Avoid placing many small batteries in parallel. Both the battery voltage and the Amp-Hour storage capacity of your battery bank should be appropriate to your needs. Instead of opting for a higher voltage, an increase in cable size could also have solved the problem. Unless the cable runs are exceptionally long or the power draw (amps) of the loads is exceptionally high this consideration would not be an issue. Hence, with a 24 volt system the cable need only be one quarter of the diameter as it does with a 12 volt system. Because the battery voltage is doubled, the percentage of the voltage drop in relation to the battery voltage is only a quarter of the percentage drop with the lower battery voltage. If the ccc is exceeded the cable will melt and/or catch fire.ĭoubling the voltage effectively halves the DC loads and halves the voltage drop. A more serious limitation of the cable is its "current carrying capacity" (ccc). There is an acceptable limit in the voltage drop in the cable before the voltage drop becomes excessive with the resultant output voltage becoming too low. The lower the battery voltage, the higher the current draw from the battery bank to supply a given load (measured in watts). If lower voltage supply is required, it is possible to use a DC to DC converter. More cells may be placed in series to increase system voltage for greater efficiency. The battery voltages commonly used for stand alone power systems are 12V, 24V, 48V, 120V DC. However, by doubling number of cells in the battery the battery voltage is doubled, therefore the current (amps) from the loads is halved, so doubling the voltage has the same effect as doubling the amp-hour storage capacity of the battery bank without having the battery bank connected in parallel. It is not recommended to increase storage capacity by connecting two or more battery banks side by side (in parallel). A single battery bank available will provide X amp-hours over a 100 hour period to be 50% discharged at the end of that period. With solar panels as the primary energy source, it was traditionally recommended to have a minimum of 5 days battery storage with the battery bank still retaining a minimum of 50% charge after the end of those 5 days. We would only suggest a 12V DC power system (such as Rainbow Power Pouch) if you need a few lights in a shed or caravan and wish to wire it yourself. The criteria we use is power consumption and scalability. To summarise: Most systems we design are 24V or 48V with a 230V inverter. Further, the movement towards a greater use of Lithium based battery chemistry limits economics to 24 & 48V based on economies of scale of manufacture. Not to mention the fact that only very few companies sell extra low voltage appliances or lighting and cater largely to the RV market. A 12V DC system with a tiny inverter is difficult if not impossible to upgrade/upsize. In addition, most customers seem to want more power over the years. In recent years, inverters and solar panels have become more efficient and a lot more affordable. This was achieved by using 12V or 24V appliances & lighting that do not require an inverter. In the past we tried to reduce the cost of an off-grid system by limiting its size. This way you can use standard AC appliances and lighting, most of which are a lot more affordable to buy and many are increasingly more efficient. This means the wiring of the house does not have to be different from any other grid-connected household and cabling cost is greatly reduced.įor 230V (low voltage) wiring you must get a qualified electrician to wire your house for 230V AC. Today, most systems are 24V or 48V and include a 230V AC inverter. 100A would melt it and could start a fire! Industry Standardġ2 volts used to be a standard for extra low voltage power systems. A perspective: a standard household extension cord rated at 10 amps max current (a common value). By doubling the voltage (I = P/V) you get double the power (Watt) at the same current.ĭealing with currents over 100A is costly (and therefore inefficient) and potentially dangerous. High currents require larger diameter cables and fuses/breakers, both of which are expensive. The higher the current (measured in Ampere or Amps) the larger the wiring and circuit protection components need to be.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |