Sharing Solar-generated Electricity in Bangladesh – Could This Be Useful In The U.S.?

I saw a pretty interesting youtube video about a system (hardware and software) being sold in Bangladesh which links multiple solar PV systems together to form a mini-grid for off-grid people. And here’s a link to an article that explains the details of SolShare’s system. According to the youtube video almost 20 million in Bangladesh use solar power now, and Bangladesh has one of the largest number of solar PV systems in the world; I haven’t verified if that’s actually true or not, so don’t quote me. A company named SolShare has developed a piece of hardware and associated software to allow customers to form Peer-to-peer microgrid systems. One of the crucial services provided by SolShare’s system is the ability of people who are sharing electricity with their neighbors to be able to accurately charge their neighbors for electricity that leaves the solar PV owner’s system. It seems like a great idea, and theoretically should work well in Bangladesh – but is there any instance where this would work well in the United States? For this to work, you’d have to have a lot of people who are off-grid living quite close to other people living off-grid. I don’t think that’s common now, but maybe eco-villages might have an interest in this type of technology? Peer-to-peer sharing of energy between households is pretty far off in the United States, but this is an interesting concept.

Solar Thermal Hot Air Boxes Must Have An Airtight Seal On The Outlet Duct!

There are solar thermal hot air boxes (STHABs) videos and write-ups all over youtube (videos) and BuildItSolar.com (pictures& text) that show how to make them yourselves for maybe a couple hundred dollars USD (or even a lot less if you have the right stuff laying around) but I have yet to find one that includes an airtight seal for the inlet/outlet ducts. An airtight duct seal makes the difference between getting free heat in the dead of winter and getting free heat AND unwanted free freezing air conditioning in the dead of winter. The laws of physics are pretty reliable, and they work the same way during a sunny day and a dark freezing night – air temperature is changed by what the exterior environment is doing to the inside of the the solar thermal hot air box. On a sunny day, the sun sends photons through the glazed front of the solar thermal hot air box, which hits something that changes the sunlight into heat, and thereby heats the air being moved through the STHAB (solar thermal hot air box). In the middle of a freezing cold winter night, the ambient temperature will chill the interior of the STHAB and thereby chill any air that passes through it. You would wipe out any benefits from the daytime heating if you don’t have an air-tight seal covering the exit duct during long winter nights. You might not care about that if the STHAB is just being used to provide heat during the day to a place that won’t be negatively impacted by severely cold weather – for instance, if this is attached to an unheated shed/garage with no plumbing or items that will be damaged by freezing temperatures. This also doesn’t apply to STHABs that are entirely inside a conditioned space – in that case, the cold doesn’t get to it, and it doesn’t become a cold generation machine.

The STHAB shown in my picture is a commercially made box, from Northern Comfort / Sunsiaray, but I think the guy who made them retired in 2018?

I also made one myself, which my brother sort of remade, but that is not as good looking, and probably not as productive, though I haven’t been able to test that carefully. I used two old window sashes that I got for free as the front glazing, which has the benefit of being able to easily withstand the heat generated inside the box on a sunny day, though putting a sheet of Lexan over those window sashes would trap more heat inside the box, and thereby make it more productive. If you do a really good job of building one of these boxes and then put an acrylic or polycarbonate sheet on the front of it, instead of a glass sheet (window sashes, screen door, etc), you run the risk of that potentially expensive sheet melting. I was able to measure temperatures of over 200 degrees Fahrenheit coming out of my homemade STHAB on a sunny day when no fan was running, and how long would polycarbonate or acrylic stand up to that?

This is really great and durable technology, and I encourage you to give it a try, but remember to make sure you have an airtight seal on the ducts when the sun is not shining on it!

Solar Microgrids That Survive Hurricanes?

60 Minutes did a report on how the Bahamas are upgrading their electrical grid to better handle the increasingly violent and increasingly frequent hurricanes hitting their low-lying islands, and I encourage you to watch their video if you can.  If you can’t watch it, you can at least read the transcript at the link above.

It’s incredibly exciting to see progress being made in the search for hurricane-proof solar PV microgrids, and I really hope they succeed.   The solar panels are much closer to the ground in this new type of installation and will supposedly withstand 180 mile-an-hour winds; I think it would be ground-breaking if this microgrid actually does withstand what are expected to being increasingly frequent category 5 hurricanes.   This type of installation will become more in-demand in more places as our world continues to warm.

I do have one quibble about this otherwise well-done presentation and it’s this – Bahamian Prime Minister Hubert Minnis  mentions that he said at the U.N.  ‘First World nations make the greatest contribution to climate change, (t)hey are the ones responsible for the changes that we see. The increase in velocity and ferocity of the hurricanes and the different– and the changes, typhoons that we see today, but we’re the innocent victim. We’re the ones that are being impacted by what you have created.”  Minnis seems to want the U.S. and European countries to contribute to an insurance fund to help rebuild from future storms.  My quibble is this – the electricity generated on these islands is so expensive now that installing solar PV arrays/microgrids even with battery backup will surely cost what they’re already paying now, or, more likely, even cost less.   I could see asking for loans to help with the initial installation of solar, which could be paid back with money paid by electricity customers on their monthly bills.    And I could see asking for some financial help to rebuild after climate-change-influenced storms, but solar is such a good financial move that it would be a freebie /handout to ask for the U. S. and Europe to pay for that.