Solar powered home AC

[J1000]

Thought I'd share this simple but effective way to power any home AC using solar. Does not require dealing with the power company nor backfeeding the grid. All takes place outside of the home so it does not need permits either.

Very simply, I have a wooden rack with 3x 300 watt panels I got for free. On each panel I have a Enphase IQ6 microinverter.

I then use a simple extension cord to connect the outputs of the microinverter to the switchable side of my AC relay. The microinverters sense when the relay is closed and sync to the 240v from the grid and then power on, which takes about 5 minutes. When the AC switches off, the microinverters also switch off and there is no risk of backfeeding the grid.

House idle power: 920 watts

Switch on AC: ~3000 watts, drops to ~2500 watts after a few minutes of running

Microinverters switch on: ~1770 watts

I'm going to add a few more panels and see if I can run the AC fully off solar.

Solar array angle can be adjusted throughout the year.

Very simple wiring to the AC relay. Just connect the solar to the switched side of the relay:

I also have an AC mister kit which as the name implies, mists the AC condenser which increases efficiency.

 

[nakman]

this is super cool, Jimmy. also how I see the future of home power in a way. Twice now I've created a stand-alone system in a camper/rv which could successfully keep a 12v fridge running, music, tv, all the lights I need, as well as power a 12v heater somewhat indefinitely. I know propane forced air camper heaters aren't likely practical for a big house, but not really the point as there are other ways to heat a house also. But the idea is to me it's easier to start with nothing, then build up the panels, inverters, and batteries needed to satisfy the need- for example I ran out of battery a couple times overnight so I added a second battery. Then I wasn't getting a full charge with the fridge at near 100% duty cycle, so I added a couple panels... in the end I'm pretty sure 400 watts and 2 batteries is enough juice to maintain camper life.

If I were to build a home from scratch I could see taking the same approach... starting with lights and a fridge, then what do I need for heat, least important running a dryer or AC, but both doable by scaling up. In your case you're starting with AC but also have a lot more capability at figuring out this stuff.

In our trucks we're often chasing parasitic drains... like alarms and fridges that we're not exactly using, which run our batteries down. My bottom up approach for a house would look at all of that from a home perspective, as when I look around the house at all the clocks, printers, computers, power supplies, tv's, speakers, etc. just sitting there waiting for someone to need them I wonder how much all of that is costing me. If I had a more closed system, where I was in more touch with my actual consumption, and/or an actual consequence of over consumption, I'd probably think of this differently.

 

[J1000]

this is super cool, Jimmy. also how I see the future of home power in a way. Twice now I've created a stand-alone system in a camper/rv which could successfully keep a 12v fridge running, music, tv, all the lights I need, as well as power a 12v heater somewhat indefinitely. I know propane forced air camper heaters aren't likely practical for a big house, but not really the point as there are other ways to heat a house also. But the idea is to me it's easier to start with nothing, then build up the panels, inverters, and batteries needed to satisfy the need- for example I ran out of battery a couple times overnight so I added a second battery. Then I wasn't getting a full charge with the fridge at near 100% duty cycle, so I added a couple panels... in the end I'm pretty sure 400 watts and 2 batteries is enough juice to maintain camper life.

If I were to build a home from scratch I could see taking the same approach... starting with lights and a fridge, then what do I need for heat, least important running a dryer or AC, but both doable by scaling up. In your case you're starting with AC but also have a lot more capability at figuring out this stuff.

In our trucks we're often chasing parasitic drains... like alarms and fridges that we're not exactly using, which run our batteries down. My bottom up approach for a house would look at all of that from a home perspective, as when I look around the house at all the clocks, printers, computers, power supplies, tv's, speakers, etc. just sitting there waiting for someone to need them I wonder how much all of that is costing me. If I had a more closed system, where I was in more touch with my actual consumption, and/or an actual consequence of over consumption, I'd probably think of this differently.

Yeah I agree with the principle of doing more with less. I've been more vigilant with unplugging unused stuff and trying to use LED lighting etc to lower overall consumption, but it seems like our Xcel bill just keeps going up and up even though we're using less and less. I'm kicking around ideas of how I can use the solar to help offset heating costs this winter as well. Luckily (or maybe not) Xcel upgraded our meter to a smart meter a few years ago so now they are actually charging for what we use, and not just averaging it against our neighbors like how it used to be.

 

[DanInDenver]

Does a mini-split have a similar AC relay? Solar power a min-split for heat or at least supplemental heat.

 

[HDavis]

This is a great idea, Jimmy. I think a ground source or air source heat pump powered by solar would be the ultimate solution to heating and cooling your home with solar energy.

In the best world our homes wouldn't be mass built by unscrupulous developers and instead are designed and built thoughtfully to take advantage of our environment in a way that does not impact it negatively.

As an architect I have reference this book titled Sun. Wind, Light often throughout my career; https://archive.org/details/sunwindlightarch0000brow/page/n7/mode/2up. There are many ancient principles of design that harness the natural environment to produce harmonious living conditions without negative impacts.

Another strategy I use to confirm that my design meets my intent is to perform energy modeling, this allows me to visualize the performance of my design and make modifications to the areas that are under performing.

I say this because the built environment is responsible for 40% of our annual CO2 emissions and solutions like yours no matter how small will help us reduce that number.

End of rant.

 

[Notyourmomslx450]

A buddy that moved to Wescliffe has a house that is off grid.
The only thing he is reliant on is propane for stove, back up generator and boiler. He's also equipped with one of those solar water heaters.
The house was placed on the lot to get the best sun exposer for is solar all year. It has 2x6 walls instead of the standard 2x4 walls.
He's built a bigger battery bank and added a few more panels to keep things powered up better. He's lazy when it comes to unplugging things when not in use. He also bought a dishwasher because again, he's lazy.
He's also got a shop so the propane generator usually powers that when he's running the big tools.
He's high enough that he doesn't need AC. When it's hot he just goes to the basement.