diy solar

diy solar

Brown bear destroyed our yurt powered by Yeti 3000, so I'm designing solar for a cabin & a bit lost

AlaskanNoob said:
Here is a look at t

Ah, I didn't realize the inverter also charged the battery. That's good to know. I guess I may have to get an inverter (or just a charger since I'm not planning on running any AC loads from the 12V) to connect the generator to the 12V battery. Will the inverter/charger know "the battery isn't full and no PV is coming in, so start the generator?"
Click to expand...

If it's an inverter/charger, it will charge its source battery. Looking at it again, you don't have the 12V attached to an inverter/charger, so you will need to purchase a suitable AC-DC converter.
 
snoobler said:
If it's an inverter/charger, it will charge its source battery. Looking at it again, you don't have the 12V attached to an inverter/charger, so you will need to purchase a suitable AC-DC converter.
Click to expand...
That's very good to know, thank you!
 
snoobler said:
Curious.

PV Watts takes globe location into consideration and includes average influence of weather, i.e., it knows you'll never get 1000W/m^2. Why would you cut it in half arbitrarily?

Selecting Fairbanks, optimal annual tilt would be about 65°:

View attachment 40120

Do you really think you'll only get 1/2 of the listed values?
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My misunderstanding of the term PVwatts. I thought it were the listed PV power of the panel.
Anyhow your result page is only valid for grid connected PV, where you can value every coulomb received.
With off-grid, the picture is heavily different.
I recommend using PVGIS, (off-grid option) which is much more informative and takes the installed battery capacity into account.
 
If you need that much power, and the Relion batteries are only capable of 12 volts, I would definitely consider stepping up the voltage to 24-48 volts, and using a different set of batteries. Like stated above, you would need to spend a LOT on charge controllers (and wire) to be able to charge at 400+ amps.

A 48 volt system would take 1/4 of the amperage to charge at the same rate as a 12 volt.

I just got sixteen 90ah Lifepo4's for under $700 shipped, 4.3kw @ 48 volts. You would save a metric ass-ton of money if you built your own battery bank. It looks like the Relion batteries are $3k each, so it's about $9000 for 10kw. Diy price for 10 kw is probably about the same price as a single Relion, mabye a little more for a good BMS to go with it.

I also trust my own hand-built batteries (and know more about them) than ones I would buy.
 
A.Justice said:
If you need that much power, and the Relion batteries are only capable of 12 volts, I would definitely consider stepping up the voltage to 24-48 volts, and using a different set of batteries. Like stated above, you would need to spend a LOT on charge controllers (and wire) to be able to charge at 400+ amps.

A 48 volt system would take 1/4 of the amperage to charge at the same rate as a 12 volt.

I just got sixteen 90ah Lifepo4's for under $700 shipped, 4.3kw @ 48 volts. You would save a metric ass-ton of money if you built your own battery bank. It looks like the Relion batteries are $3k each, so it's about $9000 for 10kw. Diy price for 10 kw is probably about the same price as a single Relion, mabye a little more for a good BMS to go with it.

I also trust my own hand-built batteries (and know more about them) than ones I would buy.
Click to expand...
I'm currently planning for a 24V battery bank and a single 12V Relion-LT battery. I will run the numbers in the morning for a 48V battery bank to replace the 24V bank and see how that affects things. Thanks for the advice!
 
AlaskanNoob said:
Here is a better look at our sunrise and how it will change in winter. We have no chance of seeing the sun on Dec 21st... November and January are more than likely out too, but if we cut a few trees maybe, just maybe...
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Don't guess, use the free online-tool PVGIS, that will help you to perfectly plan for your northern location:
PVGIS
You should also consider using 3 strains each one with an own controller oriented east, south, west since the sun turns heavily around.
Sun tracking should be difficult and expensive, considering the amount of panels and the harsh environmental conditions.
 
rin67630 said:
Don't guess, use the free online-tool PVGIS, that will help you to perfectly plan for your northern location:
PVGIS
You should also consider using 3 strains each one with an own controller oriented east, south, west since the sun turns heavily around.
Sun tracking should be difficult and expensive, considering the amount of panels and the harsh environmental conditions.
Click to expand...
I'll check that out thanks, although I'm skeptical it will have accurate terrain data with that kind of fidelity (even Google Earth gets the terrain elevation wrong) and I'm pretty sure it won't have our forest. But I'll give it a look.
 
AlaskanNoob said:
I'll check that out thanks, although I'm skeptical it will have accurate terrain data with that kind of fidelity (even Google Earth gets the terrain elevation wrong) and I'm pretty sure it won't have our forest. But I'll give it a look.
Click to expand...
OK, i would not bet much to get terrain data accurately, and not trees. But it is miles better than all other applications especially to give you realistic battery simulations.
 
I ran PVGIS on the several arrays and I sure hope it's accurate. It's showing we'll average 800 watts a day in December. That would be excellent if true!
 
rin67630 said:
OK, i would not bet much to get terrain data accurately, and not trees. But it is miles better than all other applications especially to give you realistic battery simulations.
Click to expand...
It gives me an idea of what might be done with some tree cutting. And the battery calculations are great. Great tool, thanks for sharing!
 
Unless I made some kind of mistake, I found it interesting that PVWatts said my solar would produce 3000 watts a day (that would be a dream) in January, while PVGIS gave a more realistic number of about 800 watts a day in January (which is probably still optimistic since it likely doesn't account for our trees). Weird. I'm sure I must have done something wrong in PVWatts.
 
rin67630 said:
Don't guess, use the free online-tool PVGIS, that will help you to perfectly plan for your northern location:
PVGIS
You should also consider using 3 strains each one with an own controller oriented east, south, west since the sun turns heavily around.
Sun tracking should be difficult and expensive, considering the amount of panels and the harsh environmental conditions.
Click to expand...

What am I missing?

1615324000821.png

It appears PVGIS has essentially no location information for Alaska and won't work for it.
 
rin67630 said:
That's not much to live on for a big family. You will have to be VERY greedy on power.
Click to expand...

Just me and the wife. I think we'll end up making a ground array in a spot that gets the best winter sun and running a wire from that spot to our place if we need to. For this first go it'll just be a generator for backup.

Unless Elon releases some great season shifting super cheap new battery....
 
AlaskanNoob said:
Fortunately I'm in a blue spot so it worked for me.
Click to expand...

Talk about lucky.

I do not believe PVWatts has any horizon data. It assumes location, elevation and weather conditions. In varied terrain, it may be horrifically inaccurate, and no tools takes trees into consideration.

I checked PVGIS for my location and system, and either I have no idea what I'm looking at, or it is grossly inaccurate. It predicts my battery is depleted a significant percentage of the time for 6kWh of daily usage on a 12kWh battery. That never happens.

It also shows that I always have unclaimed energy equal to or greater than my energy output most months.

I suspect it just assumes I use 250W for 24hours per day. As a result, it's not indicative of actual usage patterns. I don't brew coffee or run the microwave at night. It's grossly conservative. Even a 24kWh battery with 6kWh of usage is still indicated as depleted a small percentage of the time.
 
rin67630 said:
Ten pounds of plutonium could have been a solution...
:ROFLMAO:
Click to expand...
If it weren't for the fact that I'm dumb and live in a forest that would catch fire, I'd be really tempted to try using water plus solar in the summer to fill tanks with hydrogen to feed a hydrogen-to-electric motor...
 
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