Twistedtree, as we are talking alternative power sources, and I have had solar and wind on the boat for years, so was already sold on the concept, so few months ago we finally took the plunge, as the move is gaining momentum rapidly here in sunny Queensland, (there are Govt rebates to encourage this, and if you put excess back into the grid you get a modest credit for it), and went solar on the house as well. We put up one of the larger arrays around, 24 x 250w panels giving a theoretical max of 6kw, (compared to your 3.6kw), and we are pleased with the output, but are yet to see how much of a dint in our power bill it will actually make - as opposed to what the salesman claimed, that is. If you get the sort of performance you mention out of 3.6kw, then we should do pretty well with 6kw, surely..?
I was intrigued by your mentioning almost no power required from other sources (generator in your case - off the normal grid in our case), except for you coldest, shortest daylight months, so how do you cover the night time when there is no solar output..?
I am keen to ultimately use the same concept we use on the boat, so we might be virtually free of grid requirement, but up to now there have not been batteries with enough capacity. I gather that is being developed even as we speak, however, but they are not currently readily available. Do you use batteries for night demands, or how else do you do it..? I am really interested.
Cheers,
One reason we get by with 3.6KW of solar is because we have paid a lot of attention to reducing our power load. But there are few if any compromises. We have just carefully selected propane instead of electric where possible (fridges, stove, hot water, clothes drier), and carefully screened for phantom loads (things that are on even though you think they are off, like the satellite or cable box). When I buy appliances, I check their "off" power draw before I buy. The US EPA Energy Star program has also been a huge help and has exposed poorly designed consumer electronics. New Energy Star TVs, for example, draw next to nothing when you turn them off...as they should. And like Bay Pelican, we have installed wall switches and/or switched power strips to really turn things off where needed.
A Kill-o-watt meter is an inexpensive and incredibly useful and revealing too. You plug it into an outlet, then plug an appliance into it. It will tell you exactly how much power the thing is drawing. I'd encourage anyone with the slightest interest in this topis to buy one and start measuring your appliances. Then you can be acting based on data, not guesses.
While on phantom loads, another source comes to mind. The little black wall adapters (wall warts) that come with many devices can be either very efficient or very inefficient. Older ones were transformer based and very poor. Newer ones are switching converters and are very efficient. It's easy to tell the difference. The old ones are much heavier because of the transformer inside, and they will be very noticeably warm to the touch. The switching converters will be cool or slightly warm, and are quite light. Even though they are small loads, they run 24x7 and really add up. It's just like the Satellite box. It only draws 20-30W, but because it runs 100% of the time (even your fridge cycles on an off) it becomes a top ranking power hog. Finding and replacing them can help a lot.
Back when almost all adapters sucked, I spent a lot of time seeking out gadgets where the adapter was 12V, then cutting off the end and running it straight off 12VDV from the house bank. I did this with phones, wifi, network hubs, computers, security systems, heating controls, etc. Now I don't do it anymore because the adapters are so efficient.
OK, I've gotten completely side tracked and forgot the question. Oh yes, running at night. It works just like your boat - batteries. Physical size and weight doesn't matter, so most use traditional flooded lead acid batteries, which is what I use. They still offer the lowest cost per Ah of storage capacity, by a lot. My current battery bank is huge. My system is 48V, and the battery bank is 1300 Ah, so that's about 67 KWh of storage. It will run the house for 2-3 days with no solar output. The inverter, by the way, is 6KW split phase 120/240V. That runs everything just fine, including my shop with a good size 240V compressor and car lift. I even run a welder off it. Those are huge loads, but they run for very short periods of time so the overall energy consumption is small. It a whole other story, but I think I have too much battery capacity, and will make it smaller next time. Bigger isn't always better.
Back to the batteries and running at night, there is no magic to it. Solar covers the loads and charges the batteries during the day, and we run off the batteries at night. When too much of a deficit accumulates, the generator automatically starts and runs until the batteries are charged, which is typically about 6-7 hrs.
As for battery capacity, it's been available all along. No new developments on the lead acid front. Where development is happening is around other technologies that are light weight for applications where weight matters. These are wonderful performing devices, but hideously expensive compared to lead acid. There also are thin plate lead acid and some other lifo or something - I forget the exact name - that sounds very interesting, but I would want to spend a lot more time with them before depending on them for my house, let along my boat. There is an extensive thread on CruisersForum on these new batteries if you want to learn more.
Your place is grid-tied, or grid interactive, where I am off grid. Your situation is preferable, in my opinion. You have the grid as a backup in case your system fails, and you can run off the grid at night and on rainy days. It essentially serves as your battery bank. Batteries are expensive and require replacement every 5-10 years. If you can eliminate them, consider yourself lucky.
