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Go solar or not?

I can ask elswhere but I would rather hear from a bunch of enginners and scientists....


I purcahsed most of a solar/wind power system and have all of the components stashed in my shed or in a Farady cage. The major thing I am lacking is a bunch of batteries and the heavy copper wire to connect everything. Untill recently I figured I would have plenty of time to harvest batteries from noop cars and a solar flare or EMP attack.


But this week-end I watched a YouTube video from a guy that has been selling power back to the grid with his solar panels.


So pretened we are discussing this topic after dinner...


What are your thoughts ?


Install now and make money ?


Save until I  need it ?


If you have one already, do you have any suggestions you would like to share?


Other ideas.


Thank you!



Retired Senior Automation Systems Architect with Data Science Automation LabVIEW Champion Knight of NI and Prepper LinkedIn Profile YouTube Channel
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Message 1 of 14

For me,  I would ask about the battery tech, the inverter effecientcy and the ability to duplicate post-<Bad-stuff-happening>


Lead-Acid has a limited life and, lead has other uses-(Pb makes good bullets! Those can be useful) Li is hard to dig out (They call it a "Rare Earth Metal" for a reason).


I like the idea of going green- but, the refined metals might be troublesome to repair/replace  Sticking to elements that can be forged at wood or coal fire temperatures seems advisable.  And, after <Bad-stuff-happening> "Green" won't be so importantSmiley Sad


No answer, just questions. [Edit] dinner tasted great!

"Should be" isn't "Is" -Jay
Message 2 of 14

Batteries - Automotive batteries are generally a poor choice for uninterruptible service.  Their cells are designed to deliver a high current for a very short amount of time (starting a vehicle).  When you put a small load on them for extended periods of time, they tend to lose both voltage and capacity real quick. 

Deep-cycle batteries are designed to provide lower currents for longer periods, as with marine (lights, radios, navigation, radar, trolling motors, etc) or backup power service. 

A better route is to chain 6V (or even 2V) batteries in a series-parallel configuration to the appropriate voltage (assuming 12v, but some PV systems can do 24 or 48V). 


I'm not really sold on solar... power just isn't there.  First law of thermodynamics and all that... you only get so much energy from the sun per unit area... at 100% efficiency (which solar cells are nowhere near), that's all you're going to get.  Ever.  So you chain more cells together, more surface area... there's still only so much you can get.

It's great for certain applications, but it's never going to replace more efficient generation techniques for everyday life.

One of the radio sites I work with is on top of a mountain (12,600ft).  Utility service up there is unreliable to say the least (measure 90-100v at the plug... little bit of loss in that cable running up the mountain!).  Solar works most of the time, but if  there's any snow on the panels it doesn't take long for the system voltage to drop low enough that the equipment starts backing off power or shutting down.  Need to head back up there sometime... analog link has some issues.  Digital and IP's running great though, and that's the system I deal with. Smiley Wink




Colorado's a pretty good place to get high... Smiley Tongue

Message 3 of 14

Selling back to the utlitity is a nice idea, but...


- The protection interface will likely need to be purchased from a source approved by the utility.  Probably not real cheap.  Think about what happens when a drunk driver hits a pole down the road fron your facility or lightning hits nearby.

- Utilities here have a minimum of 25 kW capacity before they will even talk to you.  The protection and coordination issues are too expensive for the utilities to justify the effort for smaller systems.

- The installation (at least of the grid interface) will need to be done to the utlitity's standards. Again, this may require an authorized contractor or certification from a qualiifed engineer.

- The inverter needs to be capable of being synchronized with the grid. This adds significant cost compared to a simple keep-the-lights-on-at-home system.

- The economics are not favorable for small systems due to the capital costs of all the items above. These extras might cost close to what the simple, isolated, off the grid solar panels, batteries, and basic inverter cost.



Message 4 of 14

I agree that lead acid batteries are not such a great storage medium (heavy, low capacity, short life). Things like the tesla powerwall seems to be better. If you have a water reservoir up the hill, you could even design a pumped storage system, pumping water up during overproduction and using hyropower at night. (Sorry, no opinion, only heard of it).


Solar, at least in Southern California is cheaper than grid power, but not all utilities buy overproduction back. I have a solar grid-tie system since 2009 and the initial investment has been basically recovered.  Things got quite a bit cheaper since then. My total production is ~43MWh so far.


LADWP does not pay cash for the overproduction, but keeps it in an account to be applied during underproduction in the winter months. My balance is already about $1k. Oh well. Maybe I need to buy a plug-in car in the future.... 😄

Message 5 of 14

Thank you for the replies one and all.


Yes car batteries are something I would resort to only in an emergency. When my allowance permits it, I was looking at some deep-cylce batteries from Batteries Plus. While the big ones are pricey, I can augment the capablitiy one battery at a time over time. Of the the techno-weenine in me want to be able to run an arc welder some day (I AM allwed to dream).


If my better-half asked today, I think I am leaning toward staying off of the grid after reading what you have posted and what others have told via private messages.




How are your solar panels holding up?


I had heard they will wear out over time. What can you say about the usage life of the panels?



Retired Senior Automation Systems Architect with Data Science Automation LabVIEW Champion Knight of NI and Prepper LinkedIn Profile YouTube Channel
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Message 6 of 14

@Ben wrote:

How are your solar panels holding up?


I think the panels have like a 25 year warranty. I don't think they really wear out, It is probably more like the seals and insulation that will go at one point. Not sure if the glass develops e.g. F-centers from all the UV light over time, making it slightly less transparent. The predictions is that after 25 years, they still perform at >>80%. (don't remember the exact numbers). Of course the inverter itself will also not last forever, electronics and all. Fortunately, mine does not have any moving parts (e.g. a cooling fan) but instead has one gigantic heat sink on the outside.


(Besides, all these parts are getting cheaper rapidly due to the economics of scale and improved mfg. processes.)

Message 7 of 14

As of August last year, I moved onto a Canal Boat here in the UK (I was hoping to present to you US lot about it at the CLA Summit but in the end I couldn't go!).


Here it is on a frosty morning last month:



For my electricity, I have a bank of 4 12V 'Leisure' batteries (they are like car batteries, but designed to be deep-discharged unlike car batteries) giving about 110Ah each and a normal 12V car battery for starting my engine. Most of my boat runs on 12V (e.g. water pump, some lights, fridge etc.) but I also have AC for things like my computer/freezer/general sockets etc. I have a 16A (3.8kW) AC mains hookup which goes into an 2.5kW inverter/charger (Victron) - when the hookup is there, it charges my leisure batteries. If the hookup goes away, it instantly switches over to being an inverter and gives me an uninterrupted AC supply (I can literally pull the shore cable out and everything (like my PC) stays on - much like a UPS). You can of course hook up as many batteries as you can buy/scrounge and even link multiple inverters together for more power. My chunky diesel engine also feeds into the 12V batteries via an alternator. I haven't yet tested how long I can run on the batteries with AC power - about 12 hours is the longest I've gone without power and didn't get a 'low battery warning'. 


I don't have solar panels yet - but it's something that I'd like to look at at some point - you can buy flexible adhesive panels I can stick onto the roof of the boat, which, coupled with an MPPT solar controller I can also use to feed into my batteries/inverter to use less grid power (which I am metered on) and last for longer without a shore supply (e.g. when travelling, which I hope to do this summer). I need to paint the boat first - the panels can't really be lifted once stuck down.


The biggest cost of my system is the inverter/charger - but they come in all sorts of shapes/sizes/costs and of course the same can be said for the number/area of solar panels that you go for.


You can also get lithium batteries for exactly the same use (my inverter/charger supports both), of course, there's also the Tesla Powerwall thing that altenbach mentioned which looks interesting and I have been following with some intrigue!


As for selling it back to the grid - requires some significant infrastructure which may/may not be subsidised by your government/utility company - the so called 'feed in tariff' of selling power back to the grid just got cut here in the UK!


Oh, of course I have everything hooked up to an sbRIO from the BYOES course that NI offers 🙂

LabVIEW Champion, CLA, CLED, CTD
Message 8 of 14



Where does Giant Tetris fit on that boat??

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Message 9 of 14

@Gregory wrote:



Where does Giant Tetris fit on that boat??

And here I thought the boats were the Giant Tetris.

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Message 10 of 14