Solar panel house.

I know a family that is building a Barndo that is going to be run completely from solar panels. I asked about winter heat for the house and they said propane. How does the solar work for AC? I have not researched any, but it does not sound doable to me.

Enough solar panels can generate what's needed to run an A/C. The payback on solar has been ridiculous but is a much shorter timeframe with energy prices doubled or more. FJB

I have built a complete solar powered and battery back up system

As Paluxy has stated, with enough solar panels it not an issue.

You size your battery pack to the watts needed, times how
many hours of electricity you will require if the sun doesn’t
shine enough to completely recharge your batteries

The battery packs are very expensive

What is the predicted life of the solar batteries, and what is the disposal cost when they are replaced?

A few years ago the show This Old House was somewhere in the New England area for that season. They were a part of building a house that their goal was to have their meter spinning backwards. The homeowner was an architect so he really dove deep into even the r rating on the lumber. So instead of 16" spacing between the studs he did 12" and the walls I want to say were 12" thick. I never caught an update episode if they ever achieved their goal or not. But for it to work they better have some serious insulation.

The Tesla Powerwall batteries run $10K each. I talked to a friend this week who's cousin is now energy independent. he has a ton of solar panels and 3 Tesla batteries. Also bought one of those new Rivian trucks. We figured all that should pay for itself in roughly 20 years at current electricity and gas prices if any of it lasts that long.

I wonder how the Tesla battery system compares pricewise with Generac battery system.

How long does the three batteries run his home if he has a week of cloudy days?

There are now 38 SEER inverter-heatpump systems that can easily run on 1500 watts of solar panels ( 5x300w panels) -
https://www.alpinehomeair.com/produ...ystems/blueridge/bmkh0938#specifications
can do cooling AND heating, so they wouldn't even need propane (unless they want a gas cooktop, or propane for backup/emergency heat, like I do.

Put all the lipstick you want on it, solar and wind is not cost effective

I have solar panels on my house, and will do a write up after a year with hard data. Payback appears to be 11 years or so. I keep my house at 65 and have large trees blocking ghe sun half the day. Elec bill was $59 last month.

BTW - managing electricity is important in the winter months.

My meter was running backwards fairly quickly this afternoon with the A/C running. My last electric bill was $20.....all Oncor charges and taxes plus I upped my energy holdover to 750kw...

that’s big enough maybe for a container home w 3” closed cell insulation

Seems to me it would be much more practical on an underground home.

The house is a two story Barndo and they have 4 kids. And there is no outside electrical backup.

Don,

I have a lot of customers who run large homes with air conditioning on solar only and have been doing so for many years. A couple of them are huge homes.

Like so many other things, the 80/20 rule often applies: It is not hard to run everything without a grid connection 80% of the annual hours. The other 20% requires either a much, much larger system or a small supplemental generator to bridge the gaps.

Generally, I see off grid systems driven by a desire for energy independence or when the cost to bring power out to the property is insanely high.

We typically see around a 9-11 year life for an AGM battery bank. I got into the solar battery business 14 years ago and almost all of the first battery banks that I sold have been replaced in the last few years.

A common size battery bank is around 40-60 kWH of storage capacity. Larger homes will have more like 100-150 kWH of battery storage. Using AGM batteries, that is a $10,000 to $35,000. investment. (The Tesla Power Wall is around 14 Kwh each)

Marc

Hey Mark, what do you think of the Generac Powerwall system?

What you say is very interesting, though at my age (74) I don’t know if we’d reach a payout. Could you please give us an idea of what it would take, in $, to set up and run a 2000 square foot foam insulated house on solar.

A $20 a month electricity bill sounds mighty attractive, but what’s the up front cost of all the bits and pieces to get us there? Thanks.

Bump! I’d like to know the answer. How much does it cost up front to save a lot of money with solar?

Just my opinion, but it has a lousy "bang for the buck" ratio. A $10,000. module stores 14 kWH.
- That's the same as running a 14 kW generator for exactly one hour.
- Or a portable 7 kW generator for two hours.

Yes, there is a discount when you buy multiple modules, but it all depends if that is enough power for a person's needs. It may be great for some folks. Look at your power bill to see what you use per day/hour. Then decide how many modules that you need.

Bottom line: It's cool way to store a little energy for short power outages with light loads, without needing fire up the Genset.

My opinion is worth exactly what you paid for it!

Marc

Appreciate the info.

That question is like "How long is a piece of string? or "How much does a car cost?" Soooooo many factors involving your needs and expectations must be considered. Don was talking about a totally off-grid system because there is no power there already. That is very different than adding some solar to reduce your power bill.

In general, adding solar to an existing home with grid power will have a very looong ROI in Texas. I will go so far as to say that the math does not work without Government incentives. And remember: That money comes from taxpayers.

Marc

well, yes, I wasn't 'sizing' a system for them - just giving an example of modern efficiencies.

In fact, if they're serious, they'll likely use a modern gshp 45 seer system like this -
https://www.climatemaster.com/Homeowner/side-links/products/product-details/trilogy,
which also give you 'free' hot water out of the deal as well.

Plus I'm sure they'll be putting 20+ panels up for a full-size dwelling.

Some say "it's not cost effective" - in many places yes, but If you got land in the boonies that's gonna cost $20k+ to have utility power ran out there, a sizable solar array instead makes sense.

Neighbor in Az is a electrical engineer nerd. He runs a 3Ksf home on all solar. His place looks like a spaceship. Pretty sure he’s OCD.....always crawling around messing with stuff. Always on the move.
I asked him once if he wanted to come over for a drink. He said sure, thanks....I haven’t seen him since
Dude cracks me up. He’s a busy pilgrim. Wears me out watching him

Yes, indeed. In fact, I have several customers who couldn't get below $35K+ - just so they could pay the utility for all future power. Solar modules (panels) are downright cheap compared to the past, so good designers are "over paneling" in order to improve output under marginal conditions.

When going off grid, it is important to set aside funds for future repair/replacement. One thing not often discussed is the impact on "salability" of a home with no grid connection.

Marc

I believe in capitalism ========== IF solar worked every builder would be putting it on every house they built. None of them are.

Agree on the builder install. I think it will get there some day, it's just the ROI, it's hard for me to bite off on a 15+year return. Solar technology will likely surpass today's technology in 5 years and then you'll have an antiquated system that needs replaced...with 10+ more years to pay on it. That said I'm thankful some do choose to be early adopters of technology, otherwise technology would not progress as fast.

Yep....and every commercial building with a flat roof would have them as well. You know it's not a good deal when even those who can write off 100% of the cost don't do it.

What's it's worth when the lights go out? Daddy my batteries are dying, again.......

There's lot of stuff that works that builders don't use because the payback is further out and doesn't allow them to advertise low pricing if they put something in the house that won't pay back for 5 years.

That said, the payoff on solar is basically never at this point. I'm an engineer and looked into it a few years ago. Our energy bill is normally around $150-$250. Sure a $20 bill would be nice, but if I'm paying $30k to save $200 a month and I look at what I could have made investing that money instead, it starts to make very little sense. It also becomes an even worse calculation when you realize you have to replace the banks every 10 years or so and at some point, the panels will begin to become less efficient also.

Indeed. What's it worth when you can't keep your insulin at a safe temperature, or use your CPAP or oxygen generator, etc. Do a fuel calculation and see how long your generator will run.

Years ago, most off grid type solar systems were driven by the super high cost of getting grid power out to remote locations. Now, concerns over losing grid power for more than a few days is driving large a large number of standalone solar installations. None of the battery based systems are chosen for cost savings. The existence of Jackery type systems should tell you something. (Unfortunately, they don't produce nearly enough power for most people's longer term needs.)

Keep in mind that MOST commercial and residential systems that you see, cannot produce power when the utility power is down and batteries cannot be added.

I have several customers with spare solar system components in shielded storage in case of a Carrington type event or something more nefarious. More and more people are becoming aware of just how fragile a lot of our power infrastructure really is. Some are spending big $$ on a powerful trailer mounted solar rig to haul out to their remote property if/when things get ugly.

Marc

It’s kind of funny in a way. A lot of the folks on here talking about ROI and cost effectiveness while spending untold thousands of dollars in the pursuit of deer meat. You aren’t saving money on meat vs. buying meat at the grocery store.

People sometimes do things because they want to, not because it is cost effective. Sometimes it’s about taking back control of your life vs. relying on big monopolistic service providers who can now, thanks to smart meters, cut off your power from wherever they choose. No need to actually send someone out any more to do their dirty work. Being self sufficient and independent is not a bad idea in many cases. If the grid goes down, you’ll have power. If the grocery store loses power, you won’t be buying any meat there so being able to procure your own has merit.

People lived for thousands of years without electricity. If the electric grid goes out, that will be the least of my concerns. We ran a few things off a generator during snow-maggedon in 2020. Worked fine until power came back. Now we moved to a new house with a wood burning stove and are even more prepared in the event of an outage.

Day to day reliance on an electrical grid? Sure, spend money on that. Hope you're also not dependent on water systems, cell network, internet service, etc. - or are the folks buying solar to be independent creating their own ISP and cell network also?

My thought exactly. Being a finance guy looking at the payback solar panels are just not worth it. When I was working for a large company and submitting project requests we had a 3 year rule for most projects and 5 years for utility projects. Another consideration with solar panels is your age. They won't do you any good if they don't pay back before you die.