Live data from Hacker News

Puerto Rico's Solar Microgrids Beat Blackout

spectrum.ieee.org

211–220 of 251 posts

Re: Puerto Rico's Solar Microgrids Beat Blackout

#211

I don't know much about electrical grids, but I'm wondering if something like this concept could help South Africa with its endlessly struggling electrical grid problems. My city constantly has power outages and the majority of people cannot afford installing solar into their homes.

South Africa's problems with the electrical system and structure are well documented but also complicated. Here's a good recent video covering it, there are many others. https://www.youtube.com/watch?v=dUnR8PBtVW8

Re: Puerto Rico's Solar Microgrids Beat Blackout

#212

Earlier quoted context omitted.

A healthy regulated will encourage maximizing profit for power and bring in competition which drives the cost down until energy is a commodity and the cost of electricity is actually based on the price of production and a small profit based on the cost of capital. Any situations that cause price spikes result in investment to harvest the difference. The fact that you can add to the grid by installing solar and batter…

> A healthy regulated will encourage maximizing profit for power and bring in competition which drives the cost down until energy is a commodity and the cost of electricity is actually based on the price of production and a small profit based on the cost of capital. That is not how the electricity market works, in Australia anyway, and somewhat fundamentally everywhere. The network needs to maintain a frequency and v…

What it sounds like is Australia needs negative energy prices during peaks, again arguing for market forces, if you pay people to take electricity (charging people who produce electricity more than you pay people to take, keeping the difference) the "having more electricity than we can use" problem goes away and you don't have to prevent people from hooking up new capacity.

Well regulated markets enable this, charge consumers 0 or even pay them to use energy during the solar maximum, same for industry. People will build storage to make money.

You must have variable pricing driven by markets when you have a lot of variable renewables, fixed rates just don't work. Too much electricity is one of those good problems to have if you manage it correctly. Free or very cheap energy could be a huge competitive advantage for Australia.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#213
Just taking the article’s title at face value, what does it mean to have a blackout with microgrids?

Microgrids are, by definition, impervious to blackouts.

If a microgrid loses power due to a fault, neighbouring grids are unaffected. If all the neighbouring grids lose power due to a common fault, but your local grid is unaffected due to design or implementation choices, you’re golden.

Microgrids aren’t a solution to blackouts, and blackouts are not an issue microgrids have.

Looking at the article, the first paragraph claims:

When power went out across all of Puerto Rico on 16 April [well, clearly it didn’t as the very next sentence goes on to claim] a lot of the lights in the town of Adjuntas stayed on.

It can’t be both. It’s not a blackout and the lights stayed on.

Grid segmentation and multiple generation sources can do this too, and is a common feature of existing, traditional, power grids. The city I live in has these features with feed-ins from multiple hydro electric plants and wind factories, and a HVDC link to the next state over which has a full spectrum of generation sources bar nuclear.

As a result, the electricity here is very stable, and I don’t recall the last time we had even a brown out that affected the entire greater metro are and satellite towns.

Microgrids with interconnects are grids.

We can build grids that work, thereby leaving the general population free to pursue other, more important, economic endeavours.

Failing that, build microgrids.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#214

Does anyone have a good link/step-by-step for doing some sort of home solar system where: - it's sufficiently small-scale that no building permit is required - it looks nice enough that neighbors won't complain - the wiring is essentially plug-and-play The best approach I've been able to come up with is to purchase a medium size battery pack such as is used for glamping (glamour camping), plug it into the wall and co…

Pretty much exactly what you’ve described.

Where I am ya don’t been a permit for a shed if it’s under a 18 square metres, so 6x3m sheds are common.

You could look in to off-grid / caravan appliances, thereby saving on a smaller inverter, but they tend to be around 3x the price of regular appliances.

Highly recommended going for 48v system if you’re starting from scratch to save on ridiculously large diameter cables and stupidly high amperage you’ll be dealing with with a 12v system.

I did a repair this week on a poorly designed 12v system that had a 12v to 230v 7amp (1600 watt) inverter powering a 230v 10amp cook top in a camper van. That cooktop was pulling 235 amp from the battery through a very hot 175amp slow blow fuse.

Which is great if you want to melt the fuse post and the supply cables and… I found the fault before the fire started.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#215
post #106

Earlier quoted context omitted.

Wild. I wonder how they deal with the back feeding issue. Is there something about the home wiring in those countries that prevents it? (or do they just not care and line workers know to check if a line is truly dead?)

I feel the real danger of back feeding is not that american line workers can't be bothered to check if the line is truly dead before starting to work. It's that the line could be reenergized at any time.

Automatic transfer switches are a thing, but generally you want the supplies sync’ed.

A manual break-before-make transfer switch will do the job. Not much help if you’re not home and the mains goes out and your food spoils, though fridges will stay cold for hours if left shut, and longer if there’s a lot of thermal mass in them - try to keep most of the empty space in your fridge and freezer filled with water bottles.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#216
post #180

Earlier quoted context omitted.

Grid synchronizing is not the same as being able to operate in island mode. The only reason you can run those inverters without an automatic transfer switch is because they don't function when there's no grid to follow so they shut off when power goes out meaning they don't backfeed the grid outside the home. A lot of inverters are just grid following and you need some other source creating the 60-hz signal for the s…

> motors starting This is a big problem when working with single stage HVAC condensers. These motors can have a LRA rating of well over 100 amps.

The bang-on, bang-off compressors are a dying breed, however. The efficiency and output modulation of the inverter units means even the conventional split systems have been switching over. Likewise, the 'minisplit' (originator of these efficient compressors) definition has expanded to include ducted models, even ducted models with conventional high-cfm blower wheels.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#217
post #106

Earlier quoted context omitted.

Wild. I wonder how they deal with the back feeding issue. Is there something about the home wiring in those countries that prevents it? (or do they just not care and line workers know to check if a line is truly dead?)

it is actually simpler. The inverter stops power flow if it does not detect a grid voltage. The actual power coming from a balcony setup is tiny, a thousand watts ballpark. The typical house will consume the vast majority of that capacity. Even if some flows back to the grid, it will likely be consumed by losses in the transformer and wires.

You’d be surprised how few watts a fridge and a TV draw, 500 watts combined, and that’s only while the compressor in the fridge is running. Don’t open the fridge very often, or keep a lot of thermal mass in the form of filled water bottles in there, and the compressor in a fridge will spend most its time not running.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#218

Just taking the article’s title at face value, what does it mean to have a blackout with microgrids? Microgrids are, by definition, impervious to blackouts. If a microgrid loses power due to a fault, neighbouring grids are unaffected. If all the neighbouring grids lose power due to a common fault, but your local grid is unaffected due to design or implementation choices, you’re golden. Microgrids aren’t a solution to…

I think the average reader will understand exactly what they are trying to say.

Re: Puerto Rico's Solar Microgrids Beat Blackout

#219

Does anyone have a good link/step-by-step for doing some sort of home solar system where: - it's sufficiently small-scale that no building permit is required - it looks nice enough that neighbors won't complain - the wiring is essentially plug-and-play The best approach I've been able to come up with is to purchase a medium size battery pack such as is used for glamping (glamour camping), plug it into the wall and co…

The answers here have been pretty solid, a lot of what you want depends on where you live. For example, it is very likely that this is not possible if you're property is covered by an HOA. The definition of "it looks nice" is super hard to pin down (neighbors will complain at everything), and unless you're doing something really small, there is going to be some wiring involved. None of that should discourage you however.

"Zero emission generators" (aka battery boxes) are pretty easy to build, and even a 2kW inverter is relatively easy to hide/disguise. If you're doing this in a home situation (vs a camping situation) the 6V "golf cart" lead/acid batteries are really solid. A couple of those will give you 240 AHrs of 12V that can run a bunch of stuff. 240W panels can be stored at night and brought out during the day so keep them 'temporary.' Etc. Victron[1] makes nice chargers and monitors and are popular in the RV / Vanlife communities. Lots of online resources for hooking them up. And generally things you can roll around your property to different places are pretty easily defined as 'not a building' so immune from the permitting process generally.

[1] https://www.victronenergy.com/chargers

Re: Puerto Rico's Solar Microgrids Beat Blackout

#220

Does anyone have a good link/step-by-step for doing some sort of home solar system where: - it's sufficiently small-scale that no building permit is required - it looks nice enough that neighbors won't complain - the wiring is essentially plug-and-play The best approach I've been able to come up with is to purchase a medium size battery pack such as is used for glamping (glamour camping), plug it into the wall and co…

https://craftstrom.com/how-it-works/ is closest to what you want.

You don't need permit, and you don't even need new wiring.

Post reply on HN