No, not an estimate of what it will cost you to buy, although if you are buying on the basis of time and materials, rather than fixed contract price, a cost estimate is a good idea. What I mean is an OUTPUT estimate: how much electricity, or hot water, or whatever, is this thing going to make in a calendar year?
Having an output estimate is really helpful for a number of reasons. First, it is a litmus test for installers, to see if they know what they are doing. If you have someone who comes with many positive recommendations, that's one thing, but if the installer is new to the technology, you can test to see whether they understand that they are installing a dynamic system, not a piece of lawn furniture. Secondly, once the system is installed and up and running, IF there are malfunctions in the early going -- bugs that need to be worked out -- you and the installer both have a basis for figuring out how far you are from the target.
The estimate may come out of a software package for the purpose. But it does not need to: the installer may be able to show you their own way in which the estimate was calculated.
Happy purchasing!
Friday, May 15, 2009
Monday, May 4, 2009
Do's and Don'ts of DIY home renewable energy
Are you interested in building your own renewable energy system for your home to cut your costs and reduce pollution? Here are my picks for do's and don'ts.
Solar hot water, solar hot air, solar cooking: My preferred DIY technologies. These systems take some time to build well, and will cost something in materials, but they can be built without super-specialized skills and you can get yourself an effective and reliable system while saving compared to the cost of buying a commercial system. Of course, if you don't have the time, maybe a commercial version is the way to go...
Solar PV: I'm not sure. It is possible to scrounge together the cells and wire your own array -- I know of a group in Nicaragua that gathers cast-off cells from the US PV industry and wires them into arrays for use in the Nicaraguan countryside. For a country that is very tight for money and where even a small source of electricity in rural areas where there is none can make a big difference in quality of life, this makes sense. But for us in the USA, the wiring may take so long that it may be easier to leave it to a factory.
Home-made wind: be careful! As small wind expert Paul Gipe puts it in his book "Wind Power: Renewable Energy for Home, Farm, and Business", the first question to ask yourself is "why would you do this?" If you have enough wind in a location to make it worthwhile, then there are going to be at least a few times each year when it really is going to blow hard. So maybe you are cruising along making lots of electricity, and one day a gale blows through and tears your homemade system apart. Now you're back to square one. So, unless you view this as a hobby or are really up for a tough technical challenge, it is best to leave this technology to the experts, and buy a system from the professionals, even if it costs more up front.
Solar hot water, solar hot air, solar cooking: My preferred DIY technologies. These systems take some time to build well, and will cost something in materials, but they can be built without super-specialized skills and you can get yourself an effective and reliable system while saving compared to the cost of buying a commercial system. Of course, if you don't have the time, maybe a commercial version is the way to go...
Solar PV: I'm not sure. It is possible to scrounge together the cells and wire your own array -- I know of a group in Nicaragua that gathers cast-off cells from the US PV industry and wires them into arrays for use in the Nicaraguan countryside. For a country that is very tight for money and where even a small source of electricity in rural areas where there is none can make a big difference in quality of life, this makes sense. But for us in the USA, the wiring may take so long that it may be easier to leave it to a factory.
Home-made wind: be careful! As small wind expert Paul Gipe puts it in his book "Wind Power: Renewable Energy for Home, Farm, and Business", the first question to ask yourself is "why would you do this?" If you have enough wind in a location to make it worthwhile, then there are going to be at least a few times each year when it really is going to blow hard. So maybe you are cruising along making lots of electricity, and one day a gale blows through and tears your homemade system apart. Now you're back to square one. So, unless you view this as a hobby or are really up for a tough technical challenge, it is best to leave this technology to the experts, and buy a system from the professionals, even if it costs more up front.
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