Home Solar Electricity on the Cheap

[alexander]

yet another correction, hydro power turbines are AC, if you are talking about an inverter, you are talking about an AC to DC inverter, which is a rather simple inverter with a high degree of efficiency, in the simplest form, its 4 diodes and a couple of resistors and maybe a cap for cleanup purpose, 95% would not surprise me. A DC to AC inverters are extremely inefficient, its a lot harder to generate a good 60hz constant AC wave then it is to turn it into a line... You can turn the line into a square pretty easily, but getting those smooth bends, takes a fair knowledge of electronics, if you are not using movable parts... either case, very inefficient...

[alexander]

actually been looking at inverters, apparently they have gotten to be pretty effifient, at least so they claim... still, 95% at third load, 90% at full for a 1500w inverter at $850 from Go Power... which is fairly reasonable, but still it makes no sense to convert it twice to charge some batteries...

[alexander]

if you are looking for a straight inverter, you can go with aims too, aimscorp.net, they are reasonably priced... just remember that if you want to feed back into the grid, you need a pure sine wave inverter...

[Turtle]

Turtle, why in the name of Ronald Neil Stuart, would you use an inverter to charge batteries? You may need a filter, or a crafty vr, but trust me, there is no need to convert the power from DC that PV cells give, to AC and then back to DC to charge batteries :)

 

I have no idea where you got the idea that I have any such an idea as using the inverter to charge the battery. (see below):)

 

The photo-voltaic solar panel charges the battery, the inverter takes the 12 volt electricity from the battery, changes it to 120 AC household current, and then I use that 120 volt AC to power my everyday household electric appliances. Oh...now I remember I said charge batteries...:) So the deal with that is I use rechargeable Nickel-metal-halide (NiMH) batteries in my radio(s), flashlights, GPS, etcetera and since the charger I have for those runs on 120AC then that's why I plugged it into the inverter. If grid power goes down, I can continue to have battery power for the small devices. :)

 

What I am trying to design here is the simplest possible starter set with off-the shelf components and capable of running everyday home AC electrical devices. Wheel it in & turn it on and use it with minimum maintenance. Speaking of which, Zythryn mentioned not being handy or some such and this is some trouble for the user I won't deny. Tough for them! Give people some credit. Folks after all use and maintain home equipment all the time from the stove to the furnace to the fridge, yada yada yada. Let's get off the grid addiction, stop with the spending on useless crappola, suck it up and invest in something usefull. :shrug:

[alexander]

problem is your plan is flawed as well, you dont have a system in your system to share your clean power. For example, i have a UPS unit, i can extend it, if i get a couple of marine-type batteries, i can go out and get 2 pv cells, run them at 24 volts, get an inverter, and aside from charging my batteries, which won't charge forever, give out the power that i won't necessarily need, back into the grid during the days, when i am typically not home, and when i typically dont have a lot of stuff running at home consuming the power. In all reality 2 PV cells is not all that much, but, given that i can create a low power system that can make a more efficient use of the pv cells without much of my intervention, either getting more light then the pv cells can normally catch by the use of reflectors, or by figuring out that reflectors simply don't have light to reflect, and point the pv cells up where they can catch more light then in their normal, slanted position, thus maximizing the benefit from regular sunny days, and still producing power in those clowdy ones... without anyone having to do squat to control the unit.

 

Problem with your thing is that there are already companies making it happen... get an RV PV system, it already comes with batteries, cells, and an inverter, all you have to do is plug into it. But i am after making a smart system for home, one that knows day from night, one that uses a system to detect light direction and uses a light meter to figure out its next function. One that is ready for plug and play testing of pv cells and extendability of a system by the means of simply connecting more reflectors, and pv cells, and basically, plugging them into the control unit, plug and enjoy going green :)

 

besides for me it will be my first interesting experience with micro-controller boards, though i did make a tv remote controlled robot that had an alarm system... that is still being used by the electronics student club at my college... hehe... with an annoying easter egg that played the christmas carol, and there is no way to stop it till it finishes... hehehe

 

but this will be home-made mechanics, that will have to be built and calibrated, it will need to figure out its orientation, it will need to be accessible and controllable, perhaps even an ir interface that i am now fairly familiar with :shrug: and i know the kit comes with an led display, so hopefully i can use it to tell me things, like voltage, status of the system, if i can figure out how, current...

 

hopefully once i build this, my friends will start getting interested in building remotely controlled telescope system, that will be easily affixed, orientated and synced, allowing us to take shots of various areas of the skies, from various places, and then combine those shots for a higher res image, eventually accumulating more high res images from a regular consumer-grade telescope systems... which will be neat, i mean if the system is self-powering, and aware of it's own issues, as well as capable of self-communication, it should not be hard to convince other enthusiasts to build such systems, and possibly even join them to a network of telescopes around the world... maybe even combine the databases for any and every participant, into one giant collection of sky shots, which will be neat, to any astronomer, i think anyways... though i am not an astronomer, i've been talking to a couple, they seem to be interested, though currently busy with finishing their radio telescopes...

[Turtle]

problem is your plan is flawed as well, you dont have a system in your system to share your clean power.

 

There you go again. :hyper: But no really; you're missing the point. Your additional plans are fine for the other thread on solar power, but they add cost & complexity to a system and that is exactly what I mean to reduce by what I have proposed.

 

You mentioned such systems are available? Can you direct me to some sources? :( Perhaps we can simply improve them. ;) ;)

[alexander]

noo, you are missing my point, you already have a system that can potentially allow you to share your power, you just need to make sure that the parts you use comply with your power company standards, and there are good inverters out there, that are decently cheap, and for a small increased cost, you get a system that during the day, will spin back your electrical meter...

 

as for existing systems, you can find them, a couple of companies make the rv and home systems: Go Power, Silicon Solar, Southwest Photovoltaic to name a couple of companies that have, and/or install systems like yours, battery backups and all... they are mostly not cheap, but they work...

 

actually while looking around stumbled across this, thought it was a neat write-up: Doing a Starter Solar PV System - Chapter 8

[Turtle]

noo, you are missing my point, you already have a system that can potentially allow you to share your power, you just need to make sure that the parts you use comply with your power company standards, and there are good inverters out there, that are decently cheap, and for a small increased cost, you get a system that during the day, will spin back your electrical meter...

 

as for existing systems, you can find them, a couple of companies make the rv and home systems: Go Power, Silicon Solar, Southwest Photovoltaic to name a couple of companies that have, and/or install systems like yours, battery backups and all... they are mostly not cheap, but they work...

 

actually while looking around stumbled across this, thought it was a neat write-up: Doing a Starter Solar PV System - Chapter 8

 

I don't want to share my power. I made it, i want it, i get it. :hyper: Good link though, and they bring up a problem with sharing when it comes to using one of the RV systems already on the market. To whit:

6. Automatic ground switching if needed.

 

This feature is needed if you have an RV or marine PV system – it is strictly prohibited by NEC for residential and commercial application. Automatic ground switching disconnects the inverter’s internal VAC grounding when the inverter is hooked to a RV or shore (marine) remote power source. See the grounding section (page 19) for more information about why this is essential.

Doing a Starter Solar PV System - Chapter 8

 

Those guys aren't cheap either, going just under $2500 for their 'simplest' system wheras I'm at ~$600 in retail off the shelf components. This grounding issue does have a concern for me as far as using a metal locker, and that is in regard to whether the inverter is grounded to it, and what if any special grounding either way is required if my proposed system is installed in a home. Need a qualified electrician on that one me thinks.

[DFINITLYDISTRUBD]

This grounding issue does have a concern for me as far as using a metal locker, and that is in regard to whether the inverter is grounded to it, and what if any special grounding either way is required if my proposed system is installed in a home.

The various goodies I have that have metal cabinets (amplifiers, a welder, stereo equip, and computers) are grounded to the cabinet, and the inverter in my RV was grounded to the body by the factory so I'd say it's most likely a good idea.

[alexander]

Mr. D, what Turtle is saying is that while you have to have a grounded system like that for RV, if you plan to feed back into the grid, you never ground your system to their ground, tis prohibited, you run a separate ground on your pv system, from the electrical grid (and you have to be smart about not making grounding loops)

 

Mr. Turtle, i have figured out a slight snag with a grid connected system, those inverters are 96-120 volt dc in, at the minimum, which is a ridiculous amount of .55 volt pv cells. so for now, i will be going your way Mr.T and be building an off grid system with an off grid inverter/battery charger/monitor

 

well sometime before next summer that is...

[DFINITLYDISTRUBD]

This grounding issue does have a concern for me as far as using a metal locker, and that is in regard to whether the inverter is grounded to it, and what if any special grounding either way is required if my proposed system is installed in a home.

I don't know Mr.A ...I'm pretty sure at the minimum you have to be tied in to the a secondary ground similar house's main ground which ties into the Earth through a wire which runs from the breaker box to a stake in the earth (usually) outside the house and is supposed to be run to every outlet inside and out (it's required by law here)...and it's generally a good idea to tie the cabinet of electronics into this to prevent electrocution which is why electronics manufacturers do so.

 

But as far a Turtles question is concerned it seems to me that he's wondering whether or not to ground the inverter to the cabinet which is a good idea but not necessary as long as the inverter itself is tied to either the house's main ground or a second like it.

[Turtle]

This grounding issue does have a concern for me as far as using a metal locker, and that is in regard to whether the inverter is grounded to it, and what if any special grounding either way is required if my proposed system is installed in a home.

I don't know Mr.A ...I'm pretty sure at the minimum you have to be tied in to the a secondary ground similar house's main ground which ties into the Earth through a wire which runs from the breaker box to a stake in the earth (usually) outside the house and is supposed to be run to every outlet inside and out (it's required by law here)...and it's generally a good idea to tie the cabinet of electronics into this to prevent electrocution which is why electronics manufacturers do so.

 

But as far a Turtles question is concerned it seems to me that he's wondering whether or not to ground the inverter to the cabinet which is a good idea but not necessary as long as the inverter itself is tied to either the house's main ground or a second like it.

 

Just to clarify, that quote is mine not Mr. A's. :) But you're right about my questions/concerns. My house has every outlet with a 3-hole plug and the round 'third' hole is connected to a separate ground wire run directly to a bus in the main box and the bus bar has a heavy dedicated wire going to a metal stake driven into the ground outside the foundation.

 

So I got out the manual for my inverter and it only mentions grounding the case when you power a TV and get bad reception. :Alien: :shrug: Even then, it only says you can ground it to your vehicle frame, RV ground, or a metal rod driven into the ground, and makes no mention of use inside. I figured I could make a modified plug that only contacts the grounding terminal in my house outlets and ground my inverter case to that. What concerns me there though is that the ground lead and neutral lead in the house join at the box and so I have my unit vulnerable to surges or lightning where if it weren't grounded or had a separate dedicated grounding rod it would remain protected.

 

I have more on the cabinet but it's gonna have to wait as I have used up too many words already. :) :shrug:

[alexander]

yes, you dont ground that system to the electrical grid. You need to have a different inverter if you are connecting to that grid, but basically as long as you are not, take a steel stake, drive it into the ground, and use it as your ground for your system.

 

note, be careful and don't create grounding loops though, they are not fun, but this will somewhat protect your system. Also adding a fuse or two would be good, and i dont know if you have, but i would also add a diode to prevent feedback from batteries to panels, also, i can probably link you to a diagram, if you want me to and haven't done this already...

[Turtle]

yes, you dont ground that system to the electrical grid. You need to have a different inverter if you are connecting to that grid, but basically as long as you are not, take a steel stake, drive it into the ground, and use it as your ground for your system.

 

note, be careful and don't create grounding loops though, they are not fun, but this will somewhat protect your system. Also adding a fuse or two would be good, and i dont know if you have, but i would also add a diode to prevent feedback from batteries to panels, also, i can probably link you to a diagram, if you want me to and haven't done this already...

 

Roger all. :) Don't make a grounding loop. :doh: :) The inverter is fused (even came with replacements) and the panels are manufactured with diodes in place.

[alexander]

neat, yeah most pannels today do have at least a couple of basic things to protect from a couple of minor things, that reminds me, which panels do you have, what did you pay for them, and what is the voltage you get out of them and the current on a good day?

[Turtle]

neat, yeah most pannels today do have at least a couple of basic things to protect from a couple of minor things, that reminds me, which panels do you have, what did you pay for them, and what is the voltage you get out of them and the current on a good day?

 

I have 1 15 watt panel that I bought at GI Joes about 4 years ago. I paid $130 on sale then, and last I checked a few months ago they are at $150. :) In bright full sun I think I measured 18-20 volts max. I never measured the current. It's in a plastic frame with about 6 feet of cord and came with battery clips.

 

I also have 2 smaller 5 watt panels. They have diodes as well, are in metal frames, and came with battery clips. I think I measured 18 volts for them too, and I did get some current readings when I was doing that electrolysis experiment. I'll try & find the info in the thread on that experiment as I don't recall.

 

In reading my inverter manual they recommended disconnecting it from the battery when not in use, because apparently even when switched off, it continues to draw current. That's a problem for my proposed turn-key setup. The only thing that comes to mind for an off-the-shelf solution is a marine battery switch and there's a few more bucks. :) AUTOS & BOATS : Maintenance & Repair : Marine Batteries: Installing the Battery Switch and Wiring the Battery : DIY Network

 

More later; it's noon news time. :doh:

[alexander]

thats odd, generally these things are wither 12 or 24 volts... 18 seems a bit odd for battery charging too...

 

they are basically fixed voltage, its the current that goes up and down :doh:

 

You could use a heavy duty switch, you dont have to use a large marine switch unless you are positioning this whole system outdoors, batteries and all...