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I've been in your boots for 15 years, and I barely convinced anyone. Even my thermal panels are viewed with suspiction, and people don't believe me when I told

I've been in your boots for 15 years, and I barely convinced anyone. Even my thermal panels are viewed with suspiction, and people don't believe me when I told them my hot water come from them with a little help from an electric heater in the winter. They pay themselves once per year, easily. Frustratingly, the more common doubt is "if it's so good, how are there so few people doing it?" At this point I gave up. I enjoy my free electricity, and even earn some money, but quietly. A pending change in households is going 24/48V DC. The inverters are costly, and they feel stupid when you know a lot of appliances have an AC/DC transformer to undo what your $3K inverters are doing 10 meters away, losing maybe 20% in the process.

ChatGTP 3y ago
Frustratingly, the more common doubt is "if it's so good, how are there so few people doing it?" Do you think that 15 years back it was prohibitive from a cost perspective now? Was it always this economically viable? I mean ~ $200 a panel, it's a true no brainer, maybe the initial outlay was a little too much for people way back when? On the other hand, I guess with peaking electricity prices in many parts of the world, it would've easily paid itself off by now for most people.
- otherme123 3y ago
  Yes, it make less sense 15 years ago. I got some help from the government with the loan. IIRC, I calculated the break even in 7-8 years. In fact, I also bought a sun tracker, because at the time it was cheaper than to buy more panels.
Mountain_Skies 3y ago
Every time I bring up that subject, people get aggravated and point out that lower voltage means larger cables, which is true, but I wonder if the tradeoff of paying more for thicker cables is worth the simplicity it brings.
- XorNot 3y ago
  What simplicity? Houses aren't limited from being off-grid because of 120vac conversion efficiency, and the new hotness in batteries is HVDC which makes chargers cheaper because it aligns battery voltage to common DC MPPT voltages from solar panels. The industry has been literally moving away from low voltage DC recently.
- ssl-3 3y ago
  It might pay for itself eventually. Suppose I'm making toast -- a process that normally uses around 1100W, anywhere in the world. At 120V, that's about 9A, which is fine for a 15A branch circuit running with 14AWG wire (the very cheapest of wire that we ever use for this stuff in the States). At 48V, making toast requires about 22A, and thus needs something more like 10AWG wire, which uses about 2.5x as much copper. But that bigger wire only needs to be purchased and installed one time, while any efficiency gain gets to be kept (presumably) forever. And that efficiency gain (achieved by having fewer, simpler electronics between the sun and the toast in my kitchen) means a smaller solar array, and a smaller battery bank -- stuff that does wear out eventually. So why not do both? Why not stick with high voltage (because it's cheaper), and also switch some things over to DC? Neither the wires in my walls nor the electromechanical bits of my toaster know or care if things are being powered with 120VAC or 120VDC. The toast comes out the same either way. Why must voltage also decrease?
JumpCrisscross 3y ago
> my thermal panels How cold is it where you're at? I'm weighing putting in a new tankless boiler system, as well as a rooftop PV, but thermal solar might be a better bet.
- Y-bar 3y ago
  Solar thermal works well even in northern latitudes, for example this municipal bath uses them extensively: https://maps.app.goo.gl/w571B7hTXCUBpN7Q6 https://maps.app.goo.gl/w571B7hTXCUBpN7Q6 Edit: This building is of course a bit exceptional in that it is both well-aligned south-facing and has no trees or other things shading it. Another thing working in it's favour is that reflections from water, ice, and snow also provide a non-negligible boost in captured energy.
- otherme123 3y ago
  Winters average 5-10ºC, summers 15-20ºC (nights included). Winter months average 100 hours/month of sun.

ChatGTP 3y ago

Frustratingly, the more common doubt is "if it's so good, how are there so few people doing it?" Do you think that 15 years back it was prohibitive from a cost perspective now? Was it always this economically viable? I mean ~ $200 a panel, it's a true no brainer, maybe the initial outlay was a little too much for people way back when? On the other hand, I guess with peaking electricity prices in many parts of the world, it would've easily paid itself off by now for most people.

otherme123 3y ago
Yes, it make less sense 15 years ago. I got some help from the government with the loan. IIRC, I calculated the break even in 7-8 years. In fact, I also bought a sun tracker, because at the time it was cheaper than to buy more panels.

Mountain_Skies 3y ago

Every time I bring up that subject, people get aggravated and point out that lower voltage means larger cables, which is true, but I wonder if the tradeoff of paying more for thicker cables is worth the simplicity it brings.

XorNot 3y ago
What simplicity? Houses aren't limited from being off-grid because of 120vac conversion efficiency, and the new hotness in batteries is HVDC which makes chargers cheaper because it aligns battery voltage to common DC MPPT voltages from solar panels. The industry has been literally moving away from low voltage DC recently.
ssl-3 3y ago
It might pay for itself eventually. Suppose I'm making toast -- a process that normally uses around 1100W, anywhere in the world. At 120V, that's about 9A, which is fine for a 15A branch circuit running with 14AWG wire (the very cheapest of wire that we ever use for this stuff in the States). At 48V, making toast requires about 22A, and thus needs something more like 10AWG wire, which uses about 2.5x as much copper. But that bigger wire only needs to be purchased and installed one time, while any efficiency gain gets to be kept (presumably) forever. And that efficiency gain (achieved by having fewer, simpler electronics between the sun and the toast in my kitchen) means a smaller solar array, and a smaller battery bank -- stuff that does wear out eventually. So why not do both? Why not stick with high voltage (because it's cheaper), and also switch some things over to DC? Neither the wires in my walls nor the electromechanical bits of my toaster know or care if things are being powered with 120VAC or 120VDC. The toast comes out the same either way. Why must voltage also decrease?

JumpCrisscross 3y ago

> my thermal panels How cold is it where you're at? I'm weighing putting in a new tankless boiler system, as well as a rooftop PV, but thermal solar might be a better bet.

Y-bar 3y ago
Solar thermal works well even in northern latitudes, for example this municipal bath uses them extensively: https://maps.app.goo.gl/w571B7hTXCUBpN7Q6 https://maps.app.goo.gl/w571B7hTXCUBpN7Q6 Edit: This building is of course a bit exceptional in that it is both well-aligned south-facing and has no trees or other things shading it. Another thing working in it's favour is that reflections from water, ice, and snow also provide a non-negligible boost in captured energy.
otherme123 3y ago
Winters average 5-10ºC, summers 15-20ºC (nights included). Winter months average 100 hours/month of sun.