Solar panel system for the home?

Frustrating...I looked into it a bit too. I think the technology just is not far enough along to make for any payback on solar right now. Even with incentives. But I doubt you can get off the grid any other way. You might try solar water though - they are relatively cheap and very efficient I think. As for electric, I realize it is mostly AC in AZ, but going CFL and LED on lighting and closely controlling all other power consumption has done wonders for my electric bill. Plus if you have gas, you could convert your dryer, stove, and h20 heater to gas if not already. The last thing might be going to time of day pricing on your electric, if your supplier offers it. Then you can crank the AC before daytime rates begin and leave it off for much of the day.

Going "off the grid" sounds great, but not practical, especially in AZ!

 

Good to see some sensible discussion on solar panels. Most of the enthusiast seem to conveniently forget the $20-$40K plus they have or are paying when quoting their monthly energy expense. Plus interest on the loan. It may be a great idea someday. Now if I could just get the Gov't to pay for my solar panels....

 

I don't think they forget it. The cost of the solar panels increases the value of the house by approximately the same amount, so it is considered equity in the house.

 

Is the $20,000 gross, or net of the 30% federal tax credit? Around here, I calculate that a well-sited system pays roughly the same rate of return as long-term US treasury bonds, once Uncle Sam picks up the first 30% of the cost.

Something doesn't quite add up here.

You're using (say) 2500 KWH/month. At $0.10/KWH, offsetting 60% of that saves $1800/year. ($0.10 x 0.60 x 2500 x 12). Assuming the $20K was the net price after federal tax credit, then in effect, you're investing $20K to get 30 (?) years of payments at $1800/year.

That's not a bad deal, as I calculate it. You can either do the analysis crudely, or plug it into Excel to get your rate of return. I come up with 8%. And that's an after-tax rate of return -- you don't pay tax on the money you save.

So investing your $20K in this deal is like getting a Treasury bond paying 8%. If the system only lasts 20 years, you're still getting 6% after-tax return.

Either way, what's not to like about that?

Maybe you're being put off by the monthly payment. You're going to buy this on credit? How long do the payments last, compared to the system? Are you going to be making 20 years of payments on a system that is going to give you 20 years of electricity? If not, then how many years of "free electricity" go you get once the system is paid off?

Finally, you need to be careful with the "house price" argument. You can either count the discount on your electric bills for the life of the system, or you can count the increase in the value of your home (which, to a first approximation, ought to match the present value of the future discounts on the next owner's electric bills), but don't count both.

 

That price you were quoted for that size system is actually about half of what my system was 3 years ago for a 5.2kw system. For 20k, I would imagine there might be other ways to cut your usage, as 3100kwh is quite a bit of usage. My peak months here are usually half that usage.

My guess is those are your summer months. Not knowing anything about your house, orientation, usage patterns, etc. it's hard to say much other than that price is still really "cheap". My system provides about half of my usage, and would be closer to 75% if I were ideally situated.

To achieve 100%, I would say you'll have to really reduce your consumption. Good ways to do this are (and these are suggestions not knowing your current situation): New Windows, Additional insulation in the attic/walls, more efficient appliances (esp A/C and water heaters), trees that'll provide shade, etc.

 

Let's wait for the many solar experts here to chime in, but I would seriously consider the solar hot water first, efficiency improvements, and then one of those new solar panel companies that charges you a monthly fee less than your current elec bill. Now all I need is a house I feel like doing this to (long term spot).

 

Just to clear up a couple of misperceptions. First, "off grid" solar comes at about twice the price and half the efficiency of grid tied PV (per kwh).

Second, conservation is your cheapest energy dollar. Te general rule of thumb is that for every dollar spent on conservation, will save ~$10 in PV costs.

Third, solar hot water is much cheaper on a btu basis than PV. Hot water heat capture heat pump is very efficient, making you AC work more efficiently, and you get hot water out of the deal.

Grid tie PV is currently running~$5/watt, and is going down. (exclusive of rebates and tax credits). Typical payback is largely dependent on utility rates, metering regime etc, but is typically on the order of 8-10 years. (this equation does not typically include any allowance for the increase in energy costs going forward!)

If you are considering solar, find a reputable installer, who can steer you thorugh the whole deal, such that your pay off numbers are understood. I also suggest you visit, read and learn here:Solar Electric Power Discussion Forum by Northern Arizona Wind & Sun - Powered by vBulletin

There is lots of misinformation, do your homework before making any choices.

Icarus

 

Just want to point out that I'm on the same page as Icarus on cost-effectiveness. Unless you've worked over your house thoroughly, efficiency gains have the best payoff.

That said, 8 year payback, on a system that last 20 years, is just about exactly an 8% rate of return. After tax. It's a very good investment in today's market.

 

Is that chandler arizona? If so, consider putting in a swamp cooler to take some of the load off the AC unit. How many old refrigerators do you have in the garage? If a 9.4kW system is only providing 60% of your electricity needs, you really should look at the efficiency side of things first. Like Icarus said, those are the best dollars spent.

 

maybe he lives in an al gore type of residence.

 

Back to the original post. $20k for a 9.2 system? I assume that is 9.2kw system? That is under $2/watt! I would also have to assume that is after any utility rebates and maybe after tax credits. In any case,, that is a steal!

By my quick PVwatts calc, it should yield ~15,000kwh/year with a current energy value of ~$1300/year. If my math is right, that is return of ~6%, not factoring in tax credits, future energy price increases. A payoff of less than 15 years with hardware warranted for better than 20 and a real world life span much longer (PV's not inverters)

Geeze, what's not to like?!

If it doesn't cover your load,, as we said, reduce the loads and or add more PV. Where else are you going to see a stable 6% in this economy, and do good for the environment?

 

It is 6% after inflation.

There is a risk though, that the unrealized amortized cap cost will not be recouped when the house is sold. Stupid, but true.

 

If you have less than 12" of attic insulation, you want to increase it to a minimum of that. When went from 6" to 12" in my attic, it made a large difference. If you can go higher, that's even better esp considering being in AZ.

What temperature do you keep the AC set at? A 5 ton unit also sounds a little large for 2100 sq ft of house. I think I have half that size unit for the same size house. Granted, I don't live in AZ either. I would look into a higher SEER AC unit than 14. Isn't 13 the bare minimum now, or am I mistaken?

Also, do you have nat gas water heater or electric? If you have electric, I would tend to stay away from tankless. Either way, you can get a GE Hybrid Water Heater (electric) for around $1500 and it's a straight drop in replacement of a typical one. It's supposed to save like 50% on water heating costs, as it combines heat pump technology with standard electric elements.

Another option, is a solar attic fan. As you know, attics are great for trapping heat and the more air flow you can have going out of there, the cooler that gets, and the easier load on your AC unit.

 

I think the added insulation and new AC unit will make the biggest improvement for you. I keep my AC at 75 (lowest setting in a few years). I have ceiling fans in every room that is used to sleeping/sitting and that makes a BIG difference also. Here we get humidity, so I keep a de-humidifier running almost 24/7, depending upon when the bucket gets full and I have to empty it. I would also recommend possibly raising it at night if you can stand it. Use fans in the bedroom to make them more comfortable.

I would do the Lowe's insulation using the blown in. Just make sure you keep it 6" from the edge of the roof line to allow for proper air flow. I think if you do that, you'll notice a big difference.

The electric tank less units function fine, but they usually have a harder time getting the water to temp. If you're looking at spending $1000 for a regular water heater, I'd recommend that GE hybrid one for not much more. You could hook it up yourself, it's really not difficult.

Your AC unit is around 14 years old, so it's really close to the end of its lifespan anyway. A new, high efficient one is a good idea at this point.

Me? I'd start with the insulation. If your water heater is close to the 15 yr mark, I'd do it next. Since the AC unit is going to be a little pricey, maybe you could hold off for another year. You might notice a decent savings after the insulation is done. If you don't have ceiling fans, I'd recommend those if you can. You could probably bump up the AC another degree or two and make up for it with the fans.

 

I'm no HVAC expert, but it makes sense to me to start with insulation and ventilation. They help reduce the amount of heating and A/C required, with potential to reduce the cost of the heating and A/C units as well as increase their efficiency.

 

If you are going to look into new AC and potentially new hot water, consider a hot water recovery AC unit. It makes your AC run more efficiently as well as gives you "free" hot water.

On a side note, using PV to generate electricity to then use that electricity to heat water is hugely inefficient. A solar hot water heating system (especially in AZ) comes at about 1/3 the cost, with about 5 times the efficiency. (wag numbers,8 do some research, but PV will convert ~ 15% while hot water can convert better than 80% of solar input into useable energy)

I have a simple flat plate home made collector, circulating into a preheat tank, (45 sq ft) and it give u s 100% of our hot water in the summer, 30
% in the winter in the grey pacific NW. Coupled to a demand propane water heater it works great. Consider a propane demand water heater~$1000. I would avoid a Bosch unit from Home Depot or Lowes and go with a Rinnai, or a Takagi' or a Paloma. I have had very bad luck with the newer Bosch units.

Icarus

PS More insulation and venting in the attic will reduce your AC loads dramatically, if you only have 6". Go for 12" minimum,,, it is cheap at twice the price!