$2000 to connect to grid again... Should I just go solar? (refrigerator, dorm)

[whtviper1]

Originally Posted by mikereilly

I've places where rippers stole solar systems, catchment pumps, sinks, bathtubs, toilets, appliances and more when looking at real estate in Puna subdivisions.

This story is unfortunate:

Homes spared by lava are being hit by looters, evacuees say - Hawaii News Now - KGMB and KHNL

"On the Big Island, homes spared by lava are now being hit by looters. "

"They also stole his solar panels with the storage battery, and his catchment cover and pump. That means he doesn't have power or water."

[hapci534]

Well, I got 2400W of solar for starters. The used 20 year old panels were $1000 total. (They work OK.) For charge controllers I bought three $80 SunYoba 80 Amp units from Amazon. The batteries are six $130 Interstate GC2's from Pahoa Auto parts. Cables were $600, installation by electrician another $600. Total cost $3220. Had I known how to install the rig myself, the cost of full ownership would have been $2600, or roughly a dollar per watt, without the electrician's fee.

Now instead of running the generator 14 hours a day, I only need to run it 5pm to 10pm to add extra juice to power the whole house till next sunrise.** (Fridge, chest freezer, about 30 light bulbs, all outlets, cable modem, phones charging, small 12V water pump.)

The system works since months, the only flaky device is the Schumacher 15Amp car battery charger, which sometimes errors with a red light and stops charging. I learned to check on it hourly and reset it if needed. I guess I could get a more dependable charger for $100, if checking it for 5 hours felt too bothersome. Once I add more solar wattage, the generator and the Schumacher will be needed only on rainy days.

It's great to wake up 8am-ish knowing the solar rig had been charging since an hour at least...

**(5pm to 10pm extra gear: used Honda eu2000i generator $600, Schumacher 15 Amp car charger $50, but I had these two from before)

[Arktikos]

Way to go, though I'm surprised you need to run the generator at all with that many panels. Maybe more battery storage would help? Also, not having 30 lights on.

[hapci534]

Even with just 6 batteries, the only time I reach 100% charge in sunny weather is when I forget to connect the chest freezer.

I forgot to list the 4000W (peak) inverter in my solar rig. Another goodie I had from years ago. This power-thirsty box might be one of the reasons why I rarely reach full charge, actually.

[terracore]

I'm not a solar pro, clearly an amateur but I built my own off grid system 3-4 times over the years as I've had money to expand it and learned a few things along the way. Here's a few take-it-or-leave it suggestions:


I don't know what kind of charger you have but it sounds like the type for an automotive battery which is wasting a lot of generator gas if it is the "automatic" type (it's probably spending a lot of it's time trying to charge at far less than 15 amps, so it pukes out an error, it's charging algorithms have no idea how to deal with flooded batteries hooked up like yours). I recommend a heavy duty manual charger. The one I have that I like isn't currently on amazon but it allows me to switch between 2/10/40 amps. And when it's on, that's what it puts out. No more, no less. Here is a similar model:


https://www.amazon.com/Schumacher-SE...language=en_US


I'm guessing your solar panels are arranged in 3 arrays, which is why you have 3 charge controllers. There is nothing wrong with that type of setup but those charge controllers are holding your system back. They look to be PWM and you need MPPT controllers, especially here with all our clouds. The quickest way for me to describe the difference between the two types is like this: Let's say that your battery array is configured for 12v. That means your charge controller can put maybe 14v on a regular basis into the batteries without damaging them. But under full sun, your solar panels may put out 18 or more volts. What happens to the extra volts? Nothing. The PWM charge controller holds them back because it's not capable of converting the voltage. An MPPT controller will convert the 18v to 14v (or whatever) to a higher amperage your batteries can use so almost 100% of your electricity gets used. Think of a PWM charge controller's job to hold electricity back and an MPPT charge controller to use every last bit of energy. If your system is configured for 24v or something else, the same applies.


MPPT controllers covert voltages in other useful ways too, like you can have a 12v solar array hooked up to a 24v battery array, or the other way around. While they may seem more expensive, they really aren't. And not just because they pay for themselves by salvaging electricity that would have otherwise been wasted. Most MPPT controllers can accept energy at 3x their output rating. For example, a 40amp charge controller can handle the power of 120amps worth of solar panels without damaging the controller.



MPPT controllers make something like a million calculations per second to optimize the charging of your batteries. They actually have CPUs and memory in them (they are little computers with a big voltage converter in them). This means that under cloudy/changing conditions your controller is adjusting it's charging profile several times per second if necessary to ensure maximum charging. Nothing wasted. PWM controllers are just voltage regulators that discard "extra" power.



You didn't say if your panels are wired in series or parallel, or how long your wire runs are or the wire gauge, so it's hard to make specific recommendations on your wiring configuration but an MPPT controller doesn't care if they are hooked up in parallel or series. If hooked up in series it will for example convert (pulling number out of air) 120 volts at 1.5 amps to 14v at whatever amps your batteries can take. No damage to batteries, all the power going in.


You don't have a lot of battery storage especially for an off grid setup. I think the batteries you have are either $89 or $99 at costco. Think about that for future purchases. The price difference on buying 2 batteries would have paid your yearly membership and most of the gas for your trip. Costco also sell a 12v golf cart battery that is about 150 amp hours. They are of course more expensive but you would be hooking up half as many of them to achieve the same storage which translates to less cabling and greater efficiency, half the maintenance, etc. I asked the sales guy if they ever had any warranty returns on them and he said no, and also that people only buy them for solar power systems. They are about 90 pounds each so not the easiest things to lug around but their taller profile means they take up less square footage floor space per watt stored.



You didn't talk about your inverter but if it is a modified sine wave it is going to require a lot more power from your PV system to do the same job as a pure sine wave, and it is slowly going to degrade your motors and electronics in the process. For example a MSW inverter can run a microwave, but the microwave is going to draw 20% more electricity and it will heat the food only 80% as hot when operated for the same amount of minutes compared to a pure sine wave inverter. The same goes for the compressors in your refrigerator, freezer, etc. They will draw more current and run hotter, and that will reduce lifespan. MSW inverters aren't kind to inductive draws for permanent use (short term is fine), if your fridge compressor needs 110v to operate it's only going to "see" about 86 useful volts from the MSW so it makes up the difference by drawing more power from the inverter, making it run hotter. In the long term, PSW inverters are worth the higher price, but because of their higher price I recommend only using reliable name brands with long warranties and also buy an extended warranty on them. There are several PSW inverters on the market that will automatically start a generator and switch to it's power when the batteries are low, and even charge the batteries if you configure them that way.

[hapci534]

Originally Posted by terracore

I recommend a heavy duty manual charger. The one I have that I like isn't currently on amazon but it allows me to switch between 2/10/40 amps. And when it's on, that's what it puts out. No more, no less. Here is a similar model:

https://www.amazon.com/Schumacher-SE...language=en_US

Perfect timing for the charger recommendation, Terracore. After our Schumacher wasted 2 hours of generator output yesterday and today without charging, I just sat down to the computer to order a replacement. Not necessarily Schumacher brand, though...

I understand your point on MPPT. But true MPPT controllers are $500-ish, I believe. So if a MPPT box captures $20 more power a month than my PWM cheapie, the $420 price difference would require 2 years to pay off. And that's presuming ideal circumstances. In my case, however, during installation TWO charge controllers went up in smoke. (It wasn't me.) So, had those been $500 boxes, not $80 cheapies, my MPPT break even point would have been a whopping 4 years, not even 2.

[hapci534]

These large Schumacher SC1285 chargers don't seem to be very dependable. At least, not for daily use with my six 6V 225 Ah batteries wired into one 12V 675 Ah bank.

The first charger lasted 4 months. I actually paid the $100 to ship it back to the continent for an exchange. Schumacher sat on that for 5 months, then sent me a replacement. Their replacement unit just quit after 10 months.

So average life calculates to 7 months. Average repair time, 5 months. Hmmm...

[Dreaming of Hawaii]

Good to hear from you, hapci. It's been a while. Sorry to hear about your problems with your charger.

[terracore]

That sucks. I have a 20 year old Schumacher still going strong. I guess like everything else that has been off shored the quality goes to crap.

[hapci534]

I think it's not about where it's built, Terracore, it's about whether it was "value-engineered". That is, designed with the cheapest, junkest components that will still work out of the box, but not for long. A common theme with goods bought at a(ny) mega-mall.

Typically the answer would be to go to a specialist store, where one gets higher quality goods at higher prices too. I just don't know what would a specialist store be for chargers on the Hilo side; do we even have one.