Gasing Up on Sunshine

[Gale Hawkins]

Efficient and stable inverted perovskite solar cells with very high fill factors via incorporation of star-shaped polymer | Science Advances

Something for solar geeks.

 

[Gale Hawkins]

Singapore’s 60 MW floating PV array up and running

I'm surprised that all the ways people come up with to do solar without utilizing important land mass.

 

[Gale Hawkins]

While I happen to like Two Bit he includes links to solar calculators when reviewing his 11 year history of solar use at his house. I didn't know anyone in the USA was paying $0.50 per kilowatt peak rates.

Paying under 11 cents flat rate going solar while better than buying a speedboat will make for a long payback. Plus we lucky to be the last house on a 3-phase grid. The trees are trimmed more often and first repaired in an outage. After the 2009 ice storm we were out of power for 65 hours while neighbors south, west and north of us were out 2+ weeks.

 

[ponytug]

When you say you are the last house on a three phase grid, what do you mean? That you have three phase at the house? (WYE? Delta?) (If so, that has repercussions for grid-tie solar...)

Just curious.

All the best,

Peter

 

[Gale Hawkins]

When you say you are the last house on a three phase grid, what do you mean? That you have three phase at the house? (WYE? Delta?) (If so, that has repercussions for grid-tie solar...)

Just curious.

All the best,

Peter

A 3 phase grid has 4 wires and a single phase grid only require 2 wires.

I might run by our power utility office today and ask because I had never thought about that in doing a grid tie.

Our house is single phase so they just pull the power from one of the three lines and it is connected to our transformer so we're single phase at the house but we would have to have three transformers all wired to our house if we had three phase but basically three phase is for industrial use let's say we had wanted a machine shop or something like that with machines with big motors at our house.

Actually I have no concept how a grid tie works so I will figure that out too.

 

[ponytug]

Thanks for clarifying. I happen to have both three phase and "single" phase on the property. The three phase (hot leg Delta) runs a well at some distance from the pole/meter. The single phase is pulled off one of the three phase transformers down to the house at a second meter, where we have solar with grid-tie microinverters that produce 240V AC per panel (helps with shading, which we have daily, and also reduces inverter failures to a panel, rather than a large fraction or all of your panels. Much easier to repair and faster.).

The reason the well doesn't have solar is that it is three phase. At some point the pump will die and it will be replaced by a solar pump, batteries, and generator backup for wildfires. We pay the equivalent of $4.+kWh for the pump power because of demand charges from our local utility for having a pump.

Technically, single phase is two hots (240V hot to hot) and a "neutral" grounded conductor to handle any 120V load imbalance between the two hots. Life gets kind of ugly when you lose that third wire.

Three phase residential solar is really uncommon in the US. Large solar, yes. 50Hz 220V solar overseas, yes. 208/240V 60Hz, uncommon. Victron makes inverters that can be wired to do it, but for most people there isn't the need.

Good luck!

All the best,

Peter

 

[Gale Hawkins]

I like the 2 hour fire rated cement board idea.

 

[Gale Hawkins]

How Low Can A Perovskite Solar Cell Go? Pretty Low!

This seems to be the holy Grail being chased today.

 

[Gale Hawkins]

Tesla launches initiative to build first solar neighborhood in Austin

This might be setting a trend for EV manufacturers.

 

[ponytug]

Tesla launches initiative to build first solar neighborhood in Austin

This might be setting a trend for EV manufacturers.

I am not so sure. There are some physics issues that work against a solar roof, the primary one is that they get hotter, which reduces the efficiency of the sunlight to electrical energy conversion. Having solar panels on your roof, or more correctly 4-6" off of your roof, keeps the panels cooler, which generates more electricity (it also keeps your roof cooler, too, unlike a Tesla solar roof). That's why for many (most?) solar owners have peak production in May, rather than June, when it is hotter, and the cells are less efficient.(Northern hemisphere)

I think that Tesla has been having real teething problems with these roofs. They don't seem to be able to do pricing, permitting, and installation efficiently, and they don't seem to appreciate that it is a roof first and foremost. I know of folks with Tesla roof issues, e.g. leaks, and Tesla has demonstrated it's typical nonexistent customer service with the predictable results of leaks and damages. If a car breaks down, anyone can tow it to Tesla dealer for repair, a Tesla battery can have a breaker flipped and it is out of the loop not doing any harm, but a roof is a much more expensive item and not readily serviced by a non-Tesla roofer, at least at the moment. I like the idea, and I am impressed with much of the engineering that Tesla has done so far, but as someone who has personally done a few roofs, it looks to me like Tesla didn't have very many roofers contributing to the design/installation/customer service process, or they weren't being listened to. I do think Tesla is under directives to improve, but I am not sure that there is a corporate culture that is set up to listen to anyone other than Elon. As an example, for the latest generation of non-solar tiles, it is said that to repair a tile on the roof, all the tiles above it must be removed. And the part of the roof most likely to have incidental contact with ladders and people on it? The lower part of the roof...

I do think that this developer relationship might be helpful for Tesla to learn how to standardize their installation techniques, and perhaps lower their costs. Personally, I wouldn't install a Tesla solar roof until there were plenty of third party installers who could come the moment a leak or broken tile was spotted.

The only automobile company that has solar operations that I am aware of is Tesla as a result of the Solar City acquisition. Whether that was smart, stupid, above board, or illegal, I have no knowledge. But from a distance, buying a relative's company of which the CEO is a board member looks unusual at a minimum, which may be why the acquisition is being litigated at the moment. On a personal level, I see very few synergies between an electric car company and solar (yes more people could charge at home, but only if the car is home during the day). Charging at work is a far better option, but that will require more chargers more places and grid improvements to handle the power flows. More national grid interties would help as well, but that is a bigger picture issue.

Per a number of Powerwall owners, the round trip energy cost of a Tesla Powerwall seems to be about 82-85%, so a home owner would take a significant energy loss to store solar at home to charge a car (which would lose another 8-10% charging), not to mention the high cost of 80-100kWh of battery storage.

The world needs a ton more solar, but I think that there are lots of details to be worked out, e.g. how to get solar from the US West to the Southeast in the summer to run AC units, or from the Southern areas to the Northern areas during the winter to run heat pumps for heating, (and installing those heat pumps in the first place!) and what is to be done with surplus power in the Spring and Fall? What about painting more roofs white, or installing more insulation on homes, or upgrading windows? Just because a decision made short term economic sense when the cost of energy was low, doesn't mean it still makes sense today or ten, twenty years from today. "Super" insulated homes take less energy to be habitable, a lot less, and it doesn't take scientists working for the next thirty years to figure out how to do it. We know how to do it today. Based on other technology evolutions, non-silicon solar cells are, I think, at least twenty or thirty years away at the moment. For better or worse.

All the best,

Peter