Off Grid Calculator

What is in an Off Grid Solar System?

First, we should start with a fully tested, factory pre-wired Power Center, which includes a complete Inverter / Charge Controller system with all the necessary components properly wired to seamlessly function together. To this we add all the rest of the components to round out a fully functional independent solar electric system.

What equipment completes the whole system?

  1. Solar Panels
  2. Storage Batteries
  3. Power Panel
  4. Solar Panel Racking and Mounting
  5. Additional components for Off Grid (i.e. Generator, Well Pump, Appliances Water Filtration etc.)

Solar Modules (solar panels)

Solar Modules take the radiation from the sun and convert it into electricity. When a solar system is properly designed, we first determine the size of battery storage needed for the expected load.

Next, we size the Solar Modules to be able to charge the battery bank typically for 8 to 9 months of the year from solar alone. This is determined by the number of “Sun Hours” at your location.

The few winter months require supplementation by either a Generator, or wind turbine or a hydro turbine. This way you do not have a situation where you have way too much solar in the summer months.

Storage Batteries

Solar will power your house during the day but, the sun goes down at night, so you will need a reserve of energy to get your house through the night. That is what your battery bank does. Storage battery banks can also support large temporary loads and can also help during days of heavy overcast clouds.

The Power Center (the heart of the system)

Pre-wired Power Panels (Power Centers) from the Factory are the way to go for many good reasons. They are done right, and they save hours of installation time. They are completely bench tested and warranted by the manufacturer. They come with a complete wiring diagram for easy connection to the other system components.

The equipment includes the Inverter(s) the System Controller / Monitor, Distribution Panel (DC and AC breaker box[s]), Charge Controller(s), Networking components together, Mounting plate and Circuit Breakers.

Don’t do-it-yourself. There is nothing worse than planning to wire up your power panel yourself on the weekend only to find you don’t quite understand the factory manual, or worse yet you forgot to get all the required small parts. If it’s the weekend, there’s no tech support to call and if this off-grid you are probably fifty miles down a bad road from the now closed electrical supply house.

You are not going to have any problem with your electrical inspector because it’s a complete factory wired unit.

Other Off Grid Products and Components

The Solar Power System gives you the energy needed for Independent Living, but you will need other equipment suited for Off Grid living like appliances, Water Pumps, Storage Tanks, Water Filters, A Back-up Generator

Solar Module Mounting and Racking

There are several ways to mount your solar modules. Most pictures show panels mounted on a roof and, this may be the only choice for urban areas, with small yards. I am not fond of putting holes in a roof, if it is not necessary. Also, most houses are not oriented to “Solar South” which can greatly compromise the Solar Panel output.

Off Grid is typically in “the country” where you have plenty of room to choose the best solar gain location. In these instances, a customized pole mount or a locally welded rack would make the most sense.

RV and Marine

The main difference between Marine and Recreational Vehicle solar electric systems and Off-Grid home or cabin solar electric systems, is that Marine and RV systems rarely have enough space for the solar panel array necessary to meet their needs.

While they may be able to accommodate the necessary battery bank for their electrical loads, the problem of adequately keeping the batteries charged typically falls to a fossil fuel generator and “shore power” along with however much solar that can fit into the small amount of real estate available.

Also boats and RVs have special grounding considerations. But, in every other aspect the equipment necessary to provide power is pretty much the same.  

The solar modules, mounting hardware for them, the storage battery or bank of batteries, solar charge controller(s), an inverter to provide AC power, a battery monitoring system, a system controller to program the various components to maintain the system, usually a communication system between the various equipment and lastly and most importantly protection for all the circuits which includes surge suppression and circuit breakers and some sort of enclosure to house them. 

Off-Grid Solar Power Calculator

Step 1 Add Appliances - Add, Edit or Remove Appliances as Needed.

Step 2 Enter Sun Hours - See map below to find your zone

Step 3 Review Results - Battery Bank Amp Hours and Required PV Array will show your requirements

Step 4 Fill Out Form - We will call you to schedule your free consultation!

Start with this prepared list of appliances. We have populated it with common appliances using average loads and runtimes based on our design experience.

Add extra fields by selecting the 'Add Appliances' button and scrolling through our list, or just type in your appliance or medical device. Most of the drop-down listings have the average loads filled in, so you need only add the estimated hours of use and number of days used per week.

Some items are not used every day - the calculator automatically calculates the watt hours per day over the entire week. For example: if you only use your hair dryer three days a week, it will spread the calculated watt-hours over 7 days. Clicking 'More Information' provides insight into how this particular load is calculated.

Step 1 Add Appliances

ApplianceQuantityWatts(Volts x Amps)Hours On per DayDays On per WeekWatt Hours per Day  
More Informationx
More Informationx
+ Add Appliance

*Please set valid number in the fields to calculate accurate result.

Step 2Enter Sun Hours

Click to view larger map

Choose your average sun hours, by location per day from the map.

Sun hours:

Step 3Review Results
Total watt hours per day will automatically calculate as you add items
DC battery voltage is most often 48-volt, for both small and large systems. If you have a Boat or RV it is usually 12-volt. Medium sized systems can be 24-volt, but they are less efficient than 48-volt.

(3 is recommended)
For the most economy from batteries choose 3 days energy storage. This keeps the depth of discharge low rewarding you with long life batteries.

Required Battery Bank:

PV Array Required 0

*Low end costs do not include batteries & mounting - costs of batteries depend on individual requirements. Contact us for more information.

Step 4Free Consultation

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Inverter (minimum running power)Inverters run off battery voltage and they run 24 hours a day, usually in idle. The typical watts and runtime are filled in for one inverter. If you have more than one inverter just change from one to the number that you have. Reduce time if Inverter will use "sleep" mode.
Inverter (minimum running power)
LED Lights are the way to go as they use a fraction of the energy that other types of light bulbs consume. When calculating the number of average lights on at a given amount time, we use 2 and a half lights per person. We don’t include babies or dogs because they don’t turn on lights. The other point here is we use the number of people that will be there constantly and not guests. 2.5 lights per person (not including babies or dogs)
LED Lights
AC Well Pump (1 hp) It is true that 746 watts is one horsepower, but when we figure that for a pump when it is pumping water it averages 1100 watts per horsepower. So, if you have a ½ hp. Pump figure it a 550 watts. If it is 1.5 hp. 1650 watts and so on. Well pumps pumping into a cistern may only come on once every three days. If you are using the well pump as a pressure pump as well the number of times it runs is going to be determined by the size of the pressure (bladder) tank. In this case if you have three people the pump will average about 2 hours runtime a day. 2.5 lights per person (not including babies or dogs).
AC Well Pump (1 hp)
AC Pressure Pump (1/2 hp) It is true that 746 watts is one horsepower, but when we figure that for a pump when it is pumping water it averages 1100 watts per horsepower. So, if you have a ½ hp. pressure (booster) pump figure it a 550 watts. If it is 1.5 hp. 1650 watts and so on. The number of times it runs is going to be determined by the size of the pressure (bladder) tank. In this case if you have three people the pump will average about 2 hours run time a day.
AC Pressure Pump (1/2 hp)
Refrigerator (Energy Star Rated) Refrigerators have really come a long way in a short period of time as far as efficiency. Today a typical energy Star Refrigerator, at normal ambient temperature, runs an average of 9 hours a day, it consumes somewhere between 1350- and 1575-watt hours a day. Remember the old side by side units from the 1980s that came in either avocado or gold? Those puppies consumed around 10,000 watts a day, or more than a whole off grid house If you are just going off-grid get a new Energy-Star refrigerator. It is cheaper than buying more solar panels and batteries to keep the old one.
Refrigerator (Energy Star Rated)
Freezer Freezers efficiencies have not improved as much as refrigerators. They run an average of 8 hours a day and consume a lot. If you have a chest freezer you can cut down on the runtime by gluing 2 inch (blue board) closed cell foam board to the bottom, as all the lost cold is generally out the bottom. You have to be careful as to the type of glue you use, as construction adhesive will melt blue board. If you want a really efficient freezer, we sell DC Freezers which are way more efficient and quite a bit more expensive.
Freezer
A Flat Screen TV the typical size is about 40 inch which uses about 90 watts. However, if your Screen is substantially larger, look up the watts online and change it. We have found that the average time for most folks is going to be around 3 hours.
Flat Screen TV
Washing Machine (Front Load) Front Loading Washing Machines. There is a lot of really good reasons to go with a front loader, off grid, first they use about a quarter of the energy of a top loader and less than half the water. Your clothes will last 4 times as long. Some folks say that the washer smells but the simple trick to stop that is to just wipe the door dry and leave the door opened for a while to let it dry out.
Washing Machine (Front Load)
Washing Machine (Top Loader) Top loading washers have been around for a long time and they are cheaper than their front-loading counterparts. They use a substantial amount more energy and usually twice the amount of water, which if you are Off-Grid this makes your well pump run times longer too.
Washing Machine (Top Load)
Gas dryers are the way to go for Off-Grid and they are second only to a solar dryer (clothesline) But if you really like those fluffy towels a machine dryer is a requisite. We often get asked “how about an electric dryer?” while you can do an electric dryer you have to be willing to spend the extra up-front cost for extra solar panels and batteries. Gas dryers do use more energy than a front-loading washer because they typically have bigger motors, but given the weekly use they don't add much to the daily load calculation.
Gas Dryer
Electric Dryer. We often get asked “how about an electric dryer?” while you can do an electric dryer you have to be willing to spend the extra up-front cost for extra solar panels and batteries.
Electric Dryer
Cell Phone Chargers are a necessary annoyance as it seems like every time, I look at mine, it needs charging. They hardly use any energy but this assessment lists everything that gets used at least once a week.
Cell Phone Charger
Furnace (1/2 hp) Forced-air Gas Furnace while they sure beat bucking and chopping wood, they do make an impact on the monthly budget. The good part is that with solar you don’t have to pay to run the fan. Typically, they have about a half horse motor which puts them at 550 watts times a usual runtime of 8 hours so it adds up.
Forced Furnace Air (1/2 hp)
Coffee Makers come in all sorts of shapes and sizes. Some use none or appreciable amount of energy, a French Press comes to mind, while others especially the ones with a hot plate, to keep the coffee pot warm, often wind up using as much energy as the whole house! Like when at lunchtime you notice that you have left it on since breakfast. If you like filtered coffee get one with a thermal carafe that will keep the coffee warm for about 4 hours without using a drop of electricity.
Coffee Maker
Toaster (2 slice) or Toaster Oven Toaster and toaster ovens are quite acceptable due to the small amount time of use. Sure, they use 1400 to 1500 watts an hour, but it only takes 3 minutes or less to make toast. If we factor it out over the whole day and then all week (toasters are used an average of 3 days a week) the electrical load contribution is almost negligible. If you use a two-slice toaster just put two for the quantity.
Toaster (2 slice) or Toaster Oven
Microwave ovens are very efficient users of electricity. Like the toaster they are generally used for brief amounts of time thus rendering their daily electrical load to be quite small.
Microwave
Laptop computers and tablets are part of the lives of a good portion of the population. Many of us work from home so the times of use are going to vary a lot with these items. We do not recommend leaving them on 27-7 like you may have been used to when you were “On-the-Grid”.
Laptop
Desk Top Computers are part of the lives of a good portion of the population as well. As many of us work from home, so the times of use are going to vary a lot with this item as well. We do not recommend leaving it on 27-7 like you may have been used to when you were “On-the-Grid” either. Also, with a desktop there is more of a chance of having a laser printer which if you have one should be turned off when not in actual use.
Desktop Computer
Router or Modem here we have a piece of equipment that uses very little energy but it is on 24-7 in most cases .
Modem-Router
Hair Dryer here is an item that hands down, gets a bad rap and it does not deserve it. Once again sure, it uses 1700 watts it says that right there on the thing 1700 watts, and I have had hotel owners tell their guests… “but here in this hotel you can’t use a hair dryer, because we’re on solar”… I say, are you nuts? If you used a hair dryer long enough to use an appreciable amount of electricity your hair would fall out. Most folks use one about three times a week so like the other equipment in this category factored out over a week… not much energy use at all.
Hair Dryer
Blender Seems like everyone owns a blender but there the similarity ends. There are those who use them every day, sometimes more than once and there are some of us that just own one and rarely use it at all. The question here is do you use it every week or not, if not don’t count this appliance. .
Blender
Ceiling Fans are probably the most overlooked appliance you can have. First, nobody ever turns them off. Second, they don’t cool the air they just cool people. While they typically use slightly less than 90 watts, if they are left to run all the time, they can rack up quite a bit of energy usage. I have visited off-grid resorts with a large verandas replete with chaise-lounges and 5 or 6 ceiling fans going strong with nobody there. Like I said nobody ever turns them off when they move away from them. What to do? Go down to the local hardware store and get the push-button timers that replace the wall switch. Get the kind that let you push either two, four or eight hours. Even if you are sitting there and the fan goes off you can just push an additional two more hours and if there is one over your bed just choose eight hours.
Ceiling Fan
Dishwasher (cool dry) These labor-saving devices actually use less water than hand washing dishes. They give you the choice of hot dry or cool dry. If you are not running a restaurant you do not need to sanitize your own dishes so if you are going to have one use the cool dry option.
Dishwasher (cool dry)
Dishwasher (hot dry) If you are not running a restaurant you do not need to sanitize your own dishes so if you are going to have one use the cool dry option.
Dishwasher (hot dry)
Electric Toothbrush or Shaver Small appliances like these don’t really use much power but we include them because they are used every week. If you have both or more just enter how many.
Electric Toothbrush/Shaver Charger
Sound System These days most people just stream their music but some of us still have big surround sound stereos. Because of the wide range of potential energy usage you will have to figure this equipment load yourself and the time of use. Add custom value depending on type of sound system.
Sound System
Tablet Lot’s of folks have tablets as a compromise between a laptop and a small cell phone. For this computation it is best to figure the usage time and the charge time the same.
Tablet
DC Pressure Pump Water pumping can use up a lot of energy, but DC motors tend to use half the energy of AC motors. DC Pumps cost more than their AC counterparts but are often better quality and have much longer life. In some circumstances they can be utilized Solar-Direct eliminating the need for Inverters, Charge Controllers and Batteries.
DC Pressure Pump
Solar DC Well Pump Water pumping can use up a lot of energy, but DC motors tend to use half the energy of AC motors. DC Pumps cost more than their AC counterparts but are often better quality and have much longer life. In some circumstances they can be utilized Solar-Direct eliminating the need for Inverters, Charge Controllers and Batteries.
Solar DC Well Pump
DC Ceiling Fan Years ago, DC ceiling fans were more popular than they are today. Solar Panels were very expensive and anything you could do to cut the energy load, you would try. Today however DC fans are typically used in situations where a fan is desired but running AC Power over a long distance is cost prohibitive Plus a DC fan can be wired solar direct without the need for a lot of equipment and it just runs when the sun shines which is when it is needed anyhow.
DC Ceiling Fan
DC SunDanzer DCF225 Freezer AC freezers are not energy friendly but they’re popular because they are cheap. DC Freezers and by comparison very efficient but they cost more. Some situations cry out for them. We sell a lot of DC freezers to beach front beer stands who run them from a couple of solar panels. They turn the thermostat up to 32 and stuff it with beer or other drinks. In a home situation you will probably save money by not having to buy more solar panels and batteries to run an AC unit.
DC SunDanzer DCF225 Freezer
DC SunDanzer DCF225 Refrigerator DC Fridge of the chest type can be used for longer term refrigerated storage, but a chest unit is very hard to find anything. We sell units that can run on one solar panel and can transport vaccines and refrigerated medical supplies on the back of a donkey.
DC SunDanzer DCF225 Refrigerator

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