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Comment by andrewmcwatters | Hacker News Reader

The cost of panels themselves is really incredible now. I just recently parted a 10kW system down to $0.31/watt, but now the microinverters cost more than the solar panels.

Ultimately, I think labor costs will prevent more solar installations more than the cost of the hardware itself short-term.

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If panel costs become a smaller and smaller fraction of installation cost over time, I wonder what sort of innovations we see where we install them "sub optimally" because it's easier to put them there. E.g. hanging them vertically on the side of a fence or on a wall might be easier (and thus cheaper) than placing them on the roof.

I'm already planning to have a robust inverter and battery stack offgrid and do all the actual solar panel wiring myself. They're going to be thrown in the field face up, and if they have problems, I'll just add more or replace dead ones. $0.31/w is actually kind of expensive, you can get crappy clearance used panels for more like $0.15/w or even less if you shop around (shipping is the largest expense at that point!)

Does it even make sense to set up racking for panels that are ~1/4 the price of a rack, even if you are using ballasted cheapo racking?

One company is trying the approach of placing the panels flat on the ground[0]. So long as you put a fence around it to stop local wildlife from crushing them, seems easy enough. Maybe give it a monthly sweep if it is more prone to collecting debris.

[0] https://electrek.co/2022/12/12/texas-solar-farm-flat-on-the-...

Wow, that’s incredible pricing.

I had the idea to have them floating, sort of, where you angle them by pumping up a sort of canal or something. And potentially the water could be used to create condensation based irrigation for crops planted with in the panels.

That or installations that mimic trees with preserves ground space being maximized.

Yeah that's actually very close to what I am thinking, if I get some expensive high value panels, I'm at a fairly high latitude (46N) so the winter-summer angle difference is extreme - winter 69.77 degrees, summer 17.27 degrees. I plan to do it with something like angle iron and fasteners but it's a big angle adjustment. I may actually hang them on the side of the barn with standoffs at the bottom in the winter, and in the summer lay them flat on the ground.

There are also panels available as surplus, rotated out old stock from large solar farms (at least in Australia)- when they start to dip and an engineer determines it's cost effective to replace with brand new and more efficient (than the older panel ever was).

I've seen a lot of panels on cars | vans to charge batteries for fridges etc.

Also more professional offerings such as mobile charging for field work.

https://www.solarbatterywarehouse.com.au/solar-battery-shop/...

and farmers with workshops just buying the batteries, inverters, panels and fitting those to existing trailers | tractores | trucks, etc.

Ditch microinverters, get a large MPPT. Sure you spend more in cabling but microinverters are poorly-made and fail a LOT.

For those of us just tuning in, what is a MPPT? Doing a web search turns up https://en.wikipedia.org/wiki/Maximum_power_point_tracking but that's not a device like I'd assumed, it's... are you just saying to use something that can sink a lot of DC current straight from the panels? Or to just use a smaller number of bigger inverters?

The one you link is the one he's talking about. They basically electronically optimize the panels to put out max power. It's a physical embodiment of the theoretical calculation.

Instead of having a mini-inventer on each panel, you have one MPPT and inverter for ~20 panels in a string. This has cheaper costs but the downside that e.g. shading on one panel can cause the entire string to reduce output, depending on how your MPPT and panels are wired.

Indeed, this is why micro inverters are spec’d for residential rooftops, and MPPT for utility scale solar. Rarely is shading a concern with utility scale, where as it’s much more common in small scale installs.

I've had great luck with Enphase IQ8 series micro inverters fwiw from a cost and reliability perspective on smaller scale systems.

They're still so expensive that it's hard to justify in my mind. I'd rather just install an extra string or two of cheap panels and eat the shading losses, since I have the space available

Oh, this is the "string inverter" approach that came up in my search. I assumed it wasn't that because running in series seemed like it should result in less cabling [cost], not more. Is it less cabling but thicker to handle the current?

Yeah it's a straight DC high voltage (~150-500v) to the inverter, which means running two 10-gauge cables the entire length of the array. With mini-inverters you have ~6 inches of 10-gauge cable into a mini inverter and the rest of the connection is via standard 14gauge 3 strand romex or something.

Thanks for explaining:)

No worries at all, I just learned from youtube mostly, I think this guy has the best content https://www.youtube.com/@WillProwse

Did you diy a roof install? I’m really looking into this as I live in the southeast, but I’m getting ridiculous quotes (60k for a 10kw system with two power walls).

I've been really frustrated with price gauging in the installation quotes (also in the southeast). I'm no professional installer but I have done a few systems, one was a concerted cargo van with an off-grid 1kW system an 7.2kWh of lithium. The other system I'm in the progress of now, 9.1kW solar and around 70kWh of slightly used automotive cells.

For the system I'm working on now I have around $10k into the hardware if I'm not mistaken. There's plenty of skill and time that goes into designing the system, custom wiring, etc. I also had wuotes around $50k-60k. There's no way in hell I can justify 80% of the price in labor, very happy I happen to live in an area where I can install this myself without running into regulatory issues.

Where did you get the automotive cells?

I got them from Battry Hookup[1] late last year. I wasn't ready to do the full build yet, I've since built a "shed" that is way overbuilt and more of an kff-grid tiny house to store all of our solar equipment.

That site is pretty hit or miss with stock since it is all repurposed equipment, but if you happen to catch the right equipment going by you can get a really good deal for anything DIY.

[1] https://batteryhookup.com/

You were not kidding. On the front page of this moment is "14,000 3v Lithium CR2032 Coin Batteries" held in two barrels with a weight of 200 pounds. A tremendous bargain, if you can snatch it at the current bid of $20.

Hah, yeah just be careful with those tiny batteries if that's the way you choose to go. Different chemestries have very different outcomes and I've never been comfortable with scaling tiny batteries up to a whole-home use.

I was about to order a pallet of new lithium cells from one of the US resellers when the batch of repurposed automotive cells popped up. When I was pricing them out I could get the cells and a DIY BMS for around half the price as rack batteries often used by DIYers today. There's more work involved in putting the cells together yourself, but it is nice knowing how it works and how to fix it should a cell fail.

Yeah, self-installation. You can part a 10kW for under $10,000.

You’re getting terrible quotes because the construction industry has been doing phenomenally the last several years.

I built a contractor search product to compete with HomeAdvisor because the quotes were such a joke. I don’t use it as much as I did when I first built it though. I now know more about residential construction than some contractors I’ve worked with.

I’ve saved literally tens of thousands of dollars.

Very cool! What is it called

McWatters Home

We’ve been operating privately in Arizona by invitation. It’s ready for general availability, but not terribly useful to people outside of AZ right now.

We’re ready to start rolling out to other states and include their registrar of contractors’ directories.

Are you looking for contributors?

I would normally, but unfortunately this product is proprietary.

Interestingly there's a job add on HN for Mech Engineers to help build robots for this:

Charge Robotics is a Series A startup building robots that build solar farms

https://www.ycombinator.com/companies/charge-robotics/jobs/m...

The challenge wrt deployment rate at utility scale is grid interconnection queues. Reform is taking time to speed deployments. “Where plug?”

https://www.spglobal.com/marketintelligence/en/news-insights...

https://www.klgates.com/FERC-Interconnection-Reform-Is-Full-...

https://emp.lbl.gov/news/grid-connection-backlog-grows-30-20...

https://decarbonization.visualcapitalist.com/gridlock-visual...

https://www.utilitydive.com/news/grid-interconnection-queue-...

https://energypost.eu/1500gw-or-renewables-deployment-delaye...

Grid solar is the future, not placing an expensive system on your roof (though homeowners will do that for other reasons, like disaster preparedness).

At the moment, you can part out a system that immediately has a greater savings on your power bill than keeping the same amount of money in a 4% high yield savings account. So we've passed a threshold where the ROI makes sense if you're doing your own installation.

The biggest hurdle is almost no one is installing their own solar systems.

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