Anyone know anything about solar Power?

So I have a cabin up in the hills that has a solar system. When we bought the place there were no batteries. The cost to use IREA electricity is only around $26/month. I would like to install a hot tub outside and would like to run it off solar. First question is how do I determine the output of the panels and approximately how many batteries would be needed to accomplish this? Do solar systems switch back and forth between solar and line electricity when the batteries are running low?

Thanks
Lurch

Why don't you just heat the water in the hot tub with hydronic panels? Instead of converting the energy again

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Originally Posted by Lurch

So I have a cabin up in the hills that has a solar system. When we bought the place there were no batteries. The cost to use IREA electricity is only around $26/month. I would like to install a hot tub outside and would like to run it off solar. First question is how do I determine the output of the panels and approximately how many batteries would be needed to accomplish this? Do solar systems switch back and forth between solar and line electricity when the batteries are running low?

Thanks
Lurch

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You would need a rather large battery bank I'm assuming. My guess the economics for the batteries might exceed the cost of reliable power from the utility.

Solar to electric conversion will be more expensive (short and long term) than buying electricity. The only time it makes sense is if running the utilities is a big fee. Having designed several off-grid systems from $20 K to $300K, there are some pretty cool pieces of equipment out there for solid waste heating that are more economical, especially if you have a supply of wood.

Hydronic panels with a drain down feature, directly preheating the water, is a good option that should save you some $.

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First question is how do I determine the output of the panels and approximately how many batteries would be needed to accomplish this? Do solar systems switch back and forth between solar and line electricity when the batteries are running low?

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Without reading the tags or labels on the panels, you won't know. The technology is varied and changes every year. Most systems are designed with an automatic switch that will run the batteries down to a certain level then transfer to utility and back.

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Originally Posted by MarkCO

Solar to electric conversion will be more expensive (short and long term) than buying electricity. The only time it makes sense is if running the utilities is a big fee. Having designed several off-grid systems from $20 K to $300K, there are some pretty cool pieces of equipment out there for solid waste heating that are more economical, especially if you have a supply of wood.

Hydronic panels with a drain down feature, directly preheating the water, is a good option that should save you some $.

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I have a very good supply of wood. Could you point me towards a website about the wood option.

Here is a general information site: http://www.combustionportal.org/hydronicheaters.cfm

If you already have a wood stove inside, you can add a kit like this: https://www.northerntool.com/shop/to...2034_200362034

If not, you can buy a wood stove with a hydronic loop in the back. They run in the $1000 to $3000 range for small units, which will be less than the batteries. If you are only heating the hot tub, you will want a way to keep from delivering water that is too hot which will take a throttling valve on a cartridge circulator pump. The ones I use are a bit more money since they are used to heat 4,000 to 8,000 square foot homes You can always go cheap and build yourself a barrel stove from a kit and drop one of those hydronic loops in it as well.

http://www.acehardware.com/product/i...hoCzckQAvD_BwE

Here is a guy who did just that: https://diybarrelstoveoutdoorfurnace...tdoor-furnace/

Thanks for all the info.