by Ben N on November 14, 2014


Just the other day, I got the latest copy of HOME POWER magazine in the mail. The cover article was about a DIY 6 Kilowatt system that is about 13 miles from my house. What I wasn’t expecting to learn from the article is how CHEAP solar can be!

I live in south-eastern Wisconsin. We are not known for great solar access, nor has the state government or utilities been particularly supportive of renewable energy. However, this article was great, because everything listed in it DIRECTLY applies to me! These articles usually have some lists of costs and components as well as solar charts.

The solar panels used on the project were from Helios, the same people from whom I got my 48V solar panel for EV charging. (Who are unfortunately now out of business. They manufactured in Milwaukee, just 30 miles from me!) The article also lists our area as having 4.52 daily average peak sun hours and being at 43.1 degrees north latitude.

Finally, the article also listed the total cost of the system, including available financial incentives. While Wisconsin has pretty minimal support for renewable energy, it does have one shining star – the Focus on Energy program. In this case, a $2,400 refund on a solar system. The one catch is that there is only so much money per year, so you have to get it before it runs out! (PS: It’s gone for 2014. But that’s OK, start a project in January!)

So, that got me thinking. What would it really take to put up a solar system to take care of me and my family?

bill_IMG_1204To start with, we need to know how much energy we already use. That’s pretty easy, just check the electric bill. Last month, we used 270Kwh. That’s less than a third of what the average American home uses, and frankly, it was a pretty good month for us. Our energy use has historically been a little higher than that, but I did also just recently refit the entire house with LED light bulbs and WAS expecting to see at least a little drop in electric use. (No joke, the other day, the power company stopped by to look at my meter, thinking it wasn’t working right!)

So, if I know how much energy I used (270 Kwh) and I know how much sun we get in my area (4.52 average peak per day,) then I can figure out how big of a system I would need to make that much energy. I thought I would run a test example based on a system exactly one-half of what the author of the article built. So, 3,000 watts (3Kw) times 4.52 (peak sun hours) times 30 (days in a month) is 3,000 x 4.52 x 30 = 406800 or 406.8 Kwh. That’s MORE than the 270 we used last month, and right around what I believe our new average will be.

I visited an online solar equipment seller and priced out 10 315 watt panels. They were right around a buck-a-watt, or $3100 for the set. Looking at grid-tie inverters in the 3Kw range, they were priced from $1500-$2000. So, for about five grand, I could have the main solar components, although I would still need cables, a disconnect, shipping, etc, which would of course add to the cost.

altE_kitWhile I was on that particular web page, I did see that they sold some solar “kits”. These include all the major components for a system, INCLUDING disconnects and the solar panel racking. One of the kits was for a 2.5KW grid-tie system using micro-inverters. The kit costs just under $6,000.

But wait! Let’s figure in what’s available for financial incentives in my area. There’s a federal tax CREDIT of %30 for solar systems (any excess on the tax bill can even be carried over to the next year!) and there’s that $2,400 refund through Focus on Energy. So….
-$1800 (30%)
-$2400 (Focus on Energy refund)
=$1800 final cost

What? Really?! I could basically never have to pay for electricity again (or burn any coal or nuclear fuel) for under two grand!?!? Yep, that’s right. Well, it does presume a few things. This would assume that I do the labor myself AND I already have an appropriate place for the panels. On top of that, I would still need to shell out some money for permits and to get an official qualified electrician to sign off on the project.

DSC_7210Keep in mind that physical space is also a major consideration for solar. You need a good sunny location, free of trees and other shadow-producers to make that kind of energy. Unfortunately, I have a narrow “double-deep” city-style lot that runs north and south, and a heavy tree-line from the neighbors. The ONLY legitimate location for solar at my house is on the roof of my garage. (The exception to that was mounting a 48V solar panel on a custom child’s playhouse to get it out of the shadow of the house!)

solar_chickenscratchings_IMG_1203The garage itself is a a little over 20-foot square. Will that many solar panels even FIT on my roof?! Those 250-watt Kyocera panels measure 66 inches high by 39 inches wide. So, a configuration of five-wide by two panels tall would be 16.25 feet wide by almost 11 feet high. 16 feet is less than the 20 foot width of the building. Running Pythagoras’ theorem on a 12/12 pitch roof of a 20′ square building comes up with a roof height of just over 14 feet. The solar panels wouldn’t just fit on the roof, they would fill it nicely, and LOOK GOOD!

So, solar power for the cost of an old used car? AND it fits on my roof? Sign me up! Even going with a 2.5K system instead of a 3K, I’d still be averaging 339 Kwh per month. Again, more energy than I used last month, although probably a little under our monthly average use. Using the slightly larger Solar World 315 watt panels would get me to right about my average energy use.

Some people like to think about things solely in terms of financial return on investment. If so, how would this theoretical solar system stack up?  Well, it would save me $40 a month on my bill. At a cost of $2000, it would pay for itself in 50 months, or just over four years. Every month after that, it’s like I’d be getting paid $40. (Although I’d still have to pay the $6 monthly meter fee!)

So, does solar energy cost a lot of money? Think again, it might not cost what you think!

Stay charged up!


PS: Am I going to run out and buy a system right now? Sadly, no. My garage is very old, and the roof faces east/west instead of north/south. I intend to rebuild it anyways, and since I will, I’ll design it specifically with a south-facing 45-degree roof. Needless to say, I won’t have a “real” solar setup until after dealing with lot lines, permits, and building plan meetings…..

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1 Scott November 19, 2014 at 9:26 am

270 kW? That is insanely low, my lowest is 750′s and 1150 when the extremes are around. But I am also about 2500 sqft farm house with barn chicken coop and detached garage new windows, also all LED new furnace and some new doors.

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