Help with inverter size

Normally we work from the loads to what you need, it appears you have jumped the gun.

So how much wind do you get, do you know the wind profile of the win generator? You they have a diversion load for the wind generator? Maybe it just has a heat sink with the aluminum frame of the charge controller? if so when Your batteries are charged and you have strong steady wind you will have a 400 watt heater in stead of a charge controller. Since electronics and heat don't play well together, lets hope they suggest or have a diversion load, from my read it doesn't nor does it explain not having one. Not a lot of fans of small wind here.

So you have 200 watts of solar panels on what I will assume is a pwm charge controller, they also don't give any specs on the solar panels so I'll leap to the assumption that they have a VMP of 18 which would mean they produce 18 volts under load. so that would put the amperage at about 5.5 amps. There are 2 of them so figure about 11 amps from the solar panels. in direct sunlight close (2.5 hours either side) to solar noon.

You have purchased "Seahawk "epm products" Model DP27 battery." which a quick search returned no results, so using your numbers they appear to be great batteries to start your boat! Unfortunately we aren't trying to start a boat.

Generally we find batteries for marine use that have cca (cold cranking amps) values published and no amp hour values to not truly be deep cycle batteries and have a poor life in a true deep cycle use. If you can return them I would. Best value would be golf cart batteries, which are true deep cycle batteries and mass produced which keeps the cost down. I'll use this Group 27 marine battery from Sam's club for it's rating, they claim 90 amphours at a 20 hour rate.

https://www.samsclub.com/sams/duracell-marine-battery-group-size-27dc/prod3590231.ip

So you would have 2 in series, in series the voltage adds and the amperage remains the same, so each string would have 24 volts at 90 amps. Then you would have 2 strings in parallel, In parallel the voltage remains the same and the amperage adds, so you would end up with a 180 amp hour battery bank at 24 volts.

Typically a flooded lead acid battery will want a charging rate of about 10-13% so 18-23 amps, so depending on how much  wind you get you may or may not have enough charging capacity for your battery bank.

Assuming you have enough energy to charge your battery bank, we typically would like to use only the top 20% each day during relatively normal days. so you have about 36 amp hours at 24 volts to use. To convert that to watts, you can use this formula, amps x volts = watts, so you have 36 amp hours at 24 volts = 864 watt hours. Most inverters will lose about 15% of the energy converting Dc to AC so you would have about 864x85%=@735 watt hours, This will run a modern 55 inch TV setup for minimal usage for about 9 hours at 80 watts, so a small invert would work fine. Small chest freezer will use about this amount of watts during a 24 hour day, but running at around 100 watts and turning on and off during the day. Because it is starting a compressor, it will require a much larger amount of current for a brief time starting the motor. So likely you would need a 800-1000 watt inverter. So much depends on how you would like to use the energy.

There are 2 types of inverters, pure sine and modified sine. If you want to run sensitive electronics like a TV of desktop computer, or any thing with a motor, like a fridge! you are better off with a true sine wave inverter. If you want to run a pure resistance load like an old incandescent light bulb or a toaster, or non sensitive electronics, usually something with a rechargeable battery which will buffer the energy, Laptop or cell phone. a modified sine wave will work fine.

Hope this helps!

bradleydavidgood777 said:

So all of the calculations about how much it all may produce are very interesting but not really what I'm looking for.  I would like to know how to calculate the inverter size necessary for my bank of 4 batteries 24v when they are charged to capacity.  This way, even if it takes several days to charge up completely, I'll have the proper inverter to handle it when I need it.

Off grid,  Battery based, solar is very hands on, suggest if you don't want to learn the concepts, you sell the equipment now and save the grief! seriously! I don't care if you don't want to reread my drivel, but try to read and understand the concepts Bill has presented, it will allow you to use solar effectively.

Sorry, I've given you a comprehensive answer.  If you want a "Buy this" answer any sales person will give you one! Bill has also given you a good answer.

Perhaps this will help others understand that the inverter size depends on the load you want to run.

Best of luck to you. Maybe you will run into "Sunking" on another forum, I might have to monitor that interaction! It would be fun!

@BB You should really, really, really sticky this thread at the top of this same subforum, as how not to act on a public forum, when you don't have the slightest idea what you're talking about.

edit: Oh, I forgot to add that B.B., Photowit and myself belong to every solar forum on the planet, just with different usernames. See you at the next one.