Green Homes
You are here
Heat Load Analysis - Heating Degree Days
If you have a heat-load analysis performed on your property, the results are likely to come back in a very odd measurement: Btu per heating degree day per square foot. How can you use this to work out your solar thermal space heating requirements?
What is Inverter Capacity?
Inverter capacity is the amount of power which can be supplied continuously by the unit. The inverter rating must be at least 25% more than the total power required by all connected appliances operating simultaneously. Multiple inverters can be series-wired or parallel-wired for the required capacity.
Inverter Surge Capacity
Inverter Surge Capacity
An inverter's surge capacity indicates how it handles short-term overload before "tripping". Surge capacity is essential to start up some large loads, especially motors that need 2-3 times their running power to get going. The start period may be very short – a fraction of a second – but it still needs to be considered.
Fossil Backup Power
An unsuitable backup power supply is the Achilles' heel of an off-grid energy system. The problem does not lie in the renewable energy equipment's reliability; a well-designed system is often more reliable than the electrical grid.
Problems are more often related to the weather than the equipment. When the winter months are dark without any sun or wind, your system will require more batteries.
Types of Generators and Fuel Economy
Generators or "gensets" come in various fuel choices that include gasoline, propane, natural gas and diesel. Cheaper gensets are built around gasoline engines running at 3600 rpm. Bigger industrial units tend to use natural gas, diesel or propane with a slower and more frugal 1800 rpm engine. Your model choice depends on factors such as unit capital cost, accessibility to fuel source, ease of use and economy.
Options for Backup Generators
A genset unit is durable and long-lasting if it is maintained well. A good quality generator has no problem with run times but it should be maintained regularly. For example, a diesel engine may need servicing at various hour intervals, such as 25, 250, 500 and 1,000 hours of operation.