In this series, we conclude with a handy on-line power budget calculator. . Part 4 we coveredPower Budgets [4] data you can use" rel="bookmark" href="../genverters/power-budgets-4-data-you-can-use/"> Power Budgets [4] data you can use. In this installment we present more details for your power budget and details on how to use the free on-line power budget calculator presented below.[editors note: The entire series can now be found on our new Power Budgets page for your convenience!]
I’ve created an online calculator to help you create your off grid power budget. These calculations will help you determine what your can run, and how long you can run it when operating on what I call “battery time”.By battery time I mean is that your charging sources are wind, solar, hydro, or other renewable sources. Backup generator charging often results in free power time. and is generally not “on budget” time.
When operating your system on battery time, you are ‘on budget’. To protect your battery investment do not entertain the idea that you’ll never need a backup generator source, you will. Deep cycle batteries need some TLC to keep them going beyond a few years to the payout years of 6, 7, or even 8 years for replacement. Currently, I’m looking at replacement only 5 years later, ouch!
The basic form presented below will help you get some ideas of what your off grid power needs might be. Don’t forget to consult the data you can use page for some real ideas on the actual power needed by various appliances. If you have something that might be a large load, consider getting a P4400 Kill-a-Watt monitor and do the real measurement.
The greatest value found in creating a power budget is the knowing realistically how many deep cycle batteries you’ll need. Your power budget will determine how many dollars go into batteries, and what is left for a charging system(generator), and what solar / wind / hydro equipment will fit in your first phase of the power system.
As an added bonus to those in the US, here is a map that indicates how many equivalent hours of solar energy that are on annually available. This gets kind of technical, but can give you a guide to start out with. You may want to use these numbers below for your location to get more of a worst case idea about solar contributions.
The one caution: the map below is an anual average. At my location it indicates 4-4.5 hours, while in the winter its probably 3 and in the summer it gets up to 8 hours. The wide variation is explained because we are in the Northern US and by the green road sign above.
How many "Equivalent" hours of Sun light?
Power Budget Calculator
Budget Calculator Instructions:
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I hope you’re short coding this table in, and not punching it in or copy/pasting into the code. Got a divide by zero error when entering on only one line.
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Table is simple html form. The results page would divide totals by solar hours to get required panel watts. If no solar hours entered, divide by zero, now fixed to read “null watts”.
I tested the online calculator from my Linux computer. There was a calculation saying I would need to run my genverter 1.5 hours per day to meet my needs. Doesn’t that depend on what output my particular generator outputs? At this time my particular model delivers 100 amps to the battery. 100 amps at a nominal 12V is 1200 watts and my daily load is only 600.4 watts. So in reality that particular calculation needs an input of the actual charging capacity being provided by the genverter. ( dont forget to allow for power factor) I also have a Prosine inverter that can deliver 120 amps to a battery bank. It is not wired up yet since we moved recently.
For the SEGS system the calculator tells you how many TIMES the generator must be run to recharge the battery. It does not say how LONG the charge time will be, because and you and I know, that involves many variables.
On the subject of power consumption by various appliances… [ Marshall moved comment to best location: http://www.genverters.com/genverters/power-budgets-4-data-you-can-use/ ]
Regarding the SEGS. Would it not be useful to have a field where you could enter a number that might be different than what you assume their particular SEGS would be. Since you are driving the charger with 120V AC from the generator they could substitute something else.
Marshall I have a data point for you. A George Forman grill rated 1100 watts cooks three 8 ounce hamburger patties at a time. Including preheat time it used 0.14 kilowatt hours from start to finish. AS measured with a P4400. I love a good grilled steak or hamburger but in winter the Propane BBQ just doesn’t hack it. The meat is half cold before you can serve it.
When the wife serves up grilled garlic prawns and a California salad the cooking time is less than for 8 ounce Black Angus hamburger patties so it would be slightly less than the 0.14 kilowatt power consumption I measured.
More data points to follow.
How about freezing plastic bottles of water during ‘free time’ when generator is running to help ride through the power off period at night? In fact this may allow extending this period. The ice bottles would take up any empty volume in freezer and provide added thermal mass to hold down temp rises during hotter portion of daily cycle.