Going solar - where to begin?

[gthomas785]

Hi I am thinking I want to start looking for quotes for a grid tied solar PV system but whenever I start trying to do research there are so many companies with advertising online that I can't even weed through all the greenwashing and rebate offers to know who to call. It all seems super scammy. I guess I'm asking if anyone has direct experience and could recommend where to start. We are in north central Massachusetts.

We have ben saving the capital for this project and would be looking to directly buy the system rather than get involved in a PPA or any of that kind of stuff. Of course we are looking to take advantage of Massachusetts rebates and net metering.

To complicate matters we own a historic (1850s) house with a complex roofline. It's in a historic district and we can't put anything on the front (east-facing) roof, but we could probably use the rest of it. Would need approval from the HDC after getting a quote. I have a 100A service that would probably need upgraded to 200A. Do the solar contractors usually bring an electrician or do I need to find one separately before talking to the solar people?

 

[peakbagger]

Buy a copy of Solar Power your Home for Dummies, read it then ask questions.

Any company worth talking to has to do a site visit and use an ap based device to determine site characteristics, things like shading, available roof exposure and roof pitch all factor in. Your statement that you cannot install panels on the East roof cuts out a lot of generation. If they come up with pricing using google earth or some other method that does not involve a site visit, they are not serious or they are just trying to get their foot in the door.

Yes, its pretty likely you need a service upgrade if you want one. If you do, you typically can include the cost to do the upgrade into the solar cost and take the rebate on it. There is something called a line side tap that would go between your panel and the utility meter that may be less costly.

In Mass most of the installation needs to be done by an electrican or his/her apprentices working under his/her license. If they do not do the service upgrade work they will probably have someone who works with them who does.

The incentive structure in Mass is complex, you need to work with a firm that understands the rules. Mass is really pushing home batteries and that may limit who you want to work with.

 

[gthomas785]

Hey @peakbagger, thanks for the reply.
I have another technical question that you might know something about. Around 20% of our most "solar" roof area is on an outbuilding. That building is about 50 feet from the house and gets power through an underground #2 aluminum (90A) feeder. Is there a way I can backfeed solar power into that subpanel or will I most likely have to pull a separate line to tie in at the service?

 

[sirlight]

Hi I am thinking I want to start looking for quotes for a grid tied solar PV system but whenever I start trying to do research there are so many companies with advertising online that I can't even weed through all the greenwashing and rebate offers to know who to call. It all seems super scammy. I guess I'm asking if anyone has direct experience and could recommend where to start. We are in north central Massachusetts.

We have ben saving the capital for this project and would be looking to directly buy the system rather than get involved in a PPA or any of that kind of stuff. Of course we are looking to take advantage of Massachusetts rebates and net metering.

To complicate matters we own a historic (1850s) house with a complex roofline. It's in a historic district and we can't put anything on the front (east-facing) roof, but we could probably use the rest of it. Would need approval from the HDC after getting a quote. I have a 100A service that would probably need upgraded to 200A. Do the solar contractors usually bring an electrician or do I need to find one separately before talking to the solar people?

Solar is a complex decision. There are so many factors to consider. Start with the most basic of questions: Why do you want solar? It is it strictly for environmental reasons or are you trying to save money? I went through this entire process back in 2017. There are so many variables that I had to put together a rather complex spreadsheet to do all the calculations. Knowing the payback period is critical to the decision. You will need estimates of expected solar production from your own calculations so you can compare to the sometimes "generous" estimates from solar companies you are considering. Check out pvwatts or another solar estimator and enter data about your location. Review your previous couple years of electric bills to determine how much power you actually use. Speaking of companies, you want one that specializes in solar installation with a long track record. The company I chose was part of a company that does general electrical work and has been in business 40 years. Perhaps your electric company (like mine did) has rebates and they require you to choose a solar company from a recommended list. That will narrow down the choices. And one last bit of advise, buy a larger system than you think you need. Power consumption always seem to go up when you are making your own.

 

[sirlight]

Hey @peakbagger, thanks for the reply.
I have another technical question that you might know something about. Around 20% of our most "solar" roof area is on an outbuilding. That building is about 50 feet from the house and gets power through an underground #2 aluminum (90A) feeder. Is there a way I can backfeed solar power into that subpanel or will I most likely have to pull a separate line to tie in at the service?

That can be done. My solar system is on a workshop. It has a 200 amp panel and feeds back to the power pole before the meter. The house is on the same meter. Don't know how big of service you need to support the solar system. I your panels are split between two structures, you will likely need two inverters and that can be expensive.

 

[peakbagger]

I think you can to a limited extent but not sure of the details. I think it comes down to you can only connect 20% of the busbar rating. If you need to upgrade the outbuildings electrical panel that also is covered under the solar credit.

 

[gthomas785]

Why do you want solar?

Well I have basically been thinking about solar energy ever since we bought the house, mostly for of environmental reasons but also because I only expect my electricity usage to increase over time and electricity is already one of my highest recurring expenses after the mortgage. We just installed 2 heat pumps and love them but our electric bill is now consistently $200+ a month. Rates are going up in January. I know it's a long payback but my wife and I were also talking about the current energy crisis and unpredictability of rates in the future, so who knows maybe the payback would be shorter than we think. I'm not banking on that though. I just want to get the ball rolling because at this point we have saved up enough money to pay for a ~10 kW? system and I'd rather have that generating power for me rather than sitting in the bank losing value.

I have done more googling since I posted the question above about the subpanel, and it does seem like I can make it work. I have 100A rated bus bar in the shop panel, it's currently only fed by a 60A breaker anyway but if I swap out the subpanel breaker to 60A then I could in theory also have 60A of solar. Not that I need that much - I think that side of the roof is about 200 sqft (at a 10:12 pitch) so I'd get at most around 4 kW from that building which converted to AC 240V would be 16 amps.

 

[sirlight]

Well I have basically been thinking about solar energy ever since we bought the house, mostly for of environmental reasons but also because I only expect my electricity usage to increase over time and electricity is already one of my highest recurring expenses after the mortgage. We just installed 2 heat pumps and love them but our electric bill is now consistently $200+ a month. Rates are going up in January. I know it's a long payback but my wife and I were also talking about the current energy crisis and unpredictability of rates in the future, so who knows maybe the payback would be shorter than we think. I'm not banking on that though. I just want to get the ball rolling because at this point we have saved up enough money to pay for a ~10 kW? system and I'd rather have that generating power for me rather than sitting in the bank losing value.

I have done more googling since I posted the question above about the subpanel, and it does seem like I can make it work. I have 100A rated bus bar in the shop panel, it's currently only fed by a 60A breaker anyway but if I swap out the subpanel breaker to 60A then I could in theory also have 60A of solar. Not that I need that much - I think that side of the roof is about 200 sqft (at a 10:12 pitch) so I'd get at most around 4 kW from that building which converted to AC 240V would be 16 amps.

Sounds like you are doing it for good reasons. Still, up front cost and payback period is an important factor. The system I put in had power company, state and federal rebates. The (initial) system I bought had a payback period of 3.5 years, but I added 4 more panels and that brought it to (still respectable) 5 years. I am in oregon. I helped my sister decide on her system and her payback is 9 years. She lives in San Diego with much higher electric rates. They have eliminated all but the federal rebate in San Diego. If you are planning on staying in your house for a long time it can make sense. You need to work out the long term numbers using all the data you can gather.

Example of my calculations and current data from my 7.2kw system:

From what you are describing, you will likely need an additional inverter for the worksop. You will have do do the calculations and ask yourself if it makes sense paying for an additional inverter to get 20% more output. You will likely decide that it does not. Also, though inverters are not really considered a consumable, they typically cannot be expected to last more than 10 to 15 years and will likely need to be replaced before the panels.

Oh, and if you can't answer the simple question "What is your electric rate", don't even start looking for a solar installer yet. Do all the research up front and you will know all the correct questions to ask them.

 

[peakbagger]

In Massachusetts, if you do not install solar on your roof, you are paying for your neighbor to do so by very high electric rates. I saw a study that even if the price of electric power stays steady, the bills in Mass will go up 8% per year just to cover all the incentives being handed out and that were handed out in the past. I am surprised Mass has not passed right to solar legislation that overrides local regulations on installing panels on roofs.

 

[gthomas785]

Thanks, I'm going to start working on a calculator similar to what you showed. It seems to me that the most challenging part is getting accurate estimates of the output per sqft for a given location, roof pitch, type of panel, time of year. Can I ask generally how you came up with the "best case" and "worst case" numbers on your spreadsheet?

My electric rate now is $0.24 per kWh all inclusive.

 

[peakbagger]

Read the book !

 

[gthomas785]

Read the book !

Okay I will lol

 

[sirlight]

Can I ask generally how you came up with the "best case" and "worst case" numbers on your spreadsheet?

My electric rate now is $0.24 per kWh all inclusive.

If I remember correctly, my best/worst case were from PVWatts or some other online calculator. The average is the midpoint between those two values. Most of the numbers are available online. Panel degrade rate is on the panel spec sheet. Electric rate increase is available from your power company or other online sources. Funny, but the rate of increase in my electric has not panned out as I estimated. Our electric rate has actually gone down over the past 5 years.

 

[John Galt]

Don't forget about snow when calculating how much power you can get. There are roof mounted systems around here that are covered for 3 months. I brush off my panels most mornings, sometimes twice a day.

 

[stoveliker]

Random thoughts.

I think that the "google and calculate what your panels would produce" is similarly bad as installers coming in and going off of satelite info. The outcome of such calculations are not useful to gauge what installers are telling you due to the large assumptions and approximations in them. (One installer quoting me did that, saying "but we see the trees in the satelite pic". I asked him how tall the tree was with respect to my house, and he had to go look outside...) If you want to check the numbers from the installers, go and check the numbers of the installers. Don't compare them with useless numbers from some online site that *can't know* the details needed for a *good* estimate.

I comcur with peakbagger: if they don't go and measure on your roof, show them the door.

My company went on the roof (N/S ridge, so E and W sections), put a fisheye lens on all 8 corners and took pics. I asked them to send me the pics. Together with a compass, (or gps), they can plot in exactly when try X will block the sun at both solstices and in between - the pics showed the curves "this is where the sun will travel at this time of the year" etc. Then based on local climate data, they can calculate the potential output. Go over the calculations so you can see the assumptions. My system produces about 200 kWh more per year than they predicted (6.3 MWh vs 6.1 MWh).

Be careful about the "total $ saved over the lifetime" finger-licking numbers, as it heavily depends on the unknowable rate increase amounts 20 years out. And on what you could have done with the $$ otherwise (invest, inflation, etc.).

Yes, go larger if you can - though note that there are limits due to the credits (they don't want to finance you making money off of putting kWhs into the grid rather than covering your own usage).

Inverters: if you have shading, you'll need microinverters, and at that point it does not matter that you ahve the panels split into two locations.

If you have net metering (at least yearly reset, or not resetting at all), don't do a battery, unless you absolutely should avoid power outages at all cost. I don't have a battery, but a small gasoline generator. I can keep my fridge cold, light some lights, use a fan. My stove heats my home. The grid is my battery due to the net metering, and so far that's been a pretty good situation.

If you need a new roof in the next decade or so, do that now. I believe it is included in the credits (though I did not keep track of limits on credits).

 

[sirlight]

Random thoughts.

Good, solid comments and I agree.

The online calculators like PV Watts actually produce very good results, but you need to feed them accurate data. It is that "garbage in, garbage out" thing. The closer you are to providing exact data on your location and proposed installation, the more accurately it will estimate your solar output.

+1 on the suggestion for micro inverters. Even if you don't have shading, micro inverters (optimizers) will provide more stable and higher production. They are not that much more expensive than just a single strand inverter setup.

Agree that you have no way of knowing when electric will cost 20 years down the line, but I can guarantee if will be higher than it is now. For my estimates, I just took the average yearly rate increase over the past 10 years and used that.

 

[tlc1976]

Read the book !

I’ve thought about adding solar every now and then. Since I’m on property where I can pretty much do whatever I want. So I read the book. And at the end, this is what it said.



I’m near the tip of the mitt, about 5 miles from Lake Michigan, a constant source of clouds. Clear sunny days are limited. Cold more often than not. Long snowy winters. Electric rate is 10c/kWh, supposedly going to 11c/kWh next year. No time of use differences. Which is cheaper than most I’m reading about on here.

Sounds like this applies to me. I’ve already been using a pellet stove, and the house stays cool in the summer without having AC. I have enough land to do geothermal, but I’d have to remortgage my house to pay for it, and I’m not sure how efficient it is when the frost can go 3-4 feet down. I also don’t have a forced air system to add it to. With solar, one can always start small and build up.

My roof is an 8/12 pitch with the slope facing south. Would hold 18 panels. But I’ve got a lot of trees, so the available sun (on actual sunny days mid summer) would be from about 11am to maybe 4 pm in the south, then a few hours in the evening if I could mount something on the west end of the house. The trees block sun and wind, which saves energy costs without spending a dime.

Though it seems plenty of people in the north do solar, and I’ve also read that panels don’t perform as well when being cooked in direct sun, as they do in diffused sun and cooler temperatures. So it can be confusing.

 

[begreen]

Yes. We are getting a lot of shading now on the arrays due to the low angle of the sun. This is the best we could do today. Solar is in green.

Today

Late July

 

[peakbagger]

I will quibble with the recommendation for microinverters instead of string inverters. The OP may actually be looking at combination of both. The garage system does not need to meet the Rapid Shutdown requirements and if there is minimal shading, a string inverter in the garage may be the lowest cost most reliable. String inverters reside in far nicer operating environments than microinverter does sitting under a panel. The biggest issue with string inverters these days is not converting DC to AC rather its communications to the corporate mothership. Depending on the array size, the string inverter may have multiple MPPT inputs which deals partially with shading, or someone can go with panel optimizers rather than microinverters.

On the house, my guess is its down to optimizers or microinverters due to complex roof and RSD requirements. Installers tend to like microinverters as they require a bit less inventory and planning to install a system. The trade off is that to date, microinverters have a higher failure rate and they can be major PITA to replace especially on complex roof with steel pitch. Panel level optimizers with a string inverter tend to be in between a Microinverter and just a string inverter in reliability. I think there is a slight savings going with optimizers and a central string inverter.

Some general comments/biases. Installers and microinverter folks advocate over paneling, installing panels with higher wattage ratings than the microinverters internal rating. They claim that this is okay as a panel rarely puts out maximum wattage. I agree but my bias is not running electronics at 100% especially ones that are routinely baked on the back of a panel. I really do not like clipping.

Most installers do not look out for the long run with respect to power surges and surge protection. Nothing stops a direct lightning strike, but good practice will take care of 99% of indirect surges. A car crash or lightning strike miles away can feed a surge into homes that do not have protection and there can be surges created inside the house. There is also confusion on surge protection. Most suppressors may stop high voltage from flashing across marginal insulation, but any electronics will be long since fried. A good Surge Suppression Device (SPD) is going to "clamp" high voltage to ground at a low enough surge to keep the electronics working. IMHO, there should be good quality SPD on the main panel and if a line side tap is used one on the Solar inverter. Note that many older homes have a very poor grounding system, frequently tied to household water lines that at one point may have been converted to non conductive plastic. There may be a need to review the grounding and get it straightened out including getting the garage system straightened out as in many cases they use just tie the two buildings together via an electrical ground and do not install a separate ground road bonded to the main house ground. I and a lot of others use the Midnight Solar SPDs as they have low clamp voltage.

The other unknown is the power quality coming in from the utility, the grid was not designed to be run the way it currently is being asked to run and the result if potentially bad power quality coming in from the street. The UL171 SA protection required in any grid tied system is designed to shut the output to the grid whenever the grid power goes outside a tight operating range. It is not unusual especially in older neighborhoods that the power is outside that range on occasions. That can cause intermittent drop outs of grid tied electronics, both string and microinverters. Figuring this out is not something a typical homeowner can figure out easily and many installers just do not support this well as it can take weeks or months of operation to get the issues pinned down to the utility. This is where vetting the contractor is important, the big national firms are getting paid to crank out systems and they tend to really lag with troubleshooting.

 

[NoGoodAtScreenNames]

If you are looking for a reference I used

(broken link removed)

I think they cover all of MA. They took care of everything including permitting, rebate work with the utility, panel upgrades for the solar and some miscellaneous electrical I had them do while they were on site. They did a solar exposure measurement before we locked in the contract. That was important since I have some shading and required a certain exposure to get utility rebates. I’m on a municipal company so the rules were different for me (not part of MassSave). They were better than other companies that just said to cut a bunch of trees down. It turned out I didn’t need any (but choose to on my own - longer story there).

 

[zak77]

I've heard very good things about PV Squared out of Greenfield. I've talked to a couple people who were very happy with them but still get a couple quotes just to compare.

 

[peakbagger]

Revision Energy covers at least some of Mass. They have good rep. Its employee owned and they are large so they can buy at volume. They are based out of Maine and definite work in NH but not sure how far then extend into Mass. Electrical labor in Mass is very high so any solar installs will be pricey.

 

[mpaul]

Buy a copy of Solar Power your Home for Dummies, read it then ask questions

I am just starting the solar process and hope to go solar for my house in the coming year. I have been on this site for several years learning so much from everyone about heating my home with wood. Now I’m trying to learn from this site about going solar.
Reading this thread I immediately looked up this book and planned on buying it. My only concern is that it was published 12 years ago. Hasn’t technology changed over this time that makes this book outdated?

 

[peakbagger]

If you are looking at grid tie, things really have not changed.. The sun still shines and the basics havent changed. If you are considering a battery or a hybrid on and off grid system the basics are still good and gives you some background but batteries and hybrid tech is changing monthly.

 

[mpaul]

If you are looking at grid tie, things really have not changed.. The sun still shines and the basics havent changed. If you are considering a battery or a hybrid on and off grid system the basics are still good and gives you some background but batteries and hybrid tech is changing monthly.

Thanks. Although we are not prone to power outages, with a well system for water and a ZC fireplace that really needs a blower to efficiently heat the home, we are looking at a battery backup system to run at least the essentials in the house. Not sure of pros and cons yet for hybrid vs off grid yet. (Just getting started (a lot to learn still).
I’ll grab that book as it sounds like there is still a lot of good up front knowledge terminology and planning requirements to capture.