Daily Archives: November 12, 2015

Your Questions About Solar Energy Generator Suppliers

George asks…

SOLAR PANELS what do you think?

With the current discussions re climate change & renewable energy should the goernments of the world enforce (through legislation) that all new buildings constucted have solar panels & wind generators installed that supply at least 80% of the predicted electrical usage of that particular building….. what do you think???

admin answers:

Not all building sites will have enough of a solar or wind resource to make these technologies feasible, or cost-effective. So, integrating site analysis into the construction process can help determine what combination of energy sources are appropriate for a new building.

There are many types of energy efficiency and renewable energy technologies, including biomass, and geothermal. But by far, the most effective renewable technology is the practice of energy efficiency, and proper resource management. Construction practices that focus on reducing heating, cooling and electric loads and ensuring proper ventilation are key to sustainable living. Once buildings are well insulated, tight and efficient, renewable energy systems can be adequately sized, and produce as much or more than the building needs.

There are a few issues to keep in mind though – first, while renewables are the way to go, the manufacturing processes and transportation costs still produce waste and pollution (embodied energy). Also, we need to transition to a “smart” electric grid that uses modern digital technology and is reliable, efficient and secure. For areas where individual buildings cannot generate all their power due to site restrictions, the local municipality or coops can opt to either buy or generate clean energy from green suppliers, or procure their own power.

I think legislating new construction codes would work well along with subsidies for clean technologies, but hitting the 80% mark may be too aggressive to start. The bottom line is to affect the bottom line ($ in your pocket), and make it attractive to install these technologies. Maybe this could turn out to be like FDR’s New Deal Programs during the Great Depression, where hundreds of thousands of jobs were created to build highways, schools, parks, and other infrastructure-related projects. Analogize to new green jobs in almost all sectors of the economy, but especially construction.

One final major point: remember that over 80% of the real estate inventory in the US is made of older and inefficient buildings…what about those? Retrofitting these buildings has been VERY challenging, with or without the government incentives. Improving older buildings is requires a lot of redesign, and is complicated and expensive.

Mark asks…

which is best? inverter or diesel generater.?..please answer?

For cost wise and maintenance wise which is best,i am having small office(6 systems,2 fan)

admin answers:

Of course Gintable is right. If your office has 6 computers and 2 fans and a couple of lights and a router maybe is will be something like 1000W, maybe more, depending exactly what you have. I am assuming you have no electricity, but it is possible this is just for standby when the electricity is off. In that case the inverter/battery system is called a UPS (uninteruptable power system) and you specify it for the time (minutes) you want it to support your equipment until you can get the generator started. Make sure you get a pure sinewave type. For standby I would use a petrol machine as below, as it is too small for a diesel. Some can be automatically started, but very few.

If the inverter takes this power from a 12V battery the result is ridiculous, with 83A drawn from the battery (not counting losses). A large 100AH battery will have a capacity at this current of maybe 30 minutes, but it won’t, because it will get too hot. The losses charging a battery are high, about 1.4 times the energy used. A better battery is made of 100Ah x12V units in series to get a maximum of 10A each. That will be about 96V battery, 8 or 9 of the 12V ones in series. Chosen to match the available inverters round that voltage. If you use solar panels it needs about 3.7KW of panels to recharge the 8 hours of operation in the 4 hours of effective full sun you may have if you are lucky. That is a lot, say 20 panels at maybe 200W per panel. The fuel is zero, but really you need a generator too if there is no reliable other power available.

Th capital cost is high. It will need a significant and expensive battery that needs quite a lot of charge each day. Battery life, 3-10 years depending on quality and how well they are looked after. Solar panels, you hope for 20 years, but the capacity drops over time.

There are certainly issues with a diesel or petrol generator. This size is a bit small for a diesel generator. The single cylinder types are not attractive because they are noisy and have a lot of vibration. The idea of operating in a city area seems unreasonable. Get mains electricity if you possibly can, it is cheaper. The exhaust gas from any engine is deadly, due to the carbon monoxide, but diesels can be better with that. It will need to be exhausted up in the air to help it dissipate. This is more toxic than cyanide gas if you could compare them that way.. Engines can be put in a hole in the ground or a sound proofed building and with good exhaust silencing can be very quiet, even diesels.

A petrol generator can be quiet on its own, and they are made in these smaller sizes. The types that have an inverter in them are more expensive, but save fuel because the engine slows down when the load is lighter. Petrol engines are more expensive to run and probably have a short life compared to a larger smoother operating multi cylinder diesel. There is the greater fuel risk too.

The fuel costs for a 2KVA or 3KVA unit (I wouldn’t get smaller) delivering 1KW approx. Would be something like 150-200g per hour. Call that somewhere around 250 milli-liters of fuel per hour. Doesn’t sound much, but it is 6 liters a day, maybe 2 liters if you only run for 8 hours. The electrical mains will supply that for about 15c per KWh using US or Australian prices. Yours could be different. So for 8 hours a day in Australia it would be 2 liters costing $2.80 against 8KWh costing $1.20, about half.

This is a difficult decision, as there is no clear cut “good” solution except mains electricity, and your situation is not clear either. Look up suitable generators, visit suppliers, get quotes. You will need qualified persons to install any of these systems. You need to consult with an expert who can look into all aspects, including local regulations..

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