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Ejm
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# Posted: 12 Jul 2018 12:13
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I am new to solar, so go easy on me.
I want to start a solar system and I would think spend a little more and go with a 5000 watt inverter, so you have plenty of power for the future as you upgrade your system. What are the pros and cons? is it just overspending the reason for not getting the 5000 watt instead of the 1500 watt or are there other reasons? I only plan on using around 1500 watts because I will use the bigger stuff on my generator, but one day when I have a lage enough battery bank I wont have to buy a new inverter. Please let this rookie know before I waste my money : )
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creeky
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# Posted: 12 Jul 2018 16:31
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too big an inverter wastes money two ways. one. you pay to much for your inverter. two. your too large inverter eats power. so say it eats an extra 20w/hr. Not that unlikely. that's 500w a day. so you need more solar panels. bigger solar controller. bit extra battery.
a 1500w inverter will handle a surge of 3-4.5kw. I ran my cottage on a 1200w for years. lots of others here do to. smart is better than big.
one system I built last year is now running two full cottages. on a 4kw inverter.
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Wilbour
Member
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# Posted: 12 Jul 2018 22:44
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If you buy a quality inverter in the 1500w range you can always sell it later when you need more.
Or perhaps you will not need more.
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Ejm
Member
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# Posted: 13 Jul 2018 09:17
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I think I figured out what inverter I am going with. I have been talking to the guys at Backwoods solar: Great company, I bought my well pump from them. They are very knowledgeable if any one needs another source for off grid stuff.
This is the inverter I am thinking about going with! Let me know what you guys think.
http://www.backwoodssolar.com/schneider-conext-4000w-24v-inverter-120v-240v-ac
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creeky
Member
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# Posted: 13 Jul 2018 09:41
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that's a great inverter. I have a build using the 48v model to run 2 cottages with everything (2 big fridges etc). they use up to 13kw a day.
on 6 chevy volt modules and 3kw solar. they don't go below 45v.
I would suggest you go with the 48v model. Easier to wire. slightly more efficient. They are both slightly piggy on the base load consuming 40w/hr.
for your described loads I would get something smaller. a 1200 victron for instance.
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Ejm
Member
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# Posted: 13 Jul 2018 11:18
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Don't confuse me I was just talked into buying the 24V lol
They are putting together a kit. I am going to just hold off on the solar panels. I am going to charge most of the system with the generator in till I could add more panels where I would use the generator less.
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razmichael
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# Posted: 13 Jul 2018 12:28
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IMO you are putting together something much bigger than you need but, assuming you intend to increase the use in the future then OK (although that is one big inverter you are looking at)- but I would think it makes sense to add some panels now as these can always be increased in the future easily (unlike battery banks). You might not have enough panels to keep the batteries charged while at the cabin but, given you are only there 30 days a year, that gives lot of time to charge them up between visits so the first thing you do can be enjoy a drink in peace, not start the generator. These things are always a trade-off in cost and complexity - perhaps a smaller inverter as Creeky suggests and some panels.
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Fanman
Member
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# Posted: 13 Jul 2018 12:46
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Watts/hour is meaningless. Watts are already a measure of the rate energy is delivered or used, specifically one joule/second. Watts also equals volts times amps. The total amount of energy used is often expressed as watt-hours, not watts per hour. It may sound like a trivial distinction but in engineering discussions the words have very specific meanings.
If your inverter consumes energy at a rate of 20W, then the total amount of energy consumed in one hour is 20WH (or 72 kilojoules for the physicists out there).
Battery capacity is usually given in amp-hours which is a measure of charge capacity, not energy. The actual energy capacity (what you really care about) of the battery is the amp-hours times voltage, which gives you watt-hours.
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Ejm
Member
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# Posted: 13 Jul 2018 13:19
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This solar stuff is so confusing before I buy I should make sure I am choosing the correct system. All your help is much appreciated!
Here is the info I sent Backwoods solar. Let me know what system you guys think I should go with....
For the most part my generator runs at a quarter of the load because it lasts a long time on a full tank of gas I would say around 16 hours. “great generatorâ€
Here is what I am powering
3000 watt generator, it is an inverted generator Eu3000IS. It will idle low and not burn as much gas if it is not running at 100% power.
I have a Grundfos well pump. I don’t know what model, but I know it does not draw much power and has a small surge. I have a shallow well 16 feet deep and 100 feet horizontal. The well water is pumped to a 26 gallon pressure tank and a 40 gallon propane hot water tank, so the well pump does not come on too often, just when we need a refill or if someone is taking a shower.
Small refrigerator uses 358 kWh/yr.
I have a ceiling fan, with 4 led lights (about 4 hours a day)
Small led tv and Xbox to watch movies. (about 2 hours a day)
I have a total of 7 extra high hat LED lights (about 4 hours a day)
I have two flood lights 100 watts each (both about 2 hours a day, the single flood light another 3 hours a day)
I have a smaller flood light 50 watts (1 hour a day)
Small freezer box: I don’t think this kicks on much at all we store all frozen stuff in here and usually a bag of ice.
Small microwave (about 20 min a day if that)
Coffee maker 14 cup drip (once a day)
I have 4 small fans at 30 watts each (if it is hot we will keep it on a night)
I have 5 iPhone chargers (overnight charge)
We use this cabin about 30 days out of the year
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Wilbour
Member
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# Posted: 13 Jul 2018 17:00
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So I didn't add up all the usage here but I think you have a lot of stuff for a small system. You are really stepping into the 48v area.
The 100w flood light is a killer. I am using a vehicular fog light that is more than adequate. Plus it runs on the 24v load without being inverted (right in line with your 24v system)
Coffee makers are super hard on electricity but if you want t to budget for that then ok. I boil water with propane and drip coffee as I need.
Just my 2c
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creeky
Member
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# Posted: 14 Jul 2018 10:35
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watt-hour
ˈwädˌou(ə)
noun
a measure of electrical energy equivalent to a power consumption of one watt for one hour.
ye olde batteries measured power in amp hours. the newer lithium batteries are most often seen in kw. most people drop the hour. ie. Tesla has a new 100kw battery.
of course when you're calculating loads and such you need to have reliable references. watts per hour. or watt-hour per hour if you prefer. not many engineers here nitpicking.
I would replace those floods with led floods. a 100w flood is around 15w in led.
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groingo
Member
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# Posted: 17 Jul 2018 23:35
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Ejm:
First rule is Electricity is not your friend, get a Killawatt meter and get some real time power readings.
Next, make out the "LIST" and determine what you absolutely must have and what you can do without… .simplify.
Take it in baby steps as you learn, there is no one size fits all.
My system that the "Professionals" told me I would need based on my power usage ten years ago would have cost over $20,000, but by being realistic and making some life changes I did it for under $2,000 and live comfortably in my 195 square foot cabin for 6 years now.
You just need to get your priorities straight first and the rest will come together.
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Wilbour
Member
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# Posted: 18 Jul 2018 07:47
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groingo is right. I would be nice just to swap power source and continue as we do at home but that's not the case.
For example, I've been making coffee at home for almost 40 years with an automatic drop coffee maker. But camping just as long making it with hot water boiled on the stove then dripped into a filter.
Using an electric appliance for this could be done on solar but I figured it wasn't worth the extra cost. That was a personal choice so I'm still boiling water via propane, but I watch movies on a TV.
Personal choices
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