Solar panels reuse

[reidy]

I have just had an upgrade done on my solar system and said to the installer I would like to keep the old panels. My wife asked me what I am going to do with these as they still work. The inverted needed replacing and it was better value for a new bigger system. At this point I have no answer but they might come in handy. I don't like to see waste and can be considered thrifty, see some Guzzi content.

So any suggestions or experience with using old solar panels. For instance can I run an aircon when the sun is shining without the need for a battery backup.

Please share your experiences, Than I can let the wife know what I am using them for.   

Thanks

Steve

[Testarossa]

Of course you can reuse solar panels but only for a purpose suitable to the voltage and amperage available. And if you don't have another inverter your application must be DC at 12 or 24 volts. How many panels do you have and what's the total watts available? You may be able to drive a water pump, charge batteries, run a DC fridge or even a small RV-style DC air conditioner. For instance if you charge batteries you could power an electric fence or emergency lighting or gate opener. I have a couple of older 140 watt panels sitting around which I plan to use to drive a bilge pump. Doubt you could run a room air conditioner -- they start at about 500 watts AC.

[Perazzimx14]

With solar tech being antiquated about 10 minutes after its installed I'd bin them. Hoarding old broken stuff until is comes in handy is a theory I have in recent years abandon. Kind of like keeping old worn out tires because someday you might need one.

[Lannis]

Hoarding stuff until is comes in handy is a theory I have in recent years abandon. Kind of like keeping old worn out tires because someday you might need one. Put them on your version of Craigslist or FBMP and see if you can get a few dollars for them if not bin them.

Like you, my way of thinking has changed the older I get and the lower the chances are that I will ever need some of the stuff I've been keeping.   My Mom kept every old worn out thing, gadget, piece of equipment, or things that were still good but were obsolete.    She was sure that someone in the family would be able to use the stuff when she was gone.

Nope.   We sold or tossed almost everything.

I did that for a while - I've got stuff that I've kept for 40 years because I might need it.   Now, since my longest possible horizon is a smaller or larger fraction of that, I've quit doing that, and I either scrap, give away, or sell things I don't need even though I have a lot of space to store junk.   For me, if you have it, it sort of weighs on your mind in the background - once it's gone, you're free of it ....

Lannis

[larrys]

The short building inspector answer to all questions is, "It depends." How old are the panels? What wattage are the panels? You will need the proper sized inverter for the total wattage of this system that you want to build. You will need a battery bank or connect to the grid to operate it. The excess electricity that the PV system makes has to have someplace to go.
Larry

[Wayne Orwig]

Running AC without batteries, very very unlikely. The inrush current needed to start the motors is just too high. You need a reservoir.

You could (and this would take some $$$$) use them to preheat water before it goes to the main hot water tank. As in, if it heats the water, great, if it doesn't, oh well. Depending on the panels, you could run the heating element off of DC and avoid all of the batteries and controllers. Just let the water heater thermostat kick them off and on.
 

[Testarossa]

Solar panels typically lose around .5% of efficiency annually when in use, with no measurable degradation when stored. So if your modules are 20 years old they'll probably produce 90% of rated power. They're not useless junk. If you don't use them, someone else can. Sell 'em cheap. The fact that your old panels are 13% efficient compared to today's 21% efficient doesn't matter to most people -- what matters is dollars per watt. Today"s panels can sell for under buck a watt so price accordingly. Of course if you use them yourself the cost is $0 per watt plus any new wiring and racking.

The water heating idea is pretty good. I used to have a heating rod that screwed into the top of the water heater and ran on solar DC. If you can put a few hundred watts of wild voltage into the water heater for five hours a day that will save money on the utility bill. See butlersunsolutions com. And btw if there's no draw on a PV array there's no "excess" power that needs to go anywhere. Finally, if you charge batteries or run anything that needs steady voltage you'll need a charge controller.

[kirb]

They have value, but the real costs are the inverter, batteries, install, racking, etc...

The collection efficiency improves all the time. cells that are 10+ years old do not have near the collection availability of today. I would just let them go. Usually not worth the hassle.

[Perazzimx14]

Like you, my way of thinking has changed the older I get and the lower the chances are that I will ever need some of the stuff I've been keeping.   My Mom kept every old worn out thing, gadget, piece of equipment, or things that were still good but were obsolete.    She was sure that someone in the family would be able to use the stuff when she was gone.

Nope.   We sold or tossed almost everything.

I did that for a while - I've got stuff that I've kept for 40 years because I might need it.   Now, since my longest possible horizon is a smaller or larger fraction of that, I've quit doing that, and I either scrap, give away, or sell things I don't need even though I have a lot of space to store junk.   For me, if you have it, it sort of weighs on your mind in the background - once it's gone, you're free of it ....

Lannis

Its something how we collect stuff we know we'll need but end up never needing it. Heck in the extremely rare event I've needed one of these treasures I could not find it or it was incomplete and I still needed to buy something else. 


In the long run it cheaper to buy what you need when you need it instead of tying up money and space housing attic stock in anticipation of needed it. Some habits die hard and I still inventory a few oil filters for each bike. I don't know why when I can hop online and order a filter and it'll be here in 1 to 2 days. Its not like oil changes are a surprise maintenance thing.

[Testarossa]

If you decide it's too much trouble to reuse or recycle, donate the panels to a school. A science class or shop class will be glad to have them.

[reidy]

Well it would seem that a number of you agree with my with in saying I should just give them away or dispose of them. On that logic my wife may be right. I like the hot water idea as a small hot water heater up the shed would be handy.

The panels in question are about 9 years old and were serviceable. The inverter died and it worked out cost effective to buy a 5 kw inverter and 3Kw of new panels. They had to remove 4 of my old panels as I would have exceeded 600V per line. He than offered 8 serviceable panels of slightly newer vintage from a previous job that hes was going to dump. This gives me 12 panels.

So what I may have learnt is think before saying yes to free stuff. It is an old habit developed from younger days on a farm. I am not sure if there is a support group I can join  . Hello, my name is Steve and I keep things because they may come in useful. It has been twenty four hours since I last did this.

Steve   

[GonzoB]

Hi Steve.

If you're considering using the panels for water heating, using an old 240V unit doesn't work. The power able to be produced through a resistance heater goes down with the square of the voltage. So is it was a 1kw heater, you would end up with a 7w heater running it on 20V. I guess you could put the panels in series, but then the voltage starts to get dangerous and switching high current DC is tricky.

Join the support group!

Gonzo

[wrbix]

Any need to set up an electric fence?.....around a garden, keep goats in/neighbors out, etc.  Solar 12v ideal for that.
Or electric gate opener, or 12v security light, or......
Or on roof of a golf cart...
Or on an RV....
Or a 12v fan in your shed....
Or a trickle charge system for vehicles...

I seem to eventually find a use for everything.

[John Ulrich]

My pal would hang it on a "trike".