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It’s always frustrating to me to see an inverter in these setups. All of your digital devices actually run on DC current! Your computer, monitor, phone charger…

It’s always frustrating to me to see an inverter in these setups. All of your digital devices actually run on DC current! Your computer, monitor, phone charger… Inverters consume energy just being on, whether current is being drawn or not. And they’re expensive! Without the inverter, a solar panel+battery setup is super simple and I’m curious to see a movement towards low-voltage circuits in homes. You can easily power all of the lights in your home with a solar panel connected to a 12v battery. Double in size and you can power your TV and router as well. This isn’t going to save you a significant amount of money though. It’s just interesting. Big ticket items like your water heater or air conditioner consume a lot more power and will probably need an inverter, etc.

louwrentius 3y ago
The key issue is that all my existing equipment is 230v. I would have to rebuy everything. If you need an inverter anyway for hvac, you have added complexity and no gains. Although not mentioned, I’m using 230v ikea fixtures with 12v led e27 bulbs wired to 12 volt, as you mentioned. Is indeed quite efficient, no inverter running.
- ccorcos 3y ago
  Yeah, but the annoying thing (from an engineering elegance perspective) is that most of those appliances that are on 230VAC convert to 12-48VDC internally (e.g. TV/monitor, LEDs).
  - louwrentius 3y ago
    Yeah regarding those appliances 100% I see the inelegant solution. Imagine all new equipment below x watt would be required to have a 12v input in addition to 120/230
kamranjon 3y ago
I always thought it would be cool wire parts of your home using PoE (power over ethernet) if you had some solar panels and a battery bank.
- ccorcos 3y ago
  Yeah, I think PoE is 48V but it would be cool for adding connectivity to everything. WiFi more or less solves that problem these days though.
- m463 3y ago
  I know there are POE lighting panels for commercial spaces. When I looked they were pretty (prohibitively?) expensive. Maybe when powered by solar there are network effects that make them cheaper in overall system cost.
jacquesm 3y ago
You really don't want to run HVDC through your house. Solar panels in a string configuration make 100's of Volts, and what they produce is changing depending on the load and the amount of incident sunlight. So you would always have some kind of DC/DC conversion going and that's an inverter in all but name. You really don't want 12V if you DC either, the currents will be ridiculously high and for what you have saved on an inverter you'll be spending it on cabling and fuses. Much, much better to just go with AC and wire it straight into the distribution panel, it will save you thousands compared to a DC system of comparable power and the DC system will never be as safe (because breaking a DC circuit that carries 100A or more is very hard to do in a non-hazardous way using gear available to ordinary mortals).
- ccorcos 3y ago
  I’m curious to hear more about the difficulty of breaking DC current. I was also thinking planning to research more into GFCI for DC current. Seems like it’s possible if you tie the negative terminal to ground just like with AC but that feels weird to me. I guess cars usually have the negative terminal tied to the chasis so it seems reasonable. Low voltage, high amperage is definitely going to cost a lot in cabling though, that’s for sure. My understanding is that the only reason AC is preferred to DC for transmission is because it’s easier to transform. But rectifying is super simple and cheap — I wonder what the primary drawbacks are of using DC in homes…
  - jacquesm 3y ago
    AC goes through zero 50 or 60 times per second so that helps you to interrupt a running current. DC runs steadily, continuously so if you try to break a DC current it will arc like mad and with a bit of luck you'll end up losing your contacts the very first time you try to break the circuit under load. DC in homes is not used because lots of gear relies on the AC frequency to provide a rotating field (easy to achieve with a capacitor).
m463 3y ago
In some whole-house solar systems, there is a DC component. I find this interesting: https://www.generac.com/generaccorporate/media/library/content/clean%20energy/pwrcell/pwrgenerator-spec-sheet.pdf?ext=.pdf https://www.generac.com/generaccorporate/media/library/conte... [PDF] Generac has a whole-house power system with a DC generator as part of the system. I don't see why there can't be a "DC power panel" for dc-only compoents where it makes sense. also, there are POE lighting systems (although when I looked they were expensive): https://www.axislighting.com/innovations/poe-lighting https://www.axislighting.com/innovations/poe-lighting
- ccorcos 3y ago
  Yeah totally. I think the main hurdle is just the fact that a DC circuit isn’t saving any significant money… But as a quality of life improvement, I could totally see this as a selling point for rural homes: 100% off-grid for everything except for heating/cooling. StarLink is pretty power hungry, but still, DC scales up pretty easily. I remember reading about there being a difference between a typical generator and an inverter generator. Apparently inverter generators are newer and more fuel efficient… so it’s interesting that even generators output DC these days…
  - m463 3y ago
    I've noticed two things about inverter generators: noise - they are quieter because they decouple the frequency of the electricity from the generator RPM. "normal" generators turn at a fixed RPM, which becomes the 60hz component of the AC output. inverter generators allow the generator to run at lower speed that is generally much quieter. power - They seem to be smaller, usually less than about 3kw probably because the cost of the inverter scales with capacity. It's easier to package a 2kw sinewave inverter with an engine to get a modestly price generator. But I haven't seen 7kw inverter generators generally available. But looking for standalone inverters there seems to be a sharp increase in price of inverters of that size.

louwrentius 3y ago

The key issue is that all my existing equipment is 230v. I would have to rebuy everything. If you need an inverter anyway for hvac, you have added complexity and no gains. Although not mentioned, I’m using 230v ikea fixtures with 12v led e27 bulbs wired to 12 volt, as you mentioned. Is indeed quite efficient, no inverter running.

ccorcos 3y ago
Yeah, but the annoying thing (from an engineering elegance perspective) is that most of those appliances that are on 230VAC convert to 12-48VDC internally (e.g. TV/monitor, LEDs).
- louwrentius 3y ago
  Yeah regarding those appliances 100% I see the inelegant solution. Imagine all new equipment below x watt would be required to have a 12v input in addition to 120/230

kamranjon 3y ago

I always thought it would be cool wire parts of your home using PoE (power over ethernet) if you had some solar panels and a battery bank.

ccorcos 3y ago
Yeah, I think PoE is 48V but it would be cool for adding connectivity to everything. WiFi more or less solves that problem these days though.
m463 3y ago
I know there are POE lighting panels for commercial spaces. When I looked they were pretty (prohibitively?) expensive. Maybe when powered by solar there are network effects that make them cheaper in overall system cost.

jacquesm 3y ago

You really don't want to run HVDC through your house. Solar panels in a string configuration make 100's of Volts, and what they produce is changing depending on the load and the amount of incident sunlight. So you would always have some kind of DC/DC conversion going and that's an inverter in all but name. You really don't want 12V if you DC either, the currents will be ridiculously high and for what you have saved on an inverter you'll be spending it on cabling and fuses. Much, much better to just go with AC and wire it straight into the distribution panel, it will save you thousands compared to a DC system of comparable power and the DC system will never be as safe (because breaking a DC circuit that carries 100A or more is very hard to do in a non-hazardous way using gear available to ordinary mortals).

ccorcos 3y ago
I’m curious to hear more about the difficulty of breaking DC current. I was also thinking planning to research more into GFCI for DC current. Seems like it’s possible if you tie the negative terminal to ground just like with AC but that feels weird to me. I guess cars usually have the negative terminal tied to the chasis so it seems reasonable. Low voltage, high amperage is definitely going to cost a lot in cabling though, that’s for sure. My understanding is that the only reason AC is preferred to DC for transmission is because it’s easier to transform. But rectifying is super simple and cheap — I wonder what the primary drawbacks are of using DC in homes…
- jacquesm 3y ago
  AC goes through zero 50 or 60 times per second so that helps you to interrupt a running current. DC runs steadily, continuously so if you try to break a DC current it will arc like mad and with a bit of luck you'll end up losing your contacts the very first time you try to break the circuit under load. DC in homes is not used because lots of gear relies on the AC frequency to provide a rotating field (easy to achieve with a capacitor).

m463 3y ago

In some whole-house solar systems, there is a DC component. I find this interesting: https://www.generac.com/generaccorporate/media/library/content/clean%20energy/pwrcell/pwrgenerator-spec-sheet.pdf?ext=.pdf https://www.generac.com/generaccorporate/media/library/conte... [PDF] Generac has a whole-house power system with a DC generator as part of the system. I don't see why there can't be a "DC power panel" for dc-only compoents where it makes sense. also, there are POE lighting systems (although when I looked they were expensive): https://www.axislighting.com/innovations/poe-lighting https://www.axislighting.com/innovations/poe-lighting

ccorcos 3y ago
Yeah totally. I think the main hurdle is just the fact that a DC circuit isn’t saving any significant money… But as a quality of life improvement, I could totally see this as a selling point for rural homes: 100% off-grid for everything except for heating/cooling. StarLink is pretty power hungry, but still, DC scales up pretty easily. I remember reading about there being a difference between a typical generator and an inverter generator. Apparently inverter generators are newer and more fuel efficient… so it’s interesting that even generators output DC these days…
- m463 3y ago
  I've noticed two things about inverter generators: noise - they are quieter because they decouple the frequency of the electricity from the generator RPM. "normal" generators turn at a fixed RPM, which becomes the 60hz component of the AC output. inverter generators allow the generator to run at lower speed that is generally much quieter. power - They seem to be smaller, usually less than about 3kw probably because the cost of the inverter scales with capacity. It's easier to package a 2kw sinewave inverter with an engine to get a modestly price generator. But I haven't seen 7kw inverter generators generally available. But looking for standalone inverters there seems to be a sharp increase in price of inverters of that size.