Davin T's posts

Hopefully you'll get some replies from people with more intimate technical knowledge, but as an owner of a unglazed, black plastic solar heating system, I would encourage you to go with the more expensive glazed panels.  Although the unglazed panels work fine, and overall I am very happy with them, the truth is they take up a lot of space.  As I understand it the glazed panels are supposed to be more efficient, so you won't need to have as many square feet, or you can get more heating from the square footage you have.  The downside, of course, is expense.  The unglazed are a lot cheaper, so you might want to just compare the price and maybe that will make up your mind for you. 

I have approximately 450 square feet of the unglazed panels and a pool that is 35,000 gallons.  If anything I would consider the system to be a little bit overpowered.  I barely have to run it in the summer (4 hours per day max), and can easily maintain my preferred swimming temperature of 94 degrees for 7-8 months a year.  In addition to the solar panels, I also use a bubble cover, although primarily to prevent water/chemical loss, and only secondarily to help maintain temperatures. 

I don't know where you are, but this is in San Diego for climate comparisons.  If I were willing to settle for water in the 80s, I wouldn't be surprised if the pool would be swimmable for at least 10 months per year.  I've actually had the pool at 99 degrees one time before, when I decided to test the system.  I think it could have gotten even hotter, but I didn't want a 35,000 gallon jacuzzi. 

Anyway, the black unglazed collector panels should be more than adequate for your purposes.  If you want to save space, considering the glazed panels may be worthwhile. 

Part of the problem may actually be the government subsidies.  What I mean by that, is by offering massive subsidies on PV panels, California, Germany and other places have spurred demand for PV systems.  The sudden surge in demand has ironically resulted in prices going up, since the supply just isn't there (with silicon being a major bottleneck).  The end result is even with the subsidies, you might end up paying about the same.  Hopefully 2007 does see PV panel prices start to come down a bit, because in all honesty the price right now is not competitive.  It was on the right trajectory for a while, but then with the sudden surge in demand it turned around. 

Of course, it's not a level playing field as we don't pay the full real price for coal, which would take into account the environmental and health hazards offered by it.  If the government got serious about requiring cleaner coal plants, and made it so that old, badly polluting plants are not basically given waivers, then the price of coal generated electricity would rise.  It's not a level playing field right now by a long shot. 

I would consider putting them on the ground, but it simply is not practical due to space constraints.  I would not be struggling with the whole east/west orientation issue if the ground was an option.  Unfortunately, it's just isn't. 

I am in San Diego, just about as far South and West as you can get, without either ending up either in Mexico or the Pacific.   

Some of the links provided above have been very helpful in assessing my situation.  I tend to agree that being in a relatively southern latitude, the less then ideal placement of my panels is not that dire.  I do believe that reorienting the panels to the south would be worthwhile, and it's something I plan to do eventually, but I am not going to treat it as an emergency. 

I have already more or less optimized my power usage with CFLs, energy efficient appliances, etc, so there is not much more I can do in that area (although always striving for improvement).  The balance of my generation to usage is already generally positive, but then again it never hurts to have a little bit of extra cushion, and in the end if I don't use the power I suppose I can rest easy knowing I have displaced a little bit of polluting power from the grid. 

If you really want to jump in to solar/energy efficient stuff, it might not be a bad idea to get the solar hot water heater.  If you don't use that much gas, probably that means you don't need a very large system.  Solar hot water is supposed to have a fairly short payback period.  Also going with a tankless water heater for backup is definitely a good idea.  Tankless heaters are much more efficient than having a tank. 

I wonder if it wouldn't be possible to slowly build up a PV array rather than getting it all installed at one time.  If you could learn about it and do the install work yourself it seems like you could slowly expand your system, provided you buy a large enough inverter to be able to handle a larger system.  I don't know if there's any problems with runnin an inverter with a much smaller load than its supposed to have, but I would guess it's not a problem.  I'm sure there are many people here more knowlegeable who would be able to tell you. 

Thanks for the links to those sites guys, those should help a lot.  I am seriously considering reorienting the panels, but I have two concerns. 

I looked at the adjustable mounting racks on this site.  I was thinking the low profile design might be best, as they will be on a roof, and I think having solar panels sticking 5 feet up in the air might be kind of weird.  But I was wondering just how easy it is to adjust these racks.  It looks like they are of fairly basic design (I won't go so far as to say crude), and I was wondering with the weight of several panels on them how hard it would be to adjust them.  Would it require two people, one holding the panels in place while the other unbolts and rebolts the rear support in order to adjust its length? 

My other concern is how to figure out how far apart I'd need to place the racks so they don't end up shading each other in the winter (when there will be the combination of steepest angle of panels, and lowest angle of sun).  There is limited room on the roof, so if I have to space the racks out too much it might be counter productive.  As an example, if I lose too much space, I might be better off just resorting to brute force by putting up more panels, albeit in terms of expense that option will probably be a lot higher. 

I would suppose in terms of shadowing, I should be most concerned about the middle of the day when most generation occurs.  The whole fact that the roof is not completely flat so there will be some east/west tilt of the installation makes figuring out shadowing a little more difficult. 

I am looking for some advice regarding the impact of solar panel orientation and its impact on power generation.  Just to give you some idea of the situation, my current solar array was installed flush mounted to the roof.  Fortunately our house happens to be nearly perfectly oriented to the cardinal directions (it's not exact, but for luck of the draw you couldn't ask for closer).  At the same time, unfortunately, the house is rectangular and the end which faces North/South is the shorter side.  The roof is not a standard v-shape, but rather made up of 4 triangles, the two on the ends being smaller.  The end result of this is the longer sides of the roof face nearly east/west, while we have one shorter side facing south. 

The panels on the southern portion of the roof already have a southern orientation as a natural result of the roof's inclination, but the others on the west and east sides are flush mounted so they are flat, facing slightly west or east with no southerly orientation.  My question is, whether there would be a significant advantage to reinstalling these panels on tilted racks to orient them towards the South?  I suppose it may be important to note that I live in Southern California at approximately 32 degrees latitude. 

I am trying to determine how much difference orienting the panels to the South would make, in order to decide whether it is worth going to the trouble and expense of reracking and reorienting them, rather than leaving them as they currently are.