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Author Topic: Solar Panels and inverters  (Read 4515 times)

2E0EZE

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Solar Panels and inverters
« on: June 09, 2011, 11:40:15 AM »

Hello
Seriosly thinking of solar panels on the roof.  About 12 of them covering half of my 3 bed semi.  This involves an inverter to change it to ac as you would expect.
My antenna mostly is a g5rv over the top of the hous being clear of it by about 8 feet at the apex.  Antenna wouldn't be directly over the panels and the invertor would be in the loft with my 2 ele 6 meter beam (sort of)

Anyway....

Will I be subject to noise?  My shack is at the end of the garden and it's nice down there but I wouldn'tr want to spoil things even for cheap electyricity.

Anyone have any idea if my radion life will be disturbed?

Any advice appreciated,
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W8JX

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RE: Solar Panels and inverters
« Reply #1 on: June 09, 2011, 03:47:27 PM »

I would try it. I would also install a very generous battery bank for solar cells to keep topped off and provide power when sun is not out. I would used a 24v based inverter system though and no one based on 12v.  When I lived out west in 90's there was a repeater on a mountain top that was solar powered. It had a very generous battery bank that could maintain repeater for up to 2 weeks without sun due to storms or snow built up on solar panels.
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Ham since 1969....  Old School 20wpm REAL Extra Class..

AD6KA

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RE: Solar Panels and inverters
« Reply #2 on: June 09, 2011, 06:58:15 PM »

Quote
This involves an inverter to change it to ac as you would expect.
Is this solar power project for the entire house or just the shack? Just curious.

The inverters will have to be good, expensive sine wave ones.
A lot of them on the market are REALLY noisy with tons of ripple.

Good luck with your project.
I hope it is cost effective.
Do you have all that many sunny says at your QTH
to make the investment worthwhile?

73, Ken  AD6KA
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K0IZ

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RE: Solar Panels and inverters
« Reply #3 on: June 13, 2011, 05:41:04 AM »

With that many panels, I recommend a series/parallel arrangement with 4X in series (ie nominal voltage of 4x17V = 68).  That way your voltage drop in cabling will be much less (I2R).  I also strongly recomment the MPPT type controller, not the PWM type, since you will get anywhere from 10 to 25% more out of your panels.  The better controllers will work on the higher input voltages from series panels.  I use Blue Sky.  Be aware, however, that most controllers WILL cause RFI due to the modulation.  So plan on clampon ferrites, etc.

As comment above, sine wave inverter is to be preferred.  However I am using a Tripplite APS1250, which is modified sine wave, without any problems on my equipment, and other stuff.  There are some very heavy duty inverters available (4KW) made for whole-house applications.  Most run on either 24 or 48 volts, due to current draw.    Even with a 1KW inverter, you will have over 100 amps on a 12V battery setup, so 24 or 48 is much preferred.

Aside from electrical considerations, make sure your location has FULL sun for at least most of the day.  Even part shading of some panels will significantly affect your power.  Adjust angle for your latitude (using same angle as latitude is compromise between winter/summer).   Some prefer to favor lower angle for wintertime due to shorter days.   Center on true due south (not magnetic).
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K5LXP

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RE: Solar Panels and inverters
« Reply #4 on: June 14, 2011, 06:20:18 AM »

Seriosly thinking of solar panels on the roof. 
...
I wouldn't want to spoil things even for cheap [electricity].


"Solar" and "cheap" are not synonymous.  It's not possible to have a solar system with batteries and ever have it break even.


Mark K5LXP
Albuquerque, NM
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W8JX

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RE: Solar Panels and inverters
« Reply #5 on: June 14, 2011, 09:05:11 AM »


"Solar" and "cheap" are not synonymous.  It's not possible to have a solar system with batteries and ever have it break even.


I think that would depend on what you pay for electricity too. It does take a long time for payback. Wind power would offer better pay back potential.
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Ham since 1969....  Old School 20wpm REAL Extra Class..

KC2UGV

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RE: Solar Panels and inverters
« Reply #6 on: June 14, 2011, 09:47:09 AM »

Seriosly thinking of solar panels on the roof. 
...
I wouldn't want to spoil things even for cheap [electricity].


"Solar" and "cheap" are not synonymous.  It's not possible to have a solar system with batteries and ever have it break even.


Mark K5LXP
Albuquerque, NM

Solar generation generally has a payback within a decade.  More so, if you sell power back to the grid.  If it weren't possible, you'd never have companies building data centers purely on renewables (Which they do).
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N0YXB

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RE: Solar Panels and inverters
« Reply #7 on: June 21, 2011, 08:09:25 PM »

And some states offer tax breaks that help speed up the payback. 

Vince
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K5LXP

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RE: Solar Panels and inverters
« Reply #8 on: June 22, 2011, 07:37:14 AM »

I worded my comment carefully - it is not possible for a solar system *with batteries* to ever break even.  Grid tied systems, depending on prevailing kWh rates and "government incentives" can achieve a break even at some point.  But when you throw a storage battery bank in the mix, it can't happen.  Batteries have a finite Ah throughput, and finite life.  They incur a conversion efficiency loss in and out, increasing panel costs.  About the time you think you're gaining on it, you have to replace the bank at significant expense.  Panels degrade over time so the further out you project, the less output you get which needs to be factored in.  You can't get there from here.

With the cost of panels dropping like they are, you might make a case for grid tied systems depending on cost basis, how far out you want to project and what you're trying to accomplish.  It's the storage that gets you, and I don't see that changing anytime soon.  If solar systems with batteries were an economically viable alternative to grid power on almost any level, you'd be seeing a lot more of them than we are.


Mark K5LXP
Albuquerque, NM
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W8JX

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RE: Solar Panels and inverters
« Reply #9 on: June 22, 2011, 07:52:53 AM »

I somewhat disagree you raise some valid points but I think you could break even one day not connected to grid. Batteries can have a long life span and they have the ability to power home without grid. (a battery system could be setup to sell surplus back to grid)  What is the point of a home solar or wind power system that has no self contained redundancy?  It is little more than a "toy" or a conversation piece at time because it still relies on grid to feed it at times. I think ideal system would be a mixture of solar and wind generation because while there are days with out wind and days without sun they do not happen together that often and wind can work at night and through in batteries to power house when either system is not producing and you are pretty solid and you could still sell surplus back but grid could fail and you would be fine.
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K5LXP

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RE: Solar Panels and inverters
« Reply #10 on: June 22, 2011, 11:53:01 AM »

If you can engineer a wind-solar-battery system that can compete with the grid you'd be a billionaire tomorrow.


Mark K5LXP
Albuquerque, NM
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W8JX

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RE: Solar Panels and inverters
« Reply #11 on: June 22, 2011, 03:48:40 PM »

If you can engineer a wind-solar-battery system that can compete with the grid you'd be a billionaire tomorrow.

It is the up front/start up costs that are the biggest deterrent here. If they ever come up with cheap efficient solar cells this could change.
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Ham since 1969....  Old School 20wpm REAL Extra Class..

N2EY

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RE: Solar Panels and inverters
« Reply #12 on: June 23, 2011, 07:29:57 AM »

What is the point of a home solar or wind power system that has no self contained redundancy?  It is little more than a "toy" or a conversation piece at time because it still relies on grid to feed it at times.

The point is that often it can drastically reduce your energy costs. Particularly during the high-demand summer days. It all depends on how much you pay per kWh, how much the grid will pay you for your surplus, how much you can generate and how much the installation costs.

I have known people who have installed solar electric systems where the breakeven point is less than 3 years.

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So why doesn't everybody do it?

1) Even with tax breaks and other incentives, you still need to invest serious $$$ in the system.
2) Some people's homes aren't good sites for it. Besides the need for a good view of the sky where the sun is, you need a good roof area, a place for the inverter, etc.
3) Some are waiting for the price to come down. Remember when VCRs were $1000?
4) In some areas electricity is so cheap the payback is a long way off. (How much do YOU pay per kWh?
5) In some situations there are better investments. For example, if you have an old inefficient central AC system, replacing it with a new high-efficiency system may be a better investment. Same for an old inefficient refrigerator or freezer, upgrading windows and doors, insulation, etc.
6) Some people would rather not bother, don't understand the situation, etc.

73 de Jim, N2EY
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