More off grid power is wasted than used! We need better power storage options!

[Biggkidd]

Have you ever thought about how much power your solar panels waste, maybe I should say how much power your micro grid power system wastes? Anyway the point is almost all of us who live using micro grid power have far more panels or power making ability than power storage. So how much of the time is your system burning off excess power. For us I know on sunny days by 11am our battery bank is fairly well full and from then on till dark the panels just carry the loads of what’s running at the moment. So literally thousands of watts of potential power are being flushed everyday the sun shines or the wind / water moves. Take my system for example we have 3600 watts of panels in use at the house and another 1200 watts at the shop. Lets just talk about the panels at the house for now. Our daily power usage is mostly under 5kwh a day, except in mid summer when AC runs. On sunny days our 3600 watts an hour times 4 hours is 14,400 watts so lets say we average 12,000 watts a day on average of sunny days. So more power is being squandered than what’s being used. At my lowered numbers for real life not lab conditions of 12,000 watts a sunny day and we generally use less than 5,000 watts so 7,000 watts is being wasted. That’s something like 35 or 40% being used and the rest is wasted.

We as in all of us living the off grid / micro grid lifestyle really need to do better at finding ways to capture and use all this excess power we waste. I personally do not believe adding more chemical batteries is the answer but I do believe there is an answer out there we just need to find it.

The answer may be so simple as to seem stupid. But here’s a possible option solid mass or liquid mass storage! In this instance what I’m talking about is a LARGE heat storage vessel. Electric to heat is about as close to being 100% efficient as we have been able to get in energy conversion. Now whether you store and use that as heat or convert it to another form is up to your needs. I do know converting heat in to electricity is not even in the same ball park as it’s reverse being less than 50% and often as little as 3% efficient.

So what are your thoughts? Anyone have any viable ideas?

 

[DrJenner]

This is an interesting topic that is completely out of my wheelhouse, but given that we are just setting up our system and getting it going, I had to look into this!
Apparently electrolyzers are a thing, but mainly used in industrial settings.

https://www.environmentbuddy.com/en...rolyzers,mainly used for industrial purposes.

 

[HippoTwilight]

There is an unbelievable amount of money being thrown at R&D for grid-scale energy storage. Just about every conceivable avenue is being explored by someone. Thermal, pressure, chemical, and mechanical.

The apples-to-apples comparison for all these is "levelized cost of energy". For a provider, this is basically the price they need to sell energy from the system to break even on the system's lifecycle expenses. For a consumer, it's essentially an amortization of your "battery" costs. You could use it to compare expensive/long-life vs cheaper/shorter life battery chemistries. There aren't really any other consumer-oriented direct-energy storage methods beyond your typical electrochemical batteries.

The indirect methods are only limited by your imagination. Most of the grid-scale stuff is aimed at maximizing total-cycle cost efficiency. If you were planning something from scratch, you figure up your daily demand needs. Then you figure up your daily generation capability. Then you compare the two and figure up how much energy storage you need to cover the gaps during the annual worst case scenario, like a cold dark winter. You do all these calculations so you don't over buy solar, and throw the extra money at a storage system.

If you already over-bought the panels like biggkidd, there's not really any financial benefit to the energy storage because you're already producing more energy than you use. At that point it becomes a question of how much storage reserve do you want.

Don't think of it as wasted energy. If you are energy independent, you aren't wasting anything. If you were a power utility, and had to turn off panels during the day b/c of surplus generation...but then fire up a natgas plant at night...that is wasted energy. We'll start seeing grid-scale batteries pop up once the LCOE beats peaker plants.

You can bottle 100gal of water per day, but you're only using 40gal. You can build up a month reserve and cycle it to maintain freshness, but the fact is you still have a surplus of 60gal per day. Either accept the surplus or start using more of it. IMO, using it for the sake of using it is more wasteful than just not collecting it to begin with.

 

[Biggkidd]

There is an unbelievable amount of money being thrown at R&D for grid-scale energy storage. Just about every conceivable avenue is being explored by someone. Thermal, pressure, chemical, and mechanical.

The apples-to-apples comparison for all these is "levelized cost of energy". For a provider, this is basically the price they need to sell energy from the system to break even on the system's lifecycle expenses. For a consumer, it's essentially an amortization of your "battery" costs. You could use it to compare expensive/long-life vs cheaper/shorter life battery chemistries. There aren't really any other consumer-oriented direct-energy storage methods beyond your typical electrochemical batteries.

The indirect methods are only limited by your imagination. Most of the grid-scale stuff is aimed at maximizing total-cycle cost efficiency. If you were planning something from scratch, you figure up your daily demand needs. Then you figure up your daily generation capability. Then you compare the two and figure up how much energy storage you need to cover the gaps during the annual worst case scenario, like a cold dark winter. You do all these calculations so you don't over buy solar, and throw the extra money at a storage system.

If you already over-bought the panels like biggkidd, there's not really any financial benefit to the energy storage because you're already producing more energy than you use. At that point it becomes a question of how much storage reserve do you want.

Don't think of it as wasted energy. If you are energy independent, you aren't wasting anything. If you were a power utility, and had to turn off panels during the day b/c of surplus generation...but then fire up a natgas plant at night...that is wasted energy. We'll start seeing grid-scale batteries pop up once the LCOE beats peaker plants.

You can bottle 100gal of water per day, but you're only using 40gal. You can build up a month reserve and cycle it to maintain freshness, but the fact is you still have a surplus of 60gal per day. Either accept the surplus or start using more of it. IMO, using it for the sake of using it is more wasteful than just not collecting it to begin with.

You make some valid points. But you need to consider the cost factor. First I have 33kwh at 48 volts so it's not a small undersized bank and 5000 watts of panels isn't really to many panels if you want enough power on cloudy days. Up until now I've been using AGM batteries I buy used, well I need new batteries but I lost my connection to the industry and don't have xxxxx to spend for a new bank at this time. But what if I make a low budget way to recoup some of the power that's not used on sunny days. Say I made something that gives me an additional 10% of storage for the price of junk I have laying around and time? Of course there are other ways to use that stored heat or for some added dollars you can buy equipment to turn some of that heat back in to power. There are options for those of use who don't have a lot of money if you get creative.

 

[HippoTwilight]

You make some valid points. But you need to consider the cost factor. First I have 33kwh at 48 volts so it's not a small undersized bank and 5000 watts of panels isn't really to many panels if you want enough power on cloudy days. Up until now I've been using AGM batteries I buy used, well I need new batteries but I lost my connection to the industry and don't have xxxxx to spend for a new bank at this time. But what if I make a low budget way to recoup some of the power that's not used on sunny days. Say I made something that gives me an additional 10% of storage for the price of junk I have laying around and time? Of course there are other ways to use that stored heat or for some added dollars you can buy equipment to turn some of that heat back in to power. There are options for those of use who don't have a lot of money if you get creative.

Your batteries are getting old, and you (understandably) don't want to pay retail to replace the lot. So you're looking to supplement your aging batteries with some kind of junkyard thermal system?

You have 3 basic options. Sensible heat like solar water heaters, but this doesn't help your excess electricity problem. You could do something like an electric boiler. Heat up a pressure vessel of water (or anti-freeze mixture) during the day using electric heating elements. Hope it gets hot enough to produce steam and spin a turbine as the sun sets. Or there's the good ole fashion Sterling engine, which might work better at sub-steam temperatures.

My point in sizing the system was... your annual panel production = you annual consumption. At some point in the year you will have a huge surplus, and at another point in time you will have a huge deficit. But over the long term (e.g. annual), it all balances out. Your storage capacity (AGM batteries, flywheels, molten salt, compressed air, whatever) should be sized to hold whatever your peak deficit is.

 

[Biggkidd]

Basically yes but that's not the point of this thread. The point here is to make full use of what you're making already. Absorb any excess power that you can for later use.

 

[Neb]

Use excess to pump water to an elevated pond and then use the potential energy in the water to drive a micro hydro...

Ben

 

[Biggkidd]

As you already know that's one of my many multi use projects. I'll be getting back on the pond dig once the weather straightens out. When it comes to power I like options, lots of options.

The rest of the world might go dark but I'm working a hundred ways to keep it from happening to my family.