solar noob with lots of questions

John A.

Good evening folks. This is my first post and I have enjoyed reading through the forum so far.

I have some wiring experience and am not totally incompetent in that regard, though I am far from an electrical engineer so that is why I am here trying to decide which is going to be the best and most efficient route to get me off to a good start and am why I registering to learn more, and to get the most for my investment, so please be easy with me.

Here is my starting materials list.

four Renogy 250w panels

Depending on the most efficient way to design the system I can purchase up to:

Charge Controller:
one or two RioRand 50A 12V 24V 48V ViewStar VS5048N EP MPPT PWM Solar Charge Controller(s) and could wire one or both to the battery bank if that would not cause a problem (which I prefer to just use one if I can), but I am trying to figure out how to wire the panels to achieve the best efficiency.

Battery banks:
three to six 100Ah deep cycle batteries wired in series (I'm still unsure how to determine how many I will need)

Invertor:
one or two 2500w constant pure sine 120v invertors, though again, I prefer to only purchase one if I can.

Some more information, the panels would get no less than 8 hours of sun in the winter and 10 or more in the summer.

AC output power requirements:
I went through and not taking into consideration line/wire loss or invertor efficiency, etc, the maximum power consumption of the devices out of the invertor would be about 2250w, though typically would hover in the 1600 w range.

While 2500w output would not be required 24 hours a day, I'm going to pretend the invertor is going to be maxed just to help me determine how to do this.

For the last 3 months, I've been hit with rather high electric bills, so I am going to wire the most used 110v items in my house to solar to offset as much as I can.

Without going into unnecessary details about how I am going to re-wire some circuits in my house, all of the 220v items like the stove and dryer, will remain on the grid at this time, but I am also going to install a timer on my hot water heater so that during the off peak hours when everyone is in the bed it will be inactive, so that too should help lower my electric bill.

But I was rather surprised at just how much power a lot of these electronics and devices eat every day, so, here I am.

I want to thank anyone in advance that has any suggestions and for helping.

John

Cariboocoot

Re: solar noob with lots of questions

Welcome to the forum John.

Well you've got some terminology mix-up and you're starting the system design wrong-way 'round, but we're here to help.

First off, you start with the load demand not the panels. I hope you mean you need up to 2250 Watt hours per day. In which case when they are needed is not particularly important. If you need to supply 2250 Watts at any given time you need to know for how long. Frankly that's a lot of power, and brings up the issue of why you are going off grid at all; it will be more expensive than grid power.

Anyway, without a Watt hour figure you're are nowhere because you can't size the battery bank (nor determine system Voltage) to supply it. Without knowing the size of the battery bank you can't determine the array size needed to recharge it.

You may well get 8 hours of sun in Winter, but that is not the same as 8 hours of direct sunlight on the panels. Regardless of the length of day the "equivalent good sun" on the panels of a fixed array rarely exceeds 6. This is because the angle the light travels through to reach the panels has a significant effect on their output; early and late hours will produce less power than midday.

If your goal here is to reduce your electric bill I'll suggest you spend the money on conservation first, and grid-tie second. Forget off-grid as it is never economical with a dependable utility supply connected. If your goal is back-up power for occasional outages I'd suggest buying a good generator. Again, far more economical. If you're doing this for personal/political reasons, I hope you have a lot of money to spend to make your point because the equipment involved isn't cheap, and that which is will not be very good. Once more a waste of money.

waynefromnscanada

Re: solar noob with lots of questions

John A. wrote: »

I was rather surprised at just how much power a lot of these electronics and devices eat every day.

John

So now you know where you can start with your conservation measures.
The following is not directed at you, but rather North American society in general. Only you can decide if it sounds familiar.
It's very unfortunate that so many of us were brought up wasting energy, and grew up thinking such waste was not wast, but a normal way of living. Then we're surprised at the size of our electric bills.
As Cariboocoot said, going off grid to save money over grid power is a non starter. Instead it will cost you much more. The very first job if considering going off grid is to Conserve, Conserve, Conserve, and the reason for that is because off grid power is so expensive. With most folks who go off grid, it's only AFTER they make the move that they begin to realize the real value of energy. It's very unfortunate that some people tend to spread the idea that all we have to do is mount a $300. solar panel on the roof and all our electricity woes are over. Oh that it were the case.
If indeed your listed wattage consumption is correct, and that relatively extreme consumption rate is not vastly reduced, you'll be looking at a huge and extremely expensive solar system, with ongoing maintenance, electronics and battery replacement costing many thousands of dollars, every five or ten years.
Sorry to be the bearer of bad news, but I would not be honest if I didn't give you these things to consider.
Living off grid requires a whole different mindset when it comes to electricity use, it's no longer relatively free and easy.

John A.

Re: solar noob with lots of questions

Thank you for the reply sir.

According to the power ratings on the devices, would add up to the mid 2200w ballpark. Granted they are not all used for 24 hours a day, or even all at the same time, but what I planned to do was run all of my lights 720watts, computer 430w, entertainment center up to 630w, and 3 bedrooms which do not have much in the terms of electrical demands except for a tv and video game in the kids rooms and a tv and alarm clock in my bedroom.

As I mentioned, all of my power demands are not constant, and usually not even maxed out because they're obviously all not going to be on at the same time all the time either.

So, that was the reason why I was considering the 2500w invertor.

I wasn't going completely off of the grid either. I was still keeping all the 220v devices and the kitchen and laundry room and bathrooms on the grid (other than lighting), but I would really like to take some of the pain out of my electric bill. Since my electric company has raised rates, since December, my bill has doubled and I've paid out nearly a thousand bucks in electric bills. Granted I know that it's been pretty cold during that time and I have used more electricity as a result, but I have also used kerosene heaters during waking hours to help lower that too.

As for conservation, I am going to install an off peak timer on my hot water heater, but with kids and grandkids running around all over the place, is not entirely possible the majority of the time LOL.

I could make a full time job of just following them around turning off lights and TV's and the door closed LOL.

Cariboocoot

Re: solar noob with lots of questions

What you should invest in to begin with is a Kill-A-Watt meter. With that you can measure the actual consumption in Watt hours of each and every item you plug in to the wall. You will see what things have nasty 'phantom loads' (like PVR's and satellite receivers) and what things can be adjusted to use less (turn down the back lighting on the TV) and what should be replaced with more efficient models.

The numbers supplied by manufacturers (Amps, Watts) tend to be science-fiction rather than fact. Things like computers do not constantly use their maximum power, but the tag on the back will show that maximum rating. Therefor multiplying it out over estimate hours of use results in an erroneous consumption number.

Electric heat is murder, for sure. So is a household full of people who have never heard of the "OFF" position on a switch. Believe me, I know; been there, done that, raised the brood, moved away. But unless your electric company charges like $1 per kW hour the off-grid system isn't going to save you a dime; it will just change who you give the money to. The reason for this is that the capital outlay has to be amortized over the life of the equipment, which is finite (especially batteries). As a result the net cost per kW hour is very, very high.

Look into every other possible option first, including installing natural gas or propane for heating. Do not use portable kerosene heaters in a house! Carbon monoxide is a dangerous thing and they produce plenty of it. If you weren't affected by it then the chances are very good that your house leaks terribly and could do with improved weather seals and probably more insulation.

Finally from a heating perspective look into direct solar to help out. It's far more cost-effective than PV and can be a safe and even fun DIY project. Check out Build It Solar for ideas: http://www.builditsolar.com/

BB.

Re: solar noob with lots of questions

And that is the problem... Way too much power usage for an "average" off grid system to even make a dent in.

If you have never done conservation before--It is not out of the possibility to reduce your electrical usage by 1/2 with newer/more efficient appliances, and flat out changing your "solutions" (i.e, using a laptop vs desktop computer, new LED TVs which use 1/10th power, double pane vinyl windows, lots more attic insulation, heat pump vs electric resistance heating for hot water/hot air, etc.).

More or less, take all of your costs for solar (parts, installation, maintenance/battery replacement, etc.) for 20 year system life and divide by kWH used over 20 years, and you will find that that power costs you on the order of $1-$2+ per kWH (a few people get better costs, some worse). And you pay ~50% of the costs "up front" before your first kWH is generated.

So, if your power bill went up by a factor of 10x (utility bill vs pure off grid power), what would you do regarding your loads?

At $1,000 per month, we are not talking about just a new refrigerator, tv, or laptop--We are looking for other big power users (heating/cooling/hot water/cooking/computer server farm, etc.).

Just to give you an idea of "levels" of power usage:

• 1,000 WH per day (1kWH per day or 30 kWH per month)=Lights, radio, laptop, some water pumping.
• 3,300 WH per day (3.3 kWH/day or 100 kHW/month)=Add refrigerator, TV, well pump, clothes washer--Close to a "normal" electrical life with lots of conservation.
• 10 kWH/day or 300 kHW per month==A very efficient modern home using Natural Gas/Propane for central heat/several refrigerators/freezers, multiple computers+network, etc.
• 33 kWH/day or 1,000 kWH per month==Typical North American home usage
• 100 kWH per day or 3,000 kWH/month==Lots of A/C use, electric heat/cooking/hot water

For most people, around 1kWH to 3.3 kWH per day is about the limit for "out of pocket" off grid power systems ($10,000 - $30,000 or so up front).

If your utility allows Grid Tied Solar and offers "good" Net Metering plan / pricing, then a GT system can get down to $0.20 or even $0.15 or less per kWH of costs--And for some regions (east/west coasts) where we can have high power rates ($0.30 to $0.50 per kWH), GT solar can save money.

Note that many utilities are starting to actively work against home based GT solar by modifying regulations/increasing per month charges, etc... Utilities do not (in general) make money with distributed GT power systems.

A Kill-a-Watt type meter to measure "120 VAC 15 amp" plug in loads will help with the smaller appliances. A whole house monitoring system can help with the bigger stuff (120/240 VAC hard wired stuff).

Do not spend any money until you have a plan... It is very difficult to even begin purchasing "useful/cost effective equipment" until you have a paper plan that will meet your needs.

-Bill

solar_dave

Re: solar noob with lots of questions

Just to give you an example of a pretty substantial grid tie system you can look at my signature. That system today will cost about $40-50 thousand dollars installed in today's market at the best current installer prices. you can trim about $1 a watt off for DIY but that has substantial challenges as well stemming from permitting and utility interconnect. The Feds still have a 30% tax credit that runs till 2016 I believe so some of your costs can come from that, but you have to front the moneys and have the system operational to take advantage of it.

Now that being said a 12.5 KW system like mine not the norm, most folks do 5-8 Kw systems but I have lots of Air Conditioning to support in the desert south west. We also charge 2 Chevy Volts off the system. Our net-metering plan is advantageous to carry watts month to month so spring generation can be used in summer months. It is like a free unlimited long term battery that is 100% efficient. That is what the utilities don't like.

Just to be clear if I had to go off grid on this system I would need at least double the panel farm, a huge battery bank and many charge controllers and inverters to support the peak loads in July of 131 kWh a day. This certainly would drive my costs into the 6 figure realm.

SolarPowered

Re: solar noob with lots of questions

Is NEM offered in your neck of the woods?
I'm confused, sounds like you have grid, but you want off grid.

Which is it?

The greatest efficiency is to stay on grid, if you have NEM, if you don't have NEM then you have to see if your meter allows roll back.

If so you can do a small system, and with a small system micro inverter is the easiest, most efficient and simplified solution for those that are not totally electrically inclined to understanding DC to AC derates, or the entire 1 line design engineering required for a string inverter system.

Micro inverter system de rate defaults for PV watts calculations are adjusted for 85% de-rate, while string inverter systems are derated for 77%, and most off grid because of peukurt's law are rated @ 66%, so as you can see there is greater efficiency from micro grid tied systems than string grid tied, or string off grid. In order to fight consumption usage, look for the highest efficiency possible for the smaller solar systems.

Kindest Regards

John A.

Re: solar noob with lots of questions

Again gentlemen, thanks for the replies.

I had expected to spend between $3000 to $3500 to get a decent start, but while I may could afford more, that was about the top of my comfort level starting out.

As for my home, it's insulated very well. It is a rock house (not hollow cinder blocks, it's actually 6 inch mortared rock) on the exterior walls, and behind that is a 2 inch interior wall and even has blown cellulose insulation in the interior wall. The ceiling is glued foam squares over top of 1/4 inch plywood with blown insulation in the attic as well, then the old shingled roof and then over top of that is a vapor barrier and metal roof over top of it.

There is no insulation downstairs, however, it is a 12 inch thick reinforced concrete walls and a full basement (underground on 3 sides) and in all fairness, it stays between 60 and 70 degrees f year round regardless of the outside temperature.

The dishwasher is less than a year old, the 50 gal. hot water heater is also less than a year old, the central heat/air is almost 3 years old, and the washer and dryer is probably 3 years old, but sat unused for almost a whole year, so in all fairness, I have been addressing many of the recommendations you guys have made for some time now since we have been in this house.

@bb, I'm in the average 33kwh per month range, but I'm a greedy old fart when it comes to trying save a buck where I can, and thus why I have been considering getting my feet wet in solar.

westbranch

Re: solar noob with lots of questions

Bsed on my experience with building an R50 ICF concrete basement wall, I would suggest you expend the effort to add foam insulation (plus the mandatory fire stop gyproc) to those basement walls, you will NOT regret it. On a -15C day outside, with no heat inside yet, the basement was +7 C in the basement...

SolarPowered

Re: solar noob with lots of questions

westbranch wrote: »

(plus the mandatory fire stop gyproc)

Dry-Tex gypcrete, one brand that works extremely well.

There is also an epoxy water tight bond and foam method that works extremely well also.

waynefromnscanada

Re: solar noob with lots of questions

John A. wrote: »

@bb, I'm in the average 33kwh per month range, but I'm a greedy old fart when it comes to trying save a buck where I can, and thus why I have been considering getting my feet wet in solar.

"33kwh per month"? If this is not a misprint, you could do this with solar at a very reasonable price, but on the other hand, even if you were paying 50 cents per kwh for grid power, your monthly usage costs for grid would be less than $17. However, I suspect it's a misprint.

John A.

Re: solar noob with lots of questions

SolarPowered wrote: »

Is NEM offered in your neck of the woods?
I'm confused, sounds like you have grid, but you want off grid.

Which is it?

The greatest efficiency is to stay on grid, if you have NEM, if you don't have NEM then you have to see if your meter allows roll back.

If so you can do a small system, and with a small system micro inverter is the easiest, most efficient and simplified solution for those that are not totally electrically inclined to understanding DC to AC derates, or the entire 1 line design engineering required for a string inverter system.

Micro inverter system de rate defaults for PV watts calculations are adjusted for 85% de-rate, while string inverter systems are derated for 77%, and most off grid because of peukurt's law are rated @ 66%, so as you can see there is greater efficiency from micro grid tied systems than string grid tied, or string off grid. In order to fight consumption usage, look for the highest efficiency possible for the smaller solar systems.

Kindest Regards

Sorry, I do not know what NEM is.

I had planned to stay on the grid, especially for my high power devices (heat, air, cook stove, fridge/deep freeze, etc), but I was wanting to use the solar setup I mentioned earlier to run all (or at least a lot) of my smaller devices that are used a lot.

Basically my lights, living room and bedroom outlets.

John A.

Re: solar noob with lots of questions

waynefromnscanada wrote: »

"33kwh per month"? If this is not a misprint, you could do this with solar at a very reasonable price, but on the other hand, even if you were paying 50 cents per kwh for grid power, your monthly usage costs for grid would be less than $17. However, I suspect it's a misprint.

It is per month according to my bill.

February electric bill said I had 3383 metered KWh usage, and I haven't seen March yet. They usually read my meter on (or near) the 15th of each month.

I understand that we've used more power in the last couple of months due to running the heat pump more because we've had temps down in the single digits and below zero temps for the biggest part of January, but I'm still not a fan of $332 electric bills either.

Cariboocoot

Re: solar noob with lots of questions

John A. wrote: »

It is per month according to my bill.

February electric bill said I had 3383 metered KWh usage, and I haven't seen March yet. They usually read my meter on (or near) the 15th of each month.

I understand that we've used more power in the last couple of months due to running the heat pump more because we've had temps down in the single digits and below zero temps for the biggest part of January, but I'm still not a fan of $332 electric bills either.

Couple of things.
3,383 kW hours per month is about 113 kW hours per day. That is huge in off-grid terms.
Stone or masonry of any type is not a good insulator, and it sounds as though the vapour barrier for your attic is on the wrong side (it should be on the heated side of the insulation, not the cold side).
Even so the off-grid electric costs are huge and this concept is not going to save you any money.

I wouldn't be a fan of those bills either. Used to get them like that too, in a relatively mild climate (with electric heat). These days we (just two) use 16kW hours per day and our electric bill is always <$50 per month. Part of that is low usage, part of that is cheap BC Hydroelectric. How much are they ripping you per kW hour? Because that is the only part of the bill solar will have any effect on.

SolarPowered

Re: solar noob with lots of questions

John A. wrote: »

Sorry, I do not know what NEM is.

I had planned to stay on the grid, especially for my high power devices (heat, air, cook stove, fridge/deep freeze, etc), but I was wanting to use the solar setup I mentioned earlier to run all (or at least a lot) of my smaller devices that are used a lot.

Basically my lights, living room and bedroom outlets.

NEM stands for (Net Energy Metering). Its a contract between your utility provider, and you. So the energy you don't use that goes back to the grid is offered at a wholesale rate, or Feed In Tarrif, that utility companies have to provide you for unused power, or to offset the power durign your hours of use.

What you are telling me is a structuring issue, if your time is money, to build off grid and restructure for the smaller components of your home is a waste of your invested time management.


Your best bet is to go NEM, your system is small enough that it bypasses the utility approval processes. Over 5kWh there is either approval time for your NEM, or you have to file for variance. Typically if its micro inverter systems over 4.8kWh you may run into variance issues having separate disconnect switches for your systems if they are not on the same horizon of azimuth.

If you have NEM, and you lack a high level of engineering, micro inverter is all you should be considering, and its simple.

waynefromnscanada

Re: solar noob with lots of questions

John A. wrote: »

It (33 Kwh) is per month according to my bill.

February electric bill said I had 3383 metered KWh usage, and I haven't seen March yet.

Something wrong with your numbers. according to your bill you're using (in Feb) almost three thousand four hundred Kwh, not 33 kwh.
In fact, you used an average of over 120 Kwh PER DAY. (3383/28 days = 120.82)
What do I use per day? Roughly 4 kwh per 24 hour day. Not bragging, just stating a fact. 4 Kwh per day is doable with solar.
You're using over 30 times as much power as I am. OUCH! No wonder your bills are high.

John A.

Re: solar noob with lots of questions

Here's a quick snapshot of the bill.

Sorry, but my computer scanner is boxed up so, a snapshot will have to do.

---

Cariboocoot

Re: solar noob with lots of questions

Yes that's 3,383 kW hours for the month. Not 33. Or 3,383,000 Watt hours.
Your per kW hour charge is only $0.08 per kW hour (the "energy charge" and "electric DSM" together).
At that rate solar will do nothing for saving you money. Nothing.

SolarPowered

Re: solar noob with lots of questions

WOW, that's going to need to be a line side tap, with some major real estate!

4 panels will not make a dent in the energy bill, that s over 40,500kWh a year estimated.

Grid tied solar on a 200amp service max's out at 15,000kWh annualized with high efficiency 16.5% conversion panels at 180 south azimuth, micro inverter with 34 mono crystalline panels.

You would need 3 times that amount of solar just to break even on the annualized consumption.

Sounds like to reduce those consumption costs you have alot of electric heating elements to get rid of and convert to natural gas, so you can then maximize your conservation to consumption ratio.

waynefromnscanada

Re: solar noob with lots of questions

Cariboocoot wrote: »

Yes that's 3,383 kW hours for the month. Not 33. Or 3,383,000 Watt hours.
Your per kW hour charge is only $0.08 per kW hour (the "energy charge" and "electric DSM" together).
At that rate solar will do nothing for saving you money. Nothing.

WOW! Only 8 cents/Kwh! I could only wish for that rate. Here, it's fast approaching double that rate and is going up every year!
Can you imagine doubling the bill that John now gets?

John A.

Re: solar noob with lots of questions

waynefromnscanada, $650 electric bills would make me cross my eyes and turn purple and swear.

Thanks for all of your replies gentlemen. I have appreciated the help, and most of all, your honesty and experience and advice.

If it's not cost effective or feasible, then it's not. But I am greatful that you guys didn't let me spend a couple of thousand bucks on a mistake.

John

Blackcherry04

Re: solar noob with lots of questions

It's hard to be on a Solar site and talk about how to cut the cost of Utilities without having Solar. If most people would take less than $10,000 they could reduce their cost's 25-30% with just Insulation, Windows and Doors. I had 6" of additional Insulation blown in my attic, it was amazing as I was able to follow them as they were blowing in overhead. I was in one room and within 10 Minutes you could feel the temperature change. ( drop, was in the summer ) It sure made a believer out of me, best $600 I ever spent ( took 3 hrs to do ). Windows the same, you notice a immediate difference. I had thermo-pane from the 70"s it was like night and day with new ones, 11 windows, $5,300.

solar_dave

Re: solar noob with lots of questions

John A. wrote: »

waynefromnscanada, $650 electric bills would make me cross my eyes and turn purple and swear.

Thanks for all of your replies gentlemen. I have appreciated the help, and most of all, your honesty and experience and advice.

If it's not cost effective or feasible, then it's not. But I am greatful that you guys didn't let me spend a couple of thousand bucks on a mistake.

John

I used to get bills like that and more in the summer months here. Last summer the max bill was like $100 mostly for night time AC usage.