Grid-tied solar

[dave1949]

We have been bumping 32KWh for the last three months. Our 5KW system, has us hitting net zero for the year. We're an all electric house, but do a lot of heating in the winter, with a wood stove.View attachment 276782

I have seen hinted, that many are comparing just todays electricity rates for the payback. Electricity rates keep rising, so the payback times shortens.

Glad to hear your system is doing well. I didn't opt for any PC or Web interface, your display is nice though.

I have read that solar pv leasing is a growing business is SoCal. The article gave as an example, the leasing co. puts panels on a roof, a $100/mo elec. bill is reduced to $85/mo. The leasing company makes all the investment, sells the energy, not sure if Cal. has renewable energy credits, but those can be sold too and the leasing co. would have a good block of them. I'm not sure if they are actually leasing the use of the roof, or the hardware.

I did read one article saying the output hasn't been as high as expected, but no reason was given. I am guessing in that climate, rains are infrequent for long periods, so perhaps soiling/soot, etc. plays a role. And, if the panels belong to someone else, there isn't a lot of incentive to get the hose out. What have you heard?

 

[JCByrd24]

That is great Dave, sounds like quite a place. The house we have designed for our new land is passive solar minded as well and super insulated, in addition to the "active" PV array planned. It's a no-brainer to me. I just read in another thread that meburdick burns several cords of wood a year in addition to his electric usage, which is great, but even at only 30 years old, I'm liking the idea of not dealing with 2-3 tons of wood pellets per year at the "next house", let alone 5-6 cords of wood. Though I know I would hate filling the oil tank even worse. We are down to less than 50 gallons/yr of oil as backup heat for the pellet stove in our current house now that we've switched hot water over to a GE Geospring heat pump water heater.

 

[dave1949]

That is great Dave, sounds like quite a place. The house we have designed for our new land is passive solar minded as well and super insulated, in addition to the "active" PV array planned. It's a no-brainer to me. I just read in another thread that meburdick burns several cords of wood a year in addition to his electric usage, which is great, but even at only 30 years old, I'm liking the idea of not dealing with 2-3 tons of wood pellets per year at the "next house", let alone 5-6 cords of wood. Though I know I would hate filling the oil tank even worse. We are down to less than 50 gallons/yr of oil as backup heat for the pellet stove in our current house now that we've switched hot water over to a GE Geospring heat pump water heater.

Well, it's our place, great or not. We like it. We lived in Wells, Maine for 12 years before moving up here. Along the coast is milder than here, but heating does cost. We decided to avoid the oil truck. And, really, why shouldn't you if you can?

Have you run across these PassivHaus designs? Passivhaus:The world's leading fabric first approach to low energy buildings
That's not a great link, but if you Google around, you can find info. They are built very air-tight, I mean very. Before the wallboard is put on, the house has to pass a pressurized air-leak test.

What is nice about them, is they can built to look like like any other Cape, Colonial, or whatever your taste is. The walls are thick, about 1 foot IIRC. They need air/heat exchange systems for indoor air quality. They count the btu's down to a gnat's butt. Usually use a few small electric heaters here and there, not central heating.

If you will be using financing, run the house design past your loan officer, banks can be picky about alt. energy construction. I would think PassivHaus has big advantage there. You can show them a picture and they see a normal looking house.

 

[JCByrd24]

Yes Dave, we may not go for the official certificate, but the passive standard is what we are shooting for, inc. the air infiltration standard. The financing will be the only potential hold up, you are correct the banks are behind the times. Cookie cutter McMansion's are the comparables down in this neck of the woods so trying build a 1700 sq ft house with no oil boiler is an issue. Hopefully we get an appraiser who knows what net zero even means.

 

[meburdick]

Well if I had $.05/kwh rates my thought process would be different too, especially consuming at the rates you are. I'd probably build the same house and be doing swell with a sub $50 average monthly electric bill (including heat) instead of coughing up $15K on a PV system. It amazes me that power is that cheap anywhere, especially CT. The amount of power you consume would cost me $245/month here.

I wouldn't exactly consider Maine a mild place to live though, little cooling costs but lots of heating to do from Nov through April, even compared to CT.

I'm not sure if you're thinking I have $.05/kwh rates in CT, but I do not. Triple that number foot myrates.

 

[dave1949]

Yes Dave, we may not go for the official certificate, but the passive standard is what we are shooting for, inc. the air infiltration standard. The financing will be the only potential hold up, you are correct the banks are behind the times. Cookie cutter McMansion's are the comparables down in this neck of the woods so trying build a 1700 sq ft house with no oil boiler is an issue. Hopefully we get an appraiser who knows what net zero even means.

It silly. When you think about it, if your energy costs are minimal, your ability to afford a payment increases. But they don't like to hear about no central heat, neither do insurance companies.

 

[JCByrd24]

I'm not sure if you're thinking I have $.05/kwh rates in CT, but I do not. Triple that number foot myrates.

I must have gotten confused, I thought it was you throwing around the $.05/kwh rates. I double check against google and saw $.07-.08 in CT so thought you must be getting just a little bit better rate for some reason. At similar rates to ME I would think solar would be nearly equally as attractive.

 

[RobertN]

Ya, I snip snapshots and send them to other work team members; I am involved in Energy Star test and development for a large chip maker. We're always doing some test or another on PC's to see if they comply with Energy Star 5.2 for computers. I'm the most energy compliant member on the team!

Our setup is 5KW. I bump 4800-4900 frequently. We have a 6KW inverter. It was only about $200 extra. We'll add another 1000W of panels in the future. I need to wash my panels; I have got pretty close to full capacity with clean panels this time of year.

Our neighbors went with a lease program. They just kind of did it; I was surprised they did not inquire more about our system. I have not had a chance to sit down and ask them much about the system. I know the company we went thru does a lot of lease installations, but was not as active in that market a couple years ago when we bought our setup.

We're in N. Calif; I am unsure of the market in S Calif. It is like a whole different state down there.

Glad to hear your system is doing well. I didn't opt for any PC or Web interface, your display is nice though.

I have read that solar pv leasing is a growing business is SoCal. The article gave as an example, the leasing co. puts panels on a roof, a $100/mo elec. bill is reduced to $85/mo. The leasing company makes all the investment, sells the energy, not sure if Cal. has renewable energy credits, but those can be sold too and the leasing co. would have a good block of them. I'm not sure if they are actually leasing the use of the roof, or the hardware.

I did read one article saying the output hasn't been as high as expected, but no reason was given. I am guessing in that climate, rains are infrequent for long periods, so perhaps soiling/soot, etc. plays a role. And, if the panels belong to someone else, there isn't a lot of incentive to get the hose out. What have you heard?

 

[dave1949]

Ya, I snip snapshots and send them to other work team members; I am involved in Energy Star test and development for a large chip maker. We're always doing some test or another on PC's to see if they comply with Energy Star 5.2 for computers. I'm the most energy compliant member on the team!

Our setup is 5KW. I bump 4800-4900 frequently. We have a 6KW inverter. It was only about $200 extra. We'll add another 1000W of panels in the future. I need to wash my panels; I have got pretty close to full capacity with clean panels this time of year.

Our neighbors went with a lease program. They just kind of did it; I was surprised they did not inquire more about our system. I have not had a chance to sit down and ask them much about the system. I know the company we went thru does a lot of lease installations, but was not as active in that market a couple years ago when we bought our setup.

We're in N. Calif; I am unsure of the market in S Calif. It is like a whole different state down there.

It must be fun to do Energy Star chip evals. and be the most energy compliant

Here is a brief article Compare Solar PPA & Lease that explains two flavors of non-owned systems: power purchase agreements and leasing. It seems which you can do, depends on which state you live in.

Since the upfront cost of solar is a high hurdle, I can see the attraction of alternatives to those who want to be "green" and get some of the rewards at the same time. It could be a win-win. I did see some hits that talk about having a knowledgeable lawyer look over a lease agreement before signing, guess that applies to leasing anything.

 

[Dutch445]

here's a thought,
maybe deserves a new thread
i currently have a propane forced air furnace in the cape cod i purchased,
i am considering solar, with a large pole barn/shop that has a south facing roof of
about 18000 sq feet, plenty to do what i'd need at the house.
the question is what are the new electric forced air furnaces like? i'm sure more
expensive to run, but if i convert my propane hot water heater, and furnace over
to electric, then size the solar correctly, will it be worthwhile looking into? i don't care for
the propane, in my prior home i heated with a coal stove very reasonably, but i wasn't
thrilled with the propane usage we had in the short time we were in the house this year,
and with this house's layout in the basement isn't easy to put in a freestanding stove
like i had, but there is a forced air furnace i've considered adding a wood or coal
add on to.

 

[deezler]

Dutch, you would need an awful lot of batteries to supply electric furnace and water heaters on demand. Unless, of course, you only want to run them during sunny days. Sounds like a cold winter in upstate NY to me!

Dave, this is a great thread. My wife and I are trying to start our home build within the next few years, and an earth sheltered, passive solar, PV array, woodstove design is at the top of the wish list.

 

[Dutch445]

i wasn't looking for an off grid system, thinking of converting appliances over to electric
then using a solar system with net meter,

 

[deezler]

Oh, duh, my bad. Hence the thread title "grid-tie". haha.

 

[dave1949]

i wasn't looking for an off grid system, thinking of converting appliances over to electric
then using a solar system with net meter,

You are sure welcome to use this thread, but I think if anyone has good info on electric furnaces, you would get their attention with a thread name asking about them.

I am not familiar with elec. furnaces, but I picture something that uses a goodly amount of elec. That would take a big/huge solar system to make a dent in your overall usage unless you are planning a super efficient home that barely needs any heat.

The top-down method is to make an "energy budget" that lists all of your btu uses and attempt to put numbers with them. This can be difficult for heating because you don't have enough information, and it can be hard to supply the info using the canned programs that predict the heat load for a home unless you are an architect or engineer of the right flavor.

If you look around you can find such programs free online, but for them to be accurate you have fill in thermal coefficients of walls, roofs, windows, doors, etc., etc. There are some tables for those values using standard construction. I tried one briefly and decided it was (1) above my pay grade , and (2) I was putting in so many guesses that the result would be a guess.

A useful measure is overall energy usage based on annual btu's per sq ft of conditioned space. For your current home, you can calculate that easily from your energy bills by converting everything to btu's. Here is an idea of that: How to Calculate BTU Per Square Foot: 11 steps - wikiHow

About five years ago, I read the US average for homes is ~100,000 btu/sq ft/year. Mine, excluding sunshine, was 43,187 btu/sq ft/year before the solar system. I think some of the better building techniques may be able to beat that. The need for AC will make a difference, and long winters do too. Anyways, it is some way to get a relative measure of where you are in energy use. And a useful method of comparing building/heating techniques if you have the numbers.

 

[Dutch445]

I agree, i don't have enough information seeing we moved into the house
in feb/march. I did pay to heat it during the winter after the purchase offer
was accepted, to help seal the deal with the prior owner who was out of state
and going further in debt. But, dec/feb was only minimal heat, 60 or so, to keep
pipes ok etc, and we had an unusually mild winter. so i have no track record.
Once i can find a reasonable guestimate of the home heating requirement, then
i guess i can answer more of my own questions. what it would come down to is:what are
the up front costs of the extra capacity of the system to heat with, compared to
using fossil or other type fuels for heat. right??


i did find some references that help put things in perspective. here's an excerpt from
another forum: Heating Help

fuel costs
1 kW-hr of electricity is 3413 BTU so you'll need 29.3 kW-hr for 100,000 BTU of heat, that's $3.22/100,000 BTU at $0.11 kW-hr. LP (propane) has 92,000 BTU/Gallon so you'll need 1.09 gallons for 100,000 BTU of heat that's $3.28/100,000 BTU at $3.00/gal or using the DOE's EIA weekly price survey results for PA for week of 10/15/2007 of $2.54/gal it's $2.77/100,000 BTU. (KY & OH are cheaper, NJ, NY, DE & MD are more for LP so it seems the further west your are in PA the better, so check local pricing. see: Weekly Petroleum Status Report - Energy Information Administration Again, using DOE EIA price data residential retail NG is $20.79/ million BTU in PA or ~$2.08/100,000 BTU but again check your utility's rate schedule. see: U.S. Energy Information Administration (EIA) Heating oil may be another option (not sure how common it is down there though) #2 oil has 140,000 BTU/gallon and DOE EIA shows a 10/15/2007 PA price of $2.28/gallon (residential retail) or $1.63/100,000 BTU One time installation costs will vary (e.g. nat. gas line installation cost, vs. LP tank install), so you've got to factor the payback for cheaper long term operating costs in, also you will have to adjust the costs for the efficiencies of the equipment, again higher efficiency equipment will cost more up front. Get local fuel cost and plug in to get costs per 100,000 BTU and go from there. Also, do you have an interest/desire in replacing the electric stove and/or dryer w/ gas (NG or LP)? Additionally, with a hot water (or steam) system you could also use the eboiler to provide hot water via an external "indirect" hot water tank, vs the electric HW heater

and here's another entire page with more of that info, including building specs etc:
Energy Engineering

 

[meburdick]

You *MAY* be able to gain some insight into the costs that the previous owner of the house incurred if you contact their fuel supplier. Explain that you've recently purchased the house and are trying to budget for the upcoming winter which should be much more 'typical' than last. Ask if they have any information on average amount of fuel used by that customer over the last few winters.

 

[meburdick]

Oh.. And if they make a statement about not being able to tell you that based on privacy or something, say this...

"Let me ask it another way, then. Based on your knowledge of the home, how would you set me up on a budget plan based on the estimated heating costs over the upcoming winter?"

You may have to do a little math at the end, but you'll get some information.

 

[dave1949]

-snip-

what it would come down to is:what are
the up front costs of the extra capacity of the system to heat with, compared to
using fossil or other type fuels for heat. right??
-snip-

That sounds right. My impression is it will be very expensive to install enough solar pv to offset electric heat unless you can reduce your heating requirements to something very low.

I just remembered the town up the way from us has their own elec. utility. They offer reduced rates on off-peak hours (night time) for electric space heaters that have a brick pile the elements heat up. http://www.madelec.net/ets Is that the type you are referring to?

 

[Redneck in training]

You might use geothermal heat pump to heat the house. It will use about 25% of the power required by direct electric heater. The upfront cost even though still high will be less than solar panels required to supply power for direct heat.
FYI. We have floor heating with geo in our house. We heat about 3800 sq ft for about $100 at coldest month. Our heating rate is 4.2 cent/kWh. Geo does AC also. It ises about 4.8 kW when it runs while it generates about 19 kW of heat.

 

[dave1949]

You might use geothermal heat pump to heat the house. It will use about 25% of the power required by direct electric heater. The upfront cost even though still high will be less than solar panels required to supply power for direct heat.
FYI. We have floor heating with geo in our house. We heat about 3800 sq ft for about $100 at coldest month. Our heating rate is 4.2 cent/kWh. Geo does AC also. It ises about 4.8 kW when it runs while it generates about 19 kW of heat.

If pairing solar pv (assuming an area with sufficient sunshine) with geothermal were affordable in upfront costs, that would provide some very green heating. Or, if the utility power came from green sources, same result but with transmission losses.

Any idea what your payback period is? For example, comparing your costs to other available fuels in your location. You probably have a pretty good idea of your annual kWh's for heating and cooling which can be converted to gallons of oil, propane, direct electric, etc.