New System Questions

[thundercowpoke]

The grid power is based on the amount of the cost of the install spread over 5 years plus the monthly bill and the same install cost over a 20 year pay out plus the monthly bill. We only pay about $0.13/kWh but with taxes, fees, and the monthly charge for the privilege of being connected the bill for 20kWh/day runs about $225/month for an effective electric rate of $0.36/kWh. The rest is the install cost of $35K and that is not a firm number. It could cost more if they run into any problems. The equalizer for the grid connection is that after 25 years it is still there. It is not cheaper to go off grid in the long run but it takes 25 years to break even.

[SunEagle]

The grid power is based on the amount of the cost of the install spread over 5 years plus the monthly bill and the same install cost over a 20 year pay out plus the monthly bill. We only pay about $0.13/kWh but with taxes, fees, and the monthly charge for the privilege of being connected the bill for 20kWh/day runs about $225/month for an effective electric rate of $0.36/kWh. The rest is the install cost of $35K and that is not a firm number. It could cost more if they run into any problems. The equalizer for the grid connection is that after 25 years it is still there. It is not cheaper to go off grid in the long run but it takes 25 years to break even.

Wow. $225 for 600kWh of power. At $0.13/kWh that comes close to $150 for added taxes and fees per month.

I can understand why grid power for you is expensive. Thanks

[Sunking]

Battery cost alone are going gto be 60-cents to $1 per Kwn and there is no payback ever. Battery prices rise faster than utility. So be sure you know what you are asking for and talking about, and do not forget you will need a large generator with LPG tank if you go off grid. Large enough to run your home and charge batteries.

[thundercowpoke]

Rural electric is not as cheep as if you are inside a town. My nearest neighbor is two miles away. There is a lot of transition line per customer.

I have gas from my wells to take care of the genset. That is why I won't have much if any battery reserve. They are a necessary evil to run off grid.

At this point I have only two viable options. 1. Go on grid 2. Solar/generator Financially doing a grid tie system is the most expensive option and basically doubles the cost with no payback.

[thundercowpoke]

Has anyone run the Rolls S-550 battery at 60V? That looks to be the most efficient voltage for my system the way I have it thought out. I not saying that it is right but it looks good on paper.

[Mike90250]

Has anyone run the Rolls S-550 battery at 60V? That looks to be the most efficient voltage for my system the way I have it thought out. I not saying that it is right but it looks good on paper.

That is a 6V battery, How would you possibly think you can apply 60 volts to it and not have a toxic mess in half an amp hour ?

[thundercowpoke]

Ten of them wired in series to form a battery bank.

[SunEagle]

Ten of them wired in series to form a battery bank.

What type of inverter or loads works on 60v DC?

I thought you were talking about a charging voltage of 60v for a 48volt bank.

[thundercowpoke]

I was just looking at theoretical capacity based on the capabilities of the FM80 . After looking at it more, I will be running the whole system at 48V. My panels are called 24V but the spec sheet shows their rating to be 37.8V with a Voc of 46.7V at 25 C. I will only be able to run series pairs with 4 pairs in parallel giving me 75.6V 34.08A with a 112.08 Voc at -40. Well within the limits of the FM80 CC.

[littleharbor]

If going 48 volts you need Higher voltage than two series panels put out . Those are 24 volt panels. Two in series gives typical 48 nominal voltage. MPPT controllers need higher than nominal voltage. The only issue you could have is in really cold temps your Voc could push the limits of your controller. I don't recall your location. Is your expected low temperature really -40? If so you would do better with 3 series wired 60 cell panels. x 3.

[thundercowpoke]

It has gotten that cold in the last few years but it was a record. The coldest this year so far has been 1 F so that rating is for the extreme. I could get away with three in series and run the array at 72V. That would let me run 12 panels per string and stay within the limits of the FM80 if I run at 40V on the battery.

I suppose I could disconnect from the array if it was going to get that cold.

[thundercowpoke]

48V on battery*

[Sunking]

You can charge a 12 volt battery with 600 volts of panels. Just takes the right controller. At a minimum it takes 16 volts for every 12 volts of battery. That does not mean 60 volt panels is ideal, far from it. You want to run panel voltages as high as the controller will accept at maximum efficiency.

There are Inverters that operate at higher voltages than 48 volts, but you cross a line in the code once you go above 50 volts. Things get real expensive when you do that. No longer can batteries be in the open. All conductors and equipment must be enclosed in approved enclosures unless you are a utility with trained personal.

[Mike90250]

Are the limits on the FM80 input watts,? I know there is a hard voltage limit (about 150V) but it should not care otherwise.

As to simply disconnecting on a cold morning, I don't think it will work well.

And now, there is the Magnum PT-100 controller, 100A output, #2ga wire ports, max 240VOC *, 187V working PV About $750

[Sunking]

And now, there is the Magnum PT-100 controller, 100A output, #2ga wire ports, max 240VOC *, 187V working PV About $750

I got my hands on one and testing.