No idea what I'm doing...please help.

[KEVHOL]

I'm new to this forum, new to solar living, new to off grid power...I need help.

A brief background. My wife and I are in our 50's (I'm 59) and we are about to downsize significantly. We want to build a tiny home, 500 to 550 sq ft. Where we are building is on property on a lake in N. Louisiana. We will have to obtain access to water, electricity and sewer. I would like to explore the use of solar power. Sewer and water are taken care of.

Here's my line of thinking. Again, I have NO IDEA of what I'm doing. I would like to tap into solar power as total supply of my electrical needs. I would like to have propane for all appliances (water heater, stove/oven, washer/dryer, refrigerator and furnace) and as a back up to charge my batteries during low charge times. Access to sunlight will be probably 6-8 (or more) hours a day.\

Is this something that is even do-able? Where do I start? I ask these here because I've learned in my life to trust the experts in the field. There is tons of information on this forum, so much so that I don't even know where to start looking. I have months to make these decisions and I need some major guidance.

Thanks in advance for any help

kevhol

[bob-n]

This sounds like a worthy project and a fun retreat.

Solar power comes in a few flavors: Grid-tie allows you to use the grid at night and pump into the grid during the day. Off-grid requires that you either shut down or run from energy stores at night. Unfortunately, energy storage is currently expensive and wears out.

The most common energy storage for electric use is batteries. Buying propane or gas for a generator is often more economical, but not as clean and has transportation issues. Flooded lead-acid batteries (FLA) are large and heavy but cheaper than Lithium Ion batteries. One friend is powering his house with solar panels during the day and forklift FLA batteries at night, because it would have been too expensive to run power cables to his location. That's proof that it can be done.

Are you ready to estimate your energy needs? Can you break it down into nighttime electricity needs and daytime electricity needs in kWh per day? Will you need heat? Air conditioning? Refrigeration? Well pump? What else? That will help sizing the system. You'll need panels, inverters, chargers and batteries. They are all commercially available and go together relatively cleanly. The devil is in the details.

If you're handy, you can do the labor yourself. If you have to hire someone to do the job, expect 2X to 3X higher cost for the same project.

I'd love to exploit using gravity to store energy by pumping water uphill during the day and having the water flow downhill drive a turbine at night, but the quantity of water involved would be almost astronomical. As an example, lifting 1000 kg of mass up 10 meters stores 27 watt hours. You would probably want to store many kilowatt hours of energy. Where would you put all of that water?

An interesting alternative is to pump air instead of water. You're on a lake. Envision a large balloon underwater in the lake. During the day, you pump air into the balloon and raise the water level of the lake above it a tiny amount. At night, you use the stored air in the balloon to power a turbine. It sounds simple, but it still requires huge balloons and deep storage. Also, I don't know where to get the pieces required. My local party store sells balloons, but not this big.

https://en.wikipedia.org/wiki/Compressed-air_energy_storage

[Mike90250]

So, first, Welcome, and thanks for asking questions before you commit to a path. Way too often, it's "my fridge won't stay on overnight and my batteries are dead in the morning" .

First, get a book from the Dummy series "Solar Power for Dummies". if you hunt around, there are PDF's of the first edition floating on the web, or simply buy a copy of the 2nd edition.

Then you need to accurately calculate your loads, so you know what you will have to power. A mistake here usually requires a complete overhaul/replacement of the $15,000 you just spent last year, unless carefully planned for, "upsizing" a PV system is really tough.

Second, plan from the start, that you will have "conventional" USA 240VAC split phase service. That keeps everything standard on the power delivery side. Not 12V DC for an RV

Third, nobody gets 6-8 hours of usable solar power in USA. Yes the sun is up, but there is not much harvestable power before 9am or after 4pm. You might eek out 6 hours in the summer, but winter will be much less. And don't forget clouds. Without bright shadows on the ground, you are not getting good sunlight.

Fourth. Next to a lake. Will you have to deal with humidity ? Bugs? Do you have a reliable breeze and enough windows to take advantage of it ? Will you need air conditioning ? ceiling fans?

Will you need a sewage pump for your septic ? (next to lake, high water table, may require an "Advanced Septic" with pumped air and chambers) Well pump for water ? Elevated storage for constant water pressure, or a pressure tank and pump that cycles when you use water?

Energy storage. With a small house, you will need a utility shed for the batteries and solar gear. Orient the roofs for solar harvest, or use ground or pole mount arrays. Flooded lead acid batteries are the reliable gold standard. Lithium batteries need internal heaters below 35F. You will need a backup generator. ( I have 3 ) or risk loosing your battery bank if you cannot recharge.

Heating in winter, have you considered wood heat from a Masonry Heater (36 hour thermal reserve) Ideal for a small house, save the furnace for odd cold spells

A recent development in HVAC is Mini-Split Heat Pumps. The new efficient models have internal inverters and very little starting surge requirements. A few members here have them and like them. Some will provide heat below freezing temps outdoors.

[SunEagle]

Mike. Since you live off grid you may want to include the amount of time you spend to baby sit your solar/battery system. Some people think it is a simple plug and play operation but don't understand it may include a lot of someones spare time to make sure all is working properly.

[Mike90250]

Mike. Since you live off grid you may want to include the amount of time you spend to baby sit your solar/battery system. Some people think it is a simple plug and play operation but don't understand it may include a lot of someones spare time to make sure all is working properly.

yep all that money that you're not paying yep all that money that you're not paying to the electric company for them to have lineman out repairing things monitoring substations making sure insulators are clean all that work is now yours making sure the panels are clean rodents haven't chewed to the wires Critters haven't gotten into the nice warm inverter to spend the winter.....
Batteries need maintenance, cables checked.


And it all gets paid back when the power company cut the power to the city for five days because they might cause a fire and you are the only one that has power