1 thing I found lacking: discussion of optimal power point tracking. If ignored (PV panel -> load directly) then depending on the load's characteristics, it can pull the solar panel into very sub-optimal power generation.
That is an advantage of heaving batteries in the system: they can serve as a predictable / constant load, which a charge controller uses to have the solar panel operate at near-maximum output.
But as the article notes: any power that goes through a battery rather than used directly, is relatively expensive. So it makes sense to minimize battery size & throw money at more solar panels instead.
Batteries are a cache, they allow harvest energy to be stored and used as needed, depending on load you can forgo them so long as the load is ok with varying voltage or being cut in and out if run through an inverter of some sort or solar controller both which will have capacitors that act as little batteries or caches to try and provide consistent power until they can't and they shut down.
4 12V 200AH deep cycle lead acid batteries cost $1552 on Amazon and hold as much energy in practice as a 100AH 48V LFP battery which last 15 years, minimum, and only costs about 6% more up front. (Not linking to specific batteries in order to not shill for them, but do a little searching for 100AH 48V 4U server rack LFP batteries on youtube, and you will find dozens of tutorials.) Quality inverters last 30 years, not 10.
Are these people TRYING to light money on fire? Are they fronting for someone by trying to make solar look impractical? Or are they just stupid?
PG&E Generation Mix: 5% Biomass & Biowaste, 1% Geothermal, 2% Eligible Hydroelectric, 22% Solar, 9% Wind, 8% Large Hydroelectric, 5% Natural Gas, 49% Nuclear.
Over the past 20 years I have noticed this tendency among a subset of people people in the environmental movement. Some people loved solar power only when it was expensive and small scale. A future world powered by solar once evoked images of cozy little villages, bicycles, deglobalization, handmade wooden toys, and a slower pace of life. Now that solar power is inexpensive and scalable, it's unappealing to people who value the cozy aesthetic more than they value meeting quantifiable IPCC emissions targets.
"For example, if I omitted the battery storage of my solar installation, my system would become about 10 times cheaper: ..."
and then goes further along this interesting line of reasoning...
I think there's something to be said for time-shifting predictable large energy consumption events to points at which you're producing more solar energy than can be stored.
Scheduling an electric water heater to run at noon until 2pm for instance, depending on the insulation and size of the tank might be enough to provide all the hot water you might need for 24 hrs. Likewise, for electric car charging.
But there is definitely a minimum battery bank size requirement for maximum efficiency, especially if this is an off-the-grid setup where you can't rely on the grid to act as infinite excess storage.
Without batteries, you're either overproducing (and therefore throwing that power away by backing off the MPPT point), or you're underproducing (and therefore browning out). Therefore, you have to size your solar array for the worst case spike. AC locked rotor might be 30A for instance -- better make sure you're producing at least 7.2kW (~9.5kW of solar+) at any time the AC might flick on.
The higher the peak-to-average of your daily load, the more inefficient your setup will be. In our 9.5kW array example, this means any time you're consuming less than that, you're paying for panels that are effectively offline.
I think it's an interesting problem to solve, with a lot of variables. If the limiting factor is $ vs. roof space vs. ROI vs. 99.9% uptime, you might get different "optimal" answers.
For my own off the grid setup, I went with a cheep high efficiency chest freezer ($200) and converted it to a fridge using a replacement thermostat. It's about 10x less expensive than the equivalent DC fridge, has much better insulation, and does the job. I then spent a tiny fraction of the savings on a couple of extra solar panels to cover any loss in conversion from DC to AC to DC.
And the only inverters we know will last 30 years had to have been made in the 90s …
With a fridge, moisture from foods and opening the door would collect on the bottom, unless you've got it tipped on its side? Even still, given how deep it is I would think that might be problematic.
FWIW I live in a very humid climate, so maybe it isn't so much an issue for you.
A few things :
* you don't need a fridge in winter so you can just turn it off. * charging battery banks / laptops in sunny periods results in the battery bank being useful in times when the weather isn't so kind. * no amount of solar is enough in the deep of winter. * any amount of solar is too much in the height of summer. * pubs are great for charging devices. * lead acid batteries last substantially longer if you only let them drop to half their true capacity and regularly charge them. Yes alternatives exist but there's something to be said for making what you have work for as long as possible.
Lead acid is much more dangerous than that, IMO, due to the potential offgassing.
For me at least the storage is about 1/3 of the cost of the system and I'll likely have to replace it once (probably with Sodium Ion since that is taking off and $50 a KWH) and a new inverter and there is no way it costs even half the total system install over the lifetime.
> any amount of solar is too much in the height of summer
I totally agree. I can't understand how it why solar is promoted, when the winter is when you need more energy as you're in more, heating your house, etc. You can't store your summer's energy till the winter.
https://www.sanluisobispo.com/news/local/environment/article...
Diablo Canyon was expected to stop operating its twin reactors in 2024 and 2025, but the state failed to procure enough clean energy to replace the plant in time. In September, the California State Legislature passed Senate Bill 846, which allocated $1.4 billion to PG&E to fund the nuclear power plant’s license renewal costs for staying open through 2030.
That was followed by a $1.1 billion grant to PG&E in November from the U.S. Department of Energy through President Joe Biden’s bipartisan infrastructure law.
The NRC in March told PG&E it can run Diablo Canyon past its original closure dates without a current license as long as the utility company submits a valid license renewal application for the two reactors by the end of 2023.
PG&E has said it will file a license renewal application for Diablo Canyon by the end of this year.
A lot of these appliances exist already for shifting power use to the sunny hours based on electricity, but right now all the various parts don't really work together as the home grid is just dumb AC and people orchestrate it all with Home assistant where possible.
'We're renewable, as long as we do emergency measures (and override safety rules) to keep our creaking old nuke plants online because we can't get enough renewable energy.'
Charging your car is still putting energy in a battery.
And the article mentions that devices sometimes have a built in battery.
The article is talks about getting rid of batteries but really is talking about maximizing energy usage during times of cheaper energy… which is the “smart grid” stuff OP is throwing shade at.
I don’t disagree with the idea of maximizing your energy usage during times of cheap energy availability but obviously most people don’t do it because the trade off is higher scheduling complexity. What if you set a timer for your washing machine but the sun doesn’t come out — now you just have no fresh clothes..
And plus some batteries are only possible at scale — like pumped water storage. Setting up that complex distribution infrastructure allows society to invest in more efficient forms of energy storage and distribute its costs.
The discussion: Buy MPPT controller
End of discussion
> That is an advantage of heaving batteries in the system: they can serve as a predictable / constant load, which a charge controller uses to have the solar panel operate at near-maximum output.
Well the single disadvantage of batteries is cost, everything else is an advantage so there is not much else to discuss here too.
Also, where did you buy your inverters in 1993? I've used about six different brands on various deployments and ten years is about right for MTBF there. I sure wouldn't trust a fifteen-year-old inverter to handle 3500VA continuous, and god forbid there's a spike...
However, if you’re in Main and don’t have a ground source heat pump then solar thermal works great. PV is panels are still only 22% efficient and you air source heat pumps don’t work well in ultra cold weather, worse you need batteries for the long nights. But with solar thermal you’re looking at ~90% efficiency for heat collection and ultra cheap energy storage in hot water tanks. You do get less power per m2 of collection area, but that’s offset by needing heat for a longer period.
Off grid solar can work in the surprisingly far north, just expect a significant premium.
It is way too much power cause the thing is constantly being charged every time the sun shines and it is pretty hard to use 300ah in a campervan while you're sleeping.
The benefit of LiFePO4 over those AGM batteries, is that you can go to zero. It is worth every $ for that and for the weight savings (in a campervan).
Highly suggest checking out Will Prowse on YT. He's a great resource.
If you want something better and brand name, you'll pay more. Sometimes, significantly more.
It still doesn't make sense to use lead acid for off grid, deep cycle or not. UPS systems still use them because lead acid loves to stay charged at 100% and not drop below half, which is fine for UPS that are intended to run only during occasional power failures.
LFP batteries also last for thousands of cycles and are safe, probably safer than lead acid.
This is a common misunderstanding. The lithium batteries used for off-grid and RVs are not the kind you're thinking of. They are LiFePO4, and far less susceptible to thermal runaway than, for example, an average laptop battery.
Also, the author states:
> The production of lithium-ion batteries requires fossil fuels, and (unlike lead-acid batteries) they are not recycled.
I think that there's no strict requirement to use fossil fuels to produce batteries, and lithium-based batteries definitely are recycled. Unlike lead, lithium is not an environmental and health hazard.
That is, in the shortest term, limiting the amount of batteries you have and running high-powered stuff directly off solar cells is a good approach to limit your carbon footprint. But in the longer term, large amounts of energy storage (both electrical and thermal) can and should be produced completely with renewable energy, thus removing the dependency on sunshine being available at a given moment.
My point was to get useful power at a stable voltage you need some battery like components to buffer the inconsistent power delivery of a solar panel so most of the time you see a actual battery involved.
Without any batteries you typically need to way over panel and still have some caps involved. My parents have a 7kw solar system grid tied no batteries with a 1500w emergency outlet that runs when the grid is down. Works ok but if enough clouds go over it just shuts off the inverter needs a lot of excess to maintain a stable 120v output and it has rather large filtering caps.
People hardly realize (or straight up don't realize) that once you're in the tropics even the notions of summer and winter start to get fuzzy. Consider: if you're on the equator then you can go from "summer" to "winter" in only a few steps. Obviously, near the equator solar is a no brainer.
And of course the opposite is true, once you're inside the arctic circle solar is basically pointless because there literally is a period of no sun lasting anywhere from several days to several months. Of course not too many people live inside the arctic circle so it's not too much of an issue.
Even between these extremes though, the usability varies a lot.
If humans wanted to live by nature's vagaries, they would have remained chimps.
With Sodium Ion entering mass production, and whatever mishmash of solid state and sulfur techs hit mainstream, I think batteries will be the way to go. There's always flywheels too.
Perhaps some of these should be reevaluated since it appear clear that their cost means less duration as a species.
... so- putting the batteries in individual appliances? That feels like a bad idea
https://www.feinstein.senate.gov/public/index.cfm/2022/6/why...
It seems like a big chunk of the Democratic party started supporting nuclear power at roughly the same time. The IRA passed a few months later, with subsidies for nuclear.
Solar is never likely to be as important in the UK as it is for the US, but even so it seems it can be helpful because solar generation is at its highest during the summer when wind generation (over a quarter of UK total generation) is lowest.
To be clear: batteries are still not cost effective relative to a grid connection, but everyone who has an off grid system goes for LiPO for a reason.
One thing I would have like to have seen discussed, in the section on non-battery storage, is pumped liquid storage.
This is a great technology for grid scale storage, but I wonder how well it could be applied to small scale instalations.
I would think something on the scale of the Living Energy Farm would be able to make good use of this, and maybe even smaller scale, like with a 50gal tank on his balcony?
in the Middle Ages, modern technologies weren't available, and once the sun set, a candle gave light. Showering wasn't popular.
So effectively, the discussed "make the most of daylight modern society" feels like a step back to the Middle Ages to me.
Like EV cars: they had to become better than ICE cars for the switch to happen.
Mine doesn't have an internal heater, so I make sure to keep it disconnected from the solar panels when it is cold out.
I live in a warm weather area so it was worth the cost difference for me at the time. Worst case, I can just get a simple 12v heating pad for it.
[0] https://www.relionbattery.com/knowledge/how-do-lifepo4-batte...
Worldwide, the ground itself, a few feet down, stays at about 50F year-around ~~ regardless of outdoor temperature. Locally, summer heat-pumping could be directed underground in some places. Reverse in winter.
Pumping heat from where it's stored is a lot less expensive than transporting and burning fuels. We do need to get better at it.
Even here in Montana, the heat going out in the beginning of winter for a few weeks was not really as obnoxious as some of the really hot days with no AC I've seen.
There’s the problem - the expensive lead acid battery, which is not the best technology to fit the application.
I get the overall point about load shifting to suit solar output, but the point about storage being prohibitively expensive falls flat because they didn’t use the right battery.
That's because most devices use constantly varying amounts of power. For example a washing machine might use 1500 watts while heating, 150 watts while spinning, and 5 watts while filling with water. With no storage, you need to have available for it the whole 1500 watts it requires (otherwise the machine will power off). Yet the whole time it's using 5 watts you're wasting 1495 watts.
The vast majority of solar inverters don't even support non-battery non-grid powering of AC devices because of this problem - it ends up being hugely wasteful of solar area.
Near-Storagless off grid setups could be done with small amounts of batteries to even out said peaks and troughs in load. If you want to buy one, they're normally sold as 'hybrid' inverters. Even a tiny battery is enough if you have logic to, for example, turn appliances like fridges, car chargers , or air conditioners off or on based on power availability.
Instead, the laptop power supply will just cut out if it isn't provided with the power it wants to take.
I've often read that the solution to this is to get "deep cycle" marine batteries.
I've worked in a cold store way back. Like, a big warehouse filled with frozen items.
Say products needs to be maintained between -20 and -28C. That 8C is a massive amount of thermal energy. If you'd just cut power, say temperature in the cold store goes from -26 to -21C in a day (for a large cold store, probably less. Volume vs. surface area!). That means as long as you observe the outer ranges, and know how fast the store warms up (when not cooled) you can pick any time of the day to run the cooling systems. The mass of frozen product inside is your battery.
Connect to a bunch of solar panels on roof or nearby solar/wind farm, and you simply run cooling systems when that power comes up.
Versus: add battery storage & run cooling 24/7 to remain as-close-as-possible to optimal temp.
Similar things can be done with many factories, logistics, storage of thermal energy, charging EV batteries & more. Battery storage just gives more flexibility.
It's just using power in a smarter way. Not ditching modern comforts.
Have you thought about micro wind turbines? I wonder if those would provide some power in the winter just to charge phones and laptops.
It depends what latitude you are whether the (societywide) heating load in winter or the AC load in summer is greatest. And that breakpoint is moving north all the time.
It is quite dramatic how much cheaper and longer lasting the panels are, though.
In the case of your freezer example, the freezer is a form of energy storage. Similarly a battery, or a phase change heat battery, are other forms of energy storage. Energy storage is important for the obvious reasons of being able to decouple time of production from time of consumption.
Modern humans built all of civilization on their ability to decouple time of production from consumption.
Other applications for small stuff can be for spread sensors.
But running something else it's simply too unreliable. Let's imaging just a simple washing machine on p.v. directly. If it's a sunny day with no clouds at all ok, but if there are just few clouds the irregularly input power makes hard to complete a cycle safely. Similarly we can imaging cooking devices, useful yes, but you can cook only if the p.v. output is there and constant enough. Water heaters with large water storage might be used, since they do not need constant power, BUT they need something else to give hot water in adverse climate, like a wood stove with pipes or something equivalent.
Doable, yes, but I do not know how many can invest enough for having a meaningful set of solar panels + MPPTs and DC devices to power directly for such unstable usability. We have on sale a handful of p.v. direct irrigation systems and they are NOT so cheap, not super expensive, ok, but still not that cheap, so if someone can afford them probably can afford batteries as well, at least for a limited usages just to ensure intra-day services.
He probably didn't tell you that Tesla LFP EVs would degrade and lose the first 10% of range twice as fast as non-LFPs because LFP EVs must be charged to full 100% frequently.
All lithium ion batteries, including LFP, degrade much faster under high SOC or high C (or even high DOD, extreme temp). In stationary energy storage systems under low SOC/low C-rates (eg, home powerwalls), LFP could last quite longer than other LIBs and this has been studied for years and widely accepted.
But, contrary to Jeff's Dahn's claim on Tesla's LFP battery pack, we don't really know much about LFP's true lifespan/performance in moving vehicles since they were deemed unsuitable for EV's with high SOC/high C-rates until China spiked them up a few years ago and they weren't studied as rigorously in that particular application/environment. Even as they are mostly limited to entry-level, low-range EVs, there are some early data indicating that LFP degradation in EVs is significant:
Tesla LFP Battery 10% RANGE LOSS PROBLEM? | Model 3 RWD https://www.youtube.com/watch?v=suw20wPrbL0
The brand new LFP batteries will degrade substantially quicker. There's not long-term retention data for LFP batteries on the market yet, but the trend tends to be substantially faster degradation. Trends show them stabilizing around that 10% degradation mark in about half the time as non-LFP batteries - around 50,000 miles instead of 100,000 miles."
they’ll be allowed run as long as the application is pending - regardless of any fixes or not, no? That’s very convenient!