Solar Panels

Hi Guys,

I am living off grid in tiny house and wanting to upgrade my solar panels.  So far my family of 6 has made it on one harbor freight 100 watt kit with two lights.  I am interested in finding out how to source cheap batteries, what type of batteries are best, and general know how. If anyone can point me in the right direction I would appreciate your help.  I am thinking to get another 100 watt kitt or maybe two but I am thinking that I will need a better battery..so far I am using the harbour frieght deep cycle/cell battery off the shelf.


Thanks for your help!

Jason

You could look at aliibaba on the web. I can usually find an item there in a wide range of quality and price.

The duracell deep cycle golf car battery is a budget champion. There are a couple sizes. Id spend the extra 10 bucks for the 20- extra amp hours.

How much is the harbor freight system you are considering? A 300w solarworld panel is $179 right now. In the past 45w harbor freight systems were $200. The cool thing is they have all the bits in one kit, maybe have to  get a battery but it came with lights.

If it worked out reasonably for you and your not small count of occupants, and is the most practical approach doubling up pv and up sizing the battery may be a great way to extend service off grid.

If this is primary power and an investment in long term utility you can build with high quality for the same cost or less than most harbor freight or other kits of the type. I have some of the H-F panels that have worked great for years but they have wimpy frames, junctions and wiring.

If care is taken with preparing the mounting, wire strain relief and wire size is appropriate (i usually snip them a couple feet from the module and combine onto decent wire), they can sit out for some time and yet the power home reliably.

Hi Jason,

I love Harbor Freight, but their solar offerings are quite limited.  They are cheap and inexpensive too.  You are about to enter an exciting new world.  

Bless you that you and your family have gotten by on 100W, but more importantly on a small Harbor Freight battery with its limited storage.

Note that I have fully (but in good fun) "vented", we can get too the heart of the matter.

If you are off grid, good batteries are your best friend. I don't know if you have a Sam's Club nearby, but if not Batteries Plus is a good option. If you buy online and pick up in the store they give you 10% off.  Sam's has the Duracell GC2 which is a good solid $90  +/- 175AH 6V deep cycle golf cart battery.  You will need 2 of them wired in series to get 12V.  I was going to recommend the EGC2, but apparently they are no longer manufactured.  Batteries plus has a replacement for it called the Duracell Ultra GC2.  It is a 220 AH and for the extra money would be my choice.  I have a 48V bank with 8 GC2s and 16 EGC2s.  If I had it to do over again they would all have been EGCs for the small increase in $s.

I would suggest that you up your voltage to 24V at some time.  Not knowing what your budget is for this upgrade, I will not suggest what to do, but if your budget supports it, I would buy 4 batteries and wire them as a 440 AH @12 V battery which could be rewired to 220AH @24V later on.

The reason for going to a higher voltage is improving your efficiency as you grow your system.  That is why I am at 48V.  As for panels, I really like the folks at wholesalesolar.com .  They have all the parts you will require and at good prices.

As for charge controllers, you want to buy an MPPT charge controller as they are waaaay more efficient.  Here is a link that explains the different types of controllers: https://www.altestore.com/store/info/solar-charge-controller/

This is a start.  Tell me what your budget is and what you would like to run of your new system and your zip code so I.can see what the solar potential is for the area.  If you live in Phoenix you have a lot more sun to play with than in ever-cloudy Seattle.  Also give me an idea of budget and I can make sooner better suggestions.

I have had an off grid system myself for 3 years now and am a degreed EE and a PE, so I do have a decent understanding.  I would be happy to help as I know some others on the site will also.

Sincerely,

Ralph

Whatever wattage figures into your budget will have a general practical battery size for minimum or max. Your battery will appreciate at least a 20th of its amp hour capacity in charge amps. A 100ah battery will likely require a minimum 5 amps charging for most service aside from storage float. 10-12 amps in excess of standing loads is a good charger for that battery in many applications. Some lead acid batteries can take a 5th of capacity charge amps.

There is a limit to minimum and maximum charge rate, you have to have at least enough and preferably a way to control an array with current in excess of max charge amps.

Some controls would allow this setting to be tailored and allow a larger array to give leverage under adverse solar  conditions. For the ones that dont, sizing of pv at that site will be the way to not exceed the battery max charge amps.

I looked up the HF batteries.  They are sealed vs these batteries sand so it is not a completely fair comparison, but  It would take 6 ot 7 of them to equal 2 of the Duracell Ultra GC batteries.  The downside is that every 4 to 6 months you need to add water to the batteries.  However 2 of three ultra GCs are $240 vs. $420 to $490 in HFs.

I hope this helps.

Hi Ralph

Thanks so much for the detailed information.  I really appreciate it.

I'm thinking about 1000 us.. is all I can afford for the time being.  We have lived without running water for 3 years and my wife is saying it's time to get some so we are hoping to be able to run a well pump or a pump that would lift small amounts of water to tank ... would have to be big enough pump to lift water 300 feet up hill as our spring is below our house on grade... by maybe a hundred feet and about 300 feet away from the house...

We are located in 24333 zip code in the mountains of VA.  Right now the one panel I have is mounted on the roof of my tiny house and gets sun maybe 6-8 hrs a day... other than pump...we would like to ability to charge 3 phones a laptop and some other small items.. we have had no fridge for years... spring fed box keeps our milk cold in the summer.

Whatever battery you suggest I would love to make sure it doesn't impact air quality..I watched one video a few months back and host was talking about venting and I thought would not be good to breathe battery..😀...I don't mind adding water but whatever battery would have to be not offgassing obnoxiously... the batteries will have to be in our house as we have no other place...

Our electric fence charger is stand alone and we mounted it on a pole that swivels....so we can turn as the sun moves....I think due to wind this might not work for the house panels... during the winter we get some pretty good wind as house sits at 2700 feet above see level...u thought wind may be an option but risky I think due to lack of wind in summer...

I would appreciate your help and support on this upgrade...my old neighbor was an electric engineer and was experience in solar.... this was about 5 years ago but he said that  nickel iron battery..was pretty good.