Aloha from a Solar Newbie in Hawaii

[WH6FQE]

I am brand new to solar and am trying to set up an emergency power source for my amateur radio equipment and computers so that I can operate indefinitely throughout a power outage in a disaster situation.

I was getting the system set up as a 12-volt system, but I am now considering changing it over to a 24-volt system instead. I have 12 6-volt Trojan T-105 225Ah batteries which can be connected in series and parallel in either 12-volt or 24-volt configurations. The problem comes in with my 100-watt solar panels though as they were purchased for a 12-volt system. I suppose I could also connect these in series and parallel the same way as the batteries are, but I have never tried that before so I am not sure if it would work or not. My MMPT solar charge controller can handle either the 12-volt or 24-volt configuration, but I would have to replace my 12-volt desulfanating charger/maintainer/conditioner with a 24-volt version which is out of stock until next month.

My station radios and computers basically use the same power as an average entire household in a month. I have calculated almost 1000kWH per month if my calculations are correct. This is going to be extremely difficult to try to do this as a solar system with the technology that is currently available, but I am going to try to stumble through it and do what I can with the limited resources and limited space available. Luckily, here in Hawaii, I am able to augment the system with wind power along with the solar. On the mainland, wind turbines are basically useless due to the lack of dependable wind, but here they work quite well because of our constant Trade Winds. As soon as I can find a suitable mast for my 400-watt wind turbine that will be added to my system. I am having difficulty finding anyone that will ship the mast to Hawaii though.

Hopefully one of these days I will get this all figured out and have this system up and running.

Aloha
RC
WH6FQE

[bcroe]

For a starting point, your batteries in theory only hold 16 KWH, and only a fraction of that is
actually available. If you plan to do most consumption under your excellent sun, and very
little from battery capacity, you might make it work. Throw away toy 100W panels and start
thinking about generic, much cheaper per W, 250W or 300W panels. 24V sounds like a
good idea. Bruce Roe K9MQG since 1958

[WH6FQE]

Throw away toy 100W panels and start
thinking about generic, much cheaper per W, 250W or 300W panels.

I wish that I could. I have tried to order 4 of the 300 watt solar panels but they will not ship them to Hawaii, so the only thing I have been able to order so far is the 100 watt version.

RC
WH6FQE

[bcroe]

The cheapest solution by far for a power outage, is an IC engine generator set. Have had
one here for decades, barely used it. Bruce Roe

[WH6FQE]

I had a generator during Hurricane Iniki and I could not run it because there was no gas on the island to be bought for it once our supplies ran out. Generators are not a viable option for an island which must rely on incoming ships to bring fuel. had to go for 4 additional days without electricity before we were finally able to purchase gas for the generator. Also, a generator will not last any time at all being run 24-hours a day during an emergency. A generator is definitely not what I am wanting.

RC
WH6FQE

[jflorey2]

I am brand new to solar and am trying to set up an emergency power source for my amateur radio equipment and computers so that I can operate indefinitely throughout a power outage in a disaster situation.

I was getting the system set up as a 12-volt system, but I am now considering changing it over to a 24-volt system instead. I have 12 6-volt Trojan T-105 225Ah batteries which can be connected in series and parallel in either 12-volt or 24-volt configurations. The problem comes in with my 100-watt solar panels though as they were purchased for a 12-volt system. I suppose I could also connect these in series and parallel the same way as the batteries are, but I have never tried that before so I am not sure if it would work or not. My MMPT solar charge controller can handle either the 12-volt or 24-volt configuration, but I would have to replace my 12-volt desulfanating charger/maintainer/conditioner with a 24-volt version which is out of stock until next month.

My station radios and computers basically use the same power as an average entire household in a month. I have calculated almost 1000kWH per month if my calculations are correct. This is going to be extremely difficult to try to do this as a solar system with the technology that is currently available, but I am going to try to stumble through it and do what I can with the limited resources and limited space available. Luckily, here in Hawaii, I am able to augment the system with wind power along with the solar. On the mainland, wind turbines are basically useless due to the lack of dependable wind, but here they work quite well because of our constant Trade Winds. As soon as I can find a suitable mast for my 400-watt wind turbine that will be added to my system. I am having difficulty finding anyone that will ship the mast to Hawaii though.

Hopefully one of these days I will get this all figured out and have this system up and running.

Aloha
RC
WH7FQE

Some notes:

1) If you think your system will grow with time, consider 48 volts. You'll have fewer headaches with wire gauges and paralleling batteries. And at your power levels, the headaches may be significant.

2) As others have mentioned, get cheap ~300 watt panels and a good MPPT charge controller. I know they are available in Hawaii given the large number of solar installs there. (Craigslist shows half a dozen used panels on the big island right now.)

3) Wind can work well there, but be aware you are taking on a lot of maintenance headaches. In general the bottom of the rotor has to be at least 30 feet above the tallest obstruction for 500 feet in any direction, so you will likely end up with at LEAST an 80 foot tower, likely taller.

4) You are using about 35kwhr a day and have 8kwhr of usable storage. So unless you are going to run your station during the day only your battery is woefully undersized.

5) I don't know what the grid interconnect situation is with you there right now, but it's likely that your area has hit the max on grid tie and you won't be able to add any (but it's worth asking.) However, given your case, a grid zero installation using a hybrid inverter may 1) greatly extend your battery life, 2) significantly lower your power bill and 3) provide you with the backup you want. You'd be using a hybrid inverter like the Outback GVFX series.

6) A generator is still a good idea. A few tanks of propane will give you backup power for when the grid goes down and your batteries are low. And propane lasts forever.

[WH6FQE]

I have tried ordering the 300-watt Renogy 24-volt solar panels from Renogy, Home Depot, Amazon and 2 private distributors, not one of them will ship them to Hawaii. The only panels that I have been able to order online that will ship to Hawaii are these cheap off-brand Chinese-made 100-watt 12-volt panels.

I have tried to buy things from Craigslist before, and I got burned every time. I will never again buy anything from Craigslist. I definitely wouldn't trust buying used panels with no warranty from Craigslist that I am going to depend on to keep my station running in a disaster. Keeping this station operable in a disaster is a matter of life and death as it is the only station in the state of Hawaii with the intercontinental HF data links which would be our only means of communications in a large-scale disaster.

The solar companies here will not just sell you the solar panels without them installing the system and I am not paying them to install a system that I am just leasing from them which is what they do here. This system will not be grid-tied, it is not for my whole house, it is just for my desk and is a "temporary install" so I do not have to deal with the permitting nightmare from the city and HOA. I could not care less if the rest of my house has power or not, I can do without, my station cannot.

One person tells me I do not have enough batteries, and then someone else tells me I am wasting money on too many batteries if I add any more. I wanted to build the system up so that I have a total of 40 of these batteries, so in a 24-volt system, that would be 10 sets of series connected batteries.

RC
WH6FQE

[SunEagle]

I have tried ordering the 300-watt Renogy 24-volt solar panels from Renogy, Home Depot, Amazon and 2 private distributors, not one of them will ship them to Hawaii. The only panels that I have been able to order online that will ship to Hawaii are these cheap off-brand Chinese-made 100-watt 12-volt panels.

I have tried to buy things from Craigslist before, and I got burned every time. I will never again buy anything from Craigslist. I definitely wouldn't trust buying used panels with no warranty from Craigslist that I am going to depend on to keep my station running in a disaster. Keeping this station operable in a disaster is a matter of life and death as it is the only station in the state of Hawaii with the intercontinental HF data links which would be our only means of communications in a large-scale disaster.

The solar companies here will not just sell you the solar panels without them installing the system and I am not paying them to install a system that I am just leasing from them which is what they do here. This system will not be grid-tied, it is not for my whole house, it is just for my desk and is a "temporary install" so I do not have to deal with the permitting nightmare from the city and HOA. I could not care less if the rest of my house has power or not, I can do without, my station cannot.

One person tells me I do not have enough batteries, and then someone else tells me I am wasting money on too many batteries if I add any more. I wanted to build the system up so that I have a total of 40 of these batteries, so in a 24-volt system, that would be 10 sets of series connected batteries.

RC
WH6FQE

If you currently have 12 of the T105 6V and you are creating a 24v system you will need to wire 3 sets of 4 in a 3P4S configuration. That will get you a 24v 675Ah system.

To properly charge that battery system you will need about 67 amps. That will require an 80 amp MPPT CC and about 1600 watts of panels. Using 100 watt panels will require a lot of space and racking.

On average it can cost about $1500 for each kWh a system can generate. With a load of 1000kWh a month that is about 33kWh a day. That is going to cost at least $50,000. Maybe you need to think about reducing your load during a power outage.

[Mike90250]

...... Also, a generator will not last any time at all being run 24-hours a day during an emergency. A generator is definitely not what I am wanting.

RC
WH6FQE

Solar is "off" for 3/4 of the day. And it's off in cloudy weather. and if any storm debris hits the roof with the array.

Solar has it's place, but it's going to take a large array and battery bank if you want to maintain your grid lifestyle during an outage. Not saying it can't be done, but it's expensive

[jflorey2]

I have tried to buy things from Craigslist before, and I got burned every time. I will never again buy anything from Craigslist. I definitely wouldn't trust buying used panels with no warranty from Craigslist that I am going to depend on to keep my station running in a disaster. Keeping this station operable in a disaster is a matter of life and death as it is the only station in the state of Hawaii with the intercontinental HF data links which would be our only means of communications in a large-scale disaster.

Used panels are not like used cars. They either work or they don't. If you get a homemade panel or something you might regret it, but any used mainstream used panel (Kyocera, LG, Sunpower, Trina etc) is going to work about as well as a new one - and have about the same life.

Or, if this is really a life or death thing, then spend the money and get your preferred brand new panels shipped to you. Money talks.

The solar companies here will not just sell you the solar panels without them installing the system and I am not paying them to install a system that I am just leasing from them which is what they do here. This system will not be grid-tied, it is not for my whole house, it is just for my desk and is a "temporary install" so I do not have to deal with the permitting nightmare from the city and HOA.

You can still run a hybrid inverter and not feed back power. It may save you $$$ in batteries, since your batteries will be "babied" by the hybrid inverter, and only cycled when the load exceeds the service feed or there is an outage. You can also do things like run off solar when it's there, and run off grid when it's not.

One person tells me I do not have enough batteries, and then someone else tells me I am wasting money on too many batteries if I add any more. I wanted to build the system up so that I have a total of 40 of these batteries, so in a 24-volt system, that would be 10 sets of series connected batteries.

Slowly adding to a battery bank is in general not a good idea.

Battery systems are complex, and you can't treat them like black boxes that take in and give out energy. There are issues with equalization charging, state of charge vs lifetime and number of parallel strings. Lead acids need to charge at less than C/8 (C being amp-hours) and you should have enough solar capacity to charge at C/13. So the usual process is:

1) Decide how long you want to run. 3 days autonomy (i.e. 3 days with no sun) is a standard starting point. Do NOT assume "well, it will be windy then, so I don't have to worry."
2) Determine how many amp-hours you need to make that happen. (volts times amp-hours equals watt-hours.)
3) Choose a solar system to provide between C/8 and C/13 charging to your battery bank.

a generator will not last any time at all being run 24-hours a day during an emergency. A generator is definitely not what I am wanting.

A generator is an essential part of ANY off-gridder's system. Not having one is asking for trouble. If this is really an essential service you are going to provide you need a generator backup. Period. If it's more of a hobbyist thing for fun, then you might get away without one - as long as downtime is OK.

Note that the solar system will greatly extend the generator's runtime, and the generator will extend the life of the batteries.

[J.P.M.]

Solar is "off" for 3/4 of the day. And it's off in cloudy weather. and if any storm debris hits the roof with the array.

Solar has it's place, but it's going to take a large array and battery bank if you want to maintain your grid lifestyle during an outage. Not saying it can't be done, but it's expensive

If the consideration is for truly emergency power, maybe the OP ought to consider what hospitals do, get 2 generators or redundant systems that have proven reliability, one for backup, and trim loads to emergency use only when needed. You'll have real SHTF reliability that's easier to maintain and I bet it'll be more reliable than the PV as well as less up front cost. Have someone do a 6 sigma type analysis with a 6 sigma attitude toward ensuring emergency power and I bet PV won't be part of it.

[WH6FQE]

JPM,

The hospitals here have exactly 1 weeks worth of fuel, after that, they are out. If you remember when Hurricane Iniki struck Hawaii, and also with the recent hurricane in Puerto Rico, Hospital generators were running out of fuel. We have to think of things a lot different being on an island then you do on the mainland. You can't just drive a truck from the nearest town to deliver more fuel for generators, it has to be flown in or come by tanker ship, and that is only IF the airport and docks were not destroyed by the disaster, both of which are sitting at sea level and are targets for tsunamis. If anything happens to the airport and docks we are on our own for at least a month. That's why we do not like to depend on anything that requires fuel here. We have learned from past experiences.

Also, there is the fuel storage issue. We are not like the mainland where we can have a storage shed way back in the yard away from the house to store things like that in. All of that fuel would have to be stored in my garage, directly under my radio room and bedroom. Not happening. I was a firefighter for 17 years, I will not store more than a gallon of fuel in my home.

[WH6FQE]

I finally got Matthew at Renogy talked into shipping 4 of their 300 watt 24 volt solar panels to me today. They won't be here for a few weeks because they are going to come on a container ship and the shipping cost was almost half the cost of the panels, but at least they finally agreed to ship them to me now. They also agreed to ship me additional panels in the future if I want to pay their international freight shipping charges.

[WH6FQE]

jflorey2,
The solar panels that are on Craigslist are not even on this island, they are over 200 miles away on a different island. The only panels available on this island are for solar hot water, which I already have.

I finally got Renogy talked into shipping their panels to me. I have been trying to get their panels for months and they finally agreed to it today. So, hopefully in about a month or so I will have 4 new Renogy 300-watt 24-volt panels to install.

As far as adding batteries to the bank, unfortunately, I have to do it as I can afford them. I know it is frowned upon, but so is an empty bank account on grocery shopping day, lol.

[WH6FQE]

SunEagle
Once the 300-watt 24-volt panels come in, is there a way of still using the 100-watt 12-volt panels that I already have on a separate solar charge controller to add what little they can to the system until I can get more 300-watt 24-volt panels shipped in later?