I have noticed that solar panels are dirt cheap right now. And, I also heard that the current administration is pushing to put stiff tariffs on imports of solar panels from overseas (China)
because of overseas companies basically "dumping" panels into the U.S. markets. Does anyone have opinions on whether it would be a good idea to purchase enough panels now to
serve a cob home I want to build in 1-2 years and store them until I need them? How do you calculate how many panels I would need anyway? Thanks for any input from those more
insightful about solar than I.

Hey Roger. I can't claim to be any more insightful that you, but I can offer my opinions that are based only on careful research. The cost for panels truly is very low. I am a little concerned about the quality of some of these panels. However, I've noticed that the cost of highly rated Kyocera panels have dropped substantially as well. I say buying today and storing them is a great idea not merely to take advantage of the low cost today, but to possibly avoid paying a high price later due to the likely increase of general price inflation during the next several years. Basically, it seems to me that a substantial increase in the price is more likely than a marginal decrease.

Calculating how many panels you will need is pretty straightforward. You need to know your average daily electricity consumption and the average solar insolation at your location. The single most important consideration here is getting your electricity consumption down to as low as practical.

See these solar maps to find the solar insolation in your region: http://www.nrel.gov/gis/solar.html. Make sure to reference the maps for PV and not the ones for concentrating solar power. You'll find that the average solar insolation is about 5 KWh per square meter per day in most regions in the U.S. Of course, this is an average. Most PV panels are about 15% efficient, and you have to consider other losses that can be substantial depending on how the system is configured. A conservative estimate for a properly designed off grid system would take the losses at about 50% for a net efficiency of 7.5% from solar insolation to ac electricity (NOTE: 50% is a rather low estimate, but it provides a built in fudge factor - there are many more losses in an off grid system due to battery losses). Another consideration is to design the system based on the average solar insolation available during the winter months and position the panels for maximum solar gain during this time of year. For much of the U.S. this value is only about 3-4 KWh per square meter per day. I think you can see already why reducing electricity consumption is so important for off grid solar.

PVWATTS: http://mapserve3.nrel.gov/PVWatts_Viewer/index.html

NOTE: Make sure to change the derate factor to reflect an off grid system. I suggested 0.5 earlier, but 0.6 is reasonable for an off grid system (I always go for the conservative estimates as I prefer to be pleasantly surprised rather than disappointed in the results).

my experience with the cheap chinese panels has been less than acceptable. They brown and have significant reduction in out within 5-8 years. Cheap panels like this are not worth it.

I have several links about making your own PV panels. The cells themselves are relatively cheap to buy. The devil is in the details of building framework, wiring, converting DC to AC, etc.

I also have a link to a dynamically new wind turbine thats likely to gain popularity in a short span... if youre looking to supplement off-grid alternatives to go with your solar.

Roger, by the way, if you are still looking into buying some panels, then check out some of the large higher voltage Kyocera panels. I've seen them available for remarkably low prices. These are normally used on large grid-tied systems. There is a lot of money being poured into these kind of systems, and this is part of the reason why we see the prices on these panels falling. In case you're not aware, these high voltage panels can be used with lower voltage battery systems in an off grid setting by using a MPPT controller. These controllers have the added advantage of increasing the net output of the panels (especially during the winter months), and many double as advanced battery charge regulators. The prices on these controllers are going down also. The bottom line is that an MPPT controller will increase the output from an array enough to justify the added cost... but furthermore, the high voltage panels used in an off grid setting require these controllers... and these panels are the lowest cost/watt going. So, consider getting the large high voltage panels normally used in grid-tie applications even if you have an off grid system planned.

The best panels are ones you make yourself! It really is remarkably easy to wire everything together from scratch. My advice is to buy cells now since they are so cheap [sub $400 for 1kw worth of cells] and compact [you can store them in a box as opposed to having fifteen 60 watt panels sitting around.] Then when you are ready for them, just put them together and put them up!

yeah, I've made my own panels, and I will never do it again. You don't save any money, and you loose quality, especially in the glass and backing. It also takes forever to solder up all those connections.

$400 for 1kw of cells, but then the glass, the frame, the solder, the connecting tabs, the backing, the junctions. You will be lucky to have it built for under $3/watt.

You can buy panels for under $2 a watt right now, ready to go, with a 25 year warranty.

Roger Brown wrote:I have noticed that solar panels are dirt cheap right now. And, I also heard that the current administration is pushing to put stiff tariffs on imports of solar panels from overseas (China)
because of overseas companies basically "dumping" panels into the U.S. markets. Does anyone have opinions on whether it would be a good idea to purchase enough panels now to
serve a cob home I want to build in 1-2 years and store them until I need them? How do you calculate how many panels I would need anyway? Thanks for any input from those more
insightful about solar than I.

Hi Roger

It is true that the cost of panels have dropped recently. But I don't think it would be a good idea to purchase enough panels now for the future use. In the coming years, you can expect more reduction in the price. Only an expert, after visiting the site can tell you the exact number of panels required by you.