So. Many. Questions.

[jason_2022]

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:

• 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...

Questions:

• 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?

I probably have more questions, but I think those are the ones that have been nagging at me the most. If you have made it this far in my War and Peace book here, thank you very much for your time and any thoughts or experiences that you can offer! Sincerely appreciated!!
Jason

 

[WYtreasure]

It's your lucky day Jason. You've found a treasure all right.

Welcome to the party.

 

[Texican]

Hey Jason, Im in NE Texas
we currently have 10kw grid tie which runs backwards about 1/2 year during the day, giving it to the grid for free

we paid for about 20,000 kwh last year @ 10 cents/kwh is $2000/year

in the middle of adding a 12kw off grid/grid assist system with batteries to cover nights and the 1/2 year we dont run backwards with the current 19kw grid tie

The new 12kw sytem with batteries is looking to run about 22k in cost with 10k of that for batteries

here is a cost breakdown so far

2 pallets of used 250w panels 48 panels 12kw total for $2500, local pickup at signature solar
2 LV6548 inverters $3200 with shipping from watts247
6 EG4 batteries and rack $10000 signature solar local pickup
Ironridge ground mount racking for 2 mounts x 24panels each $2700
used 3 1/2 inch pipe for both ground arrays $1000
Fuses, breakers, disconnects, smart shunt, etc $1000 estimate
Wires from panels to inverters, inverters to house $1000 estimate

we have mini splits for a/c, propane stove/dryer, but have elec water heater which I just put a timer on, so it wont run at night on battery
running all the a/c at night on batts is the challenge

 

[12VoltInstalls]

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.

I would not use fixed panels in your case. Your latitude and your high demand would make adjustable mounting very beneficial.
Do you ‘forget’ to go to work? Forget to take out the trash or do laundry? No. It has to be done.
Adjusting the panels would simply be another means of effective ’income’ so you just do it three or four times a year. It’s just part of the ‘work’ you do to provide for yourself.

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.

I think what’s most important would be selecting the right equipment to harvest your needs. The top-tier equipment has some offerings that can handle microinverters but it can be done with DC input as well. If the brands/equipment that support microinverters is in your budget that is a possibility. In my observation, however, a microinverter-based system with batteries is probably not the best approach in many installations.
I would choose quality and reputation over limiting to microinverters myself. That might result in a micro inverter system but I wouldn’t focus there.

What caught my attention though is that all of them seem to be rated for less than 100 amps output....

Many big systems are ‘stackable’ to provide substantial output. It’s doable but I’m thinking you need to reconsider this:

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.

unless you can afford the outlay - a critical loads system with a conscious choice to conserve is going to be way less money.

Being that you’re all electric except for hot water is a serious consideration. In an emergency, propane generators and propane-fueled heat can give you months of off-grid capacity. Depending 100% on solar for large demand homes is really a luxury at this point in time. That may change- or should- but it’s dang expensive to use battery power for large demand.

 

[jason_2022]

Hey Jason, Im in NE Texas
we currently have 10kw grid tie which runs backwards about 1/2 year during the day, giving it to the grid for free

we paid for about 20,000 kwh last year @ 10 cents/kwh is $2000/year

in the middle of adding a 12kw off grid/grid assist system with batteries to cover nights and the 1/2 year we dont run backwards with the current 19kw grid tie

Sounds like you are going to be busy! Thanks for the tip on signature solar... I had noticed them a few days ago in a battery search, but didn't realize they were close'ish (I'm near College Station, so still like a 3.5 hour drive, but that still counts as close here). Good luck in your build!

 

[jason_2022]

I would not use fixed panels in your case. Your latitude and your high demand would make adjustable mounting very beneficial.
Do you ‘forget’ to go to work? Forget to take out the trash or do laundry? No. It has to be done.
Adjusting the panels would simply be another means of effective ’income’ so you just do it three or four times a year. It’s just part of the ‘work’ you do to provide for yourself.

I think what’s most important would be selecting the right equipment to harvest your needs. The top-tier equipment has some offerings that can handle microinverters but it can be done with DC input as well. If the brands/equipment that support microinverters is in your budget that is a possibility. In my observation, however, a microinverter-based system with batteries is probably not the best approach in many installations.
I would choose quality and reputation over limiting to microinverters myself. That might result in a micro inverter system but I wouldn’t focus there.

Many big systems are ‘stackable’ to provide substantial output. It’s doable but I’m thinking you need to reconsider this:

unless you can afford the outlay - a critical loads system with a conscious choice to conserve is going to be way less money.

Being that you’re all electric except for hot water is a serious consideration. In an emergency, propane generators and propane-fueled heat can give you months of off-grid capacity. Depending 100% on solar for large demand homes is really a luxury at this point in time. That may change- or should- but it’s dang expensive to use battery power for large demand.

This is a big dose of honest feedback.... Very much appreciated.

I didn't want to bring it up and get run out of the solar forum on my first day here, but a generator is definitely still on the table for consideration. Somehow we wound up with a 500g propane tank and, aside from propane runs to the fireplaces (which we only burn wood in, not propane), it is just our two tankless water heaters that tap into it. And the propane tank tap into the house is like 20 feet from the electric meter, not 300' away... Wire alone between the house and the solar array is going to approach the cost of a 24k generator. So yeah... those brain cells are still firing!

On the flip side, solar removes the dependency on the propane delivery guy. From what I have found, the 24k generac uses ~61g of propane when half loaded. That'd be about two and a half days. I know that some of our neighbors with generators had trouble getting delivery during the rolling blackouts last year. To your point, by far our biggest load/concern during that was for heat, so keeping warm somehow w/ propane would have dramatically reduced our electric requirements and allowed for a much smaller generator, potentially stretching out the tank.

I think what all this drives home for me is that "whole house" (solar or generator) is not realistic for us at this juncture for a sustained outage and I should start working on Plan B. Honestly, this second round of "I want solar" started out by looking at solar generators... something to keep the refrigerators going, phones charged, and a few other small'ish items as required. Those got expensive pretty quickly and it shifted to "if I'm going to spend that much, I just as well do the whole house". So we're certainly willing to get by with much less than we enjoy today... just going through the exercise of trying to get the most bang for the buck.

Again, I really appreciate your thoughts above. They were well received (and I was totally joking about not adjusting the arrays... I'd be out there with charts and graphs and my wife rolling her eyes at how much hand holding I'd be doing on something I didn't need to touch that often, haha!)

 

[WYtreasure]

So Jason, what do you think of the Treasure Chest so far?

Hybrid water heaters or DC heating elements may be worth looking into.
Over-paneling is an option to adjustable panels.
Is the beer a light or dark, amber or ale, served cold or warm?
My #1 priority has been to save the food in the fridge & freezer and other necessities.
The grid can take care of itself (or not as those near Huston will tell you). Don't let a downed grid ruin the ability of your system to provide for your family.

 

[jason_2022]

So Jason, what do you think of the Treasure Chest so far?

Still wading through it all, but definitely a great resource!

Hybrid water heaters or DC heating elements may be worth looking into.

Interesting.... both are new to me and I definitely will look!

Is the beer a light or dark, amber or ale, served cold or warm?

I try to keep some of each on hand! Preferably cold, but the kegerator may or may not make it onto the critical infrastructure list now that whole-house is starting to look impractical.

My #1 priority has been to save the food in the fridge & freezer and other necessities.

I'm starting to come around to that... We'll see....

The grid can take care of itself (or not as those near Huston will tell you). Don't let a downed grid ruin the ability of your system to provide for your family.

I'm 90 miles from Houston and have minimal confidence in ERCOT at this point. That is definitely part of my renewed interest in exploring options.

 

[WYtreasure]

Cool reply. FYI everything you hear from me is "just another newbie blabbing away".

I try to keep some of each on hand! Preferably cold, but the kegorator may or may not make it onto the critical infrastructure list now that whole-house is starting to look impractical.

That could be your test system. "Honey, I think I need to do a little ($1,000) experiment with this solar thing.

I'm 90 miles from Houston and have minimal confidence in ERCOT at this point. That is definitely part of my renewed interest in exploring options.

Keeping options open as you design is "best practice". Once you start purchasing items you've limited your options. A larger major component, initially, allows for easier expansion down the road.

 

[jason_2022]

That could be your test system. "Honey, I think I need to do a little ($1,000) experiment with this solar thing.

Haha! She's fully on board with proceeding with something here but "Here's what I think we should do... I think we should start out by protecting the kegerator..." would not go over very well!

 

[WYtreasure]

Oh no, I meant the fridge and freezer, and of course her hair dryer.

 

[12VoltInstalls]

second round of "I want solar" started out by looking at solar generators...

That’s an expensive way to not do very much.
You can start small-ish with some substantial power without spending all that expense for a fruitcase with a little battery. For the money they take for the units that actually work you can have 2-3 times the battery power and way more solar.