How big of an inverter and how much solar?
- Thread starter Johneb
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Hedges
I See Electromagnetic Fields!
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Your bill shows 2000 kWh in December.
Check an Insolation calculator on line, see how many hours effective sun. Could be about 2 hours (most of the time off angle, not full power.
2000 kWh / 30 days = 67 kWh/day
67 kWh / 2 sun hours = 34 kW
440W STC panel rating x 0.75 = 330W typical output (maybe better in the cold of winter)
34 kW / 330W = 103 panels.
Quite large, but not unimaginable.
Do you have electric heat? Can you use alternatives? Can you improve insulation?
You would need battery capacity at least enough for one night. Three days would be great considering clouds, 200 kWh is possible but also quite large. About $50k worth of server rack batteries.
How much inverter you need depends on peak watts, not watt-hours per day.
SCC needs to be sized to match array.
Check an Insolation calculator on line, see how many hours effective sun. Could be about 2 hours (most of the time off angle, not full power.
2000 kWh / 30 days = 67 kWh/day
67 kWh / 2 sun hours = 34 kW
440W STC panel rating x 0.75 = 330W typical output (maybe better in the cold of winter)
34 kW / 330W = 103 panels.
Quite large, but not unimaginable.
Do you have electric heat? Can you use alternatives? Can you improve insulation?
You would need battery capacity at least enough for one night. Three days would be great considering clouds, 200 kWh is possible but also quite large. About $50k worth of server rack batteries.
How much inverter you need depends on peak watts, not watt-hours per day.
SCC needs to be sized to match array.
pollenface
Solar Addict
Your electricity bill is in kwh, showing monthly consumption.
Solarcabin Channel
Solar Addict
What changes did you make?
Hedges
I See Electromagnetic Fields!
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Make a list of your appliances. Look up their consumer energy labels to get an estimate of consumption. Specs or nameplates to get peak power draw.
Some, like a refrigerator, may draw 800W for 30 minutes defrosting but only 200W intermittently the rest of the time.
Kill-a-watt meter can read power of 120V plug-in devices. Clamp ammeter can read power of any.
June is 300 kWh, July and August are 1000 kWh (looks like A/C).
What will your new winter consumption be? If you have other heat sources, and electric bill looks like June (10 kWh/day), then a typical system with as little as 3kW of panels should be sufficient. But panels are cheap enough compared to the rest, put in twice what you need or more, to make up for days without full sun.
The best loads use power while the sun shines. Enable water pump when battery full, etc.
Some, like a refrigerator, may draw 800W for 30 minutes defrosting but only 200W intermittently the rest of the time.
Kill-a-watt meter can read power of 120V plug-in devices. Clamp ammeter can read power of any.
June is 300 kWh, July and August are 1000 kWh (looks like A/C).
What will your new winter consumption be? If you have other heat sources, and electric bill looks like June (10 kWh/day), then a typical system with as little as 3kW of panels should be sufficient. But panels are cheap enough compared to the rest, put in twice what you need or more, to make up for days without full sun.
The best loads use power while the sun shines. Enable water pump when battery full, etc.
Micro aire easy start on our non inverter heat pump was the big one. That accounted for the major drop between February and march. Then electric on demand water heater. Will have to change that to an outside propane water heater or go back to the tank water heater with a timer. All lcd lighting. Still working on the garage lights. Sealing up any air leaks and put heavy curtains in front of the sliding glass doors leading to our deck. All in all it has helped quite a bit. Were having two doors replaced as they both are at least 1/2-3/4 inch too small for the frames letting outside air into the garage and then from the garage to the house.
I know I have a kill-a-watt meter here someplace. I will find it and do some checking. Thinking of getting some of those smart plugs.
Hedges
I See Electromagnetic Fields!
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Easy-start will help an inverter start it, probably doesn't reduce kWh reported on bill at all.
Instant electric water heater also won't reduce bill much, and of course is worse for off-grid. Tank type electric makes a good dump load. Propane take the load off electric.
Lights, sealing, insulation of course help.
But what is central heat? If electric, that's not practical for PV. Wood, coal, oil, gas of some kind.
Instant electric water heater also won't reduce bill much, and of course is worse for off-grid. Tank type electric makes a good dump load. Propane take the load off electric.
Lights, sealing, insulation of course help.
But what is central heat? If electric, that's not practical for PV. Wood, coal, oil, gas of some kind.
Our AC and heat are a central heat pump. This is what the Micro air is on. Eventually I hope to supplement wit wood heat.
pollenface
Solar Addict
Inverter output is different measrement to consumption, kw vs kwh
My suggestion is 10x 440w panels per FM80 on 2s5p
Hedges
I See Electromagnetic Fields!
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Measure the surge current using the Micro-Air. That will tell you what inverter capability is needed.
Winter kWh for the heat pump will drive your array size, to some extent battery.
Obviously being able to fall back on wood gives you a way out. Maybe put in a propane heater too, in case you want convenience during a storm?
