Solar power confusion

[Mofthegame]

Hey all
I'm so confused I think I watched to many videos
I'm looking to find out how many solar panels and batteries I will need to run a home heater. It's 120v 60hz 1500w which I believe is 12.5 Amps. I don't want to go on grid. I want off grid only and it needs to be able to turn off and on 24 hours a day for at least 3 months. gets really cold here could someone please steer me in the right direction.

 

[mopat]

I am guessing but mid-winter heater could be running constantly?
Where do you live to judge available sun/cloudy days?
Off grid only is just for the heater?
This info will help to satisfy your need.

 

[svetz]

... need to run a home heater. It's ... 1500w ...

Take a look at this post to figure out an energy budget (or if just the heater decide on a duty (i.e., how many hrs/day it's on).

... could someone please steer me in the right direction....

The FAQs!

Particularly:

• What does it mean to have solar panels in parallel and series?
• How to figure out how much Solar and inverter wattage is needed to charge a battery
• Figuring out how many panels in series and parallel based on your MPPT
• Battery FAQ

 

[Mofthegame]

I am guessing but mid-winter heater could be running constantly?
Where do you live to judge available sun/cloudy days?
Off grid only is just for the heater?
This info will help to satisfy your need.

Yes this is just for the heaters avg. Bill per month is 600 plus
I live in Massachusetts central mass

 

[mopat]

Yes this is just for the heaters avg. Bill per month is 600 plus
I live in Massachusetts central mass

OK "600 plus" does not mean anything to me. Is this dollars? If so, what is price of kWh.
Is this 600kWh/month for the heater?
P.S. I get bored real quick.

 

[Forbisher]

Hey all
I'm so confused I think I watched to many videos
I'm looking to find out how many solar panels and batteries I will need to run a home heater. It's 120v 60hz 1500w which I believe is 12.5 Amps. I don't want to go on grid. I want off grid only and it needs to be able to turn off and on 24 hours a day for at least 3 months. gets really cold here could someone please steer me in the right direction.

Running a 1500 watt heater 24 hours a day in cold MA on solar is going to shock you with the high cost of panels and batteries, plus SCC, inverter, wire, fuses etc.
1500 watts x 24 hours =36Kw a day
Heating with LP or wood would cost a lot less.

 

[Mofthegame]

OK "600 plus" does not mean anything to me. Is this dollars? If so, what is price of kWh.
Is this 600kWh/month for the heater?
P.S. I get bored real quick.

Yes it is 600 dollars a month
Kw price per month is 0.12174

 

[Mofthegame]

Running a 1500 watt heater 24 hours a day in cold MA on solar is going to shock you with the high cost of panels and batteries, plus SCC, inverter, wire, fuses etc.
1500 watts x 24 hours =36Kw a day
Heating with LP or wood would cost a lot less.

I figured the same but the part I don't get is I have friends that have solar for the entire house including the furnace and they have mo problem and it only cost around 15000.00 dollars to go off grid completely even in our winters so why so costly for I parlor heater this is why I'm confused

 

[jeff s]

if your price/kWh is correct (seems low for MA), you are using 5000 kWh per month. That is a LOT!! Like a HUGE amount for a residential application.

You will need a very large PV array to generate this amount of kWh. MA gets only about 165 sun hours a month in Jan/Feb. So to generate 5000 kWh a month, you would need a 35-40 kW array minimum, but probably larger to quickly charge your battery. The bigger problem is you would need a HUGE battery bank that can store enough energy to get you through the cloudy stretch. Probably like 1250-2500 kWh. That is a MASSIVE battery bank. We are talking hundreds of thousands of dollars just for the battery. This is the reason off-gridders almost never use electric heat, except for a dump load with wind or micro hydro. Off-gridders heat with firewood or maybe propane, and passive solar.

 

[Craig]

if your price/kWh is correct (seems low for MA), you are using 5000 kWh per month. That is a LOT!! Like a HUGE amount for a residential application.

You will need a very large PV array to generate this amount of kWh. MA gets only about 165 sun hours a month in Jan/Feb. So to generate 5000 kWh a month, you would need a 35-40 kW array minimum, but probably larger to quickly charge your battery. The bigger problem is you would need a HUGE battery bank that can store enough energy to get you through the cloudy stretch. Probably like 1250-2500 kWh. That is a MASSIVE battery bank. We are talking hundreds of thousands of dollars just for the battery. This is the reason off-gridders almost never use electric heat, except for a dump load with wind or micro hydro. Off-gridders heat with firewood or maybe propane, and passive solar.

View attachment 16377

Why so much battery fir 5000 kw per month.
Let's say 200kw per day l. Are you saying 6 days autonomy

 

[jeff s]

5000 kWh/month divided by 30 days = 166.67 kWh/day.

for 7 days autonomy, you would need 166.67 kWh/day x 7 days = 1167 kWh storage.

The lowest cost for batteries is about 150-300/kWh depending on type, size of purchase, etc...

Assuming $200/kWh, the cost for a 1167 kWh storage battery is $200/kWh x 1167 = $233,400

 

[Mofthegame]

5000 kWh/month divided by 30 days = 166.67 kWh/day.

for 7 days autonomy, you would need 166.67 kWh/day x 7 days = 1167 kWh storage.

The lowest cost for batteries is about 150-300/kWh depending on type, size of purchase, etc...

Assuming $200/kWh, the cost for a 1167 kWh storage battery is $200/kWh x 1167 = $233,400

I think there is a misunderstanding on both sides here the heater does not run non stop it runs til it reaches temp then shuts off there is no blower it's just coils that heat up this is what I need to know and don't get cause I believe it start up uses the 12.5 Amos and then used less to run the actual coils I may be wrong and maybe I should just forget about this and just free,e for 3 to 4 months

 

[Forbisher]

I think there is a misunderstanding on both sides here the heater does not run non stop it runs til it reaches temp then shuts off there is no blower it's just coils that heat up this is what I need to know and don't get cause I believe it start up uses the 12.5 Amos and then used less to run the actual coils I may be wrong and maybe I should just forget about this and just free,e for 3 to 4 months

If your heater constantly ran 24 hours a day
1500 watts x 24 hours =36Kw a day
36kwh x 12 cents x 30 days is not that much money compared to what solar would cost.

How many Kwh is used in your $600 month bill?
I suspect a lot of extra charges so really not 12 cents Kw.

 

[mopat]

I figured the same but the part I don't get is I have friends that have solar for the entire house including the furnace and they have mo problem and it only cost around 15000.00 dollars to go off grid completely even in our winters so why so costly for I parlor heater this is why I'm confused

Well seems pretty simple, ask your friends how they do it. I'm done here.
Good luck.

 

[RCinFLA]

Heating with electric is expensive on utility power, even more so on with solar electric with batteries.

In Dec and Jan, Massachusetts gets about 3.0-3.5 hours of solar irradiance a day. That means about 3.5 KWH X 18% effic. = 0.6 kWH per sq. meter per day. Should take about 80% of that number if running through batteries. Direct solar heated water tank reserve (with anti-freeze panel collectors and heat exchanger) would yield about 3 times that amount of energy per sq. meter.

Is solar electric theoretically possible, yes if you have a big enough plot of land.

It is not realistic in cost comparison terms. Would not have a pay back in many many years and just battery replacement cost would eat up most if not all savings. Instead of battery storage you heat a water storage tank during day and circulate it through heat exchanger at night.

First spend money on more insulation and maybe new windows.
Take the lead from power companies, use natural gas if it is available at your home.

Your friends are either very cold or using solar to only run furnace blower with oil or natural gas for heater burner.

20 kWH/day does not sound like near enough for electric heating per day for a normal sized house and 5000 KWH/mo. sounds like 2 to 3 normal sized houses.

Only realistic way to at least reduce your bill is to do grid-tie inverter with a large PV array and make sure your house is well insulated to help make it through the night with minimal use of grid power.

 

[svetz]

The heater uses ~1500W while it is on, how frequently it is on depends on how cold it is outside, the inside temperature, and how well insulated it is.

Your friends are probably grid-tied. So yes they have solar, but on cold days they probably get power from the grid; that cost is offset during warmer days when they can export power into the grid and through net-metering get a credit for it.

Example Math

We'll assume January with an average insolation of 2 and assume 3 different levels of cold:

1500W on for 18 hours per day (75% duty) = 1500 x 18 = 27,000 watt hours. This would be a frigid day
1500W on for 12 hours per day (50% duty) = 1500 x 12 = 18,000 watt hours. This would be a cold day
1500W on for 6 hours per day (25% duty) = 1500 x 6 = 9,000 watt hours. This would be a cooler day

In the course of the month we'll assume you have 3 frigid, 10 cold, and 18 cool days. So that's 3x27000 + 10x18000 + 18x9000 = 423 kWh/mo
(you can just look up what your electric bill is, or use a watt meter on your heater for more accurate numbers).

423 kWh ÷ 31 days = 13.6 kWh/d, this is the average usage per day that solar needs to account for.
13.6 kWh/d ÷ 2 (insolation) = 6.8 kW solar array to zero out power bill for a 1500W heater in Jan with net-metering.

You can go off-grid with batteries, but you'll want some sort of way to augment the heat as winter storms can last for days and batteries are currently expensive. You might also be interest in the FAQ for other examples, such as how to calculate battery sizes.

Hope that helps!

 

[tictag]

Have you considered solar-thermal, as opposed to solar-pv? It might at least offset the need to electrically heat your place. And don't forget wind power - the wind blows all the time, including Winter. I am assuming that the calculation provided by others have answered your primary question.

 

[DASH]

I figured the same but the part I don't get is I have friends that have solar for the entire house including the furnace and they have mo problem and it only cost around 15000.00 dollars to go off grid completely even in our winters so why so costly for I parlor heater this is why I'm confused

Talk to Your Neighbors, get the specifications they have with their system, and how they use it and any other sources to power to heat their home. Once You have that, if You can publish it here, we can examine it, and perhaps help You out. It's very unlikely that using electric resistant heating with solar would be cost efficient. Neighbors may use a combination of passive and some other active heating source.

BTW, from experience 1500 watt resistant heater, probably wouldn't be near enough to keep warm during the winter months.

 

[evad]

1500 watts is 5100 btu per hour that just does not work out.

 

[RCinFLA]

1500 watt heater would keep your feet warm during winter in northern climate.