 01:00 2025
I am on 4.5 acres. The house is a low pitch south facing ordination and also a wooden pergola
My utility offers 'Green Dot' usage data for export, so I have the last year of usage in 15 minute increments. I could not find a tool to analyze this, but in playing around in Excel and the NREL solar output model, it appears that a 10Kw system and 32KwH of batteries would meet my needs. That said, that includes EV charging at night and I am not sure how to back out that data.
In general I am looking at building a grid-tie system with batteries (either at first or wait and upgrade later).
Here are my initial questions:
- On roof or ground mount. Several people have told me not to roof mount; but the idea of trenching wires as I would want the panels somewhat away from the property's views seems like an expensive and labor intensive affair. What are everyone's thoughts? Also If I roof mount, what would the re-coating process look like.
- I have a Tesla with a Tesla wall charger, is there a way to automate both charging during peak sunlight hours and also take advantage of the low overnight rates?
- As far as deign, I have a combined load center and meter panel on my garage exterior wall. My idea is to bring in the 3-4 DC strings into the Garage where the would be an inverter/battery. Good idea?
- I would like to keep grid service, so it would be grid interactive. If I went with batteries, I was wondering if anyone other than Tesla offered a backup switch that goes behind the meter? https://www.tesla.com/support/energy/powerwall/learn/tesla-backup-switch
- I am thinking about doing some of the work myself and hiring some of it out. Anyone know how that works as far as permits, etc.?
- What am I not thinking about?
- Grid Tie Inverter and upgrade to batteries later as they get cheaper, or do it all at once?
