4 ms·

The last time I read about localized power on HN, storage came up, esp batteries and inverters. The majority of appliances now assume always on, very clean, 60

by csours 7y ago

The last time I read about localized power on HN, storage came up, esp batteries and inverters. The majority of appliances now assume always on, very clean, 60hz (or 50 or X) power, because that's what the turbines at the power company have always made. What assumptions would have to change for appliances and human life to fit with localized generation? (Ie off-grid living)

Faaak 7y ago
Not really true. Nearly all of new (i.e. Post 2000) switch-mode power supplies accept a wide range of voltage (100V-250V), and a wide range of frequency (even 0Hz, i.e. DC current would work).
- lstodd 7y ago
  Frequency is irrelevant. They would run on DC or 400Hz or 10KHz just fine - they all rectify the supplied current first. Frequency is only limited by the bridge diodes. And 100V is written on them only because there are no countries with lower than 100V standard. I'll bet a crap chinese usb charger will work off 48VDC just fine.
  - jdsully 7y ago
    The ripple filters will be tuned for a specific frequency.
  - coryrc 7y ago
    Converters in universal power supplies tend to fail around 75-85Vdc even at low loads and usually can't deliver full current at 90Vac, in my experience (was using universal power supplies in electric cars; okay for 96V+ cars, but unusuable for 72V and below). 48Vdc is not a reasonable expectation, unfortunately.
adamcharnock 7y ago
What Faak said. I’m living on off grid solar and my tech (TV, Xbox, NAS, LED lights etc) never misses a beat, even when a big load turns on. It’s the old tech (i.e. motors) that are actually a bit more fussy.
- csours 7y ago
  What about running out of power?
  - adamcharnock 7y ago
    Well at that point everything turns off :-) I’m still running the system in, so the (NiFe) batteries are not at full capacity yet (perhaps only at 30%-50% storage capacity). Even so I can easily stay up until 2am watching TV. And that’s only with 4 (25%) of the panels out (it is summer though, I’ve yet to do a winter.). Oh, and I’m running a fridge/freezer on that too. Still, probably going to get a UPS for the NAS soon. Edit: just to rabbit on a bit more - panels are cheap. They only accounted for around 20-25% of the total system cost. Power storage is the expensive part (more like 40% of the cost). It is interesting to try to tailor my systems to draw power at suitable times of day. At 2pm I have more power than I know what to do with, I could happily run 3kw load for a few hours most days around that time. At the batteries theoretical max capacity I have 10kWh stored, but I’m only getting around 3kWh at the moment. I’ve got a backup generator to cover any extreme weeks in winter. Figuring out the water pumping/irrigation has been a fun one I’ve been looking at today. The trees will have wood chip moats around them, a side effect of which is they can be watered at any time of day (which is great), but watering the grass must happen when it isn’t sunny (so maybe I can squeeze in a watering when the last rays are hitting the panels, or first thing in the morning). As a software developer it’s an absolute dream.
    - dev_dull 7y ago
      extremely cool! How easy was it to disconnect from the grid? What's your city/county? Also, just curious, why did you decide on NiFe? Most off-grid folks I know either use li-ion for density or lead acid for cost/abundance/ease-of-use. > At 2pm I have more power than I know what to do with, I could happily run 3kw load for a few hours most days around that time. A fun and interesting problem to have. This is why we need so much more research into energy storage.
      - adamcharnock 7y ago
sliken 7y ago
Generally most consumer equipment in the last decade or two is pretty flexible on voltage. The modern switched power supplies are both flexible and efficient. But generally equipment is AC, and solar and batteries are DC. So it's entirely up to your inverter how clean your power is. But generally off the grid users have to either over build a crazy amount (which is expensive) or adapt a bit. Things like hanging laundry vs using a clothes dryer might not always be necessary, but if the wind/solar is behind it would be a good investment. Even things like dressing for summer instead of blasting the AC so you can wear multiple layers can make a huge difference. If you have a surplus during the day (which is common with solar), run your most power intensive stuff then. That way your very expensive batteries don't have as much load to make it through the night. Things like air conditioning are among the hardest loads, high peaks, worst when it's hot, and overall just a huge amount of power. Who wants to pay $40k for batteries instead of just being a bit smarter with insulation, whole house fans, and dressing for the weather? In my city I'm often out in about after midnight, with a light jacket on, and listening to neighbors AC blasting with all their windows closed while their AC fights the thermal mass in their attic. Seems insane to not open the windows when it's under 60F. Generally minor changes. You can still stay up all night watching tv, still have a comfortable life pretty close to normal. But if you don't adapt you might be out of luck a few days a year or have to spend 2-3x the money.
- adrianN 7y ago
  All the things you mention would save 2-3x the money with a normal grid connection too, it's just that energy is much too cheap for people to care. Thus 10kW of continuous primary power consumption for each American.
  - sliken 7y ago
    Agreed. However on the grid running a dryer instead of hanging clothes isn't much difference in money to most Americans. Off the grid the difference in batteries+solar/wind is huge.
jws 7y ago
The good news is that sine wave inverters are no longer expensive in the context of an off grid system. The bad news is that they seem to idle at about 3% of maximum power capacity. This can easily be your largest energy consumer if you build for infrequent substantial loads.

by csours 7y ago

Faaak 7y ago

Not really true. Nearly all of new (i.e. Post 2000) switch-mode power supplies accept a wide range of voltage (100V-250V), and a wide range of frequency (even 0Hz, i.e. DC current would work).

lstodd 7y ago
Frequency is irrelevant. They would run on DC or 400Hz or 10KHz just fine - they all rectify the supplied current first. Frequency is only limited by the bridge diodes. And 100V is written on them only because there are no countries with lower than 100V standard. I'll bet a crap chinese usb charger will work off 48VDC just fine.
- jdsully 7y ago
  The ripple filters will be tuned for a specific frequency.
- coryrc 7y ago
  Converters in universal power supplies tend to fail around 75-85Vdc even at low loads and usually can't deliver full current at 90Vac, in my experience (was using universal power supplies in electric cars; okay for 96V+ cars, but unusuable for 72V and below). 48Vdc is not a reasonable expectation, unfortunately.

adamcharnock 7y ago

What Faak said. I’m living on off grid solar and my tech (TV, Xbox, NAS, LED lights etc) never misses a beat, even when a big load turns on. It’s the old tech (i.e. motors) that are actually a bit more fussy.

csours 7y ago
What about running out of power?
- adamcharnock 7y ago
  Well at that point everything turns off :-) I’m still running the system in, so the (NiFe) batteries are not at full capacity yet (perhaps only at 30%-50% storage capacity). Even so I can easily stay up until 2am watching TV. And that’s only with 4 (25%) of the panels out (it is summer though, I’ve yet to do a winter.). Oh, and I’m running a fridge/freezer on that too. Still, probably going to get a UPS for the NAS soon. Edit: just to rabbit on a bit more - panels are cheap. They only accounted for around 20-25% of the total system cost. Power storage is the expensive part (more like 40% of the cost). It is interesting to try to tailor my systems to draw power at suitable times of day. At 2pm I have more power than I know what to do with, I could happily run 3kw load for a few hours most days around that time. At the batteries theoretical max capacity I have 10kWh stored, but I’m only getting around 3kWh at the moment. I’ve got a backup generator to cover any extreme weeks in winter. Figuring out the water pumping/irrigation has been a fun one I’ve been looking at today. The trees will have wood chip moats around them, a side effect of which is they can be watered at any time of day (which is great), but watering the grass must happen when it isn’t sunny (so maybe I can squeeze in a watering when the last rays are hitting the panels, or first thing in the morning). As a software developer it’s an absolute dream.
  - dev_dull 7y ago
    extremely cool! How easy was it to disconnect from the grid? What's your city/county? Also, just curious, why did you decide on NiFe? Most off-grid folks I know either use li-ion for density or lead acid for cost/abundance/ease-of-use. > At 2pm I have more power than I know what to do with, I could happily run 3kw load for a few hours most days around that time. A fun and interesting problem to have. This is why we need so much more research into energy storage.
    - adamcharnock 7y ago

sliken 7y ago

Generally most consumer equipment in the last decade or two is pretty flexible on voltage. The modern switched power supplies are both flexible and efficient. But generally equipment is AC, and solar and batteries are DC. So it's entirely up to your inverter how clean your power is. But generally off the grid users have to either over build a crazy amount (which is expensive) or adapt a bit. Things like hanging laundry vs using a clothes dryer might not always be necessary, but if the wind/solar is behind it would be a good investment. Even things like dressing for summer instead of blasting the AC so you can wear multiple layers can make a huge difference. If you have a surplus during the day (which is common with solar), run your most power intensive stuff then. That way your very expensive batteries don't have as much load to make it through the night. Things like air conditioning are among the hardest loads, high peaks, worst when it's hot, and overall just a huge amount of power. Who wants to pay $40k for batteries instead of just being a bit smarter with insulation, whole house fans, and dressing for the weather? In my city I'm often out in about after midnight, with a light jacket on, and listening to neighbors AC blasting with all their windows closed while their AC fights the thermal mass in their attic. Seems insane to not open the windows when it's under 60F. Generally minor changes. You can still stay up all night watching tv, still have a comfortable life pretty close to normal. But if you don't adapt you might be out of luck a few days a year or have to spend 2-3x the money.

adrianN 7y ago
All the things you mention would save 2-3x the money with a normal grid connection too, it's just that energy is much too cheap for people to care. Thus 10kW of continuous primary power consumption for each American.
- sliken 7y ago
  Agreed. However on the grid running a dryer instead of hanging clothes isn't much difference in money to most Americans. Off the grid the difference in batteries+solar/wind is huge.

jws 7y ago

The good news is that sine wave inverters are no longer expensive in the context of an off grid system. The bad news is that they seem to idle at about 3% of maximum power capacity. This can easily be your largest energy consumer if you build for infrequent substantial loads.