jason_2022
New Member
- Joined
- Mar 8, 2022
- Messages
- 8
Hi everyone, I just found your treasure trove of info earlier today and have been going through it. We built our home in 2018 and I was looking pretty hard at solar at the time, but it turns out that building is expensive and solar took a back burner (an electric one, of course). We did go almost entirely electric though. Got talked into propane water heaters, but everything else is electric... induction stove, heat pumps with secondary heating coils if the heat pump can't catch up, and I'm a homebrewer and built an all-electric system that can spin the meter pretty fast. I've been trying to get mentally caught back up on solar and have found your forum awesome so far. I love love love all of the learning that DIY presents and I choose that path every time that I possibly can. That said, I had some design questions that I wondered if I could get some opinions on.
Where my thinking is currently:
Jason
Where my thinking is currently:
- I live in Texas and actually worked at the local utility company during the crazy cold spell in Feb 2021. I'm told that we were a handfull of minutes away from the grid going dark and that our spot in the pecking order of bringing things back online would have been around 4 weeks after black start began. That, the final year of 26% rebate before it drops down, and general world conditions right now are making solar attractive for us again. Ideally, we'd want a grid-tied system capable of fully meeting our needs (plus a cushion) and battery backup.
- I found the energy audit and sizing tool in your resources tab. I haven't done an itemized inventory yet, but our home has a smart meter with access to my daily usage, so I've got a 3-year daily history accumulated. Over the past 365 days, we've used 26,169kWh averaging 71.7kWh per day. Last year's cold spell is jusssst out of reach of those 365 days and not counted in those numbers, but we peaked at 360kWh one day that week. Various online solar calculators have told me I need a system anywhere from 17k to 27k (actually 37k if I used a worst-case winter insolation of 3.9). The first # I got while tinkering with the audit spreadsheet was ~24k, so I'm tentatively revolving around 25k as I work through all of the what-if scenarios.
- So, a 25k system is expensive... batteries to get us through even a full care-free day are wayyy past expensive. The audit sheet tells me I'd need a 41k battery for a half day. Seeing the price on that is bonkers, so that'd be the top end that I'd even remotely consider starting with at this time... Probably less, actually. BUT, I know battery tech is improving all the time and I'd not want to make any choices now (if avoidable) that I would have to rip and replace should battery price/kWh become more attractive in the future. We definitely can make a lot of concessions to make a smaller battery work. Hopefully if the grid goes dark, it will coincide with nice fall weather...
- When I first looked into this several years ago, I had kind of sold myself on microinverters. I'm a computer/gadget guy and liked that I could get panel-level details and that one lagging panel wouldn't bring down the output of the series. I wasn't really considering battery backup at the time though.
- It feels like that's going to add complexity... I assume I'd need to turn back around with more inverters to go from AC back to DC to get the batteries charged?
- Is there anything these days that shows panel health if a central inverter is used rather than micros?
- Is that a real-world issue or just me being a gadget freak?
- In a similar vein as the prior question, this is going to have to be a ground mount setup. The best place I have for this is about 300 feet away from the meter.
- Any general concerns with that (aside from figuring out the wire gauge required, of course).
- Back to the inverter topic, is sending AC over that distance going to be less lossy than DC if I converted at the panel? If I had to, there's a spot nearby the panel array site that I've been wanting to build a garden shed. I could theoretically reduce that first hop after the panels down to about 100 feet and put hardware in there, but it isn't exactly in the right direction, so the second hop would still be about 230 feet.... Actually, the solar project is going to wipe away any financial hope of building my shed most likely, so it'd probably have to be a pretty big reason to go that route.
- Anyone go with a fixed ground mount like IronRidge, regret it and wish you had been able to adjust the array tilt throughout the year? Seems like the sort of work that I'd probably "forget" to maintain regularly, but also seems like I'm leaving photons on the table with fixed mount.
- If someone invented an amazing battery that was affordable, I'd probably need to expand the array to keep charge times reasonable. Any gotchas there that I should think about now?
- This question just came to light tonight and it seems like a big one. I am still trying to grasp what all parts are needed and found sunwatts bundled packages. I was looking through their 25k systems just to get a general feel for price and what components I'd need to be looking for. What caught my attention though is that all of them seem to be rated for less than 100 amps output.... I have 400-amp service. Heck, my beer brewing system alone is on a dedicated 60-amp 220 circuit (and I've tripped it). I really just wanted this to flow into my two existing breaker panels and not have to do anything like peel out "important" breakers into their own panel. Obviously, if we're in a power outage and never expanded beyond a half day or so of battery, we're going to have to consciously make some lifestyle changes if we want to keep the refrigerators running. If we're in a grid-down situation though and I did have a day or two of battery reserve and sunny skies and 4 weeks to kill, I'm probably going to need to make some beer to get through that (only partially joking).
- How to I solve for that???
- I assume the limiting factor here is the inverter?
- If so, can they be stacked?
- Will that require design changes all the way back to the array?
Jason
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