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OffGridInTheCity

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Thank you for the thoughtful response.

I live off grid and grew up living off grid. We heat with wood which sounds like not an ideal option for you. We do have solar hot water panels but they do basically nothing in the winter because the days are too short to bring the water up to temp(northern MN). I have also noticed that partly cloudy days the solar hot water does nothing but the solar still brings in a decent amount. Based on all that I have decided that for my uses extra solar PV and an efficient heat pump water heater would be the way to go.
Yes, I'm with you on Solar electric panel vs Solar water panel.

As to thoughts on ways to improve your situation. Something I am sure you have heard before and have probably looked into is just to reduce the need which with heating being dominant for you and you say you have mild winter conditions more insolation and maximizing southern window solar exposure could get that huge heating load a little lower. Insulation, Insolation, Insolation :) Are you aware of the Passive House Standards? It takes a lot to go the whole way with that but when done properly even really cold MN winters can stay warm with very minimal added(beyond the natural window gains) heating.
In a way - the butt end of our house is 2 stories directly in the sun which has a huge affect in summer.

The problem I'm having right now is 9 days in a row (so far) of total dense clouds / fog / drizzle. Never happened before. There just isn't any sun to work with at all.

But its a good idea, I'll add it to my list for serious research.

As another thought that I have considered for myself but my load is low enough it hasn't made sense yet is hydrogen as energy storage(different type of battery). I imagine you have significant excess energy during the summer months so the idea is you electrolyze that extra solar energy into Hydrogen which can be stored in propane type tanks and with minimal modification fun propane appliances. Then you use that Hydrogen in the winter to heat ether directly with combustion or a fuel cell to produce electricity for your heat pump. The upfront investment hasn't made sense for me but with your high load it might be more efficient/cost effective for saving that summer energy for winter when you need it.

Or how most folks do it is to use the utility grid as the "battery" with net metering selling the summer power back to the grid and then buying in the winter
Interesting. When I add the extra panels I'll have excess PV in spring/summer that will go to waste - maybe 1500kwh. I've watched youtubes on 'toy' hydrogen generators etc. Do you have any leads / youtubes or something practical at a larger scale? Wouldn't 500kwh of potential power require a lot? For example, it takes 200gal of propane to get near 500kwh of generator output. Seems like significant hydrogen storage would be a huge danger / big no-no / I'd be a menace to the neighborhood! :)

Are there any other practical ways to convert excess PV to 9month storage for re-conversion to electricity? For example...

I did the math on lifting mechanical weights (such as my 2,500gal water tanks) to 10ft in air and then running generation as it came back to the ground but it comes out to like a few hundred watts for 10tons! I need several hundred kwh.

Spinning up flywheels is similarly impractical at useful scale for DIY and actually dangerous if the disk explodes.
 
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Oberfail

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Are there any other practical ways to convert excess PV to 9month storage for re-conversion to electricity?
The only way i'd know, would be to store hydrogen in pressure tanks under your garden. Dangerous? Yes, but so are propane tanks.
Those electrical power -> hydrogen -> power things are pretty expensive tho. A 5w one at 100% efficiency would create about 32kWh of hydrogen when run for 9 months straight.
 

Oberfail

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Can you link me to some sources / info on this?
Not really, i barely know much about them aswell. I had a small one for some experiments back 10 years ago powered with two AA batteries. Efficiency was rather meh, if i had to guess about 30% percent for the whole power -> hydrogen & oxygen -> power cycle. Those fuel cells are rather expensive, about 20€ / 1 watt of power. At that price, i rather suggest you to burn the hydrogen directly for heat in the winter because building a device to creat hydrogen isnt hard.
 
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Cheap 4-life

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Before I got into solar I dabbled with hydrogen. I made a fairly large hydrogen Separator. It worked very well. The problem was the way hydrogen is stored and the space required to store it. It’s a lot less dense than propane. They came up with this lava rock looking stuff that kinda absorbs the hydrogen and making the hydrogen more dense.. Anyways I never ended up storing the hydrogen. Seemed like more than I wanted to get into and as mentioned the fuel cells are very expensive.. I instead got into Solar. Which is much cheaper and more efficient.
OGITC I doubt you have enough space to store excess solar in the summer into hydrogen for the winter..
Maybe move to a smaller house with more land (out of the city) so you can have a wood boiler. Might not be possible for ya. And that goes against your name. But if you did that, you already have plenty of pv/battery to be completely offgrid 24/7..
 

Oberfail

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Before I got into solar I dabbled with hydrogen. I made a fairly large hydrogen Separator. It worked very well. The problem was the way hydrogen is stored and the space required to store it. It’s a lot less dense than propane. They came up with this lava rock looking stuff that kinda absorbs the hydrogen and making the hydrogen more dense.. Anyways I never ended up storing the hydrogen. Seemed like more than I wanted to get into and as mentioned the fuel cells are very expensive.. I instead got into Solar. Which is much cheaper and more efficient.
OGITC I doubt you have enough space to store excess solar in the summer into hydrogen for the winter..
Maybe move to a smaller house with more land (out of the city) so you can have a wood boiler. Might not be possible for ya. And that goes against your name. But if you did that, you already have plenty of pv/battery to be completely offgrid 24/7..
Can you name/link me that lava rock looking stuff?
 

OffGridInTheCity

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It was 8 years ago when I was messing with hydrogen.
Did a little youtube hunting today. One guy said he made/compressed 500liters of hydrogen only in a few hours to a 30lb? propane tank size - which seemed fantastic! But then showed it only ran a lawn mower engine about 10mins. So running a generator, putting out 5000w for 4 hrs would be something like 24,000 liters of hydrogen. Too much / too dangerous for 'in the city' I think and for my skillset. The Full Cells at 5kw are 30-40K!!! Too much $. I can see why it keeps coming back to propane + generator as a backup for 20kwh / day level of generation.
 

cak

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The problem I'm having right now is 9 days in a row (so far) of total dense clouds / fog / drizzle. Never happened before. There just isn't any sun to work with at all.
For me I figure in these infrequent edge cases I am okay using a propane or gas generator to produce enough electricity to get me by until sunshine. For me I also have considered a wood heat to electric backup generator but not for you :)

I don't have any specific info for you for Hydrogen other than confirming what it looks like you figured out that it is expensive to get setup on a scale that helps.
 

OffGridInTheCity

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And it get's worse, dipping to 4.3kwh today. 9 days of single digit kwh on a 13kw PV array.
1638860938411.png
I have 16% losses on the raw PV input so the 11.5kwh PV = 9.9kwh of useable power.
 
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jdeadman

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Mar 28, 2017
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Do you have other methods of generation other than solar? Do you have the ability to go on-grid for a time? I live in Canada (22' north of the 48th Parallel) and we are currently getting about 5 hours of usable Solar but it;s really low in the sky so your panels need to be almost vertical. and when I go off-grid I will require a massive array or a combination of the Solar, Wind, Water (if I can get it ) and other (generator)
 

cak

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In my area the worst months are November followed by December and more recently with climate change October has been pretty gray. I Figure a good day is 2 hours of full sun :(
 

jdeadman

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Wow that is low @cak A friend of mine lived in Yellowknife, Northwest territories and for 2 months they would have zero sun . It would get to twilight for a few min but then get dark again. and for the 3 weeks around the solstice it was dark all the time. but in the summer they had the never ending day as well. I have a hard enough time with the changes to the amount of daylight we get during the year here
 

OffGridInTheCity

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Do you have other methods of generation other than solar? Do you have the ability to go on-grid for a time? I live in Canada (22' north of the 48th Parallel) and we are currently getting about 5 hours of usable Solar but it;s really low in the sky so your panels need to be almost vertical. and when I go off-grid I will require a massive array or a combination of the Solar, Wind, Water (if I can get it ) and other (generator)
Yes I have grid, it's a 'goal' to see how far I can go 100% off-grid while still being in the middle of a city.

This is my 3rd year in operation and I've only had three episodes of 2 days and 1 episode of 3 days of single digit kwh up till now. Last year I had 520kwh of useable power for December on 13kw PV and with my 42 emergency/extra panels I could see that being 1040kwh - which is enough. So I thought I had it covered but this Dec could be 300kwh or lower? We'll see.

Until this run of 10days and counting... Maybe this is a once in a decade occurrence? It's not just clouds but THICK CLOUDS! This is making me think of Portland or Seattle!! (One of the reasons we live in Southern Oregon is that it's pretty nice weather compared to Portland)

But it's happening, so I have to face it and lay in some propane for future events like this. Ordered the first 2 100lb tanks to see if I can manhandle them OK :)
 
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OffGridInTheCity

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In my area the worst months are November followed by December and more recently with climate change October has been pretty gray. I Figure a good day is 2 hours of full sun :(
Wow! Reminds me to count my blessings of available sun instead of complaining :)
 

OffGridInTheCity

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(FYI - Love your dashboard .. :) )

Yes sir, and my clouds aren't even at ground level all the time. You can see the mountain ridge (2-3 thousand feet) so they must be very thick.
1638990372497.png
11:00 AM...
1638990214528.png

1638990709151.png
 
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