At 04:37 PM 10/1/2009, Robert Bruninga wrote:
Since Satellite design is heavy into Solar power, and I talk about that a lot, you may have heard me compare my Solar car to Solar panels on the roof of your house as not economical, I WAS WRONG. I was overlooking many recent changes in the environment:
- Solar panels (PV) are 1% of what they cost in 1970
- PV dropped 40% this year due to 2007 Energy Boom and 2009
economic bust 4) $5,000 to $20,000 tax and cash back incentives for YOU 5) Grid-tie systems operate at 95% efficiency compared to 70% of battery systems 6) Local electric rates DOUBLED in the last 2 years 7) Laws require utilities to pay you the same peak rates they charge you. 8) Solar Energy credits can gain an additional $275 per 1Kw system per year 9) Payback is at least 10% per year or better 10) The same money in the bank gets 1% interest
So I was wrong in not keeping current with all the changing environment, and now I am full speed to get my system approved and built and correct any miss-guidance I may have helped propagate.
Sorry. I am claiming this particular email is on-topic because of public statements to the contrary I have made at satellite forums. But this hot topic should probably spin off elsewhere. We need a HAM Solar Power group somewhere...?
Summary: Do NOT make the mistake (as most of us do) of thinking in terms of stand-alone Battery back-up solar power systems . They cost more and you don't need it in most places where you have access to the grid. They cost $5 to $10,000 more, are only 70% efficient (compared to 95% for grid-tie) and are a never ending maintenance headache. Instead, most any enterprising ham should be able to provide his own backup power using a cheap 1 kW inverter for about $150 from any auto store or radio shack running off his car's 12V system for any power outages.
That, a few deep cycle batteries, (and using CFL lightbulbs in your house) will give you enough emergency power to operate your full Ham station, all the lights in the house you want plus your refrigerator for as long as you can buy gas. But the other 99.99% of the time, sell your solar power to the power company (at peak rates during the day) and buy it back cheap at night (you win and you don't even have to worrry about batteries)...
And even if your grid-tie solar array produces nothing (in the way of AC power) when the grid goes out, you still have many Killowatts of DC power on your roof, that you can surely find lots of things to do with until the grid comes back. For example, have the electrician wire a 250 volt string of the 200 Watt solar panels in the array to a DPDT switch so they can be disconnected from the Grid Tie system and the 250 VDC can be available to you. THen you can plug in as many modern DC/DC pwer supplies into that 250 VDC to give you LOTS of amps at 12 volts, or ... almost any modern gizmo has a universal power supply input that will run on anything from 110V to 330V DC as is.
Anyway, for similar hints www.aprs.org/FD-Prius-Power.html
Sorry for the off-topic. But I was wrong. PV works! (even in Maryland). If you live in the SW, you are lucky, and it works TWICE as much or at HALF the price!
A Born-again Home PV junkie Bob, WB4APR
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Couple comments:
A 12-vdc battery back-up for your stations requires no conversion to AC, since most ham gear runs on 12v. A PV to battery system will keep one going when "the lights go out"! may not happen much down there in "civilization" but here in Alaska, several outages a year happen, some go for days. We have a 2500w standby gen that outputs 240vac to feed the main ckt breaker (with mains isolated). We have to load shed some areas of the house in that scenario. The same ckt can be connected to my shack to feed a small breaker box that supplies 240vc to the HV Power Supplies. (obviously we do not run the big amps when the power is out).
I have installed many PV panels in remote sites over the years. They are much more efficient these days. It gets more challenging to depend on solar year-round since winter sunlight is only 5.5 hours/day. At my company's sites we opted to use supplemental solar during the warmer months when there is long sunlight and have an auto switch that detects low voltage to switch to the primary oxygen-activated alkaline battery plant (15vdc @ 10,800 AH). The primary batteries have a life of 3-years+ so we schedule their replacement (involves helicopter delivery= $2500) on the third year ($5500). Cheaper power exists but due to extreme weather on the mountain (-30F and >200mph winds), it is not feasible to visit the mountain 8-months/year!
If one is still planning to utilize a stand-alone PV electric system, then they should look at the sine-wave inverters that are very efficient (some at 98%). They do cost more!
Side Note: one of Alaska's utilities is installing 27 wind generators to supply the grid (on an island 8-miles from Anchorage). These are the 300-foot prop "babies"! I'm sure that this implies megawatts.
73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com 500-KHz/CW, 144-MHz EME, 1296-MHz EME DUBUS Magazine USA Rep dubususa@hotmail.com ======================================