Off grid solar

[Hv&Lv]

Thanks for thinking of us, folks. Fiona wasn't anything like Maria, 5 years ago. 85mph winds instead of 140mph makes a big difference. But our trusty generator has been doing yeoman duty...we'd have no power or water otherwise. The muni water is also off and if we have no power, our pump won't work, so it's a double whammy. Our understanding is they frequently shut off the utils in anticipation of a storm, thinking that may minimize damage. I can't weigh in on the effectiveness of that strategy. From what we've heard about trees down, it may be a week or more before the grid is restored, possibly even longer. We're praying for some sun soon. Our internet, cellphones and satellite TV all have been working through the storm, so we don't have that 'cut off' feeling.

Won’t it still produce ‘some’ on cloudy days?
Im not very schooled on home systems.
we deal in MW size mainly.

 

[ggunn]

Won’t it still produce ‘some’ on cloudy days?
Im not very schooled on home systems.
we deal in MW size mainly.

Yes, but how much it will produce is highly variable depending how much light is getting through the clouds. The more the better, obviously.

 

[curt swartz]

Here in Silicon Valley it was clear on Saturday and cloudy with on an off showers on Sunday,

On Saturday my system produced 67.77 KWH
On Sunday it produced 28.29 KWH

 

[caribconsult]

Won’t it still produce ‘some’ on cloudy days?
Im not very schooled on home systems.
we deal in MW size mainly.

Definitely. Even if it's just reasonably bright out, it might kick out 1-1.75Kw, I've seen 500w when it's about to rain, so it does put out. It's been mostly cloudy all day, our grid is out and no one knows when it will return and the battery was at 42% this morning and loafing...we've been on the gen for a day so far. Today the storm passed but there was no sun, just overcast, darker and brighter variably. I switched the house to the generator and let the Tesla charge up with what's available, in the 500-1750w range and no load, and it's at 89% right now. We might have enough to start using it around 8pm, shutoff the generator and pray for sun tomorrow.

 

[caribconsult]

Tesla powerwall can have problems operating totally off grid because of software updates that require network connectivity and some operations that temporarily require grid power.

You can connect your Tesla to them via your house network. Their built-in cell connection I found to be very erratic, same for their wifi section so I ran some ethernet into the gateway and it goes right to the router. Tesla will tell you you must have a grid connect to update but I think they are full of you know what. I've had my system upgraded via the internet connect and it works flawlessly. The only thing you might need after an upgrade is a restart, just like installing some new something in your computer and for that you usually need the grid momentarily to get it booted. There is a way to use a 12vdc power supply and some test leads to boot it up, so the grid is not absolutely necessary.

 

[caribconsult]

We just had an interesting sequence here in Puerto Rico. We got seriously sideswiped by TropStorm Fiona, which was a CAT 1 hurricane when it left, with 85+mph winds and an enormous amount of rain. That was a month ago. The whole island was in "apagón" as they call it...blackout everywhere. We were some of the last to be lit up, and it was raining all afternoon almost every day afterwards, so our solar harvest was really suffering. And there was no grid. Sooooo....back to basics and fire up the generator, we'd use it during the no-sun periods in the afternoon and let the battery charge with what little bit of light there was, and by doing this, we could shut the gen down at bedtime and run on the battery through the night in peace and quiet, and pray for sun the next day. Sometimes we got sun, other times we used the gen. But we always had power until they finally lit up our grid a few days ago, about a month after the storm. Big improvement over María 5 years ago, when it took 4 months for the power on our street to be connected. And we're heading in to winter weather, which is clear and sunny here, so the harvest will be back to normal imminently.

 

[gadfly56]

We just had an interesting sequence here in Puerto Rico. We got seriously sideswiped by TropStorm Fiona, which was a CAT 1 hurricane when it left, with 85+mph winds and an enormous amount of rain. That was a month ago. The whole island was in "apagón" as they call it...blackout everywhere. We were some of the last to be lit up, and it was raining all afternoon almost every day afterwards, so our solar harvest was really suffering. And there was no grid. Sooooo....back to basics and fire up the generator, we'd use it during the no-sun periods in the afternoon and let the battery charge with what little bit of light there was, and by doing this, we could shut the gen down at bedtime and run on the battery through the night in peace and quiet, and pray for sun the next day. Sometimes we got sun, other times we used the gen. But we always had power until they finally lit up our grid a few days ago, about a month after the storm. Big improvement over María 5 years ago, when it took 4 months for the power on our street to be connected. And we're heading in to winter weather, which is clear and sunny here, so the harvest will be back to normal imminently.

Glad to hear things are getting back to normal for you folks.

 

[caribconsult]

Glad to hear things are getting back to normal for you folks.

Thanks for thinking of us. It was a pain in the you know what month because it rained nearly every afternoon, as I said, so we needed to use the gen more than I ever remember using it since we got the Tesla, but things are getting back to normal and it's starting to look like we won't have another big storm. Light a candle for us!

 

[ggunn]

...it's starting to look like we won't have another big storm...

You are tempting Fate with that comment, you know.

 

[caribconsult]

You are tempting Fate with that comment, you know.

Oh, yeah, we well know about that. Our storm season is actually June - Nov. But major storms into mid Oct and afterwards are almost unheard of, in the same way June/July storms are rare. Our peak danger is mid Aug - Oct. We just passed through peak season and we got Fiona....only a trop storm when it got here but a Cat1 when it left, and it really swiped our end (west coast) the hardest. Nevertheless the whole island didn't have power, Ours was some of that last to return and it was less than a week ago. We learned years ago how to prep for a storm; we had a generator before we actually moved into our house. It got us through María just fine, although a bit noisy, then got the Tesla in the aftermath. Plus we have a big water reserve with pump and pressure tank, so we didn't suffer as bad as some others. Because we are up in the mountains there was no flooding here, just lots of fallen trees and powerlines.

What we did have was lots of days of sunny morning and then thunderstorms all afternoon, so our solar harvest wasn't nearly what it should be. We ran the gen for a few hours many days to save what battery we had, turned the gen off by just after dinner and we had sufficient battery to take us through the night and into the next day and we prayed for sun. I don't remember every having to run the gen that much after a small storms, but thankfully we had one. Things are mostly back to normal....power is on island-wide, food, hardware, gas, basics all available, cell/TV/Phone service working, Internet only went down for a couple of hours (we are considering moving to StarLink) so all in all, not exactly the disaster María. was. Thanks for thinking of us and I always like chatting with you and gadfly, amongst other here. Have a great winter season.

 

[ggunn]

Maybe so, but the worst hurricane to hit Cozumel in decades, maybe ever, all things considered, was Hurricane Wilma. It hit on October 21, 2005. You are likely out of the woods this year, though, there has been a bit of high pressure filtering into the Caribbean from the north since mid to late September. We are slated to have a pretty major cold front coming through here (Austin TX) tonight.

 

[caribconsult]

Maybe so, but the worst hurricane to hit Cozumel in decades, maybe ever, all things considered, was Hurricane Wilma. It hit on October 21, 2005. You are likely out of the woods this year, though, there has been a bit of high pressure filtering into the Caribbean from the north since mid to late September. We are slated to have a pretty major cold front coming through here (Austin TX) tonight.

I have heard that all the dust storms we've had have had a beneficial effect at holding down Atlantic basin storms. When you live here, we watch the NOAA basin maps almost daily and there's been way less activity in the Cape Verde Islands, where much of this originates. Of course, María popped up very close to us, so I don't know what that proves, but this has been a pretty fortunate year so far. As you point out, we're not totally out of the woods yet, but it's looking good.

 

[gadfly56]

I have heard that all the dust storms we've had have had a beneficial effect at holding down Atlantic basin storms. When you live here, we watch the NOAA basin maps almost daily and there's been way less activity in the Cape Verde Islands, where much of this originates. Of course, María popped up very close to us, so I don't know what that proves, but this has been a pretty fortunate year so far. As you point out, we're not totally out of the woods yet, but it's looking good.

Knock on wood the worst is over, although La Nina years, as we are having now, on average lead to more active hurricane seasons. Currently we are still below the NOAA predictions for the season.

 

[caribconsult]

Knock on wood the worst is over, although La Nina years, as we are having now, on average lead to more active hurricane seasons. Currently we are still below the NOAA predictions for the season.

Gotta be thankful for small presents.

 

[caribconsult]

If there is grid power available where your customer is building his home, a better use of his money would be to have a grid tied PV system, with battery backup if the grid is not completely reliable. Another word of caution: if you would be the one designing and installing an off grid PV system for your customer you had better know what you are doing and be prepared for service calls in perpetuity if your customer does not thoroughly understand how the system works. We have been burned a few times this way, to the point where we do not do off grid systems at all any more.

GGunn is so right about this. If you want to go almost completely off grid, you can do it but you need to understand how your system works, how to read the app and what those numbers mean, and learn just when you'll need some grid....1st rule of solar is "you can't live off the sun if there isn't any." and there will be days with little or no sun. You'll need the grid if that happens, and if the grid is also down, as was the case here in Puerto Rico recently from Fiona, you'll need a generator, if you want to have power. If there is grid available, you can have a separate breaker to either feed or kill the grid into the gateway, and use it when you need it. You can also charge the battery that way. We just had three or four days in a row of minimal sun and we used around 4Kwh of grid on each of those days to supplement the battery, and switched the grid off at night...the battery had enough to carry us through the night and into the next day, and we'd pray for sun.