Solar power questions

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here
1. What is involved other than the solar panels, wire and batteries? 2. What would keep the batteries from getting overcharged and burning out? 3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system. 4. How could I monitor the charge level of the batteries? 5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time? 6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?
I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.

dh@. wrote:

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here

Well, there are a whole nother bunch of solutions better for heating than pv, like solar water heating.

1. What is involved other than the solar panels, wire and batteries?

charge controller, disconnects, fuses ....

2. What would keep the batteries from getting overcharged and burning out?

charge controller.

3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system.

most inverters have a low voltage shut-off, but they usually will draw more than 50% from the batteries before doing so. best thing is a kWh meter showing input and output.

4. How could I monitor the charge level of the batteries?

kWh meter.

5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?

fluctuates

6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?

1.5 kw x 2 hours = 3kWh's 115ah / 2 = 57ah usable x 12v = 684 wh each. 3 kWh / 684 wh = 5 batteries. Would need 1000 watts of pv and 3 full hrs of sun to recharge in one day, or 500 watts for 2 days charge, 2 hours discharge. Some locations get more or less sun.

I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.

Some of us are happy to help. Others will insult you, or the answers we give.
-- Steve Spence Dir., Green Trust, http://www.green-trust.org Contributing Editor, http://www.off-grid.net http://www.rebelwolf.com/essn.html

wrote in message

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here

From what little I've learned, it would be much more cost effective to use the power of the sun to heat water. Then use that hot water to warm your house.
PV is very inefficient, and very expensive.

dh@. wrote:

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money....

That's the trouble. PV takes a very long time, (if ever), to see a return when pitted against the grid.
Say your installation runs $8/watt. Now use this: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/ Flat panel tilted south, annual, average.
Say it is 5kwh/m^2/day. That gives you about 5wh/panel-watt/day.
In twenty years that's 36kwh, or if you buy it from the grid at $.08/kwh, about 3 bucks. So, even if you don't have maintenance, you are paying $8 for $3 worth of electricity with twenty years of use.
Best, Dan.

dh@. wrote:

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here
1. What is involved other than the solar panels, wire and batteries? 2. What would keep the batteries from getting overcharged and burning out? 3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system. 4. How could I monitor the charge level of the batteries? 5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time? 6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?
I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.

Cheapest way is to get power off the grid, or use a gas heater.
Why solar?

dh@. wrote:

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night.

It's a rotten way to make heat. Better idea, use a liquid solar collector. You use a tiny fraction of the sun's power to make electricity, then you lose power storing it and more power converting it back to AC (which you don't need for resistive heating, anyway).

Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money.

You won't save money.

1. What is involved other than the solar panels, wire and batteries?

charge controller

2. What would keep the batteries from getting overcharged and burning out?

charge controller

3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system.

It should have a low voltage cutoff - most inverters do.

4. How could I monitor the charge level of the batteries?

voltmeter or hydrometer

5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?

fluctuates

6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?

There are solar calculators all over the web, but this isn't an appropriate use of PV power, and I'd be surprised if they actually included space-heating devices in their tables. -- derek

On Wed, 26 Oct 2005 12:58:35 -0400, dh@. wrote:

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here
1. What is involved other than the solar panels, wire and batteries?

At least a charge controller. An inverter if you want 120 VAC. If you are after efficiency from the panels, some sort of way to track the sun or at least make seasonal changes.
A hygrometer to measure specific gravity of the battery acid (auto store). Some way to protect batteries from too hot and freezing. Some way to vent battery fumes - corrosive and maybe explosive if it builds up too much.

2. What would keep the batteries from getting overcharged and burning out?

A charge controller adjusts the charge current to a safe level and tapers it off as the battery gets charged. They usually work differently but think of it as like the voltage regulator in a car. There are many flavors from rotten to pretty good.

3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system.

An inverter has nothing to do with charging. It will shut itself down (most models) if the voltage drops low enough to endanger it.

4. How could I monitor the charge level of the batteries?

Specific gravity of the acid is best. An approximation can be made by open circuit voltage after it has sat unconnected for a day.

5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?

The panel will produce voltage but not much current in low light. You only get any practical charging in full day light. Light=Watts. Watts X time = power. It's common to figure on an effective 5 hour day, less if you are in an odd place or it's cloudy.

6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?

For that much power, burning some fuel is probably better.
1,500 W / 120 V = 12.5 Amps. If you are drawing it from a 12.6 Volt battery, 1500 W / 12.6 V = 119 Amps. If you run it for 1 hour, that's 119 A X 1hr = 119 Amp-Hours. If you run it for 2 hours, that's 119 A x 2 hr = 238 A hr. If you use an inverter to change the 12.6 VDC to 120 VAC figure on using about 10% more A-hr for inverter losses.
That inverter loss is given off as heat which might be captured. On the other hand, it's better to locate the inverter at the battery rather than at the load. The battery to inverter wires carry the highest current so keep them the shortest.

I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.

You've asked some very good basic questions, and in the right order too.
-- W§ mostly in m.s - http://members.1stconnect.com/anozira

In article , Winston Smith wrote:

5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?
The panel will produce voltage but not much current in low light.

The voltage is constant, above any minor amount of light.

You only get any practical charging in full day light. Light=Watts. Watts X time = power.

No, watts x time = energy, not power.

It's common to figure on an effective 5 hour day, less if you are in an odd place or it's cloudy.

There are good tables for different parts of the world. Latitude plays a major role, not just hours of daylight. (Angle of the sun, etc.)

6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?
For that much power, burning some fuel is probably better.

For that much energy, you mean. Not power.

I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.
You've asked some very good basic questions, and in the right order too.

I disagree. Before I started posting to misc.survivalism, I used Deja News to thoroughly research what had been written on water storage, power generation, food shelf life, etc. The articles by people like Patton Turner and Al Hagan, for example.
The OP here seems to have no clue whatsoever about why he wants solar, what he wants, how much energy storage he needs, or what others have written.
Helping him is thwarting Darwin. Way too much whiggerization going on even here.
--Tim May

wrote in message

I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here

Another poster said it, but I'll say it again: PV for heat is a bad use for PV. Multiple efficency losses are gonna kill ya. You might be better off with another way of doing this.
Another question : Where are you located? How far from the equator makes a big influence on how much sun you get....

1. What is involved other than the solar panels, wire and batteries?

Charge controller is a biggy. It should included fuses inside it, but more fuses never hurt. And disconnect switches.

2. What would keep the batteries from getting overcharged and burning out?

Aforementioned charge controller.

3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system.

If all you're using the thing for is heat, let me make a suggestion: skip the inverter. There's a loss with each step you go through. Go with a 12V DC heater : http://www.boatandrvaccessories.com/RPSL-681 or similar.

4. How could I monitor the charge level of the batteries?

Some charge controllers have a meter.

5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?

It varies by how much light is hitting them. Some solar websites have a chart showing "effective hours of sunlight" by state. Florida, for example, is 5 - even though we get more hours than that, the "non peak" hours add up to an effective 5 peak hours of output.

6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?

There's an easy answer and a hard answer. The easy is 1500 W / 12v = 125 amp draw. Divide total amp-hours by draw and you get how many hours the batteries last. That's incredibly optimisitic though, when you add in inverter losses, etc. Working in all those losses makes it much harder. I'd go "rule of thumb" and drop it by half or so, and say each 115 amp hour battery gives you 30 minutes.

I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.

Ok, I'm going to go shopping for you. I'm just ballparking and doing this quick, so don't take it as set in stone.
http://www.boatandrvaccessories.com/RPSL-681 : $26.88 (15 amp x 12v) plus shipping
http://store.solar-electric.com/evso115wasop.html : get 2 for $1,030 plus shipping
http://store.solar-electric.com/ps-30m.html : $186 plus shipping
http://store.solar-electric.com/pvx-12210.html $370 plus shipping (chosen for 8-hour discharge rate being over 15ampsx8 hours, figure you use the heater for 8 hours at night)
Misc fuses, cables, etc as needed.
Chose the 2 solar panels based on a 4-hour peak sunlight. Should give you 8 hours of heater per night. A small ceramic heater in a small cabin with good insulation, you should be OK.
On the other hand, you're looking at like $1700 to set this baby up. I'm not sure what your costs are for other heating sources to break even.

Hi Depends on your climate, how much sun daily, but heating is best done with solar collectors, which are like exterior radiators that collect the heat from the air and sun rays, feeds the heat to a storage tank until needed. Photo panels are good for charging batteries, which run small electrical items, depends on size of system, but heating is out I should say. //////////////////// "Winston Smith" wrote in message

On Wed, 26 Oct 2005 12:58:35 -0400, dh@. wrote:
I'm interested in trying to use Solar power, but so far don't know anything about it. I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. Even if it takes two days to charge the batteries I'd be better off just paying for the heater every other day, than every day. Of course I'm looking for the cheapest way to do it, since the idea is to save money. Here
1. What is involved other than the solar panels, wire and batteries?
At least a charge controller. An inverter if you want 120 VAC. If you are after efficiency from the panels, some sort of way to track the sun or at least make seasonal changes.
A hygrometer to measure specific gravity of the battery acid (auto store). Some way to protect batteries from too hot and freezing. Some way to vent battery fumes - corrosive and maybe explosive if it builds up too much.
2. What would keep the batteries from getting overcharged and burning out?
A charge controller adjusts the charge current to a safe level and tapers it off as the battery gets charged. They usually work differently but think of it as like the voltage regulator in a car. There are many flavors from rotten to pretty good.
3. Would the inverter (Coleman PMP 2000) alone be enough to regulate when the batteries become dangerously low and shut down discharge, or would I need to monitor it and do it myself to avoid damage to the system.
An inverter has nothing to do with charging. It will shut itself down (most models) if the voltage drops low enough to endanger it.
4. How could I monitor the charge level of the batteries?
Specific gravity of the acid is best. An approximation can be made by open circuit voltage after it has sat unconnected for a day.
5. Do the panels only work when there's a certain amount of light available, or does their performance fluctuate depending on how much light they're getting at the time?
The panel will produce voltage but not much current in low light. You only get any practical charging in full day light. Light=Watts. Watts X time = power. It's common to figure on an effective 5 hour day, less if you are in an odd place or it's cloudy.
6. How to calculate what it would take to run a 1.5 KW heater for a certain period of time, using whatever number of 115 amp hour batteris it would take to get a few hours of use from the heater, and what type solar panels to use, etc?
For that much power, burning some fuel is probably better.
1,500 W / 120 V = 12.5 Amps. If you are drawing it from a 12.6 Volt battery, 1500 W / 12.6 V = 119 Amps. If you run it for 1 hour, that's 119 A X 1hr = 119 Amp-Hours. If you run it for 2 hours, that's 119 A x 2 hr = 238 A hr. If you use an inverter to change the 12.6 VDC to 120 VAC figure on using about 10% more A-hr for inverter losses.
That inverter loss is given off as heat which might be captured. On the other hand, it's better to locate the inverter at the battery rather than at the load. The battery to inverter wires carry the highest current so keep them the shortest.
I'm sorry to be so completely ignorant, and would appreciate any help in overcoming it.
You've asked some very good basic questions, and in the right order too.
-- W§ mostly in m.s - http://members.1stconnect.com/anozira

rebel wrote:

... heating is best done with solar collectors, which are like exterior radiators that collect the heat from the air and sun rays, feeds the heat to a storage tank until needed.

IMO, a polycarbonate "solar siding" air heater or deeper low-thermal-mass sunspace is better, with warm air circulating between the sunspace and the living space during the day and stopping at night. That can be 20X cheaper than "collectors" and 100X cheaper than solar electricity per peak watt. Thermal mass in the living space can store heat.
Nick

d: I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. =============================== How about buy a 100ft roll of pex tubing, bury it about 2 ft down, get a little pump and a little fan, and a little auto heater core. If its 50 deg F in the house, blowing that cold air across the 72 deg F coils from that nice warm gound water should warm things up a little.

BobG wrote:

d: I want to charge some deep cycle batteries during the day, and use them to run a heater for a few hours at night. =============================== How about buy a 100ft roll of pex tubing, bury it about 2 ft down, get a little pump and a little fan, and a little auto heater core. If its 50 deg F in the house, blowing that cold air across the 72 deg F coils from that nice warm gound water should warm things up a little.

What kind of climate has 72F ground temperature 2' down and 50F ambient air temp?
-- Steve Spence Dir., Green Trust, http://www.green-trust.org Contributing Editor, http://www.off-grid.net http://www.rebelwolf.com/essn.html

Another question : Where are you located? How far from the equator makes a big influence on how much sun you get....

And how much heat your house needs. :)

SS: What kind of climate has 72F ground temperature 2' down and 50F ambient air temp? ============ Florida in winter. All the springs emit 72 deg water year round. That makes me think thats what the temp is down there.